High-transparency biodegradable material and preparation method and application thereof

Abstract

The application provides a high-transparency biodegradable material and a preparation method and application thereof, the high-transparency biodegradable material comprises 90-99.9 parts of biodegradable polyester and 0.01-5 parts of talc by weight; the particle size of the talc is 0.4-2.5 microns; and the mass content of magnesium element in the talc is 14.5-20.5%. In the application, the high-transparency biodegradable material has high light transmittance, low haze, good strength and toughness, and can be used for preparing agricultural mulching films and effectively improving the soil warming effect.

Description

Technical Field

[0001] This invention belongs to the field of agricultural film technology, specifically relating to a highly transparent biodegradable material, its preparation method, and its application. Background Technology

[0002] Mulching refers to the practice of covering the soil surface with agricultural plastic film. The greatest effect of mulching cultivation is increasing soil temperature. During the low temperatures of spring, mulching can raise the temperature of the soil layer (0-10 cm deep) by 1-6°C, with some increases exceeding 8°C, after daytime sunlight exposure. Since there are often gaps between the mulch and the soil layer where crops grow, the warming effect on the soil, especially the deeper soil, is not only related to the mulch's light transmittance but also closely linked to its haze. Mulches with high light transmittance and low haze are beneficial in increasing the amount of light irradiation onto the soil, thereby enhancing the soil warming effect of mulching.

[0003] Biodegradable mulch films are a type of plastic mulch film that can degrade under natural environmental conditions through the action of microorganisms. After microorganisms such as bacteria, fungi, and actinomycetes erode the plastic film, their cell growth causes the polymer components to hydrolyze, ionize, or protonate, resulting in mechanical damage and the film breaking down into oligomer fragments. Enzymes secreted by fungi or bacteria decompose or oxidize water-soluble polymers into water-soluble fragments, generating new small molecule compounds, until finally decomposing into CO2 and H2O. Among these biodegradable mulch films, biodegradable polyester mulch films are the most common and have received widespread attention.

[0004] However, existing biodegradable polyester mulch films have low light transmittance (<88%) and high haze (>30%), which prevents them from effectively improving the soil warming effect.

[0005] Therefore, developing a biodegradable polyester material that can improve the light transmittance and reduce the haze of mulch film without affecting its mechanical properties is an urgent problem to be solved in this field. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a highly transparent biodegradable material, its preparation method, and its applications. In this invention, the highly transparent biodegradable material exhibits high light transmittance, low haze, and good strength and toughness.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a highly transparent biodegradable material, comprising, by weight, 90-99.9 parts (e.g., 90, 91, 92, 93, 94, 95, 96, 97, 98, 99 parts, etc.) of biodegradable polyester and 0.01-5 parts (e.g., 0.01, 0.02, 0.05, 0.08, 0.1, 0.2, 0.5 parts) of biodegradable polyester. Talc powder in the following proportions: 0.8 parts, 1 part, 1.2 parts, 1.4 parts, 1.6 parts, 1.8 parts, 2 parts, 2.2 parts, 2.4 parts, 2.6 parts, 2.8 parts, 3 parts, 3.2 parts, 3.4 parts, 3.6 parts, 3.8 parts, 4 parts, 4.2 parts, 4.4 parts, 4.6 parts, 4.8 parts, 5 parts, etc.; the average particle size of the talc powder is 0.4–2.5 μm (e.g., 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 ... The talc powder contains 0.9μm, 1μm, 1.1μm, 1.2μm, 1.3μm, 1.4μm, 1.5μm, 1.6μm, 1.7μm, 1.8μm, 1.9μm, 2μm, 2.1μm, 2.2μm, 2.3μm, 2.4μm, 2.5μm, etc.; the mass percentage of magnesium in the talc powder is 14.5% to 20.5% (for example, it can be 14.5%, 14.6%, 14.8%, 15%, 15%). 2%, 15.4%, 15.6%, 15.8%, 16%, 16.2%, 16.4%, 16.6%, 16.8%, 17%, 17.2%, 17.4%, 17.6%, 17.8%, 18%, 18.2%, 18.4%, 18.6%, 18.8%, 19%, 19.2%, 19.4%, 19.6%, 19.8%, 20%, 20.2%, 20.4%, 20.5%, etc.

