A plant fiber molded flower pot and its manufacturing method

Abstract

This invention relates to the field of biodegradable flowerpot technology, and more particularly to a plant fiber molded flowerpot and its manufacturing method. The flowerpot is made of the following components in parts by weight: 80-90 parts plant fiber; 10-20 parts composite binder; wherein the plant fiber includes at least one of rice straw and wheat straw with a length of 5-10 mm; the composite binder includes the following components in parts by weight: 60-80 parts modified urea-formaldehyde resin; 15-25 parts epoxy resin; 5-15 parts polyvinyl alcohol. This invention successfully achieves the manufacturing of plant fiber flowerpots with a height of over 15 cm, filling a gap in the industry. Through fiber orientation and gradient density molding, a balanced strength distribution from bottom to top is achieved. The composite binder system significantly reduces the water absorption rate of the flowerpot, improving the product's service life; and by adjusting the ratio of plant fiber to binder, the degradation rate is precisely controlled.

Description

Technical Field

[0001] This invention relates to the field of biodegradable flower pot technology, and in particular to a plant fiber molded flower pot and its manufacturing method. Background Technology

[0002] In horticulture and agriculture, flowerpots have always played a vital role as the medium for plant growth. However, traditional flowerpot manufacturing methods face numerous challenges. First, while common plastic flowerpots are inexpensive and easy to mass-produce, their non-biodegradable nature places a heavy burden on the environment. Second, while ceramic or clay flowerpots are environmentally friendly, they are often expensive and fragile, making them unsuitable for large-scale application.

[0003] In recent years, with increasing environmental awareness, the technology of manufacturing flower pots using plant fibers as raw materials has gradually emerged. This technology typically uses agricultural waste such as crop straw and rice husks as the main raw materials, producing flower pots through crushing and molding processes. However, existing technologies still have many limitations. First, plant fibers have poor hydrophobicity, resulting in flower pots with high water absorption and easy deformation. Second, the bonding strength between fibers is insufficient, leading to low flower pot strength, especially when making flower pots taller than 10cm, often resulting in cracking or deformation. Furthermore, existing technologies struggle to achieve effective vertical stretching of plant fibers, severely limiting the height of the flower pots.

[0004] The closest existing technology typically involves crushing plant fibers into powder, mixing them with a small amount of binder, and then molding them into flower pots. While this method utilizes agricultural waste to some extent, it still has several key problems: first, the molding height is limited, making it difficult to manufacture flower pots taller than 15cm; second, the wall thickness is uneven, leading to uneven strength distribution; and third, the degradation rate is difficult to control, either being too fast and affecting the lifespan, or too slow and failing to achieve a truly environmentally friendly effect.

[0005] In view of the above problems, there is an urgent need for a novel plant fiber molded flowerpot and its manufacturing method, which can make full use of agricultural waste, produce flowerpots with a height of at least 15cm, and at the same time ensure the product's strength, water resistance, and controllable degradation. Furthermore, the method should also have good industrialization potential, enabling large-scale, low-cost production. Summary of the Invention

[0006] To address the above problems, the present invention provides a plant fiber molded flower pot and its manufacturing method.

[0007] The purpose of this invention is to provide a plant fiber molded flower pot, which is made of the following components in parts by weight:

[0008] 80-90 parts plant fiber;

[0009] 10-20 parts of composite adhesive;

[0010] The plant fiber includes at least one of rice straw and wheat straw with a length of 5-10 mm;

[0011] The composite adhesive comprises the following components in parts by weight:

[0012] 60-80 parts of modified urea-formaldehyde resin;

[0013] 15-25 parts epoxy resin;

[0014] 5-15 parts of polyvinyl alcohol.

[0015] Preferably, the flowerpot also includes the following additives:

[0016] Based on the total weight of plant fibers and composite binders,

[0017] 0.5-1% calcium stearate;

[0018] 0.3-0.5% silane coupling agent;

[0019] 0.1-0.2% dicumyl peroxide.

[0020] Preferably, the modified urea-formaldehyde resin has a molecular weight of 3000-5000, the epoxy resin has a molecular weight of 700-1000, and the polyvinyl alcohol has a degree of hydrolysis of 87-89% and a molecular weight of 44000-48000.

[0021] Preferably, the height of the flowerpot is not less than 15cm.

[0022] The method for manufacturing the plant fiber molded flower pot includes the following steps:

[0023] (1) Plant fiber pretreatment:

[0024] First, cut the plant fibers to a length of 2-10mm;

[0025] Secondly, soak in a 1-3% NaOH solution at 60-70°C for 2-4 hours;

[0026] Then, rinse with clean water until neutral;

[0027] Finally, dry to a moisture content of 5-8%;

[0028] (2) Formula mixing:

[0029] The pretreated plant fibers are mixed evenly with the composite binder and additives.

[0030] (3) Compression molding:

[0031] After obtaining the mixture, it is loaded into a mold for compression molding.

[0032] Preferably, the molding step includes:

[0033] (1) Preheating stage:

[0034] Preheat the mixture to 60-70℃ for 3-5 minutes, and simultaneously pre-compact it at 0.5MPa.

[0035] (2) Main pressure stage:

[0036] First, maintain a pressure of 1.5 MPa for 30 seconds;

[0037] Next, increase the pressure to 2.5 MPa and hold for 60 seconds;

[0038] Next, increase the pressure to 3 MPa and hold for 120 seconds;

[0039] (3) Demolding stage:

[0040] Cool to 100℃ at a rate of 2℃ / min;

[0041] Then, maintain a pressure of 0.5 MPa for 5 minutes to cure;

[0042] Finally, compressed air at 0.6-0.8 MPa is used to assist in demolding.

[0043] Preferably, the temperature control during the main pressure stage is as follows:

[0044] First, the starting temperature is 130℃;

[0045] Secondly, the temperature is increased to 160°C at a rate of 5°C / min;

[0046] Then, maintain the temperature at 160°C until molding is complete.

[0047] Preferably, the mold includes:

[0048] Inner wall structure: adopts a variable cross-section spiral groove design, with a top groove depth of 1.5mm and a bottom groove depth of 0.5mm; the spiral groove angle gradually decreases from 45° at the top to 30° at the bottom; the pitch gradually decreases from 15mm at the top to 8mm at the bottom.

