Modified gallic acid ultraviolet light absorber, full-biodegradable mulching film with adjustable service life and preparation method of full-biodegradable mulching film

Abstract

The invention belongs to the field of degradable agricultural mulching films, and particularly relates to a modified gallic acid ultraviolet light absorber, a full-biodegradable mulching film with adjustable service life and a preparation method of the full-biodegradable mulching film. The full-biodegradable mulching film is prepared from the following components in parts by mass: 70 to 80 parts of PBAT (Polybutylene Terephthalate), 20 to 30 parts of PGA (Polypropylene Glycol Acetate), 0.5 to 1.0 part of a chain extender, 0.3 to 0.6 part of an antioxidant, 0.5 to 1.5 parts of a modified gallic acid ultraviolet light absorber and 0.3 to 0.5 part of a lubricating agent. The modified gallic acid ultraviolet light absorber is prepared by reacting gallic acid with 2, 5-furandimethanol. The prepared modified gallic acid ultraviolet light absorber is good in ultraviolet absorption effect, the service life of the degradable mulching film can be remarkably prolonged, the raw materials are all biomass sources, soil cannot be affected after the mulching film is separated out in the degradation process, industrial production is easy, and the modified gallic acid ultraviolet light absorber has wide market application prospects in the field of degradable mulching films.

Description

Technical Field

[0001] The present invention belongs to the field of degradable agricultural mulch films, and in particular relates to a modified gallic acid ultraviolet absorber, a fully biodegradable mulch film with adjustable lifespan, and a preparation method thereof. Background Art

[0002] As an important technical tool in modern agriculture, agricultural mulch films have the core advantage of comprehensively improving agricultural production efficiency and resource utilization. By covering the soil to form a physical barrier, they can effectively regulate surface temperature and humidity, reduce water loss caused by natural evaporation, and create a stable growth environment for crops. In addition, mulch films can inhibit weed germination by blocking light, reduce the frequency of chemical herbicide use, and reduce the burden of farmland management. However, the long-term, uncontrolled use of traditional mulch films (such as polyethylene mulch and polypropylene mulch films) can cause serious environmental problems.

[0003] In recent years, the biodegradable materials industry has flourished, and many biodegradable materials such as polybutylene terephthalate (PBAT), polylactic acid (PLA), polyhydroxyalkanoate (PHA), polycaprolactone (PCL), and polybutylene succinate (PBS) have been commercialized. Green and environmentally friendly mulch films made from biodegradable materials are considered green alternatives to traditional mulch films. For example, patent application publication number CN118006089A discloses a method for preparing a fully biodegradable moisture-retaining mulch film made from a polylactic acid / polybutylene terephthalate copolymer, patent application publication number CN117126517A discloses a method for preparing an environmentally controllable degradable mulch film made from a blend of polylactic acid / polyvinyl alcohol / aromatic polyketone, and patent application publication number CN116694045A discloses a method for preparing an ultra-thin biodegradable mulch film made from a blend of polybutylene terephthalate / semi-aromatic polycarbonate. However, the raw materials used in these biodegradable mulch films often have high requirements for the degradation environment, and the degradation cycle of the products is usually long, which cannot keep pace with the growth needs of crops. In summary, how to develop a biodegradable mulch film with mild degradation conditions and a controllable lifespan is an urgent technical problem to be solved. Summary of the Invention

[0004] In response to the above technical problems, the present invention provides a modified gallic acid ultraviolet absorber, a fully biodegradable mulch film with adjustable lifespan and a preparation method thereof. By adding the modified ultraviolet absorber, the amount of additives added in the formula can be adjusted according to the planting requirements of different crops to obtain degradable mulch films with different lifespans, thereby avoiding the impact and damage to the environment caused by the large-scale production of microplastics.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] In a first aspect, the present invention provides a lifespan-adjustable fully biodegradable mulch film, comprising the following components, calculated by weight: 70-80 parts of PBAT, 20-30 parts of PGA resin, 0.5-1.0 parts of chain extender, 0.3-0.6 parts of antioxidant, 0.5-1.5 parts of ultraviolet absorber, and 0.3-0.5 parts of lubricant;

[0007] The ultraviolet absorber is a modified gallic acid ultraviolet absorber, and its molecular structure is:

[0008]

[0009] Furthermore, the chain extender is polyepoxy chain extender ADR4380.

[0010] Furthermore, the antioxidant is composed of antioxidant 168 and antioxidant 1010 in a mass ratio of 1:0.8-1.2.

