Material for biodegradable wrapping film and method for preparing wrapping film

Abstract

The application relates to a material applied to the preparation of a biodegradable wrapping film and a preparation method of the wrapping film, and belongs to the technical field of wrapping films. The technical problem that the mechanical properties, the peeling strength and the biodegradability of the biodegradable wrapping film prepared by the material preparation in the prior art cannot be simultaneously considered is solved. The tackifier and other raw materials (PBAT, PBS) in the wrapping film also have a synergistic effect. The tackifier improves the tackiness and flexibility of the wrapping film, so that the wrapping film is not easy to break in the stretching process. Meanwhile, the raw materials such as PBAT and PBS provide the film with basic mechanical properties and biodegradability. The synergistic effect makes the wrapping film have high peeling strength while maintaining good mechanical properties and biodegradability, so as to meet the packaging requirements in different environments.

Description

Technical Field

[0001] This invention relates to the field of stretch film technology, and more particularly to a material for the preparation of biodegradable stretch film and a method for preparing stretch film. Background Technology

[0002] Stretch film is a packaging material with high tensile strength, tear resistance, and good self-adhesion, allowing it to wrap objects into a single unit and prevent them from scattering or collapsing during transport. It also boasts excellent transparency, resulting in an aesthetically pleasing wrapping that is waterproof, dustproof, and damage-resistant. This film is widely used for pallet packaging in industries such as electronics, building materials, chemicals, metal products, auto parts, wires and cables, daily necessities, food, and papermaking.

[0003] Currently, the production of stretch film mainly uses low-density polyethylene (LLDPE) as raw material. However, discarded LLDPE stretch film cannot degrade in the natural environment. Polybutylene adipate terephthalate (PEG) is a biodegradable aromatic-aliphatic copolyester with good ductility and elongation at break, as well as good heat resistance and impact resistance. It is the most suitable biodegradable material for preparing cast stretch film products, conforming to the principles of environmental friendliness and recyclability. However, the molecular chain structure of the biodegradable material in biodegradable stretch film is relatively complex, and the intermolecular forces are weak. This results in poor peel strength of the wrapping itself, which cannot meet the application requirements of stretch film.

[0004] Currently, with the rapid development of the logistics industry, there is a great demand for stretch wrapping materials in both domestic and international logistics markets. International logistics stretch wrapping is now required to be biodegradable, and there is an urgent need to develop high-performance biodegradable stretch film materials. Summary of the Invention

[0005] In view of the above analysis, the present invention aims to provide a material for the preparation of biodegradable stretch film and a method for preparing the stretch film, so as to solve at least one of the problems that existing materials cannot simultaneously achieve mechanical properties, peel strength and biodegradability of biodegradable stretch film.

[0006] In a first aspect, the present invention provides a material for the preparation of biodegradable stretch film, wherein the material comprises the following raw materials in parts by weight: polybutylene adipate terephthalate: 74.5-79.5 parts, polybutylene succinate: 13-17 parts, polypropylene adipate: 1-3 parts, antioxidant: 0.2-0.6 parts, UV stabilizer: 0.3-0.9 parts, and tackifier: 5-8 parts, wherein the tackifier is prepared by reacting rosin glycerol ester and guar gum under acidic conditions.

[0007] Furthermore, the weight-average molecular weight of the polybutylene adipate terephthalate is 90,000-110,000 g / mol.

[0008] Furthermore, the weight-average molecular weight of the polybutylene succinate is 100,000-150,000 g / mol.

[0009] Furthermore, the weight-average molecular weight of the poly(propylene adipate) is 2700-6000 g / mol.

[0010] Furthermore, the antioxidant is antioxidant 1010, and the UV protectant is UV protectant UV-622.

[0011] Secondly, the present invention provides a method for preparing a winding film using the above-mentioned material, comprising the following steps:

[0012] (1) A tackifier is obtained by reacting rosin glycerol ester and guar gum in the presence of acid;

[0013] (2) Weigh out the raw materials according to the proportions of each material used in the biodegradable wrapping film and set aside;

[0014] (3) Polybutylene adipate terephthalate, polybutylene succinate, polypropylene adipate, antioxidant, UV stabilizer and tackifier are blended, extruded and granulated, and cast to obtain the stretch film.

