Material applied to preparation of biodegradable wrapping film and preparation method of wrapping film

Abstract

The invention relates to a material applied to preparation of a biodegradable wrapping film and a preparation method of the wrapping film, belongs to the technical field of wrapping films, and solves the technical problem that the mechanical property, the peel strength and the biodegradability of the biodegradable wrapping film prepared from the material in the prior art cannot be considered at the same time. The tackifier disclosed by the invention also has a synergistic effect with other raw materials (PBAT and PBS) in the wrapping film. The tackifier improves the viscosity and flexibility of the wrapping film, so that the wrapping film is not easy to break in the stretching process, and meanwhile, the raw materials such as PBAT and PBS provide basic mechanical properties and biodegradability for the film. Due to the synergistic effect, the wrapping film has high peeling strength, meanwhile, good mechanical property and biodegradability are kept, and the packaging requirements in different environments are met.

Description

Technical Field

[0001] The present invention relates to the technical field of stretch films, and in particular to a material used in the preparation of biodegradable stretch films and a method for preparing the stretch films. Background Art

[0002] Stretch film is a wrapping material with high tensile strength, tear resistance, and excellent self-adhesive properties. It can wrap objects in a cohesive package, preventing them from falling apart during transport. It also offers excellent transparency, creating an aesthetically pleasing package while protecting them from water, dust, and damage. This film is widely used for pallet packaging in industries such as electronics, building materials, chemicals, metal products, automotive parts, wire and cable, daily necessities, food, and papermaking.

[0003] Currently, the production of stretch film primarily uses low-density polyethylene (LLDPE) as raw material. However, discarded LLDPE stretch film does not degrade in the natural environment. Polybutylene adipate terephthalate is a biodegradable aromatic-aliphatic copolyester that exhibits excellent ductility and elongation at break, as well as good heat resistance and impact resistance. It is the leading biodegradable material suitable for the production of cast stretch film products, adhering to the principles of environmental friendliness and recyclability. However, the molecular chain structure of the biodegradable material in degradable stretch film is relatively complex, resulting in weak intermolecular forces. This results in poor peel strength, which cannot meet the application requirements of stretch film.

[0004] At present, with the rapid development of the logistics industry, the domestic and international logistics markets have a great demand for wrapping packaging materials. International logistics wrapping packaging has mandatory requirements for biodegradability. There is an urgent need to develop biodegradable wrapping film materials with excellent performance. 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 the mechanical properties, peel strength and biodegradability of the biodegradable stretch film prepared by existing materials cannot be taken into account at the same time.

[0006] In a first aspect, the present invention provides a material for preparing biodegradable stretch film. The material comprises the following raw materials, in parts by weight: 74.5 to 79.5 parts of polybutylene terephthalate, 13 to 17 parts of polybutylene succinate, 1 to 3 parts of polypropylene adipate, 0.2 to 0.6 parts of an antioxidant, 0.3 to 0.9 parts of an anti-ultraviolet agent, and 5 to 8 parts of a tackifier, 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 polypropylene adipate is 2700-6000 g / mol.

[0010] Furthermore, the antioxidant is antioxidant 1010, and the anti-ultraviolet agent is anti-ultraviolet agent UV-622.

[0011] In a second aspect, the present invention provides a method for preparing a stretch film using the above-mentioned material, comprising the following steps: (1) reacting rosin glycerol ester and guar gum in the presence of acid to obtain a tackifier; (2) According to the ratio of each raw material used in the biodegradable stretch film, weigh and set aside; (3) Blending polybutylene terephthalate, polybutylene succinate, polypropylene adipate, an antioxidant, an anti-ultraviolet agent and a tackifier, extruding and granulating, and casting to obtain the stretch film.

[0012] Furthermore, in step (1), the reaction comprises: dissolving rosin glycerol ester and guar gum in a solvent, and reacting them in the presence of an acid to obtain a tackifier.

[0013] Furthermore, the acid is p-toluenesulfonic acid, and the solvent is ethyl acetate.

[0014] Furthermore, the molar ratio of rosin glycerol ester to guar gum is 1:1.5-2, the mass of the acid is 0.6-1.0% of the total mass of the rosin glycerol ester and guar gum, and the mass of the solvent is 4-8 times the total mass of the rosin glycerol ester and guar gum.

[0015] Furthermore, the reaction temperature is 60-80° C., and the reaction time is 2-4 h.