[0011] Furthermore, the lubricant is erucamide.

[0012] Furthermore, the modified gallic acid is obtained by reacting gallic acid with furandimethanol.

[0013] In a second aspect, the present invention provides a method for preparing a fully biodegradable mulch film with adjustable lifespan, which specifically comprises the following steps:

[0014] S1. Add dry PBAT, PGA resin, chain extender, antioxidant, UV absorber, and lubricant into a high-speed mixer according to the proportion, mix well, and obtain a premix;

[0015] S2, adding the premix of step S1 into a twin-screw extruder, melt blending, extruding, cooling, and pelletizing to obtain pellets;

[0016] S3. The pellets obtained in step S2 are blown into a film blowing machine to obtain the life-adjustable fully biodegradable mulch film; the thickness of the life-adjustable fully biodegradable mulch film is 10 to 15 μm; and the biodegradation rate is 100%.

[0017] Furthermore, the screw speed of the twin-screw extruder is 80-150 rpm.

[0018] Furthermore, the temperature of each zone of the twin-screw extruder is set as follows: zone 1 temperature 130-150°C, zone 2 temperature 200-210°C, zone 3 temperature 210-220°C, zone 4 temperature 215-225°C, zone 5 temperature 215-225°C, and die head temperature 205-215°C.

[0019] Furthermore, the temperature of each zone of the film blowing machine is set as follows: barrel zone 1 temperature 205-210℃, barrel zone 2 temperature 210-215℃, barrel zone 3 temperature 215-220℃, mold zone 1 temperature 210-215℃, and mold zone 205-210℃.

[0020] Furthermore, the screw speed of the film blowing machine is 40 to 70 rpm.

[0021] Furthermore, the PBAT and PGA resins are dried by placing them in an electric blast drying oven at 80° C. for 6 to 8 hours.

[0022] Furthermore, the pellets obtained in step S2 are dried before blow molding.

[0023] Furthermore, the cooling method in step S2 is air cooling.

[0024] In a third aspect, the present invention provides a method for preparing a modified gallic acid ultraviolet absorber, which is mainly prepared by reacting gallic acid and 2,5-furan dimethanol, wherein the molar ratio of gallic acid to 2,5-furan dimethanol is (1-3):1.

[0025] Furthermore, the molar ratio of gallic acid to 2,5-furan dimethanol is 1.5:1.

[0026] Furthermore, the method specifically includes the following steps:

[0027] T1. Add gallic acid 2,5-furan dimethanol and solvent into a reactor and stir to dissolve at room temperature;

[0028] T2, add catalyst to the reactor to react, control the reaction temperature at 110-120°C, and the reaction time is 4-8 hours;

[0029] T3. After the reactants in the reactor are cooled to room temperature, they are post-treated to obtain the modified gallic acid ultraviolet absorber.

[0030] Furthermore, the post-treatment method is as follows: after the reactant is cooled to room temperature, a saturated NaHCO solution is added to neutralize the residual acid, the solution is then added to a separatory funnel to separate the organic phase, and the solvent is removed by rotary evaporation to obtain the product, which is the modified gallic acid ultraviolet absorber.

[0031] Furthermore, the solvent is dimethyl sulfoxide or ethyl acetate, preferably dimethyl sulfoxide.

[0032] Furthermore, the catalyst is p-toluenesulfonic acid.

[0033] Furthermore, in step T1, the molar ratio of gallic acid to 2,5-furan dimethanol is (1-3):1, preferably 1.5:1.

[0034] Furthermore, in step T1, the molar ratio of the solvent to gallic acid and 2,5-furan dimethanol is (0.5-10):1, preferably (2-4):1;

[0035] Furthermore, the amount of the catalyst added in step T2 is 3-8 wt %, preferably 5 wt %, of the reaction solution in step T2.

[0036] The synthetic route of the modified gallic acid UV absorber is:

[0037]

[0038] Furthermore, the reactor is purged with nitrogen before the reaction.

[0039] Furthermore, the reactor is provided with a reflux device for preventing the volatilization of the solvent during the temperature-raising reaction.

[0040] In a fourth aspect, the modified gallic acid ultraviolet absorber prepared by the above method has a molecular structure as follows:

[0041]

[0042] The beneficial effect of adopting the above further technical solution is that the molar ratio selected by the present invention can effectively inhibit the occurrence of side reactions, reduce the use of solvents, and is economical and effective.

