Weather-resistant PBST bamboo powder composite biodegradable agricultural mulching film material and preparation method

Abstract

The application relates to the technical field of PBST polyesters, and discloses a weather-resistant PBST bamboo powder composite biodegradable agricultural mulching film material and a preparation method. The weather-resistant PBST bamboo powder composite biodegradable agricultural mulching film material comprises 80-90 parts by weight of polybutylene succinate terephthalate, 10-20 parts by weight of modified bamboo powder-nano titanium dioxide, 0.2-0.5 parts by weight of an antioxidant, and 0.2-0.6 parts by weight of a lubricant. The sulfonic acid modifier contains multiple sulfonic acid groups, which form hydrogen bonds and other actions with hydroxyl groups on the surfaces of the bamboo powder and the nano titanium dioxide, and at the same time, long carbon chains are stretched outward to play the role of a dispersant, improve the dispersibility of the bamboo powder and the nano titanium dioxide, improve the tensile property of the agricultural mulching film material, reduce the water vapor transmission amount of the mulching film material, and improve the water-blocking and moisture-retention performance.

Description

Technical Field

[0001] This invention relates to the field of PBST polyester technology, specifically to a weather-resistant PBST bamboo powder composite biodegradable agricultural mulch film material and its preparation method. Background Technology

[0002] Agricultural mulch films primarily serve to retain water and moisture, maintain and increase temperature, prevent pests and diseases, and improve yield and quality. Their materials are mainly polyethylene and polypropylene, but these polyolefin films are difficult to biodegrade, causing environmental pollution when discarded in farmland and the natural environment. Developing biodegradable mulch films is a research hotspot, with materials such as polylactic acid, polycarbonate, and polybutylene terephthalate (PBST) being explored. PBST, in particular, possesses good mechanical strength and toughness, is fully biodegradable, and is environmentally friendly, making it widely used. However, PBST's poor barrier properties and water-retaining capacity limit its application in agricultural film materials.

[0003] Bamboo powder is a renewable, inexpensive, readily available, and biodegradable resource. Mixing bamboo powder with plastics yields high-performance, environmentally friendly bamboo-plastic composites. Nano-titanium dioxide possesses high mechanical strength and excellent UV resistance; adding it to plastics can improve their mechanical properties and UV resistance. However, bamboo powder has poor interfacial compatibility with PBST, and nano-titanium dioxide tends to agglomerate, resulting in poor dispersion in PBST, which is detrimental to improving the mechanical properties and water-blocking and moisture-retaining properties of the PBST membrane material. Summary of the Invention

[0004] This invention solves the problem of poor compatibility between titanium dioxide, bamboo powder and PBST resin, and at the same time improves the mechanical, water-blocking and moisture-retaining properties of PBST.

[0005] The technical solution of the present invention is: a weather-resistant PBST bamboo powder composite biodegradable agricultural mulch film material, comprising 80-90 parts by weight of polybutylene terephthalate-butylene succinate, 10-20 parts by weight of modified bamboo powder-nano titanium dioxide, 0.2-0.5 parts by weight of antioxidant, and 0.2-0.6 parts by weight of lubricant.

[0006] The preparation method of weather-resistant PBST bamboo powder composite biodegradable agricultural mulch film material is as follows: (1) Add diethanolamine and glycidyl ether to isopropanol, heat to 70-80℃, stir and reflux for 6-8 hours, remove low-boiling substances by vacuum distillation, add water and dichloromethane, shake and extract, concentrate the organic phase under reduced pressure, and dry to obtain the modifier precursor.

[0007] (2) Add the modifier precursor, 1,4-butanesulfonic acid lactone, and sodium hydroxide aqueous solution to 1,4-dioxane, heat to 70-85℃, stir for 6-8h, concentrate the solution under reduced pressure to remove 1,4-dioxane, acidify with hydrochloric acid dropwise, filter the solid and add it to water, recrystallize and purify to obtain sulfonic acid modifier.