[0015] Furthermore, in step (1), the reaction includes: dissolving rosin glycerol ester and guar gum in a solvent and reacting them under acid to obtain a thickener.

[0016] Furthermore, the acid is p-toluenesulfonic acid, and the solvent is ethyl acetate.

[0017] Furthermore, the molar ratio of rosin glycerol ester to guar gum is 1:1.5~2, the mass of acid is 0.6~1.0% of the total mass of rosin glycerol ester and guar gum, and the mass of solvent is 4~8 times the total mass of rosin glycerol ester and guar gum.

[0018] Furthermore, the reaction temperature is 60~80℃, and the reaction time is 2~4h.

[0019] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0020] (1) In the material of the present invention, there is also a synergistic effect between the tackifier and other raw materials (polybutylene terephthalate (PBAT) and polybutylene succinate (PBS)). The tackifier improves the adhesion and flexibility of the stretch film, making the stretch film less prone to breakage during stretching. At the same time, raw materials such as PBAT and PBS provide the stretch film with basic mechanical properties and biodegradability. This synergistic effect enables the stretch film to maintain good mechanical properties and biodegradability while having high peel strength, thus meeting the packaging needs in different environments.

[0021] (2) The materials used in the preparation of biodegradable stretch film of the present invention employ specific raw materials and proportions, and the prepared biodegradable stretch film has both good mechanical properties and high peel strength. PBAT provides basic mechanical properties and biodegradability, while the addition of PBS further optimizes the flexibility and heat resistance of the stretch film. The two work synergistically to enable the stretch film to maintain good biodegradability while having higher elongation at break and tensile strength, meeting the packaging requirements in different environments. Polypropylene adipate can effectively improve the heat resistance and durability of PBAT / PBS biodegradable film, and can play a synergistic protective role with antioxidants and UV stabilizers. It can effectively protect the polymer molecular chains of PBAT, PBS and other polymers, preventing them from degrading due to oxidation and ultraviolet radiation, thereby synergistically maintaining the mechanical properties and peel strength of the film, ensuring that the stretch film can maintain excellent performance in long-term use and under different environmental conditions.

[0022] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objectives and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description. Detailed Implementation

[0023] The following examples, taken together with the embodiments of the present invention, are used to illustrate the principles of the invention and are not intended to limit the scope of the invention.

[0024] One specific embodiment of the present invention discloses a material used in the preparation of biodegradable stretch film. The material, by weight, comprises the following raw materials: polybutylene terephthalate (PBAT): 74.5-79.5 parts (e.g., 75 parts, 75.5 parts, 76 parts, 76.5 parts, 77 parts, 77.5 parts, 78 parts, 78.5 parts, 79 parts); polybutylene succinate (PBS): 13-17 parts (e.g., 13.5 parts, 14 parts, 14.5 parts, 15 parts, 15.5 parts, 16 parts). 16.5 parts), polypropylene adipate: 1-3 parts (e.g., 1.5 parts, 2.0 parts, 2.5 parts), antioxidant: 0.2-0.6 parts (e.g., 0.3 parts, 0.4 parts, 0.5 parts), UV stabilizer: 0.3-0.9 parts (e.g., 0.4 parts, 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts), and tackifier: 5-8 parts (e.g., 5.5 parts, 6 parts, 6.5 parts, 7 parts, 7.5 parts), wherein the tackifier is prepared by reacting rosin glycerol ester and guar gum under acidic conditions.