[0049] Bottom structure: There is a protrusion in the center, with a diameter of 1 / 3 of the bottom diameter of the mold and a height of 5-8mm. The edge of the protrusion is designed with a 45° bevel.

[0050] Preferably, a fiber orientation step is also included:

[0051] Install electromagnetic coils on the bottom and side walls of the mold;

[0052] During the preheating stage, a low-frequency alternating current of 10-20Hz is introduced;

[0053] The magnetic field strength generated by the alternating current is 0.1-0.2 Tesla.

[0054] Preferably, a gradient density forming step is also included:

[0055] The bottom of the mold uses materials with a density of 7-8 particles / cm³. 2 The compaction bar;

[0056] The top of the mold uses a density of 5-6 particles / cm³ 2 The compaction bar;

[0057] The modified urea-formaldehyde resin in the composite adhesive also contains 5-8% flexible epoxy resin, wherein the molecular weight of the flexible epoxy resin is 500-700.

[0058] Furthermore, the composite adhesive also contains 1-2% of an organosilicon modifier.

[0059] The technical solution and chemical mechanism of this invention:

[0060] This invention cleverly solves the aforementioned technical challenges through a series of innovative designs. Firstly, in terms of raw material selection, this invention uses plant fibers with a length of 2-10 mm, rather than traditional powdered fibers. This choice is based on considerations of fiber mechanical properties; longer fibers can form a network structure, providing better mechanical strength.

[0061] Secondly, this invention employs a unique composite adhesive system comprising modified urea-formaldehyde resin, epoxy resin, and polyvinyl alcohol. From a chemical mechanism perspective, these three components form a multi-scale cross-linking network. The methyl alcohol groups (-CH2OH) in the modified urea-formaldehyde resin undergo a condensation reaction with the hydroxyl groups (-OH) on the surface of the plant fibers, forming stable covalent bonds. The epoxy groups in the epoxy resin undergo ring-opening under heating conditions, reacting with the fibers and other resin components, increasing the cross-linking density of the system. Polyvinyl alcohol, through its abundant hydroxyl groups, forms hydrogen bonds with the fibers, improving the interfacial bonding between the fibers and the resin.

[0062] Furthermore, this invention introduces an innovative fiber orientation technology. By applying an alternating magnetic field during the molding process, the paramagnetism of trace metal ions in plant fibers is utilized to achieve partial orientation of the fibers in the vertical direction. This process can be explained by the spin theory in quantum mechanics; the applied magnetic field causes the paramagnetic ions in the fibers to align in a specific direction, thereby driving the orientation of the entire fiber.

[0063] Furthermore, this invention employs gradient density molding and an innovative mold design. Gradient density molding creates a density gradient from bottom to top by controlling the degree of compaction at different heights, which facilitates material flow during the molding process. The variable cross-section spiral groove design of the mold cleverly utilizes fluid dynamics principles to increase the driving force for the upward flow of material.

[0064] Finally, the optimized molding process is matched with the rheological properties of the material. The segmented pressurization and temperature control scheme takes into account the viscoelastic changes of the material under different temperatures and pressures, ensuring uniform distribution and full cross-linking of the material in the mold.

[0065] The beneficial effects of this invention are:

[0066] 1. Breakthrough in height: Successfully manufactured plant fiber flower pots with a height of over 15cm, filling a gap in the industry.

[0067] 2. Balanced strength: Through fiber orientation and gradient density molding, a balanced strength distribution from bottom to top is achieved.

[0068] 3. Improved water resistance: The composite adhesive system significantly reduces the water absorption rate of the flowerpot, thus increasing the product's lifespan.

[0069] 4. Controllable degradation: By adjusting the ratio of plant fiber to binder, the degradation rate can be precisely controlled.

[0070] 5. Environmentally friendly: It makes full use of agricultural waste, reduces plastic use, and conforms to the concept of circular economy.

[0071] 6. Cost-effectiveness: Simplified production processes and a wide range of raw material sources make large-scale industrial production possible.

[0072] 7. Multifunctionality: The unexpected discovery of surface hydrophobicity and self-cleaning ability brings additional application value to the product.

[0073] Furthermore, the flowerpot of this invention uses plant fiber as the main raw material, and modified urea-formaldehyde resin, epoxy resin, and polyvinyl alcohol as binders. The resulting flowerpot has excellent air and water permeability, which is beneficial to plant growth. During the flowering period, the pot gradually decomposes, serving as supplementary organic fertilizer for the flowers until it is completely degraded, eliminating the need for recycling. Compared with the pulp method, this invention has a wide range of raw material sources, uses less water, saves energy used in dehydration, and has low production costs. This invention uses a molding process for one-time molding, which simplifies the production process and facilitates large-scale industrial production. By adjusting the ratio of plant fiber to binder and the production process parameters, the flowerpot of this invention has good mechanical strength and air and water permeability, making it suitable for planting various flowers.

[0074] In summary, this invention not only solves the key problems in the prior art, but also achieves a comprehensive improvement in performance through multiple innovative designs, opening up new directions for the application of plant fiber composite materials and possessing significant theoretical and practical value. Attached Figure Description

[0075] Figure 1 This is a schematic diagram of the structure of the plant fiber molded flower pot invented.

[0076] Figure 2 This is another structural schematic diagram of the plant fiber molded flower pot invented.

[0077] Figure 3 This is another top view of the structure of the plant fiber molded flowerpot of the invention.

[0078] Figure 4 Another top view of the invented plant fiber molded flower pot. Detailed Implementation

[0079] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0080] Example 1: A plant fiber molded flowerpot and its manufacturing method

[0081] Please refer to Figure 1-4 The plant fiber molded flowerpot of this embodiment is made of the following components in parts by weight: 85 parts plant fiber and 15 parts composite binder. The plant fiber is selected from rice straw with a length of 5 mm. The composite binder includes the following components in parts by weight: 70 parts modified urea-formaldehyde resin, 20 parts epoxy resin, and 10 parts polyvinyl alcohol. In addition, 0.5% calcium stearate, 0.3% silane coupling agent (KH-550), and 0.1% dicumyl peroxide are added based on the total weight of the plant fiber and composite binder.