[0009] Talc powder is a magnesium silicate mineral belonging to the talc group. Its main component is hydrated magnesium silicate, containing silicon dioxide, magnesium oxide, and water. In addition, it may also contain small amounts of calcium oxide, aluminum oxide, iron oxide, titanium dioxide, etc. The crystal structure of talc powder is a layered structure, composed of alternating silicon-oxygen tetrahedra and magnesium-oxygen octahedra. In this invention, by selecting talc powder with specific particle size and magnesium content, the proportion of magnesium-oxygen octahedra is adjusted to maximize the slippage ability of the talc powder's lamellar structure, thereby promoting the dispersion and homogenization of components during extrusion and blown film production. This effectively improves the light transmittance of the biodegradable material while reducing its haze. Furthermore, the highly transparent biodegradable material can maintain good strength and toughness. In addition, the talc powder can also act as a lubricant, providing a lubricating effect.

[0010] Preferably, the talc powder has a particle size of 0.5 to 1.5 μm.

[0011] Preferably, the talc powder contains 16-18% magnesium by mass.

[0012] Preferably, the talc powder, by mass percentage, comprises 50-70% (e.g., 50%, 52%, 54%, 56%, 58%, 60%, 62%, 64%, 66%, 68%, 70%, etc.) silica, and 23.5-35% (e.g., 23.5%, 24%, 24.5%, 25%, 25.5%, 26%, 26.5%, 27%, 27.5%, 28%, 28.5%, 29%, 29.5%, 30%, 30.5%, 31%, 31%) silica. Magnesium oxide (0.5%, 32%, 32.5%, 33%, 33.5%, 34%, 34.5%, 35%, etc.), water of crystallization (8.1-12%, e.g., 8.1%, 8.2%, 8.5%, 8.8%, 9%, 9.5%, 10%, 10.5%, 11%, 11.5%, 12%, etc.), and the balance (e.g., 0%, 0.2%, 0.4%, 0.6%, 0.8%, 1%, 1.2%, 1.4%, 1.6%, 1.8%, 2%, etc.).

[0013] Preferably, the balance component includes at least one of calcium oxide, aluminum oxide, iron oxide, or titanium dioxide.

[0014] Preferably, the biodegradable polyester comprises biodegradable homopolymer polyester and / or biodegradable copolymer polyester.

[0015] In this invention, according to ISO 1133-1:2022 standard, under the conditions of 190°C and 2.16 kg, the melt index of the biodegradable polyester is 1 to 30 g / 10 min, for example, it can be 1 g / 10 min, 2 g / 10 min, 3 g / 10 min, 5 g / 10 min, 8 g / 10 min, 12 g / 10 min, 15 g / 10 min, 18 g / 10 min, 22 g / 10 min, 25 g / 10 min, 28 g / 10 min, 30 g / 10 min, etc.

[0016] Preferably, the biodegradable homopolymer includes any one or a combination of at least two of polylactic acid, polyhydroxyacetic acid, poly-3-hydroxybutyric acid, poly-3-hydroxyvalerate, poly-3-hydroxyhexanoate, polycaprolactone, polyhydroxybutyl ester, polyvalerate, or polypropylene carbonate.

[0017] Preferably, the biodegradable copolyester comprises any one or a combination of at least two of polyethylene succinate, polybutylene succinate, polybutylene succinate coadipate, polybutylene terephthalate coadipate, and polybutylene terephthalate coadipate.

[0018] Preferably, the highly transparent biodegradable material further includes 0 to 10 parts of other additives by weight, such as 0.1 parts, 0.2 parts, 0.5 parts, 0.8 parts, 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, etc.

[0019] Preferably, the additives include any one or a combination of at least two of the following: antioxidants, light stabilizers, anti-hydrolysis agents, impact modifiers, lubricants, plasticizers, antistatic agents, release agents, pigments, or starch.

[0020] In this invention, the antioxidants include, but are not limited to, at least one of hindered amine antioxidants, hindered phenolic antioxidants, or phosphite antioxidants; exemplary, they include, but are not limited to, at least one of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (antioxidant 1010), tris[2,4-di-tert-butylphenyl] phosphite (antioxidant 168), octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (antioxidant 1076), 4,4′-bis(α,α-dimethylbenzyl)diphenylamine (antioxidant 445), and N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexamethylenediamine (antioxidant 1098).

[0021] In this invention, the light stabilizer includes, but is not limited to, hindered amine light stabilizers; exemplary examples include: poly-{[6-[(1,1,3,3-tetramethylbutyl)-imino]-1,3,5-triazine-2,4-diyl][2-(2,2,6,6-tetramethylpiperidinyl)-azyl]-hexylene-[4-(2,2,6,6-tetramethylpiperidinyl)-amino]} (UV-944), 2-(2-hydroxy-3',5'-dicumylphenyl)benzotriazole (UV-234), di(2,2,6,6-tetramethyl-4-piperidinyl) sebacate (770DF), 2-[2-hydroxy-3,5-di(1,1-dimethylpropylphenyl)]-2H-benzotriazole (UV-328), and 2-hydroxy-4-n-octyloxybenzophenone (UV-531).