[0025] Compared with existing technologies, the materials used in the preparation of biodegradable stretch film in this invention employ specific raw materials and proportions, resulting in a biodegradable stretch film with both good mechanical properties and high peel strength. PBAT provides basic mechanical properties and biodegradability, while PBS has high rigidity and hardness, enhancing the mechanical strength of the stretch film and ensuring its stability under high tensile forces. Their synergistic effect allows the stretch film to maintain good biodegradability while possessing higher elongation at break and tensile strength, meeting packaging requirements in various environments. Polypropylene adipate effectively improves the heat resistance and durability of the PBAT / PBS biodegradable film. Together with antioxidants and UV stabilizers, it provides synergistic protection, effectively protecting the polymer chains of PBAT and PBS from degradation due to oxidation and UV radiation. This synergistic effect maintains the film's mechanical properties and peel strength, ensuring excellent performance even under long-term use and different environmental conditions.

[0026] There is also a synergistic effect between the tackifier and other raw materials (PBAT, PBS) in the stretch film. The tackifier improves the adhesion and flexibility of the stretch film, making it less prone to breakage during stretching. At the same time, raw materials such as PBAT and PBS provide the film with basic mechanical properties and biodegradability. This synergistic effect allows the stretch film to maintain good mechanical properties and biodegradability while possessing high peel strength, meeting the packaging requirements of different environments.

[0027] Specifically, the weight-average molecular weight of the polybutylene adipate terephthalate is 90,000-110,000 g / mol, for example, 90,000 g / mol, 95,000 g / mol, 100,000 g / mol, 105,000 g / mol, and 110,000 g / mol.

[0028] It should be noted that when the molecular weight of PBAT is too high, the intermolecular forces between polymer chains increase, leading to poorer processing flowability. During the preparation of stretch film, high molecular weight PBAT is difficult to coat evenly on the substrate surface, potentially forming an uneven coating that affects the overall mechanical properties of the stretch film. Simultaneously, increased intermolecular entanglement results in uneven distribution of the tackifier on the substrate surface, forming localized aggregations or discontinuous adhesive layers. When the stretch film comes into contact with the adhered object, this uneven adhesive layer reduces adhesion, leading to decreased peel strength.

[0029] When the molecular weight is too low, the polymer chain segments are shorter, and the intermolecular forces are weakened, leading to a decrease in the tensile strength and modulus of the stretch film. Under external force, the chain segments are prone to slippage and deformation, making the stretch film susceptible to plastic deformation during stretching and difficult to return to its original shape, thus reducing its mechanical properties. Furthermore, less intermolecular entanglement makes it difficult to form a stable adhesive coating on the substrate surface. This results in reduced adhesion between the tackifier and the substrate, making the stretch film prone to detaching or peeling from the substrate during use, thereby reducing peel strength.

[0030] Specifically, the weight-average molecular weight of the polybutylene succinate is 100,000-150,000 g / mol, for example, 100,000 g / mol, 110,000 g / mol, 120,000 g / mol, 130,000 g / mol, 140,000 g / mol, and 150,000 g / mol.

[0031] Specifically, the weight-average molecular weight of the poly(propylene adipate) is 2700-6000 g / mol, for example, 2700 g / mol, 3000 g / mol, 3500 g / mol, 4000 g / mol, 4500 g / mol, 5000 g / mol, 5500 g / mol, and 6000 g / mol.

[0032] Specifically, the antioxidant is antioxidant 1010, and the UV protectant is UV-622.

[0033] Another specific embodiment of the present invention discloses a method for preparing a winding film using the above-described material, comprising the following steps:

[0034] (1) A tackifier is obtained by reacting rosin glycerol ester and guar gum in the presence of acid;

[0035] (2) Weigh out the raw materials according to the proportions of each material used in the biodegradable wrapping film and set aside;

[0036] (3) Polybutylene adipate terephthalate, polybutylene succinate, polypropylene adipate, antioxidant, UV stabilizer and tackifier are blended, extruded and granulated, and cast to obtain the stretch film.

[0037] The tackifier of this invention contains both the rigid structure of rosin and the flexible segments of guar gum. This synergistic rigid-flexible molecular structure allows the tackifier to provide sufficient rigidity and enhanced mechanical properties in the stretch film while maintaining a certain degree of flexibility and tackiness to improve peel strength. Because rosin glycerol esters and guar gum may undergo a transesterification reaction under acidic conditions, the transesterification may introduce the hydrophobic ester groups of rosin into the polysaccharide chains of guar gum, forming a partially esterified or cross-linked structure. After the reaction, the advantages of both are combined, and the resulting tackifier improves the tackiness of the stretch film while also enhancing its flexibility and mechanical properties, achieving a synergistic performance enhancement.