[0008] (3) Add bamboo powder, nano titanium dioxide and sulfonic acid modifier to water, stir and mix at 20-40℃ for 2-3 hours, filter, wash the solid with water, and dry to obtain modified bamboo powder-nano titanium dioxide.

[0009] (4) Polybutylene terephthalate-butylene succinate, modified bamboo powder-nano titanium dioxide, antioxidant and lubricant are mixed and extruded through a screw extruder. The temperature of each zone is 140-180℃. After granulation, the granules are blown into a film by a blow molding machine with a blow ratio of 2-3 and the temperature of zones 1-3 of the barrel is 150-180℃ to obtain weather-resistant PBST bamboo powder composite biodegradable agricultural mulch film material.

[0010] Preferably, the antioxidant is antioxidant 1726 or antioxidant 2246.

[0011] Preferably, the lubricant is any one or a combination of erucamide and oleamide.

[0012] Preferably, the molar ratio of diethanolamine to glycidyl ether in (1) is (1-1.1):1.

[0013] Preferably, in (1), the glycidyl ether includes dodecyl glycidyl ether, tetradecyl glycidyl ether, hexadecyl glycidyl ether, and octadecyl glycidyl ether.

[0014] Preferably, in (2), the amounts of the modifier precursor, 1,4-butanesulfonate lactone, and sodium hydroxide are 1:(3-3.3):(6-7).

[0015] Preferably, in (3), the amount of bamboo powder is 100 parts by weight, the amount of nano titanium dioxide is 1.5-5 parts by weight, and the amount of sulfonic acid modifier is 3-10 parts by weight.

[0016] Preferably, the bamboo powder in (3) has a particle size of 60-200 mesh.

[0017] Preferably, the particle size of nano-titanium dioxide in (3) is 200-500 nm.

[0018] The beneficial technical effects of this invention are as follows: The sulfonic acid modifier contains multiple sulfonic acid groups, which form hydrogen bonds with the hydroxyl groups on the surface of bamboo powder and nano-titanium dioxide, respectively. Simultaneously, the long carbon chains extend outwards, acting as a dispersant to improve the dispersibility of bamboo powder and nano-titanium dioxide, and enhance the compatibility of bamboo powder, nano-titanium dioxide, and PBST, resulting in higher tensile properties for agricultural mulch film materials. Nano-titanium dioxide has excellent ultraviolet absorption properties; after modification, its uniform dispersion in the mulch film material can improve the material's resistance to ultraviolet aging and weathering.

[0019] This invention uses a modifier containing multiple sulfonic acid groups to bridge bamboo powder and nano-titanium dioxide, improving the interfacial interaction between the bamboo powder and nano-titanium dioxide. This allows the nano-titanium dioxide to be uniformly dispersed in the gaps between large bamboo powder particles, reducing the porosity between bamboo powder particles and preventing water vapor from passing through the mulch film. Furthermore, the long carbon chains have strong hydrophobicity, further reducing the water vapor permeability of the mulch film material, thus improving the water-blocking and moisture-retaining properties of the mulch film material. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing specific embodiments only and are not intended to limit the scope of protection of this invention.

[0021] The bamboo powder below contains 55% by mass of particles with an average size of 60 mesh, 30% by mass of particles with an average size of 120 mesh, and 15% by mass of particles with an average size of 200 mesh. It should be dried before use. The nano-titanium dioxide has an average particle size of 300 nm.

[0022] Example 1 (1) Diethanolamine and hexadecyl glycidyl ether with a molar ratio of 1.1:1 were added to isopropanol (the ratio of isopropanol to diethanolamine was 1L:0.5mol). The mixture was heated to 70°C, stirred and refluxed for 8 hours. Low-boiling substances were removed by vacuum distillation. Water and dichloromethane were added, and the mixture was shaken and extracted. The organic phase was concentrated under reduced pressure and dried to obtain the modifier precursor.