[0082] In this embodiment, the modified urea-formaldehyde resin has a molecular weight of 3000, the epoxy resin has a molecular weight of 700, and the polyvinyl alcohol has a degree of hydrolysis of 87% and a molecular weight of 44000. This combination provides good bonding strength while ensuring a certain degree of toughness and water resistance.

[0083] The manufacturing method of this plant fiber molded flower pot includes the following steps:

[0084] (1) Plant fiber pretreatment:

[0085] First, cut the straw to a length of 2mm;

[0086] Secondly, soak in a 1% NaOH solution at 60°C for 2 hours;

[0087] Then, rinse with clean water until neutral;

[0088] Finally, dry to a moisture content of 5%.

[0089] (2) Formula mixing:

[0090] The pretreated plant fibers are mixed evenly with the composite binder and additives.

[0091] (3) Compression molding:

[0092] After obtaining the mixture, it is placed into a mold for compression molding. The compression molding steps include:

[0093] a) Preheating stage: Preheat the mixture to 60°C for 3 minutes, while simultaneously pre-compacting it at 0.5 MPa;

[0094] b) Main pressure stage:

[0095] First, maintain a pressure of 1.5 MPa for 30 seconds;

[0096] Next, increase the pressure to 2.5 MPa and hold for 60 seconds;

[0097] Next, increase the pressure to 3 MPa and hold for 120 seconds.

[0098] Temperature control: The starting temperature is 130℃, and the temperature is increased to 160℃ at a rate of 5℃ / min, and then maintained at 160℃ until the molding is completed.

[0099] c) Demolding stage:

[0100] Cool to 100℃ at a rate of 2℃ / min;

[0101] Then, maintain a pressure of 0.5 MPa for 5 minutes to cure;

[0102] Finally, compressed air at 0.6 MPa was used to assist in demolding to obtain the plant fiber molded flower pot, with the structure as follows: Figure 1 As shown.

[0103] In this embodiment, the mold employs a special design with a variable cross-section spiral groove structure on the inner wall. The top groove depth is 1.5 mm, and the bottom groove depth is 0.5 mm. The spiral groove angle gradually decreases from 45° at the top to 30° at the bottom. The pitch gradually decreases from 15 mm at the top to 8 mm at the bottom. A protrusion with a diameter of 1 / 3 of the mold's bottom diameter and a height of 5 mm is located at the center of the bottom structure, with its edge designed at a 45° bevel. This design helps improve material flowability and molding performance.

[0104] Furthermore, this embodiment also employs fiber orientation technology and a gradient density molding method. Electromagnetic coils are installed at the bottom and sidewalls of the mold, and a low-frequency alternating current of 10Hz is applied during the preheating stage to generate a magnetic field strength of 0.1 Tesla. The bottom of the mold uses a fiber density of 7 fibers / cm³. 2 The compaction bar has a density of 5 particles / cm³ at the top. 2 The compaction rods. The application of these technologies significantly improves the strength and ductility of the flowerpots.

[0105] Preferably, in embodiments of the present invention, the modified urea-formaldehyde resin in the composite adhesive further comprises 5% flexible epoxy resin (molecular weight 500) and 1% organosilicon modifier. This formulation further improves the toughness and water resistance of the flowerpot, while also improving the interfacial bonding between the resin and the fiber.

[0106] Example 2: A plant fiber molded flowerpot and its manufacturing method

[0107] The plant fiber molded flowerpot of this embodiment is made of the following components in parts by weight: 90 parts plant fiber and 10 parts composite binder. The plant fiber is selected from wheat straw with a length of 10 mm. The composite binder includes the following components in parts by weight: 80 parts modified urea-formaldehyde resin, 15 parts epoxy resin, and 5 parts polyvinyl alcohol. In addition, 1% calcium stearate, 0.5% silane coupling agent (KH-550), and 0.2% dicumyl peroxide are added based on the total weight of the plant fiber and composite binder.

[0108] In this embodiment, the modified urea-formaldehyde resin has a molecular weight of 5000, the epoxy resin has a molecular weight of 1000, and the polyvinyl alcohol has a degree of hydrolysis of 89% and a molecular weight of 48000. This combination can provide higher bonding strength and water resistance.

[0109] The manufacturing method of this plant fiber molded flower pot includes the following steps:

[0110] (1) Plant fiber pretreatment:

[0111] First, cut the wheat stalks to a length of 10mm;

[0112] Secondly, soak in a 3% NaOH solution at 70°C for 4 hours;

[0113] Then, rinse with clean water until neutral;

[0114] Finally, dry to a moisture content of 8%.

[0115] (2) Formula mixing:

[0116] The pretreated plant fibers are mixed evenly with the composite binder and additives.

[0117] (3) Compression molding:

[0118] After obtaining the mixture, it is placed into a mold for compression molding. The compression molding steps include:

[0119] a) Preheating stage: Preheat the mixture to 70°C for 5 minutes, while simultaneously pre-compacting it at 0.5 MPa;

[0120] b) Main pressure stage:

[0121] First, maintain a pressure of 1.5 MPa for 30 seconds;

[0122] Next, increase the pressure to 2.5 MPa and hold for 60 seconds;

[0123] Next, increase the pressure to 3 MPa and hold for 120 seconds.

[0124] Temperature control: The starting temperature is 130℃, and the temperature is increased to 160℃ at a rate of 5℃ / min, and then maintained at 160℃ until the molding is completed.

[0125] c) Demolding stage:

[0126] Cool to 100℃ at a rate of 2℃ / min;

[0127] Then, maintain a pressure of 0.5 MPa for 5 minutes to cure;

[0128] Finally, compressed air at 0.8 MPa was used to assist in demolding.

[0129] In this embodiment, the mold design is the same as in Embodiment 1, but in terms of fiber orientation technology, a low-frequency alternating current of 20Hz is introduced to generate a magnetic field strength of 0.2 Tesla. The bottom of the mold uses fibers with a density of 8 fibers / cm². 2 The compaction bar has a density of 6 particles / cm³ at the top. 2 The compaction bar further enhances the strength and molding properties of the flowerpot.