[0038] Specifically, in step (1), the reaction includes: dissolving rosin glycerol ester and guar gum in a solvent and reacting them under acid to obtain a thickener.

[0039] Preferably, the acid is p-toluenesulfonic acid, and the solvent is ethyl acetate.

[0040] Preferably, the molar ratio of rosin glycerol ester to guar gum is 1:1.5 to 2 (e.g., 1:1.6, 1:1.7, 1:1.8, 1:1.9), the mass of acid is 0.6 to 1.0% of the total mass of rosin glycerol ester and guar gum (e.g., 0.65%, 0.70%, 0.75%, 0.80%, 0.85%, 0.90%, 0.95%), and the mass of solvent is 4 to 8 times the total mass of rosin glycerol ester and guar gum (e.g., 4.5 times, 5.0 times, 5.5 times, 6.0 times, 6.5 times, 7.0 times, 7.5 times).

[0041] Specifically, the reaction temperature is 60~80℃ (e.g., 62℃, 64℃, 66℃, 68℃, 70℃, 72℃, 74℃, 76℃, 78℃), and the reaction time is 2~4h (e.g., 2.2h, 2.4h, 2.6h, 2.8h, 3.0h, 3.2h, 3.4h, 3.6h, 3.8h).

[0042] It should be noted that the reaction temperature of this invention needs to be precisely controlled within a certain range. At this temperature, rosin glycerol ester and guar gum can undergo transesterification to generate a tackifier. This tackifier has good compatibility with raw materials such as PBAT and PBS, and can work synergistically to improve the tensile strength and elongation at break of the stretch film, while also enhancing its peel strength.

[0043] The reaction time of this invention was optimized through extensive testing. The tackifier generated within this time effectively improves the adhesion and flexibility of the stretch film, enhances its adhesion to goods, thereby increasing peel strength while maintaining good mechanical properties.

[0044] Specifically, a twin-screw extruder is used for extrusion granulation.

[0045] Preferably, the temperature settings for each zone of the twin-screw extruder are as follows:

[0046] Zone 1: 170~180℃, Zone 2: 175~195℃, Zone 3: 180~200℃, Zone 4: 180~200℃, Zone 5: 180~200℃, Zone 6: 180~200℃, Zone 7: 175~195℃, Zone 8: 170~190℃, Machine head: 190~210℃.

[0047] Preferably, the screw speed of the twin-screw extruder is 100~200 rpm, for example, 110 rpm, 120 rpm, 130 rpm, 140 rpm, 150 rpm, 160 rpm, 170 rpm, 180 rpm, or 190 rpm.

[0048] The elongation at break of the wrapping film in this invention is 519-534%, the longitudinal tensile strength is 26.7-27.8 MPa, the peel strength is 2.17-2.23 N / m, and the relative biodegradability is 98.4-99.2%.

[0049] It should be noted that all raw materials used in this invention are commercially available or prepared using existing methods. The technical solution of this invention will be further explained below with reference to specific embodiments.

[0050] The manufacturers of some of the raw materials in the following examples are as follows: Polybutylene adipate terephthalate: Xinjiang Lanshan Tunhe Polyester Co., Ltd.; Polybutylene succinate: Zhuhai Kingfa Biomaterials Co., Ltd.; Polypropylene adipate: Wuhan Shuer Biotechnology Co., Ltd.; Rosin glycerol ester manufacturer: Xi'an Dafengshou Biotechnology Co., Ltd., model 136; Guar gum manufacturer: Xibao Biotechnology (Shanghai) Co., Ltd., model AJA0082F; Antioxidant 1010 manufacturer: Tianjin Lianlong New Materials Co., Ltd.; UV stabilizer UV-622 manufacturer: BASF.