[0023] (2) Add an aqueous solution (6 mol / L) of the modifier precursor, 1,4-butanesulfonic acid lactone, and sodium hydroxide to 1,4-dioxane (1,4-dioxane and modifier precursor in a ratio of 1 L: 0.3 mol), controlling the molar ratio of the modifier precursor, 1,4-butanesulfonic acid lactone, and sodium hydroxide to 1:3:7; heat to 85°C, stir for 6 h, concentrate the solution under reduced pressure to remove 1,4-dioxane, add 8% hydrochloric acid dropwise to acidify the pH to 3, filter, add the solid to water, recrystallize and purify to obtain the sulfonic acid modifier, the reaction formula is: .

[0024] (3) Add 100 parts by weight of bamboo powder, 1.5 parts by weight of nano titanium dioxide and 3 parts by weight of sulfonic acid modifier to 500 parts by weight of water, stir and mix at 30°C for 2 hours, filter, wash the solid with water, and dry to obtain modified bamboo powder-nano titanium dioxide.

[0025] (4) 90 parts by weight of polybutylene terephthalate-butylene succinate (brand name Sinopec PBST-MD102, the same below), 10 parts by weight of modified bamboo powder-nano titanium dioxide, 0.5 parts by weight of antioxidant 1726 and 0.6 parts by weight of erucamide were mixed and extruded through a screw extruder. The temperatures of each zone were 140℃, 160℃, 175℃, 180℃ and 175℃. After granulation, the granules were blown into a film by a blow molding machine with a blow ratio of 2.5. The temperatures of zones 1-3 of the barrel were 150℃, 180℃ and 180℃, respectively, to obtain weather-resistant PBST bamboo powder composite biodegradable agricultural mulch film material.

[0026] Example 2 (1) Diethanolamine and dodecyl glycidyl ether with a molar ratio of 1.1:1 were added to isopropanol (the ratio of isopropanol to diethanolamine was 1L:0.6mol). The mixture was heated to 80°C, stirred and refluxed for 6 hours. Low-boiling substances were removed by vacuum distillation. Water and dichloromethane were added, and the mixture was shaken and extracted. The organic phase was concentrated under reduced pressure and dried to obtain the modifier precursor.

[0027] (2) Add an aqueous solution (concentration 6 mol / L) of modifier precursor, 1,4-butanesulfonic acid lactone and sodium hydroxide to 1,4-dioxane (the ratio of 1,4-dioxane and modifier precursor is 1 L: 0.25 mol), and control the amount of modifier precursor, 1,4-butanesulfonic acid lactone and sodium hydroxide to be 1:3.3:6.3; heat to 70℃, stir and react for 8 h, concentrate the solution under reduced pressure to remove 1,4-dioxane, add 8% hydrochloric acid dropwise to acidify the pH to 3, filter the solid and add it to water, recrystallize and purify to obtain sulfonic acid modifier.

[0028] (3) Add 100 parts by weight of bamboo powder, 3 parts by weight of nano titanium dioxide and 6 parts by weight of sulfonic acid modifier to 600 parts by weight of water, stir and mix at 20°C for 3 hours, filter and wash the solid with water, and dry to obtain modified bamboo powder-nano titanium dioxide.

[0029] (4) 90 parts by weight of polybutylene terephthalate-butylene succinate, 10 parts by weight of modified bamboo powder-nano titanium dioxide, 0.3 parts by weight of antioxidant 1726 and 0.4 parts by weight of erucamide were mixed and extruded through a screw extruder. The temperatures of each zone were 140℃, 160℃, 175℃, 180℃ and 175℃. After granulation, the granules were blown into a film by a blow molding machine with a blow ratio of 2.5. The temperatures of zones 1-3 of the barrel were 150℃, 180℃ and 180℃, respectively, to obtain weather-resistant PBST bamboo powder composite biodegradable agricultural mulch film material.