[0130] Preferably, in embodiments of the present invention, the modified urea-formaldehyde resin in the composite adhesive further comprises 8% flexible epoxy resin (molecular weight 700) and 2% organosilicon modifier. This formulation further improves the toughness and water resistance of the flowerpot.

[0131] Example 3: A plant fiber molded flowerpot and its manufacturing method

[0132] The plant fiber molded flowerpot of this embodiment is made of the following components in parts by weight: 87 parts plant fiber and 13 parts composite binder. The plant fiber is a mixture of rice straw and wheat straw (1:1 ratio) with a length of 7.5 mm. The composite binder includes the following components in parts by weight: 75 parts modified urea-formaldehyde resin, 17 parts epoxy resin, and 8 parts polyvinyl alcohol. In addition, 0.75% calcium stearate, 0.4% silane coupling agent (KH-550), and 0.15% dicumyl peroxide are added based on the total weight of the plant fiber and composite binder.

[0133] In this embodiment, the modified urea-formaldehyde resin has a molecular weight of 4000, the epoxy resin has a molecular weight of 850, and the polyvinyl alcohol has a degree of hydrolysis of 88% and a molecular weight of 46000. This combination aims to balance bond strength, toughness, and water resistance.

[0134] The manufacturing method of this plant fiber molded flower pot includes the following steps:

[0135] (1) Plant fiber pretreatment:

[0136] First, cut the mixture of rice straw and wheat straw to a length of 7.5mm;

[0137] Secondly, soak in a 2% NaOH solution at 65°C for 3 hours;

[0138] Then, rinse with clean water until neutral;

[0139] Finally, dry to a moisture content of 6.5%.

[0140] (2) Formula mixing:

[0141] The pretreated plant fibers are mixed evenly with the composite binder and additives.

[0142] (3) Compression molding:

[0143] After obtaining the mixture, it is placed into a mold for compression molding. The compression molding steps include:

[0144] a) Preheating stage: Preheat the mixture to 65°C for 4 minutes, while simultaneously pre-compacting at 0.5 MPa;

[0145] b) Main pressure stage:

[0146] First, maintain a pressure of 1.5 MPa for 30 seconds;

[0147] Next, increase the pressure to 2.5 MPa and hold for 60 seconds;

[0148] Next, increase the pressure to 3 MPa and hold for 120 seconds.

[0149] Temperature control: The starting temperature is 130℃, and the temperature is increased to 160℃ at a rate of 5℃ / min, and then maintained at 160℃ until the molding is completed.

[0150] c) Demolding stage:

[0151] Cool to 100℃ at a rate of 2℃ / min;

[0152] Then, maintain a pressure of 0.5 MPa for 5 minutes to cure;

[0153] Finally, compressed air at 0.7 MPa was used to assist in demolding.

[0154] In this embodiment, the mold design is the same as in Embodiment 1, but in terms of fiber orientation technology, a low-frequency alternating current of 15Hz is introduced to generate a magnetic field strength of 0.15 Tesla. The bottom of the mold uses fibers with a density of 7.5 fibers / cm². 2 The compaction bar has a density of 5.5 particles / cm³ at the top. 2 The compaction bar. This setup is designed to optimize the strength and molding properties of the flowerpot.

[0155] Preferably, in embodiments of the present invention, the modified urea-formaldehyde resin in the composite adhesive further comprises 6.5% flexible epoxy resin (molecular weight 600) and 1.5% organosilicon modifier. This formulation further balances the toughness, strength, and water resistance of the flowerpot.

[0156] Example 4: A plant fiber molded flowerpot and its manufacturing method

[0157] The plant fiber molded flowerpot of this embodiment is made of the following components in parts by weight: 80 parts plant fiber and 20 parts composite binder. The plant fiber is selected from rice straw with a length of 8 mm. The composite binder includes the following components in parts by weight: 60 parts modified urea-formaldehyde resin, 25 parts epoxy resin, and 15 parts polyvinyl alcohol. In addition, 0.8% calcium stearate, 0.45% silane coupling agent (KH-550), and 0.18% dicumyl peroxide are added based on the total weight of the plant fiber and composite binder.

[0158] In this embodiment, the modified urea-formaldehyde resin has a molecular weight of 3500, the epoxy resin has a molecular weight of 800, and the polyvinyl alcohol has a degree of hydrolysis of 88.5% and a molecular weight of 45000. This combination is designed to provide optimal bond strength and processability.

[0159] The manufacturing method of this plant fiber molded flower pot includes the following steps:

[0160] (1) Plant fiber pretreatment:

[0161] First, cut the straw to 8mm in length;

[0162] Secondly, soak in a 2.5% NaOH solution at 68°C for 3.5 hours;

[0163] Then, rinse with clean water until neutral;

[0164] Finally, dry to a moisture content of 7%.

[0165] (2) Formula mixing:

[0166] The pretreated plant fibers are mixed evenly with the composite binder and additives.

[0167] (3) Compression molding:

[0168] After obtaining the mixture, it is placed into a mold for compression molding. The compression molding steps include:

[0169] a) Preheating stage: Preheat the mixture to 68°C for 4.5 minutes, while simultaneously pre-compacting at 0.5 MPa;

[0170] b) Main pressure stage:

[0171] First, maintain a pressure of 1.5 MPa for 30 seconds;

[0172] Next, increase the pressure to 2.5 MPa and hold for 60 seconds;

[0173] Next, increase the pressure to 3 MPa and hold for 120 seconds.

[0174] Temperature control: The starting temperature is 130℃, and the temperature is increased to 160℃ at a rate of 5℃ / min, and then maintained at 160℃ until the molding is completed.

[0175] c) Demolding stage:

[0176] Cool to 100℃ at a rate of 2℃ / min;

[0177] Then, maintain a pressure of 0.5 MPa for 5 minutes to cure;

[0178] Finally, compressed air at 0.75 MPa was used to assist in demolding.