[0043] Compared with the existing technology, the beneficial effects of the present invention are as follows:

[0044] 1. The present invention creatively prepares a new type of ultraviolet absorber, and simultaneously uses PGA resin and other additives to prepare a fully biodegradable mulch film with adjustable lifespan, thereby reducing the generation of microplastics;

[0045] 2. The compatibilization system selected in the present invention can play a very good effect, allowing the life-controllable fully biodegradable mulch film blend to have high barrier properties and mechanical properties while maintaining excellent toughness;

[0046] 3. The ultraviolet absorber used in the present invention is of bio-based origin. While providing good ultraviolet protection function, it will not cause additional environmental damage to the soil during the degradation process of the mulch film.

[0047] 4. The preparation method of the fully biodegradable mulch film described in the present invention is simple, the raw material cost is low, the mechanical properties and barrier properties are excellent, and it can achieve controllable complete degradation, providing a product with good performance for the degradable agricultural film market and has broad market application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 This is the UV absorption spectrum of the modified gallic acid used in Example 1;

[0049] Figure 2 This is the thermogravimetric curve of the modified gallic acid used in Example 1. DETAILED DESCRIPTION

[0050] The present invention will be described in detail below in conjunction with specific embodiments and examples, and the advantages and various effects of the present invention will be more clearly presented. It should be understood by those skilled in the art that these specific embodiments and examples are for illustrating the present invention, rather than for limiting the present invention.

[0051] Throughout this specification, unless otherwise specified, the terms used herein should be understood as having the same meaning as commonly used in the art. Therefore, 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 belongs. In the event of any conflict, the present specification shall take precedence.

[0052] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0053] The electric blast drying oven used in the present invention is a product of Shanghai Yiheng Scientific Instrument Co., Ltd., the twin-screw extruder is an SHJ-20 twin-screw extruder produced by Nanjing Jieente Electromechanical Co., Ltd., the film blowing machine is an SCM-25 blast film blowing machine produced by Zhangjiagang Lianjiang Machinery Co., Ltd., the ultraviolet spectrophotometer is a Lambda1050+ ultraviolet spectrophotometer produced by PerkinElmer, the thermogravimetric analyzer is a Q500 thermogravimetric analyzer produced by TA Company in the United States, and the tensile testing machine is a universal material testing machine of Wance Company.

[0054] Various test methods:

[0055] (1) Tensile strength: Refer to GB / T 1040.1 and GB / T 1040.3, use type 2 specimens for measurement, and perform tensile load test on a tensile testing machine.

[0056] (2) Elongation at break: Refer to GB / T 1040.1 and GB / T 1040.3, use Type 2 specimens for measurement, and perform nominal strain at break test on a tensile testing machine.

[0057] The present invention is further described below through specific embodiments.

[0058] Example 1

[0059] Modified gallic acid UV absorber, the structural formula is:

[0060]

[0061] The preparation method of the modified gallic acid ultraviolet absorber specifically comprises the following steps:

[0062] First, 25.52 g of gallic acid and 12.81 g of 2,5-furan dimethanol were dissolved in 50 mL of dimethyl sulfoxide and added to a 250 mL four-necked reactor equipped with a nitrogen purge and reflux device. After stirring and dissolving, 4.41 g of p-toluenesulfonic acid was added to the reactor, the temperature was raised to 120°C, and the reaction was carried out for 8 hours. After the reaction was completed, a saturated NaHCO solution was added and mixed. Then, the organic phase was separated using a separatory funnel, and the solvent was further removed by rotary evaporation to obtain a yellow powder, thereby obtaining a modified gallic acid ultraviolet absorber.

[0063] Example 2

[0064] A fully biodegradable mulch film with adjustable lifespan is composed of the following raw materials, calculated by weight: 80 parts PBAT, 20 parts PGA, 0.5 parts chain extender, 0.6 parts antioxidant, 0.5 parts modified gallic acid, and 0.3 parts lubricant. The chain extender is polyepoxy chain extender ADR4380, and the antioxidant is composed of antioxidant 168 and antioxidant 1010 in a 1:1 ratio. The lubricant is erucamide.

[0065] The preparation method thereof comprises the following steps:

[0066] (1) Add the dried PBAT and PGA resins and additives (chain extender, antioxidant, modified gallic acid, lubricant) into a high-speed mixer according to the proportion, mix well, and obtain a premix;

[0067] (2) adding the mixed raw materials into a twin-screw extruder, melt blending, extruding, cooling and pelletizing to obtain pellets;

[0068] (3) The dried pellets are blown into a film blowing machine to obtain the life-span-adjustable fully biodegradable mulch film, and the thickness of the prepared mulch film is 10 to 15 μm.