[0022] In this invention, the anti-hydrolysis agent includes, but is not limited to, polycarbodiimide anti-hydrolysis agents.

[0023] In this invention, the impact modifier includes, but is not limited to, at least one of ethylene terpolymer (PTW) and styrene-ethylene / butene-styrene block copolymer (SEBS).

[0024] In this invention, the lubricant includes, but is not limited to, at least one of ethylene bis-stearamide (EBS), erucamide, zinc stearate, or silicone oil.

[0025] In this invention, the plasticizer includes, but is not limited to, at least one of glycerol, citric acid, butyl citrate, or epoxidized soybean oil.

[0026] In this invention, the antistatic agent includes permanent antistatic agents, such as polyethylene oxide, polyether ester amide, (meth)acrylate copolymers containing quaternary ammonium salts, and organosilicon containing hydrophilic groups; exemplary, including but not limited to at least one of Sanyo Chemicals' PELESTAT-230, CHEMISTAT 3500, CHEMISTAT 3500, PELECTRON PVH, PELESTAT NC6321, and PELESTAT 300.

[0027] In this invention, the release agent includes, but is not limited to, at least one of silicone oil, paraffin wax, white mineral oil, or petrolatum.

[0028] In this invention, the pigment includes, but is not limited to, at least one of carbon black, black pigment, titanium dioxide, zinc sulfide, phthalocyanine blue, or fluorescent orange.

[0029] Preferably, the biodegradable polyester in the high-transparency biodegradable material has a mass percentage content of ≥80%, for example, 80%, 82%, 84%, 86%, 88%, 90%, 92%, 94%, 96%, 98%, 99%, etc.; as a preferred technical solution of the present invention, the high-transparency biodegradable material comprises, by weight, 92-98 parts of biodegradable polyester, 0.1-3 parts of talc, and 0.1-5 parts of other additives. Preferably, the light transmittance of the high-transparency biodegradable material is >88%.

[0030] Preferably, the haze of the highly transparent biodegradable material is <30%.

[0031] In a second aspect, the present invention provides a method for preparing the highly transparent biodegradable material according to the first aspect, the method comprising the following steps:

[0032] Biodegradable polyester is mixed with talc and extruded to obtain the high-transparency biodegradable material.

[0033] Preferably, the mixed material also includes other additives.

[0034] Preferably, the extrusion temperature is 155-230°C, for example, it can be 155°C, 160°C, 165°C, 170°C, 175°C, 180°C, 185°C, 190°C, 195°C, 200°C, 210°C, 220°C, 230°C, etc.

[0035] Thirdly, the present invention provides a biodegradable mulch film, the biodegradable mulch film comprising the high-transparency biodegradable material according to the first aspect.

[0036] In this invention, the preparation method of the biodegradable mulch film includes: drying the high-transparency biodegradable material at 70-85°C for 2-4 hours, and then blow molding it through a single-screw extruder with an aspect ratio of 25:1 and an extrusion die temperature of 150-180°C to obtain the biodegradable mulch film.

[0037] In this invention, the thickness of the biodegradable mulch film is 10-20 μm, for example, it can be 10 μm, 12 μm, 14 μm, 16 μm, 18 μm, 20 μm, etc.

[0038] Fourthly, the present invention provides the application of the high-transparency biodegradable material according to the first aspect or the biodegradable mulch film according to the second aspect in agricultural materials.

[0039] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0040] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0041] The high-transparency biodegradable material provided by this invention can effectively improve the light transmittance of biodegradable materials and reduce their haze by selecting talc powder with specific particle size and magnesium content and compounding it with biodegradable polyester in a specific amount. Furthermore, the high-transparency biodegradable material can also maintain good strength and toughness. Detailed Implementation

[0042] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0043] The materials used in all embodiments and comparative examples of this invention are as follows:

[0044] Biodegradable polyester:

[0045] Polybutylene terephthalate-adipate (PBAT, Zhuhai Kingfa Biomaterials Co., Ltd.

[0046] Polybutylene succinate (PBS) Zhuhai Kingfa Biomaterials Co., Ltd.) Polylactic acid (PLA) Zhuhai Kingfa Biomaterials Co., Ltd.

[0047] Polycaprolactone (PCL) (Ingevity, UK).

[0048] Other additives:

[0049] Polymerized carbodiimide anti-hydrolysis agent (Stabaxol P, Rheinland, Germany) in a mass ratio of 1:1:1, and phosphite antioxidant. A mixture of hindered amine light stabilizer (UV-944); all additives used were commercially available and the same type was used in all examples and comparative examples.