[0030] In Example 3, diethanolamine and dodecyl glycidyl ether with a molar ratio of 1.1:1 were added to isopropanol (isopropanol to diethanolamine ratio of 1L:0.6mol). The mixture was heated to 75°C, stirred, refluxed, and reacted for 6 hours. Low-boiling substances were removed by vacuum distillation. Water and dichloromethane were added, and the mixture was extracted by shaking. The organic phase was concentrated under reduced pressure and dried to obtain the precursor of the modifier.

[0031] (2) Add an aqueous solution (concentration 6 mol / L) of modifier precursor, 1,4-butanesulfonic acid lactone and sodium hydroxide to 1,4-dioxane (the ratio of 1,4-dioxane to modifier precursor is 1 L: 0.25 mol), and control the amount of modifier precursor, 1,4-butanesulfonic acid lactone and sodium hydroxide to be 1:3:6; heat to 70℃, stir and react for 8 h, concentrate the solution under reduced pressure to remove 1,4-dioxane, add 8% hydrochloric acid dropwise to acidify the pH to 3, filter the solid and add it to water, recrystallize and purify to obtain sulfonic acid modifier.

[0032] (3) Add 100 parts by weight of bamboo powder, 5 parts by weight of nano titanium dioxide, and 10 parts by weight of sulfonic acid modifier (prepared according to the method of Example 2) to 650 parts by weight of water, stir and mix at 40°C for 2 hours, filter, wash the solid with water, and dry to obtain modified bamboo powder-nano titanium dioxide.

[0033] (4) Mix 80 parts by weight of polybutylene terephthalate-butylene succinate, 20 parts by weight of modified bamboo powder-nano titanium dioxide, 0.2 parts by weight of antioxidant 1726 and 0.2 parts by weight of erucamide, and extrude them through a screw extruder. The temperatures of each zone are 140℃, 160℃, 175℃, 180℃ and 175℃. After granulation, blow the granules into a film through a blow molding machine. The blow ratio is 2.5 and the temperatures of zones 1-3 of the barrel are 150℃, 180℃ and 180℃, respectively, to obtain weather-resistant PBST bamboo powder composite biodegradable agricultural mulch film material.

[0034] Comparative Example 1 (1) Add 100 parts by weight of bamboo powder and 1.5 parts by weight of nano titanium dioxide to 500 parts by weight of water, stir and mix at 30°C for 2 hours, filter, wash the solid with water, and dry to obtain bamboo powder-nano titanium dioxide.

[0035] (2) 90 parts by weight of polybutylene terephthalate-butylene succinate, 10 parts by weight of bamboo powder-nano titanium dioxide, 0.5 parts by weight of antioxidant 1726 and 0.6 parts by weight of erucamide were mixed and extruded through a screw extruder. The temperatures of each zone were 140℃, 160℃, 175℃, 180℃ and 175℃. After granulation, the granules were blown into a film by a blow molding machine with a blow ratio of 2.5. The temperatures of zones 1-3 of the barrel were 150℃, 180℃ and 180℃, respectively, to obtain weather-resistant PBST bamboo powder composite biodegradable agricultural mulch film material.

[0036] Comparative Example 2 (1) Add 100 parts by weight of bamboo powder, 1.5 parts by weight of nano titanium dioxide and 3 parts by weight of sodium dodecyl sulfonate to 500 parts by weight of water, stir and mix at 30°C for 2 hours, filter, wash the solid with water, and dry to obtain modified bamboo powder-nano titanium dioxide.

[0037] (2) 90 parts by weight of polybutylene terephthalate-butylene succinate, 10 parts by weight of modified bamboo powder-nano titanium dioxide, 0.5 parts by weight of antioxidant 1726 and 0.6 parts by weight of erucamide were mixed and extruded through a screw extruder. The temperatures of each zone were 140℃, 160℃, 175℃, 180℃ and 175℃. After granulation, the granules were blown into a film by a blow molding machine with a blow ratio of 2.5. The temperatures of zones 1-3 of the barrel were 150℃, 180℃ and 180℃, respectively, to obtain weather-resistant PBST bamboo powder composite biodegradable agricultural mulch film material.