[0069] Example 3

[0070] A fully biodegradable mulch film with adjustable lifespan is composed of the following raw materials, calculated by weight: 80 parts PBAT, 20 parts PGA, 0.5 parts chain extender, 0.6 parts antioxidant, 1 part modified gallic acid, and 0.3 parts lubricant. The chain extender is polyepoxy chain extender ADR4380; the antioxidant is composed of antioxidant 168 and antioxidant 1010 in a 1:1 ratio; and the lubricant is erucamide.

[0071] The preparation method thereof comprises the following steps:

[0072] (1) Add the dried PBAT and PGA resins and additives (chain extender, antioxidant, modified gallic acid, lubricant) into a high-speed mixer according to the proportion, mix well, and obtain a premix;

[0073] (2) adding the mixed raw materials into a twin-screw extruder, melt blending, extruding, cooling and pelletizing to obtain pellets;

[0074] (3) The dried pellets are passed through a film blowing machine to obtain the life-controllable fully biodegradable mulch film, wherein the thickness of the mulch film is 10 to 15 μm.

[0075] Example 4

[0076] A fully biodegradable mulch film with adjustable lifespan is composed of the following raw materials, calculated by weight: 80 parts PBAT, 20 parts PGA, 0.5 parts chain extender, 0.6 parts antioxidant, 1.5 parts modified gallic acid, and 0.3 parts lubricant. The chain extender is polyepoxy chain extender ADR4380; the antioxidant is composed of antioxidant 168 and antioxidant 1010 in a 1:1 ratio; and the lubricant is erucamide.

[0077] The preparation method thereof comprises the following steps:

[0078] (1) Add the dried PBAT and PGA resins and additives (chain extender, antioxidant, modified gallic acid, lubricant) into a high-speed mixer according to the proportion, mix well, and obtain a premix;

[0079] (2) adding the mixed raw materials into a twin-screw extruder, melt blending, extruding, cooling and pelletizing to obtain pellets;

[0080] (3) The dried pellets are passed through a film blowing machine to obtain the life-controllable fully biodegradable mulch film, wherein the thickness of the mulch film is 10 to 15 μm.

[0081] Comparative Example 1

[0082] A fully biodegradable mulch film is composed of the following raw materials, calculated by weight: 80 parts PBAT, 20 parts PGA, 0.5 parts chain extender, 0.6 parts antioxidant, and 0.3 parts lubricant. The chain extender is polyepoxy chain extender ADR4380; the antioxidant is composed of antioxidant 168 and antioxidant 1010 in a 1:1 ratio; and the lubricant is erucamide.

[0083] The preparation method thereof comprises the following steps:

[0084] (1) Add the dried PBAT and PGA resins and additives (chain extender, antioxidant, lubricant) into a high-speed mixer according to the proportion, mix them evenly, and obtain a premix;

[0085] (2) adding the mixed raw materials into a twin-screw extruder, melt blending, extruding, cooling and pelletizing to obtain pellets;

[0086] (3) The dried pellets are passed through a film blowing machine to obtain the life-controllable fully biodegradable mulch film, wherein the thickness of the mulch film is 10 to 15 μm.

[0087] Comparative Example 2

[0088] A fully biodegradable mulch film is composed of the following raw materials, calculated by weight: 80 parts PBAT, 20 parts PGA, 0.5 parts chain extender, 0.6 parts antioxidant, 0.5 parts gallic acid, and 0.3 parts lubricant. The chain extender is polyepoxy chain extender ADR4380; the antioxidant is composed of antioxidant 168 and antioxidant 1010 in a 1:1 ratio; and the lubricant is erucamide.

[0089] The preparation method comprises the following steps:

[0090] (1) Add the dried PBAT and PGA resins and additives (chain extender, antioxidant, gallic acid, lubricant) into a high-speed mixer according to the proportion and mix them evenly to obtain a premix;

[0091] (2) adding the mixed raw materials into a twin-screw extruder, melt blending, extruding, cooling and pelletizing to obtain pellets;

[0092] (3) The dried pellets are passed through a film blowing machine to obtain the life-controllable fully biodegradable mulch film, wherein the thickness of the mulch film is 10 to 15 μm.

[0093] The ground films prepared in Examples 1-3 and Comparative Examples 1-2 were tested accordingly, and the following data were obtained:

[0094] Table 1 Test data of each embodiment

[0095]

[0096] As can be seen from the above table, the present invention limits the raw material composition of the degradable mulch film, uses PBAT and PGA as the base material, and combines them with modified gallic acid and other additives to obtain a fully biodegradable mulch film with adjustable lifespan.