[0051] Example 1

[0052] This embodiment describes a material used in the preparation of biodegradable stretch film. By weight, the material comprises the following raw materials: 74.5 parts of polybutylene adipate terephthalate, 17 parts of polybutylene succinate, 1 part of polypropylene adipate, 0.6 parts of antioxidant, 0.3 parts of UV stabilizer, and 8 parts of tackifier. The tackifier is prepared by reacting rosin glycerol ester and guar gum under acidic conditions. The weight-average molecular weight of polybutylene adipate terephthalate is 90,000 g / mol, the weight-average molecular weight of polybutylene succinate is 100,000 g / mol, and the weight-average molecular weight of polypropylene adipate is 2,700 g / mol. The antioxidant is antioxidant 1010, and the UV stabilizer is UV stabilizer UV-622.

[0053] This embodiment provides a method for preparing a wrapping film using the aforementioned material, comprising the following steps:

[0054] (1) Dissolve rosin glycerol ester and guar gum in ethyl acetate and react at 60°C with p-toluenesulfonic acid for 4 hours to obtain a thickener. The molar ratio of rosin glycerol ester to guar gum is 1:1.5, the mass of acid is 0.6% of the total mass of rosin glycerol ester and guar gum, and the mass of solvent is 4 times the total mass of rosin glycerol ester and guar gum.

[0055] (2) Weigh out the raw materials according to the proportions of each material used in the biodegradable wrapping film and set aside;

[0056] (3) Polybutylene adipate terephthalate, polybutylene succinate, polypropylene adipate, antioxidant, UV stabilizer and tackifier are blended and extruded and granulated using a twin-screw extruder. The temperature settings of each zone of the twin-screw extruder are as follows: Zone 1: 180℃, Zone 2: 185℃, Zone 3: 190℃, Zone 4: 190℃, Zone 5: 190℃, Zone 6: 190℃, Zone 7: 185℃, Zone 8: 180℃, Die head: 200℃, the screw speed of the twin-screw extruder is 100 rpm, and the film is cast to obtain the aforementioned wrapping film.

[0057] Example 2

[0058] This embodiment describes a material used in the preparation of biodegradable stretch film. By weight, the material comprises the following raw materials: 77 parts polybutylene adipate terephthalate, 15 parts polybutylene succinate, 2 parts polypropylene adipate, 0.4 parts antioxidant, 0.6 parts UV stabilizer, and 6.5 parts tackifier. The tackifier is prepared by reacting rosin glycerol ester and guar gum under acidic conditions.

[0059] The weight-average molecular weight of polybutylene adipate terephthalate is 100,000 g / mol, the weight-average molecular weight of polybutylene succinate is 125,000 g / mol, the weight-average molecular weight of polypropylene adipate is 4,000 g / mol, the antioxidant is antioxidant 1010, and the UV protectant is UV-622.

[0060] This embodiment provides a method for preparing a wrapping film using the aforementioned material, comprising the following steps:

[0061] (1) Rosin glycerol ester and guar gum are dissolved in ethyl acetate and reacted at 70°C with p-toluenesulfonic acid for 3 hours to obtain a thickener. The molar ratio of rosin glycerol ester and guar gum is 1:1.75, the mass of acid is 0.8% of the total mass of rosin glycerol ester and guar gum, and the mass of solvent is 6 times the total mass of rosin glycerol ester and guar gum.

[0062] (2) Weigh out the raw materials according to the proportions of each material used in the biodegradable wrapping film and set aside;

[0063] (3) Polybutylene adipate terephthalate, polybutylene succinate, polypropylene adipate, antioxidant, UV stabilizer and tackifier are blended and extruded and granulated using a twin-screw extruder. The temperature settings of each zone of the twin-screw extruder are as follows: Zone 1: 170℃, Zone 2: 195℃, Zone 3: 180℃, Zone 4: 200℃, Zone 5: 180℃, Zone 6: 200℃, Zone 7: 175℃, Zone 8: 190℃, Die head: 190℃, the screw speed of the twin-screw extruder is 150 rpm, and the film is cast to obtain the aforementioned wrapping film.