[0038] Comparative Example 3 (1) An aqueous solution (concentration 6 mol / L) of trimethylolpropane, 1,4-butanesulfonic acid lactone, and sodium hydroxide was added to 1,4-dioxane (the ratio of 1,4-dioxane to trimethylolpropane was 1 L: 0.3 mol), controlling the molar ratio of trimethylolpropane, 1,4-butanesulfonic acid lactone, and sodium hydroxide to be 1:3:7; the mixture was heated to 85 °C and stirred for 6 h. The solution was then concentrated under reduced pressure to remove 1,4-dioxane, and the pH was acidified to 3 by adding 8% hydrochloric acid. After filtration, the solid was added to water and recrystallized to obtain a sulfonic acid modifier with the following structural formula: .

[0039] (2) Add 100 parts by weight of bamboo powder, 1.5 parts by weight of nano titanium dioxide and 3 parts by weight of sulfonic acid modifier to 500 parts by weight of water, stir and mix at 30°C for 2 hours, filter, wash the solid with water, and dry to obtain modified bamboo powder-nano titanium dioxide.

[0040] (3) 90 parts by weight of polybutylene terephthalate-butylene succinate, 10 parts by weight of modified bamboo powder-nano titanium dioxide, 0.5 parts by weight of antioxidant 1726 and 0.6 parts by weight of erucamide were mixed and extruded through a screw extruder. The temperatures of each zone were 140℃, 160℃, 175℃, 180℃ and 175℃. After granulation, the granules were blown into a film by a blow molding machine with a blow ratio of 2.5. The temperatures of zones 1-3 of the barrel were 150℃, 180℃ and 180℃, respectively, to obtain weather-resistant PBST bamboo powder composite biodegradable agricultural mulch film material.

[0041] Tensile properties were tested according to GB / T 1040.3-2006. Water vapor transmission rate was tested according to GB / T 1037-2021.

[0042]

[0043] The sulfonic acid modifiers in each embodiment contain multiple sulfonic acid groups, which form hydrogen bonds with the hydroxyl groups on the surface of bamboo powder and nano-titanium dioxide, respectively. At the same time, the long carbon chains extend outward, acting as a dispersant to improve the dispersibility of bamboo powder and nano-titanium dioxide and enhance the compatibility of bamboo powder, nano-titanium dioxide, and PBST, giving the agricultural mulch film material higher tensile properties. By using modifiers containing multiple sulfonic acid groups, bamboo powder and nano-titanium dioxide are bridged, improving the interfacial interaction between bamboo powder and nano-titanium dioxide, allowing nano-titanium dioxide to be uniformly dispersed in the gaps between large bamboo powder particles, reducing the porosity between bamboo powder particles, preventing water vapor from passing through the mulch film, and the long carbon chains have strong hydrophobicity, further reducing the water vapor permeability of the mulch film material, thus improving its water-blocking and moisture-retaining properties.

[0044] Compared with Example 1, the bamboo powder and nano titanium dioxide in Comparative Example 1 had poor dispersibility in polybutylene terephthalate (PBST), resulting in lower tensile strength and elongation at break of the agricultural mulch film. Furthermore, the large gaps between the large bamboo powder particles led to a higher water vapor permeability of the mulch film, resulting in poor water resistance and moisture retention performance.

[0045] Comparative Example 2 uses conventional sodium dodecyl sulfonate to modify bamboo powder and nano titanium dioxide. It contains only one sulfonic acid group and cannot bridge the bamboo powder and nano titanium dioxide. The interfacial interaction between bamboo powder and nano titanium dioxide is weak. The nano titanium dioxide is not uniformly dispersed in the gaps between large bamboo powder particles and does not effectively reduce the porosity between bamboo powder particles. As a result, the water vapor permeability of the mulch film material is greater than that in Example 1, and the water-blocking and moisture-retaining performance is better.

[0046] The sulfonic acid modifier in Comparative Example 3 does not contain long carbon chains, has poor dispersion effect, low tensile properties of the mulch film material, and high water vapor permeability.