[0179] In this embodiment, the mold design is the same as in Embodiment 1, but in terms of fiber orientation technology, a low-frequency alternating current of 18Hz is introduced to generate a magnetic field strength of 0.18 Tesla. The bottom of the mold uses fibers with a density of 7.8 fibers / cm². 2 The compaction bar has a density of 5.8 particles / cm³ at the top. 2 The compaction bar. This setup is designed to further optimize the strength and molding properties of the flowerpot.

[0180] Preferably, in embodiments of the present invention, the modified urea-formaldehyde resin in the composite adhesive further comprises 7% flexible epoxy resin (molecular weight 650) and 1.8% organosilicon modifier. This formulation further optimizes the balance of the flowerpot's toughness, strength, and water resistance.

[0181] It is worth noting that the combination of a higher proportion of composite binder (20 parts) and a lower proportion of plant fiber (80 parts) in this embodiment is designed to provide better molding performance and surface finish. The higher content of epoxy resin (25 parts) helps improve the product's water resistance and toughness, while the increased content of polyvinyl alcohol (15 parts) improves the compatibility between the fiber and the resin. This combination not only ensures the strength of the flowerpot but also significantly improves its durability and service life.

[0182] Furthermore, the fiber orientation technology and gradient density molding method used in this embodiment further enhance the overall performance of the flowerpot. By applying a magnetic field of specific frequency and intensity during the molding process, the plant fibers exhibit a certain orientation, which not only improves the mechanical strength of the product but also enhances its crack resistance. Simultaneously, the gradient density molding technology ensures that the bottom of the flowerpot has high strength while the top maintains a certain degree of ductility; this design cleverly solves the problem of uneven strength caused by increased height.

[0183] Comparative Example 1

[0184] This comparative example aims to verify the effect of plant fiber length on product performance and is compared with Example 1.

[0185] A plant fiber molded flower pot and its manufacturing method are disclosed, characterized in that the flower pot is made of the following components in parts by weight: 85 parts plant fiber and 15 parts composite binder. The plant fiber is selected from rice straw with a length of 0.5 mm; the composition of the composite binder is the same as in Example 1.

[0186] The manufacturing method is basically the same as in Example 1, except that in the plant fiber pretreatment step, the straw is cut to a length of 0.5 mm. Other steps and parameters remain unchanged.

[0187] The results showed that the flowerpots made with plant fibers of 0.5 mm in length had significantly lower strength than those in Example 1, and their surface roughness increased. This verifies the importance of fiber lengths of 2-10 mm in this invention, a range that ensures both sufficient mechanical strength and good surface quality.

[0188] Comparative Example 2

[0189] This comparative example aims to verify the effect of the ratio of composite adhesive components on product performance and is compared with Example 2.

[0190] A plant fiber molded flowerpot and its manufacturing method are disclosed, characterized in that the flowerpot is made of the following components in parts by weight: 90 parts plant fiber and 10 parts composite binder. The plant fiber is selected from wheat straw with a length of 10 mm; the composite binder comprises the following components in parts by weight: 90 parts modified urea-formaldehyde resin, 5 parts epoxy resin, and 5 parts polyvinyl alcohol.

[0191] The manufacturing method is basically the same as in Example 2, except that the component ratio of the composite adhesive is changed.

[0192] The results showed that the water resistance and toughness of the product decreased significantly due to the substantial reduction in epoxy resin content. This confirms the importance of the proportions of each component in the composite adhesive of this invention, especially the key role of epoxy resin in providing water resistance and toughness.

[0193] Comparative Example 3

[0194] This comparative example aims to verify the impact of fiber orientation technology on product performance and is compared with Example 3.

[0195] A plant fiber molded flower pot and its manufacturing method are characterized in that the components and basic manufacturing method of the flower pot are the same as those in Example 3, but fiber orientation technology is not used.

[0196] In the manufacturing method, the molding step omits the process of generating a magnetic field by introducing a low-frequency alternating current.

[0197] The results showed that the flowerpots without fiber orientation treatment were inferior to those in Example 3 in terms of mechanical strength and crack resistance. This verifies the importance of the fiber orientation technology in this invention, which significantly improves the overall performance of the product.

[0198] Comparative Example 4

[0199] This comparative example aims to verify the impact of the gradient density molding method on product performance and is compared with Example 4.

[0200] A plant fiber molded flower pot and its manufacturing method are characterized in that the components and basic manufacturing method of the flower pot are the same as those in Example 4, but the gradient density molding method is not used.

[0201] In the manufacturing method, both the bottom and top of the mold use a material with a density of 7 particles / cm³. 2 The compaction bar.

[0202] The results showed that flowerpots not using gradient density molding performed poorly in balancing bottom strength and top ductility, especially when their height exceeded 15cm, making them more prone to cracking. This confirms the importance of the gradient density molding method in this invention, which effectively solves the problem of uneven strength caused by increased height.

[0203] Comparative Example 5

[0204] This comparative example aims to verify the impact of plant fiber pretreatment on product performance and is compared with Example 1.

[0205] A plant fiber molded flower pot and its manufacturing method are characterized in that the components of the flower pot are the same as those in Example 1, but the plant fiber pretreatment process is different.

[0206] In the manufacturing method, the plant fiber pretreatment steps are as follows:

[0207] First, cut the straw to a length of 5mm;

[0208] Secondly, the product is directly dried to a moisture content of 5%, thus omitting the alkalization step.

[0209] The other steps and parameters are the same as in Example 1.

[0210] The results showed that flowerpots made from untreated plant fibers were significantly inferior to those in Example 1 in terms of strength, toughness, and water resistance. This verifies the importance of the alkalization step in this invention, which effectively removes some hemicellulose and lignin, increases the flexibility and reactivity of the fibers, and thus improves the performance of the final product.

[0211] Comparative Example 6

[0212] This comparative example aims to verify the impact of mold design on product performance and is compared with Example 2.

[0213] A plant fiber molded flower pot and its manufacturing method are characterized in that the components and basic manufacturing method of the flower pot are the same as those in Example 2, but the mold design is different.

[0214] In the manufacturing process, the mold adopts a common cylindrical design with smooth inner walls and no spiral groove structure; the bottom is flat and has no central protrusion.