[0064] Example 3

[0065] This embodiment describes a material used in the preparation of biodegradable stretch film. By weight, the material comprises the following raw materials: 79.5 parts polybutylene adipate terephthalate, 13 parts polybutylene succinate, 3 parts polypropylene adipate, 0.2 parts antioxidant, 0.9 parts UV stabilizer, and 5 parts tackifier. The tackifier is prepared by reacting rosin glycerol ester and guar gum under acidic conditions.

[0066] The weight-average molecular weight of polybutylene adipate terephthalate is 110,000 g / mol, the weight-average molecular weight of polybutylene succinate is 150,000 g / mol, the weight-average molecular weight of polypropylene adipate is 6,000 g / mol, the antioxidant is antioxidant 1010, and the UV protectant is UV-622.

[0067] This embodiment provides a method for preparing a wrapping film using the aforementioned material, comprising the following steps:

[0068] (1) Dissolve rosin glycerol ester and guar gum in ethyl acetate and react at 80°C with p-toluenesulfonic acid for 2 hours to obtain a thickener. The molar ratio of rosin glycerol ester to guar gum is 1:2, the mass of acid is 1.0% of the total mass of rosin glycerol ester and guar gum, and the mass of solvent is 8 times the total mass of rosin glycerol ester and guar gum.

[0069] (2) Weigh out the raw materials according to the proportions of each material used in the biodegradable wrapping film and set aside;

[0070] (3) Polybutylene adipate terephthalate, polybutylene succinate, polypropylene adipate, antioxidant, UV stabilizer and tackifier are blended and extruded and granulated using a twin-screw extruder. The temperature settings of each zone of the twin-screw extruder are as follows: Zone 1: 180℃, Zone 2: 175℃, Zone 3: 200℃, Zone 4: 180℃, Zone 5: 200℃, Zone 6: 180℃, Zone 7: 195℃, Zone 8: 170℃, Die head: 210℃, the screw speed of the twin-screw extruder is 200 rpm, and the film is cast to obtain the aforementioned wrapping film.

[0071] Example 4

[0072] The material and preparation method for biodegradable stretch film in this embodiment are the same as those in Example 2, except that the proportions of each raw material are different, as follows: polybutylene adipate terephthalate: 72 parts, polybutylene succinate: 16 parts, polypropylene adipate: 1.5 parts, antioxidant: 0.5 parts, UV stabilizer: 0.5 parts, and tackifier: 6 parts.

[0073] Comparative Example 1

[0074] The material and preparation method used in this comparative example for preparing biodegradable stretch film are the same as those in Example 2, except that the tackifier is rosin glycerol ester.

[0075] Comparative Example 2

[0076] The material and preparation method used in this comparative example for preparing biodegradable stretch film are the same as those in Example 2, except that the tackifier is guar gum.

[0077] Comparative Example 3

[0078] The material and preparation method used in this comparative example for preparing biodegradable stretch film are the same as those in Example 2, except that the weight-average molecular weight of polybutylene adipate terephthalate is 80,000 g / mol.

[0079] Comparative Example 4

[0080] The material and preparation method used in this comparative example for preparing biodegradable stretch film are the same as those in Example 2, except that the weight-average molecular weight of the polybutylene succinate is 90,000 g / mol.

[0081] Comparative Example 5

[0082] The material and preparation method used in this comparative example for preparing biodegradable stretch film are the same as those in Example 2, except that guar gum is replaced with guar gum.

[0083] Comparative Example 6

[0084] The material and preparation method of this comparative example for the preparation of biodegradable wrapping film are the same as those in Example 2, except that in step (1), the reaction temperature is 55°C and the reaction time is 5h.

[0085] Comparative Example 7

[0086] The material and preparation method of this comparative example for the preparation of biodegradable stretch film are the same as those in Example 2, except that the raw materials contain 2 parts of tackifier and 81.5 parts of polybutylene adipate terephthalate.

[0087] Comparative Example 8

[0088] The material and preparation method of this comparative example for the preparation of biodegradable stretch film are the same as those in Example 2, except that polybutylene succinate is not added to the raw materials, and 92 parts of polybutylene adipate terephthalate are used.

