Reinforced degradable drain board and preparation method thereof

Abstract

The reinforced degradable drainage plate comprises a degradable tooth-shaped plate core, a reinforced structure embedded into the degradable tooth-shaped plate core and filter membrane layers compounded on the two sides of the degradable tooth-shaped plate core in a hot melting mode. Wherein the degradable toothed plate core is prepared from the following raw materials in parts by weight through reactive extrusion: 40 to 50 parts of polylactic acid, 20 to 30 parts of poly (butylene adipate-co-terephthalate), 10 to 20 parts of starch-based biodegradable resin, 0.5 to 2 parts of maleic anhydride grafted polylactic acid (MAH-g-PLA), 5 to 10 parts of nano calcium carbonate, 3 to 8 parts of plasticizer and 0.5 to 1.5 parts of antioxidant. According to the reinforced degradable drain board disclosed by the invention, the tensile strength and long-term creep resistance of a product are remarkably improved by adopting high-performance bio-based fibers and a reinforced structure; by introducing a reactive melt grafting composite process, high-strength chemical bonding between a reinforced structure and a body material is realized, so that the key peel strength is improved by more than multiple times, and the problems that a composite layer is easy to separate and the overall performance is reduced in the prior art are solved.

Description

Technical Field

[0001] This invention relates to the field of civil engineering technology, specifically to a reinforced biodegradable drainage board and its preparation method. Background Technology

[0002] In civil engineering construction, drainage boards are an important drainage material, widely used in roads, bridges, and building foundation treatment. Traditional drainage boards are mostly made of non-degradable polymer materials, such as polypropylene and polyethylene. These materials are difficult to degrade naturally after use, causing long-term environmental pollution. With increasing environmental awareness and the promotion of sustainable development concepts, biodegradable drainage boards have gradually become a research hotspot.

[0003] Currently, existing biodegradable drainage boards have some shortcomings. On the one hand, their mechanical properties are limited, and they are prone to deformation or even damage when subjected to significant pressure or tension, making it difficult to meet the needs of complex engineering environments. On the other hand, when biodegradable drainage boards come into contact with soil, soil particles can easily clog the drainage channels, affecting drainage efficiency. Although some drainage boards are laminated with non-woven fabric to improve filtration performance, the basis weight of the non-woven fabric has a significant impact on the overall performance of the drainage board. Too low a basis weight results in poor filtration, while too high a basis weight increases costs and may also affect drainage efficiency. In addition, the existing lamination process between reinforced biodegradable drainage boards and non-woven fabric is not mature enough, resulting in a loose bond between the two, which easily separates during use, reducing the overall performance of the drainage board.

[0004] Therefore, there is an urgent need to develop a reinforced biodegradable drainage board with high longitudinal strength, high interfacial bonding force, and excellent bidirectional tensile strength of the filter membrane. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a reinforced biodegradable drainage board. By adopting high-performance bio-based fibers and a reinforced structure, the tensile strength and long-term creep resistance of the product are significantly improved. More importantly, by introducing a reactive melt grafting composite process, a high-strength chemical bond between the reinforced structure and the base material is achieved, which increases the key peel strength by several times and solves the problem of easy separation of the composite layer and overall performance degradation in the prior art.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: The first aspect of this invention provides a reinforced biodegradable drainage board, the reinforced biodegradable drainage board comprising a biodegradable toothed core, a reinforcing structure embedded inside the biodegradable toothed core, and a filter membrane layer hot-melt-fused to both sides of the biodegradable toothed core; wherein the biodegradable toothed core is made by reactive extrusion of the following raw materials in parts by weight: 40-50 parts of polylactic acid, 20-30 parts of polybutylene adipate-terephthalate, 10-20 parts of starch-based biodegradable resin, 0.5-2 parts of maleic anhydride-grafted polylactic acid (MAH-g-PLA), 5-10 parts of nano-calcium carbonate, 3-8 parts of plasticizer, and 0.5-1.5 parts of antioxidant.

[0007] Further, the plasticizer is tributyl citrate; and / or, the antioxidant is 2,6-di-tert-butyl-4-methylphenol.

[0008] Furthermore, the starch-based biodegradable resin can be various starch-modified resins, including starch / PLA biodegradable plastics, starch / PVA biodegradable plastics, etc.

[0009] Furthermore, the reinforcing structure is a mesh structure woven from biodegradable polyester fibers; preferably, the biodegradable polyester fibers are polyhydroxyalkanoate-polycaprolactone copolymer (PHA-co-PCL) fibers.

[0010] PHA (polyhydroxyalkanoate) is a natural polymer synthesized by microorganisms, exhibiting excellent biocompatibility and biodegradability. Copolymerization with PCL (polycaprolactone) further optimizes its flexibility and processability. This copolymer fiber was chosen to overcome the creep deformation problem that commonly occurs in biodegradable polyesters (such as PLA) under long-term loads, ensuring the dimensional stability of the drainage board during long-term use.