[0215] The results showed that flowerpots made using ordinary molds were inferior to those in Example 2 in terms of both molding height and surface quality. In particular, the success rate was significantly reduced when attempting to produce flowerpots exceeding 15cm in height, and the product wall thickness was uneven. This confirms the importance of the special mold design in this invention, which effectively improves material flowability and molding performance, making it possible to produce flowerpots with a height of 15cm and above.

[0216] These comparative examples clearly demonstrate the innovation and superiority of this invention in terms of plant fiber length selection, composite binder formulation, fiber orientation technology, gradient density molding method, plant fiber pretreatment process, and mold design. The synergistic effect of these innovations enables this invention to produce high-quality, high-performance plant fiber molded flowerpots, not only solving the problems of traditional flowerpots but also opening up new avenues for the high-value utilization of agricultural waste.

[0217] The present invention includes the following test experiment design:

[0218] 1. Mechanical performance testing

[0219] To assess the strength and toughness of the flowerpot, we conducted compressive strength and flexural strength tests.

[0220] Test method: The test was conducted using a universal testing machine according to GB / T 1041-2008 standard. The bottom of the flowerpot was cut into square samples of 50mm × 50mm × 4mm, and its compressive strength was tested. Simultaneously, the sidewalls of the flowerpot were cut into strips of 100mm × 20mm × 4mm, and their flexural strength was tested.

[0221] 2. Water absorption rate test

[0222] To assess the water resistance of the flowerpots, we conducted a water absorption rate test.

[0223] Test method: According to GB / T 1934.1-2009 standard, after immersing a 50mm×50mm×4mm sample in water at 23±2℃ for 24 hours, the percentage increase in mass is measured.

[0224] 3. Biodegradability test

[0225] To assess the environmental performance of the flowerpots, we conducted a soil burial degradation test.

[0226] Test method: According to GB / T 19277.1-2011 standard, a 50mm×50mm×4mm sample was buried in active soil and cultured at 25±2℃ and 50±5% relative humidity. The mass loss was measured every 30 days.

[0227] 4. Surface roughness test

[0228] To assess the surface quality of the flowerpots, we conducted a surface roughness test.

[0229] Test method: The arithmetic mean deviation Ra value of the sample surface was measured using a surface roughness tester in accordance with GB / T 3505-2000 standard.

[0230] 5. Fiber orientation analysis

[0231] To evaluate the effectiveness of fiber orientation technology, we conducted fiber orientation analysis.

[0232] Test method: X-ray diffraction (XRD) technique was used to measure the azimuth distribution function (ODF) of the sample and calculate the Herman orientation factor.

[0233] 6. Heat distortion temperature test

[0234] To assess the heat resistance of the flowerpots, we conducted a heat distortion temperature test.

[0235] Test method: The heat distortion temperature of the sample was measured using a heat distortion Vicat softening point tester under a load of 0.45 MPa, in accordance with GB / T 1634.2-2004 standard.

[0236] The test results are as follows:

[0237] Table 1: Test results of mechanical and physical properties of each sample

[0238]

[0239]

[0240] Table 2: Biodegradability test results for each sample (percentage of mass loss)

[0241] sample 30 days 60 days 90 days 120 days Example 1 5.2％ 12.8％ 22.5％ 35.7％ Example 2 4.8％ 11.9％ 21.3％ 33.8％ Example 3 5.0％ 12.3％ 21.9％ 34.5％ Example 4 4.5％ 11.2％ 20.1％ 32.3％ Comparative Example 1 6.8％ 15.7％ 26.9％ 41.2％ Comparative Example 2 5.5％ 13.6％ 23.8％ 37.1％ Comparative Example 3 5.3％ 13.1％ 23.0％ 36.2％ Comparative Example 4 4.7％ 11.6％ 20.8％ 33.1％ Comparative Example 5 6.1％ 14.5％ 25.2％ 39.3％ Comparative Example 6 5.4％ 13.3％ 23.4％ 36.8％

[0242] The results are analyzed and discussed as follows:

[0243] 1. Mechanical Properties: The compressive and flexural strengths of Examples 1-4 were significantly higher than those of the Comparative Example. In particular, Example 4 achieved a compressive strength of 21.5 MPa and a flexural strength of 29.8 MPa, primarily due to the optimized fiber length, composite binder formulation, and fiber orientation technology. In contrast, Comparative Example 1 exhibited significantly reduced mechanical properties due to excessively short fibers.

[0244] 2. Water Absorption: Examples 2 and 4 exhibited the lowest water absorption rates, at 28.5% and 26.7%, respectively. This is attributed to the use of higher proportions of epoxy resin and silicone modifier, which effectively improved the water resistance of the products. Comparative Examples 1 and 5 showed higher water absorption rates, at 38.5% and 36.9%, respectively, indicating that fiber length and pretreatment processes have a significant impact on water resistance.

[0245] 3. Surface Quality: Example 4 exhibited the lowest surface roughness, with an Ra value of only 2.5 μm, which was attributed to the optimized fiber length and composite binder formulation. Comparative Example 1 showed the highest surface roughness, with an Ra value of 5.7 μm, further confirming the importance of appropriate fiber length for surface quality.

[0246] 4. Fiber Orientation: The Herman orientation factors of Examples 2 and 4 reached 0.75 and 0.78 respectively, significantly higher than other samples, which verifies the effectiveness of the fiber orientation technology. Comparative Example 3, which did not employ fiber orientation technology, had a Herman orientation factor of only 0.45.

[0247] 5. Heat distortion temperature: Example 4 exhibited the highest heat distortion temperature at 101°C, primarily due to its optimized composite binder formulation and high crosslinking density. Comparative Example 1 showed the lowest heat distortion temperature at 85°C, indicating that fiber length and binder formulation significantly influence the product's heat resistance.

[0248] 6. Biodegradability: All samples exhibited good biodegradability, but the degradation rates of Examples 1-4 were relatively moderate, with mass loss ranging from 32.3% to 35.7% after 120 days. This moderate degradation rate ensures product stability during its service life while allowing for rapid degradation after disposal. Comparative Example 1 showed the fastest degradation rate, with a mass loss of 41.2% after 120 days, which could potentially lead to premature product failure during use.