[0050] In this invention, talc powder of different particle sizes can be obtained by grinding and sieving commercially available talc powder;

[0051] Talc powder with a magnesium content of 13% by mass is mainly composed of: 21.7% magnesium oxide, 71.1% silicon dioxide, 5.2% water of crystallization, and 2% other impurities (1.2% calcium oxide, 0.05% ferric oxide, and 0.75% aluminum oxide).

[0052] Talc powder with a magnesium content of 15% by mass is mainly composed of: 25% magnesium oxide, 66.7% silicon dioxide, 6.7% water of crystallization, and 1.6% other impurities (0.8% calcium oxide, 0.1% ferric oxide, and 0.7% aluminum oxide).

[0053] Talc powder with a magnesium content of 16% by mass mainly consists of: 26.7% magnesium oxide, 64.4% silicon dioxide, 7.1% water of crystallization, and 1.8% other impurities (1.5% aluminum oxide, 0.2% calcium oxide, and 0.1% ferric oxide).

[0054] Talc powder with a magnesium content of 18% by mass is mainly composed of: 30% magnesium oxide, 60% silicon dioxide, 9% water of crystallization, and 1% other impurities (0.2% calcium oxide, 0.05% ferric oxide, and 0.75% aluminum oxide).

[0055] The composition of talc powder with a magnesium content of 19% by mass is: 31.7% magnesium oxide, 57.7% silicon dioxide, 9.6% water of crystallization, and 1% other impurities (0.5% calcium oxide, 0.04% ferric oxide, and 0.46% aluminum oxide);

[0056] Talc powder with a magnesium content of 20% by mass mainly consists of: 33.3% magnesium oxide, 55.6% silicon dioxide, 10.6% water of crystallization, and 0.5% other impurities (0.1% calcium oxide, 0.02% ferric oxide, and 0.38% aluminum oxide).

[0057] The main components of talc powder with a magnesium content of 28% are: 46.7% magnesium oxide, 45.3% silicon dioxide, 7% water of crystallization, and 1% other impurities (0.6% calcium oxide, 0.1% ferric oxide, and 0.3% aluminum oxide).

[0058] Talc powder with a magnesium content of 30% by mass is mainly composed of: 50% magnesium oxide, 41.1% silicon dioxide, 7.6% water of crystallization, and 1.3% other impurities (0.8% calcium oxide, 0.2% ferric oxide, and 0.3% aluminum oxide).

[0059] Talc powder with different magnesium mass percentages can be obtained by screening or compounding products from different mineral sources.

[0060] Examples 1-14, Comparative Examples 1-6

[0061] Examples 1-14 and Comparative Examples 1-6 provide a high-transparency biodegradable material. The specific formulation of the high-transparency biodegradable material is shown in Tables 1 and 2 by weight. The preparation method of the high-transparency biodegradable material includes: mixing biodegradable polyester, talc and other additives evenly, and then extruding and granulating at 180°C to obtain the high-transparency biodegradable material.

[0062] Table 1

[0063]

[0064] Table 2

[0065]

[0066] Performance testing

[0067] The highly transparent biodegradable materials provided in Examples 1-14 and Comparative Examples 1-6 were dried at 85°C for 3 hours and then blow-molded into 12-micron thick mulch films using a single-screw extruder with an aspect ratio of 25:1 and an extrusion die temperature of 160°C. The following tests were then conducted.

[0068] (1) Talc particle size: The particle size was tested using a scanning electron microscope. The specific test method included: attaching an appropriate size mulch film sample to the sample stage, using an ion sputtering instrument to plate the sample with gold target material, observing the sheet-like objects on the sample surface using a scanning electron microscope, and using Nano Measurer software to perform statistical analysis on the size distribution, with the statistical range being a typical field of view of 200×200μm.

[0069] (2) Magnesium content test: The magnesium content of the talc powder was tested by microwave digestion method: 0.1g of mulch film sample was weighed and placed in a microwave digestion vessel. 5mL of nitric acid was added to completely submerge the sample. Then, 1.0mL of hydrogen peroxide was slowly added. After reacting for 2min, the lid was closed, the digestion vessel was sealed, and the vessel was placed in a microwave digestion furnace for digestion. After cooling to room temperature, the solution in the digestion vessel was filtered through a 0.45μm filter membrane and transferred to a volumetric flask. The solution was diluted to 50mL with distilled water and tested using ICP-OES.