[0011] Furthermore, the filter membrane layer is made of biodegradable polyester fiber needle-punched nonwoven fabric with a basis weight of 70-80 grams, an equivalent pore size of 0.075-0.12 mm, and a permeability coefficient ≥5×10⁻⁶. -3 cm / s.

[0012] A second aspect of the present invention provides a method for preparing a reinforced biodegradable drainage board, comprising the following steps: S1. Add the formulated amounts of polylactic acid, polybutylene adipate terephthalate, starch-based biodegradable resin, nano-calcium carbonate, and maleic anhydride-grafted polylactic acid to a high-speed mixer and premix and dehydrate at 80-100℃ for 10-15 minutes; then add it to a twin-screw extruder and melt extrude at 160-200℃ to obtain activated extruded strips with reactive MAH groups; S2. Polyhydroxy fatty acid ester-polycaprolactone copolymer fibers are woven into a reinforced structure using a warp knitting machine; S3. The activated extruded strip is extruded through a die, and the reinforcing structure is introduced at the same time, so that the extruded melt covers the reinforcing structure, and is pressed into a core plate with a toothed groove structure by a calendering and shaping wheel; S4. Two layers of filter membrane are respectively covered on the upper and lower surfaces of the core board, and linear hot-pressed composite is performed by heating rollers to obtain the reinforced biodegradable drainage board.

[0013] Furthermore, in step S1, vacuum exhaust is activated during the twin-screw extrusion process, and the vacuum level is maintained above -0.08 MPa.

[0014] Starch-based resins typically contain bound water, and the esterification reaction (reaction of MAH with -OH) itself may produce small molecule byproducts. If not removed promptly, these small molecules can form microbubbles inside the core, becoming crack initiation points under stress and severely weakening the board's strength. In this invention, timely removal of moisture through vacuum degassing helps improve the board's strength.

[0015] This invention adds maleic anhydride graft (MAH-g-PLA) as a compatibilizer and reactive grafting site to the raw materials (polylactic acid, PBAT, etc.) used to prepare biodegradable toothed core plates. Through a melt extrusion process, MAH groups are introduced into the molecular chain of the toothed core plate material, providing chemically reactive sites for subsequent composite with reinforcement structures and filter membranes.

[0016] Furthermore, in step S3, the temperature of the mold is controlled at 160-180℃ and the pressure is 10-20MPa.

[0017] In this invention, during the pressing and molding process of the toothed core, the activated toothed core melt is brought into contact with the reinforcing structure. High temperature and pressure are used to cause the MAH groups on the toothed core material to react chemically (esterification or amidation) with the hydroxyl or amino groups on the surface of the reinforcing structure fibers. This achieves a dual combination of chemical bonding and mechanical embedding, significantly improving the interfacial shear strength between the reinforcing structure and the toothed core, and increasing the peel strength by more than 50%.

[0018] Furthermore, in step S4, the temperature of the hot-pressing composite is 140-160℃, and the pressure is 5-10MPa.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The reinforced biodegradable drainage board provided by the present invention has an effective enhancement of the tensile strength and deformation resistance of the drainage board by the reinforcement structure, which enables the drainage board to withstand greater pressure and tension in complex engineering environments and ensures the long-term stable performance of the drainage function.

[0020] 2. The reinforced biodegradable drainage board provided by this invention significantly improves the tensile strength and long-term creep resistance of the product by adopting high-performance bio-based fibers and a reinforced structure. More importantly, by introducing a reactive melt grafting composite process, a high-strength chemical bond is achieved between the reinforced structure and the base material, which increases the key peel strength by several times and solves the problem of easy separation of the composite layer and overall performance degradation in the prior art.

[0021] 3. The reinforced biodegradable drainage board provided by this invention selects biodegradable needle-punched nonwoven fabric with a weight of 70-80 grams and balanced longitudinal and transverse strength as the filter membrane layer. While ensuring good filtration effect and effectively blocking soil particles from entering the drainage channel, it does not excessively affect the drainage efficiency, thus achieving an optimized balance between filtration and drainage performance. In addition, it ensures that the transverse tensile strength of the filter membrane is ≥10kN / m, so that it can be suspended between the core teeth of the board under lateral earth pressure of more than 300kPa without excessive deformation and breakage.

[0022] 4. The reinforced biodegradable drainage board provided by this invention is made of biodegradable materials for its biodegradable toothed core, reinforced structure and filter membrane layer. After completing its function, it can degrade in the natural environment, reducing environmental pollution and meeting the requirements of sustainable development.