[0249] In-depth analysis and unexpected technical effects:

[0250] 1. Synergistic Reinforcement Effect: This invention achieves a synergistic improvement in mechanical strength, water resistance, and surface quality by optimizing fiber length, composite binder formulation, and fiber orientation technology. In particular, Example 4 achieves the lowest water absorption and optimal surface quality while maintaining high mechanical strength. This synergistic improvement in multiple properties is an unexpected technical effect, providing new ideas for the design of high-performance bio-based composite materials.

[0251] 2. Controllable Degradability: The flowerpots of this invention exhibit controllable biodegradability, achieved through precise control of the ratio of plant fibers to the composite binder. In particular, Examples 2 and 4 maintain a moderate degradation rate while retaining a low water absorption rate. This controllable degradation performance results in an unexpected balance between product stability throughout its lifespan and rapid degradation after disposal.

[0252] 3. Improved Thermal Stability: The heat distortion temperature of Example 4 reached 101℃, exceeding expectations. Typically, plant fiber-based composites have poor heat resistance, but this invention significantly improves the heat resistance of the product by optimizing the composite binder formulation and crosslinking density. This opens up possibilities for expanding the application range of plant fiber composites.

[0253] 4. Multiple effects of fiber orientation: Fiber orientation technology not only improves the mechanical strength of products, but also unexpectedly enhances their dimensional stability and warping resistance. This is likely because the oriented fiber network structure reduces the uneven distribution of internal stress, thereby improving the overall performance of the product.

[0254] 5. Surface Functionalization: Although the initial design focused primarily on surface roughness, research has revealed that the optimized surface structure also possesses certain hydrophobicity and self-cleaning capabilities. This is likely due to the synergistic effect of fiber orientation and organosilicon modifiers, which create the microstructure of the surface.

[0255] 6. Environmental Adaptability: Test results show that the flowerpot of this invention maintains good performance stability under different environmental conditions (such as high humidity and temperature fluctuations). This broad environmental adaptability is the result of the combined effect of plant fibers, composite binders, and optimized manufacturing processes, making it possible to apply the product under different climatic conditions.

[0256] This invention, through the synergistic effect of multiple innovations, not only achieves the expected performance improvement but also produces several unexpected technical effects. These effects collectively constitute a high-performance, environmentally friendly, and multifunctional plant fiber molded flowerpot system, opening up new avenues for the high-value utilization of agricultural waste and providing valuable insights for the design and application of bio-based composite materials.

[0257] The present invention also includes the following test experiment design:

[0258] 7. High ductility test

[0259] We designed a special mold that allows for gradual increases in molding height, starting at 10cm and increasing by 1cm each time, up to 20cm. We tested the formulations from Examples 1-4 and Comparative Examples 1-6.

[0260] 8. Wall thickness uniformity test

[0261] For the successfully made flower pots with heights of 15cm and 20cm, we measured the wall thickness at different heights (bottom, 1 / 4 height, 1 / 2 height, 3 / 4 height, and top).

[0262] 9. Longitudinal tensile strength test

[0263] Longitudinal strip samples were cut from a 15cm high flowerpot and their tensile strength was tested to assess the bonding strength of the fibers in the vertical direction.

[0264] 10. Microstructure Analysis

[0265] The arrangement and bonding of fibers at different heights in a 15cm high flowerpot were observed using a scanning electron microscope (SEM).

[0266] 11. Rheological testing

[0267] Rheological tests were conducted on the raw material mixture to evaluate its flow properties under high temperature and high pressure.

[0268] Experimental results:

[0269] Table 3: Maximum moldable height and wall thickness uniformity at 15cm height for different formulations

[0270] sample Maximum moldable height (cm) Coefficient of variation of wall thickness at a height of 15cm (%) Example 1 17 8.5 Example 2 19 6.2 Example 3 18 7.3 Example 4 20 5.1 Comparative Example 1 11 - Comparative Example 2 14 - Comparative Example 3 13 - Comparative Example 4 16 9.8 Comparative Example 5 12 - Comparative Example 6 15 12.5

[0271] Note: Coefficient of variation of wall thickness = (standard deviation / average wall thickness) × 100%. The smaller the value, the more uniform the wall thickness.

[0272] Table 4: Longitudinal tensile strength and rheological parameters of 15cm tall flowerpots

[0273] sample Longitudinal tensile strength (MPa) Apparent viscosity (Pa·s) Shear thinning index Example 1 12.3 4500 0.65 Example 2 14.8 4200 0.71 Example 3 13.5 4300 0.68 Example 4 15.6 3900 0.73 Comparative Example 6 9.2 5100 0.58

[0274] Experimental Results Analysis and Discussion:

[0275] 1. High ductility:

[0276] Examples 1-4 successfully increased the extended height of the cylindrical basin shape to over 15cm, with Example 4 even reaching 20cm. In contrast, Comparative Examples 1-5 failed to reach a height of 15cm, and Comparative Example 6 barely reached 15cm, but with poor wall thickness uniformity. This result fully verifies the breakthrough achievement of this invention in solving the problem of plant fibers being unable to be stretched and molded.

[0277] 2. Wall thickness uniformity: Examples 2 and 4 exhibited the best wall thickness uniformity, with coefficients of variation of 6.2% and 5.1% respectively at a height of 15 cm. This demonstrates that the formulation and process of the present invention not only achieve high elongation but also ensure molding quality. Although Comparative Example 6 also reached a height of 15 cm, its coefficient of variation of wall thickness was as high as 12.5%, indicating poor molding quality.

[0278] 3. Longitudinal tensile strength: The longitudinal tensile strength of Examples 1-4 is significantly higher than that of Comparative Example 6, with Example 4 reaching 15.6 MPa. This indicates that the formulation and process of the present invention significantly improve the bonding strength of the fibers in the vertical direction, which is one of the key factors in achieving high elongation.

[0279] 4. Rheological parameters: The apparent viscosity of Examples 1-4 is lower than that of Comparative Example 6, and the shear thinning index is higher. This means that under high temperature and high pressure, the mixtures of the present invention have better fluidity, which is beneficial for the uniform distribution and filling of materials in the mold.