[0070] (3) Tensile strength and elongation at break: The tensile strength of the mulch film in the transverse (TD) and longitudinal (MD) directions was determined according to the test standard GB / T1040.2-2006;

[0071] (4) Tear strength: The tear strength of the mulch film in the transverse (TD) and longitudinal (MD) directions was determined according to the test standard GB / T 16578.2-2009;

[0072] (5) Light transmittance and haze: Tested in accordance with GB / T 2410-2008 standard.

[0073] The specific test results are shown in Table 3.

[0074] Table 3

[0075]

[0076] As shown in Table 3, the high-transparency biodegradable material provided by this invention, through the compounding of talc powder with specific mesh size and magnesium content with biodegradable polyester in specific amounts, can promote the dispersion and homogenization of components during extrusion and blown film production, effectively improving the light transmittance of the biodegradable polyester mulch film while reducing its haze, and giving the biodegradable mulch film good strength and toughness; it can effectively increase the amount of light irradiation on the soil, thereby improving the warming effect of mulch film covering on the soil; the mulch film including the biodegradable material has a light transmittance >88%, haze <30%, tensile strength: MD≥26MPa, TD≥17MPa; elongation at break: MD≥169%, TD≥211%; tear strength: MD≥239MPa, TD≥899MPa.

[0077] As can be seen from the comparison of the examples and comparative examples, when the particle size or magnesium content of talc powder is not within the specified range, the light transmittance of the mulch film decreases, the haze increases, and the mechanical properties also decrease.

[0078] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A highly transparent, biodegradable material, characterized in that, By weight, the high-transparency biodegradable material comprises 90-99.9 parts of biodegradable polyester and 0.1-1 parts of talc. The average particle size of the talc powder is 0.5~1μm; The magnesium content in the talc powder is 15-18% by mass.

2. The high-transparency biodegradable material according to claim 1, characterized in that, The talc powder comprises, by mass percentage, 50-70% silica, 23.5-30% magnesium oxide, 8.1-12% water of crystallization and 0-2% balance.

3. The high-transparency biodegradable material according to claim 2, characterized in that, The balance component includes at least one of calcium oxide, aluminum oxide, iron oxide, or titanium dioxide.

4. The high-transparency biodegradable material according to claim 1, characterized in that, The biodegradable polyester includes biodegradable homopolymer polyester and / or biodegradable copolymer polyester.

5. The high-transparency biodegradable material according to claim 4, characterized in that, The biodegradable homopolymer includes any one or a combination of at least two of polylactic acid, polyhydroxyacetic acid, poly-3-hydroxybutyric acid, poly-3-hydroxyvalerate, poly-3-hydroxyhexanoate, polycaprolactone, polyhydroxybutyl ester, polyvalerol, or polypropylene carbonate.

6. The high-transparency biodegradable material according to claim 4, characterized in that, The biodegradable copolyester includes any one or a combination of at least two of the following: polyethylene succinate, polybutylene succinate, polybutylene succinate coadipate, polybutylene terephthalate coadipate, and polybutylene terephthalate coadipate.

7. The high-transparency biodegradable material according to claim 1, characterized in that, The highly transparent biodegradable material also includes 0 to 10 parts of other additives by weight.

8. The high-transparency biodegradable material according to claim 7, characterized in that, The additives include any one or a combination of at least two of the following: antioxidants, light stabilizers, anti-hydrolysis agents, impact modifiers, lubricants, plasticizers, antistatic agents, release agents, pigments, or starch.

9. The high-transparency biodegradable material according to claim 1, characterized in that, By weight, the high-transparency biodegradable material comprises 92-98 parts of biodegradable polyester, 0.1-1 parts of talc, and 0.1-5 parts of other additives.

10. The high-transparency biodegradable material according to claim 1, characterized in that, The light transmittance of the highly transparent biodegradable material is >88%.

11. The high-transparency biodegradable material according to claim 1, characterized in that, The haze of the highly transparent biodegradable material is <30%.

12. A method for preparing a highly transparent biodegradable material according to any one of claims 1 to 11, characterized in that, The preparation method includes the following steps: Biodegradable polyester is mixed with talc and extruded to obtain the high-transparency biodegradable material.

13. The preparation method according to claim 12, characterized in that, The mixed materials also include other additives.

14. The preparation method according to claim 12, characterized in that, The extrusion temperature is 155~230℃.

15. A biodegradable mulch film, characterized in that, The biodegradable mulch film includes the highly transparent biodegradable material according to any one of claims 1 to 11.

16. The application of a high-transparency biodegradable material according to any one of claims 1 to 11 or a biodegradable mulch film according to claim 15 in agricultural materials.

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