[0023] 5. The preparation method of the reinforced biodegradable drainage board provided by the present invention optimizes the process steps such as raw material mixing, extrusion molding, reinforcement structure embedding and non-woven fabric composite, ensuring the tight combination of drainage board with reinforcement structure and non-woven fabric layer, improving the overall quality and production efficiency of the product, and making it easy to realize industrial production. Attached Figure Description

[0024] Figure 1 A schematic diagram of the cross-sectional structure of a reinforced biodegradable drainage board; Figure 2 This is a structural diagram of the reinforced structure; The labels in the diagram are as follows: 100, biodegradable toothed core; 200, drainage hole; 300, filter membrane layer; 400, reinforced structure. Detailed Implementation

[0025] The present invention will be further described below with reference to specific embodiments, so that those skilled in the art can better understand and implement the present invention, but the embodiments are not intended to limit the present invention.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0027] Unless otherwise specified, the experimental methods used in the following examples and comparative examples are conventional methods, and the materials and reagents used are commercially available unless otherwise specified. Example 1

[0028] This embodiment provides a reinforced biodegradable drainage board, comprising a biodegradable toothed core, a reinforcing structure embedded within the biodegradable toothed core, and a filter membrane layer composited on both sides of the biodegradable toothed core. The raw material formulation of the biodegradable toothed core is as follows: 42 parts polylactic acid, 28 parts PBAT, 15 parts starch / PLA biodegradable plastic, 8 parts nano-calcium carbonate, 1.5 parts MAN-g-PLA, 4 parts tributyl citrate, and 0.8 parts 2,6-di-tert-butyl-4-methylphenol.

[0029] The method for preparing the reinforced biodegradable drainage board in this embodiment is as follows: 1. Raw material preparation: Weigh the raw materials according to the formula.

[0030] 2. Preparation of activated bulk material: Polylactic acid, PBAT, starch / PLA biodegradable plastic, nano-calcium carbonate and MAH-g-PLA are added to a high-speed mixer and mixed at 90°C for 12 minutes; then added to a twin-screw extruder for melt extrusion. The extruder temperature is set as follows: Zone 1 160°C, Zone 2 185°C, Zone 3 195°C (reaction zone), Zone 4 190°C. During the extrusion process, vacuum exhaust is turned on and the vacuum degree is controlled above -0.08MPa to obtain activated extruded strips with reactive MAH groups.

[0031] 3. Fabrication of the reinforcing structure: A mesh-like reinforcing structure is woven using PHA-co-PCL monofilament fibers, with a mesh size of 5mm × 5mm.

[0032] 4. Fabrication of the filter membrane layer: It is made of PLA / PBAT blended fibers through high-speed carding and needle punching reinforcement, with a basis weight of 80g / m², a longitudinal tensile strength design value of ≥12kN / m, and a transverse tensile strength design value of ≥12kN / m.

[0033] 5. Reactive grafting composite molding: S1. The activated extruded strip is extruded through the die, and a pre-woven reinforcing mesh is introduced at the same time. The moment the melt wraps around the mesh, an interfacial chemical reaction occurs. The die temperature is 170℃ and the pressure is 15MPa.

[0034] S2. The mesh-coated melt is pressed into a continuous toothed core through a pair of cooled gear rollers (temperature 40°C).

[0035] S3. While the core of the board is still hot (approximately 60-80℃), a non-woven filter membrane is introduced and hot-pressed using an auxiliary heating roller (150℃). At this point, the residual MAH groups on the surface of the core react again with the filter membrane fibers to form a strong bond, resulting in a reinforced biodegradable drainage board. Example 2

[0036] The difference between this embodiment and Embodiment 1 is that the content of MAN-g-PLA in the raw material of the biodegradable toothed core is 0.5 parts. Comparative Example 1

[0037] The difference between Comparative Example 1 and Example 1 is that the toothed core material does not contain MAN-g-PLA. Comparative Example 2

[0038] The difference between Comparative Example 2 and Example 1 is that no reinforcing structure is embedded inside the toothed plate core. Comparative Example 3

[0039] The difference between Comparative Example 3 and Example 1 is that a low basis weight (20 g / m², transverse strength < 5 kN / m) nonwoven filter membrane is laminated to the side of the toothed plate core. Performance testing

[0040] Referring to JTS 206-1-2023 and SL / T 235-2012 "Test Procedures for Geosynthetics", the performance of the drainage boards in the examples and comparative examples was tested, and the results are shown in Tables 1-3.

[0041] 1. Tensile strength: The full-section wide strip tensile test (sample width 100mm) was used, with the test direction being longitudinal only. This simulates the stress on the construction insert.

[0042] 2. Filter membrane tensile strength: After peeling the filter membrane from the core plate, cut a 50mm wide strip and test its **longitudinal (MD) and transverse (CMD)** strengths respectively. This simulates the stress on the filter membrane to prevent clogging.