[0280] 5. Microstructure Analysis: SEM observation results show that the fiber arrangement in Examples 1-4 is more uniform at different heights, and the bonding between fibers is tighter. Especially at a height of 15cm, obvious fiber orientation can still be observed, which is closely related to the application of fiber orientation technology.

[0281] Explanation of the mechanism by which this invention achieves high extensibility:

[0282] 1. Optimized fiber length: This invention uses plant fibers with a length of 2-10mm, which ensures sufficient mechanical strength without excessively increasing the viscosity of the material. Fibers of this length can form a network structure during the molding process, providing sufficient support.

[0283] 2. Composite Binder System: The composite use of modified urea-formaldehyde resin, epoxy resin, and polyvinyl alcohol creates a multi-scale cross-linked network. The modified urea-formaldehyde resin provides the primary bond strength, the epoxy resin increases the system's toughness and flowability, while the polyvinyl alcohol improves the interfacial bonding between the fiber and the resin. This composite system not only enhances the overall strength of the material but also significantly improves its rheological properties.

[0284] 3. Fiber Orientation Technology: By applying an alternating magnetic field during the molding process, the fibers are oriented in a specific direction in the vertical direction. This orientation not only improves the longitudinal tensile strength but also facilitates the flow and filling of the material in the mold.

[0285] 4. Gradient Density Molding: A higher-density compaction bar is used at the bottom, while a lower-density compaction bar is used at the top. This design creates a density gradient from bottom to top. This helps the material flow upwards gradually during molding, while ensuring strength at the bottom and ductility at the top.

[0286] 5. Innovative Mold Design: The variable cross-section spiral groove design increases the friction between the mold inner wall and the material, promoting upward material flow. Simultaneously, the gradual change in spiral angle and pitch ensures uniform pressure distribution on the material during molding.

[0287] 6. Optimized molding process: The segmented pressurization and temperature control scheme is matched with the rheological properties of the material. The initial low-pressure stage allows the material to soften and flow sufficiently, while the subsequent high-pressure stage ensures the material is fully compacted and cross-linked.

[0288] In summary, this invention, through the synergistic effect of multiple innovations, successfully extends the height of plant fiber molded flower pots to 15 cm and above. Optimized fiber length and a composite binder system provide the material basis for this height extension; fiber orientation technology and gradient density molding methods improve the longitudinal strength and flowability of the material; and innovative mold design and molding process ensure that these advantages can be realized in actual production. The combined effect of these factors not only solves the technical challenge of stretching and molding plant fibers but also opens up new possibilities for the high-value application of bio-based composite materials.

[0289] The above description is merely an embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of the present invention should be included within the scope of the claims of the present invention.

[0290] The above description is merely a preferred embodiment of the present invention; however, the scope of protection of the present invention is not limited thereto; any substitutions or modifications made by those skilled in the art within the scope disclosed in the present invention, based on the scheme and improved concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for manufacturing a plant fiber molded flowerpot, characterized in that, The flowerpot is made of the following components in parts by weight: 80-90 parts plant fiber; 10-20 parts of composite adhesive; The plant fiber includes at least one of rice straw and wheat straw with a length of 5-10 mm; The composite adhesive comprises the following components in parts by weight: 60-80 parts modified urea-formaldehyde resin, 15-25 parts epoxy resin, and 5-15 parts polyvinyl alcohol; the modified urea-formaldehyde resin has a molecular weight of 3000-5000, the epoxy resin has a molecular weight of 700-1000, and the polyvinyl alcohol has a degree of hydrolysis of 87-89% and a molecular weight of 44000-48000; the modified urea-formaldehyde resin further comprises 5-8% flexible epoxy resin, the flexible epoxy resin having a molecular weight of 500-700; the composite adhesive further comprises 1-2% organosilicon modifier. The flowerpot also includes the following additives, by weight of plant fiber and composite binder: 0.5-1% calcium stearate, 0.3-0.5% silane coupling agent, and 0.1-0.2% dicumyl peroxide; The height of the flowerpot shall not be less than 15cm; Includes the following steps: (1) Plant fiber pretreatment: First, cut the plant fiber to a length of 2-10 mm; then soak it in 1-3% NaOH solution at 60-70°C for 2-4 hours; then rinse it with water until neutral; finally dry it to a moisture content of 5-8%. (2) Formulation mixing: Mix the pretreated plant fibers with the composite binder and additives evenly; (3) Compression molding: After obtaining the mixture, it is placed into a mold for compression molding; the compression molding step includes: Preheating stage: Preheat the mixture to 60-70°C for 3-5 minutes, while simultaneously pre-compacting at 0.5MPa; Main pressure stage: First, maintain a pressure of 1.5MPa for 30 seconds; then increase the pressure to 2.5MPa and maintain for 60 seconds; then increase the pressure to 3MPa and maintain for 120 seconds; the temperature control of the main pressure stage is as follows: the starting temperature is 130°C, the temperature is increased to 160°C at a rate of 5°C / min, and then maintained at 160°C until the molding is completed; Demolding stage: Cool to 100°C at a rate of 2°C / min, then maintain a pressure of 0.5MPa for 5 minutes to cure, and finally use compressed air of 0.6-0.8MPa to assist in demolding; The mold includes: an inner wall structure with a variable cross-section spiral groove design, a top groove depth of 1.5mm and a bottom groove depth of 0.5mm; the spiral groove angle gradually decreases from 45° at the top to 30° at the bottom; the pitch gradually decreases from 15mm at the top to 8mm at the bottom; a protrusion is provided at the center of the bottom structure, with a diameter of 1 / 3 of the bottom diameter of the mold and a height of 5-8mm, and the edge of the protrusion is designed with a 45° bevel. It also includes a fiber orientation step: installing electromagnetic coils at the bottom and sidewalls of the mold; during the preheating stage, introducing a low-frequency alternating current of 10-20Hz; the magnetic field strength generated by the alternating current is 0.1-0.2 Tesla; It also includes a gradient density molding step: the bottom of the mold uses a compaction bar with a density of 7-8 particles / cm²; the top of the mold uses a compaction bar with a density of 5-6 particles / cm².

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