[0047] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A weather-resistant PBST bamboo powder composite biodegradable agricultural mulch film material, characterized in that, The weather-resistant PBST bamboo powder composite biodegradable agricultural mulch film material includes 80-90 parts by weight of polybutylene terephthalate-butylene succinate, 10-20 parts by weight of modified bamboo powder-nano titanium dioxide, 0.2-0.5 parts by weight of antioxidant, and 0.2-0.6 parts by weight of lubricant. The modified bamboo powder-nano titanium dioxide preparation method is as follows: bamboo powder, nano titanium dioxide, and sulfonic acid modifier are added to water, stirred and mixed, filtered, the solids are washed, and dried to obtain modified bamboo powder-nano titanium dioxide.

2. The weather-resistant PBST bamboo powder composite biodegradable agricultural mulch film material according to claim 1, characterized in that, The antioxidant is antioxidant 1726 or antioxidant 2246.

3. The weather-resistant PBST bamboo powder composite biodegradable agricultural mulch film material according to claim 1, characterized in that, The lubricant is any one or a combination of erucamide and oleamide.

4. The weather-resistant PBST bamboo powder composite biodegradable agricultural mulch film material according to claim 1, characterized in that, The temperature during stirring and mixing is 20-40℃, and the stirring time is 2-3 hours.

5. The weather-resistant PBST bamboo powder composite biodegradable agricultural mulch film material according to claim 1, characterized in that, The amount of bamboo powder used is 100 parts by weight, nano titanium dioxide is 1.5-5 parts by weight, and sulfonic acid modifier is 3-10 parts by weight.

6. The weather-resistant PBST bamboo powder composite biodegradable agricultural mulch film material according to claim 5, characterized in that, The bamboo powder has a particle size of 60-200 mesh, and the nano-titanium dioxide has a particle size of 200-500 nm.

7. The weather-resistant PBST bamboo powder composite biodegradable agricultural mulch film material according to claim 5, characterized in that, The preparation method of the sulfonic acid modifier is as follows: (1) Add diethanolamine and glycidyl ether in a molar ratio of (1-1.1):1 to isopropanol, heat to 70-80℃, stir and reflux for 6-8 hours, remove low-boiling substances by vacuum distillation, add water and dichloromethane, shake and extract, concentrate the organic phase under reduced pressure, dry, and obtain the modifier precursor. (2) Add the modifier precursor, 1,4-butanesulfonic acid lactone, and sodium hydroxide aqueous solution to 1,4-dioxane, heat to 70-85℃, stir for 6-8h, concentrate the solution under reduced pressure to remove 1,4-dioxane, acidify with hydrochloric acid dropwise, filter the solid and add it to water, recrystallize and purify to obtain sulfonic acid modifier.

8. The weather-resistant PBST bamboo powder composite biodegradable agricultural mulch film material according to claim 7, characterized in that, The glycidyl ether in (1) is dodecyl glycidyl ether, tetradecyl glycidyl ether, hexadecyl glycidyl ether or octadecyl glycidyl ether.

9. The weather-resistant PBST bamboo powder composite biodegradable agricultural mulch film material according to claim 7, characterized in that, The amount of the modifier precursor, 1,4-butanesulfonate lactone and sodium hydroxide in (2) is 1:(3-3.3):(6-7).

10. A method for preparing a weather-resistant PBST bamboo powder composite biodegradable agricultural mulch film material as described in any one of claims 1-9, characterized in that, The preparation method is as follows: polybutylene terephthalate-butylene succinate, modified bamboo powder-nano titanium dioxide, antioxidant, and lubricant are mixed and extruded through a screw extruder at a temperature of 140-180℃ in each zone. After granulation, the granules are blown into a film by a blow molding machine at a blow ratio of 2-3 and a temperature of 150-180℃ in zones 1-3 of the barrel, to obtain weather-resistant PBST bamboo powder composite biodegradable agricultural mulch film material.

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