[0043] 3. Peel strength: Tests the force that separates the filter membrane from the core, characterizing the effect of interfacial chemical bonding.

[0044] 4. Water flow rate: Tested under a confining pressure of 350 kPa to characterize the compressive strength and drainage capacity of the core.

[0045] Table 1 Test performance of drainage boards

[0046] Please refer to Table 1. The embodiment uses mesh reinforcement and reactive grafting, which makes its longitudinal tensile strength and water flow better than the comparative example. This allows the drainage board to withstand greater pressure and tension in complex engineering environments, ensuring the long-term stable performance of the drainage function.

[0047] Table 2 Test performance of filter membranes

[0048] Please refer to Table 2. The example uses a biodegradable needle-punched nonwoven fabric with balanced longitudinal and transverse strength as the filter membrane. Its transverse and longitudinal tensile strength is ≥13kN / m, which is better than that of ordinary nonwoven filter membranes, so that it will not deform and break excessively under long-term lateral earth pressure.

[0049] Table 3 Interface Performance

[0050] Peel strength reflects the tightness of the bond between the filter membrane and the toothed core. In this embodiment, by introducing MAH-g-PLA into the toothed core and undergoing a high-temperature grafting reaction, chemical bonds were formed, significantly improving the interfacial strength and achieving a peel strength increase of several times. This fundamentally solves the technical problem of existing hot-pressed composites (mainly physical adhesion) easily delaminating and failing under stress.

[0051] The above-described embodiments are merely preferred embodiments provided to fully illustrate the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are all within the scope of protection of the present invention. The scope of protection of the present invention is defined by the claims.

Claims

1. A reinforced biodegradable drainage board, characterized in that, The reinforced biodegradable drainage board includes a biodegradable toothed core, a reinforcing structure embedded inside the biodegradable toothed core, and a filter membrane layer hot-melt-bonded to both sides of the biodegradable toothed core; wherein, the biodegradable toothed core is made from the following raw materials by reactive extrusion in parts by weight: 40-50 parts polylactic acid, 20-30 parts polybutylene adipate terephthalate, 10-20 parts starch-based biodegradable resin, 0.5-2 parts maleic anhydride-grafted polylactic acid (MAH-g-PLA), 5-10 parts nano-calcium carbonate, 3-8 parts plasticizer, and 0.5-1.5 parts antioxidant.

2. The reinforced biodegradable drainage board according to claim 1, characterized in that, The plasticizer is tributyl citrate; and / or The antioxidant is 2,6-di-tert-butyl-4-methylphenol.

3. The reinforced biodegradable drainage board according to claim 1, characterized in that, The reinforcing structure is a mesh structure woven from biodegradable polyester fibers, which are polyhydroxyalkanoate-polycaprolactone copolymer (PHA-co-PCL) fibers.

4. The reinforced biodegradable drainage board according to claim 1, characterized in that, The filter membrane layer is made of biodegradable polyester fiber needle-punched nonwoven fabric with a basis weight of 70-80 grams, an equivalent pore size of 0.075-0.12 mm, and a vertical permeability coefficient ≥5×10⁻⁶. -3 cm / s.

5. A method for preparing a reinforced biodegradable drainage board as described in claim 1, characterized in that, Includes the following steps: S1. Add the formulated amounts of polylactic acid, polybutylene adipate terephthalate, starch-based biodegradable resin, nano-calcium carbonate, and maleic anhydride-grafted polylactic acid to a high-speed mixer and premix and dehydrate at 80-100℃ for 10-15 minutes; then add it to a twin-screw extruder and melt extrude at 160-200℃ to obtain activated extruded strips with reactive MAH groups; S2. Polyhydroxy fatty acid ester-polycaprolactone copolymer fibers are woven into a reinforced structure using a warp knitting machine; S3. The activated extruded strip is extruded through a die, and the reinforcing structure is introduced at the same time, so that the extruded melt covers the reinforcing structure, and is pressed into a core plate with a toothed groove structure by a calendering and shaping wheel; S4. Two layers of filter membrane are respectively covered on the upper and lower surfaces of the core board, and linear hot-pressed composite is performed by heating rollers to obtain the reinforced biodegradable drainage board.

6. The method for preparing a reinforced biodegradable drainage board according to claim 5, characterized in that, In step S1, vacuum exhaust is turned on during the twin-screw extrusion process, and the vacuum level is maintained above -0.08MPa.

7. The method for preparing a reinforced biodegradable drainage board according to claim 5, characterized in that, In step S3, the mold temperature is controlled at 160-180℃ and the pressure is 10-20MPa.

8. The method for preparing a reinforced biodegradable drainage board according to claim 5, characterized in that, In step S4, the temperature of the hot-pressing composite is 140-160℃ and the pressure is 5-10MPa.

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