[0097] By comparing Example 2 with Comparative Example 1, it can be seen that the modified gallic acid can effectively absorb ultraviolet rays and delay the photodegradation reaction of the degradable mulch film, thereby achieving the purpose of extending the service life of the degradable mulch film.

[0098] By comparing Example 2 with Comparative Example 2, it can be seen that the ultraviolet absorption capacity of the modified gallic acid is improved, which can further enhance the ultraviolet protection effect of the mulch film.

[0099] By comparing Examples 2-4, it can be seen that the addition amount of modified gallic acid is related to the performance attenuation rate of the degradable mulch film. By adjusting the addition amount of modified gallic acid, degradable mulch films with different service lives can be obtained, thereby achieving the purpose of adjustable mulch film life.

[0100] Although the above describes the specific embodiments of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without any creative work are still within the scope of protection of the present invention.

Claims

1. A fully biodegradable mulch film with adjustable lifespan, characterized in that: The composition comprises the following components in parts by mass: 70-80 parts of PBAT, 20-30 parts of PGA resin, 0.5-1.0 parts of chain extender, 0.3-0.6 parts of antioxidant, 0.5-1.5 parts of ultraviolet absorber, and 0.3-0.5 parts of lubricant; The ultraviolet absorber is a modified gallic acid ultraviolet absorber, and its molecular structure is: 。 2. The lifespan-adjustable fully biodegradable ground film according to claim 1, characterized in that: The chain extender is polyepoxy chain extender ADR4380; The antioxidant is a mixture of antioxidant 168 and antioxidant 1010 in a mass ratio of 1:0.8-1.2; and the lubricant is erucamide.

3. A method for preparing a fully biodegradable mulch film with adjustable lifespan as claimed in claims 1-2, characterized in that: The steps include: S1. Add dry PBAT, PGA resin, chain extender, antioxidant, UV absorber, and lubricant into a high-speed mixer in proportion and mix well to obtain a premix; S2, adding the premix obtained in step S1 into a twin-screw extruder, melt blending, extruding, cooling, and pelletizing to obtain pellets; S3. The pellets obtained in step S2 are blown into a film blowing machine to obtain the life-adjustable fully biodegradable mulch film; the thickness of the life-adjustable fully biodegradable mulch film is 10 to 15 μm; and the biodegradation rate is 100%.

4. The preparation method according to claim 3, characterized in that The screw speed of the twin-screw extruder is 80-150 rpm; the screw speed of the film blowing machine is 40-70 rpm.

5. The preparation method according to claim 3, characterized in that The temperature of each zone of the twin-screw extruder is set as follows: zone 1 temperature 130-150°C, zone 2 temperature 200-210°C, zone 3 temperature 210-220°C, zone 4 temperature 215-225°C, zone 5 temperature 215-225°C, and die head temperature 205-215°C.

6. The preparation method according to claim 3, characterized in that The temperature of each zone of the film blowing machine is set as follows: barrel zone 1 temperature 205-210℃, barrel zone 2 temperature 210-215℃, barrel zone 3 temperature 215-220℃, mold zone 1 temperature 210-215℃, and mold zone 205-210℃.

7. A modified gallic acid ultraviolet absorber, characterized in that: The molecular structure of the modified gallic acid UV absorber is:

8. A method for preparing the modified gallic acid ultraviolet absorber according to claim 7, characterized in that: The method is prepared by reacting gallic acid and 2,5-furan dimethanol in the presence of a catalyst, wherein the molar ratio of the gallic acid to the 2,5-furan dimethanol is (1-3):1; the solvent is dimethyl sulfoxide or ethyl acetate; and the catalyst is p-toluenesulfonic acid.

9. The preparation method according to claim 8, characterized in that The steps include: T1. Add gallic acid 2,5-furan dimethanol and solvent into a reactor and stir to dissolve at room temperature; T2, add catalyst to the reactor to react, control the reaction temperature at 110-120°C, and the reaction time is 4-8 hours; T3. After the reactants in the reactor are cooled to room temperature, they are post-treated to obtain the modified gallic acid ultraviolet absorber.

10. The preparation method according to claim 9, characterized in that The ratio of the solvent to the molar sum of gallic acid and 2,5-furan dimethanol is (0.5-10):1, and the amount of the catalyst added is 3-8 wt % of the reaction solution in step T2.

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