[0089] Comparative Example 9

[0090] The material and preparation method of this comparative example for the preparation of biodegradable stretch film are the same as those in Example 2, except that polypropylene adipate is not added to the raw materials, and 79 parts of polybutylene adipate terephthalate are used.

[0091] Comparative Example 10

[0092] The material and preparation method used in this comparative example for preparing biodegradable stretch film are the same as those in Example 2, except that the molar ratio of rosin glycerol ester and guar gum is 1:1.

[0093] Experimental Example 1

[0094] Biodegradable wrapping films were prepared using the methods of Examples 1-4 and Comparative Examples 1-10, respectively. The performance of the biodegradable wrapping films obtained in each group was tested, and the results are shown in Table 1.

[0095] Tensile properties were tested according to standard GB / T 1040-2018, peel strength was tested according to standard GB / T2792-1998, and biodegradability was tested according to standard GB / T 35795-2017.

[0096] Table 1

[0097] ;

[0098] According to Table 1, compared with Example 2, when the tackifier was rosin glycerol ester or guar gum, the mechanical properties and peel strength of the stretch film were reduced in Comparative Examples 1 and 2. This is because the tackifier obtained by transesterification contains both the rigid structure of rosin and the flexible segments of guar gum. This rigid-flexible molecular structure allows the tackifier to provide sufficient rigidity and enhance mechanical properties in the stretch film, while maintaining a certain degree of flexibility and stickiness to improve peel strength.

[0099] Compared with Example 2, Comparative Examples 3 and 4 have lower mechanical properties and peel strength because the molecular weights of polybutylene adipate terephthalate and polybutylene succinate are outside the range of the present invention.

[0100] Compared with Example 2, when guar gum was replaced with guar gum in Comparative Example 5, the mechanical properties and peel strength of the stretch film were reduced.

[0101] Compared with Example 2, Comparative Example 6 was prepared under transesterification conditions that were not within the scope of the present invention, resulting in reduced mechanical properties and peel strength of the prepared wrapping film.

[0102] Compared with Example 2, the raw materials or proportions of the stretch film in Comparative Examples 7-10 are not within the scope of this invention, and the mechanical properties and peel strength of the prepared stretch film are reduced.

[0103] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for producing a biodegradable wrapping film, characterized by, It comprises the following steps: (1) Dissolve rosin glyceride and guar gum in a solvent, and react in the presence of an acid to obtain a tackifier; The molar ratio of rosin glyceride to guar gum is 1:1.5-2, the mass of the acid is 0.6-1.0% of the total mass of rosin glyceride and guar gum, and the mass of the solvent is 4-8 times the total mass of rosin glyceride and guar gum; the reaction temperature is 60-80℃, and the reaction time is 2-4h; (2) According to the ratio of each raw material of the biodegradable wrapping film, the raw materials are weighed separately; (3) Blend polybutylene terephthalate adipate, polybutylene succinate, polypropylene adipate, antioxidant, ultraviolet light resistance agent and tackifier, extrude and granulate, and cast to obtain the wrapping film; The wrapping film comprises the following raw materials by weight: polybutylene terephthalate adipate 74.5-79.5 parts, polybutylene succinate 13-17 parts, polypropylene adipate 1-3 parts, antioxidant 0.2-0.6 parts, ultraviolet light resistance agent 0.3-0.9 parts and tackifier 5-8 parts; the weight average molecular weight of the polybutylene terephthalate adipate is 105000-110000g / mol; The weight average molecular weight of the polybutylene succinate is 100000-150000g / mol.

2. The production method according to claim 1, characterized by, The weight average molecular weight of the polypropylene adipate is 2700-6000g / mol.

3. The preparation method according to claim 1, characterized in that, The antioxidant is antioxidant 1010, and the ultraviolet light resistance agent is ultraviolet light resistance agent UV-622.

4. The production method according to claim 1, characterized by, The acid is p-methylbenzenesulfonic acid, and the solvent is ethyl acetate.