[0016] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects: (1) There is also a synergistic effect between the tackifier and other raw materials (polybutylene adipate terephthalate (PBAT), polybutylene succinate (PBS)) in the material of the present invention. The tackifier improves the viscosity and flexibility of the stretch film, making the stretch film less likely to break during the stretching process. 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 have high peel strength while maintaining good mechanical properties and biodegradability, meeting the packaging needs in different environments.

[0017] (2) The materials used in the preparation of biodegradable stretch film of the present invention adopt specific raw materials and proportions, and the prepared biodegradable stretch film has 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, so that the stretch film has higher elongation at break and tensile strength while maintaining good biodegradability, meeting the packaging needs 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 anti-ultraviolet agents, effectively protecting polymer molecular chains such as PBAT and PBS from degradation due to oxidation and ultraviolet radiation, thereby synergistically maintaining the mechanical properties and peel strength of the film, ensuring that the stretch film can still maintain excellent performance under long-term use and different environmental conditions.

[0018] In the present invention, the above-mentioned technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of the present invention will be described in the subsequent description, and some advantages will become apparent from the description or be learned through practice of the present invention. The objectives and other advantages of the present invention can be achieved and obtained through the contents particularly pointed out in the description. DETAILED DESCRIPTION

[0019] The following embodiments of the present invention are used to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0020] A specific embodiment of the present invention discloses a material for preparing a biodegradable stretch film. The material includes the following raw materials in parts by weight: polybutylene adipate terephthalate (PBAT): 74.5-79.5 parts (for example, 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 (for example, 13.5 parts, 14 parts, 14.5 parts, 15 parts, 15.5 parts, 16 parts, 16.5 parts), polypropylene adipate: 1-3 parts (for example, 1.5 parts, 2.0 parts, 2.5 parts), antioxidant: 0.2-0.6 parts (for example, 0.3 parts, 0.4 parts, 0.5 parts), anti-ultraviolet agent: 0.3-0.9 parts (for example, 0.4 parts, 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts) and tackifier: 5-8 parts (for example, 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.

[0021] Compared to the prior art, the materials used in the preparation of biodegradable stretch film of the present invention utilize specific raw materials and proportions, resulting in a biodegradable stretch film with both excellent 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 maintaining stability under high tensile forces. The synergistic effect of the two allows the stretch film to maintain excellent biodegradability while also exhibiting higher elongation at break and tensile strength, meeting packaging requirements in diverse environments. Polypropylene adipate effectively improves the heat resistance and durability of the PBAT / PBS biodegradable film, and synergistically protects the polymer chains of PBAT and PBS, preventing degradation due to oxidation and ultraviolet radiation. This synergistic effect maintains the film's mechanical properties and peel strength, ensuring the stretch film maintains excellent performance over long-term use and under diverse environmental conditions.

[0022] There's also a synergistic effect between the tackifier and other raw materials in the stretch film (PBAT and PBS). The tackifier improves the film's adhesion and flexibility, making it less susceptible to rupture during stretching. Simultaneously, raw materials like PBAT and PBS provide the film with fundamental mechanical properties and biodegradability. This synergistic effect ensures that the stretch film maintains high peel strength while maintaining excellent mechanical properties and biodegradability, meeting packaging requirements in diverse environments.

[0023] 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, or 110,000 g / mol.

[0024] It should be noted that when the molecular weight of PBAT is too high, the interactions between polymer chains increase, resulting in poor processing fluidity. When preparing stretch film, high-molecular-weight PBAT is difficult to evenly coat on the substrate surface, potentially resulting in an uneven coating, which can affect the film's overall mechanical properties. Furthermore, increased intermolecular entanglement leads to uneven distribution of the tackifier on the substrate surface, resulting in localized aggregation or a discontinuous tack layer. When the stretch film comes into contact with the adherend, this uneven tack layer reduces adhesion and lowers peel strength.

[0025] When the molecular weight is too low, the polymer chain segments are shorter, weakening the intermolecular forces and reducing the tensile strength and modulus of the stretch film. When subjected to external forces, the chain segments are prone to slippage and deformation, causing the stretch film to undergo plastic deformation during stretching and difficulty recovering its original shape, thereby reducing its mechanical properties. Furthermore, the molecular entanglement is reduced, making it difficult to form a stable adhesive coating on the substrate surface. This reduces the adhesion between the tackifier and the substrate, making it easy for the stretch film to fall off or peel off the substrate during use, thereby reducing the peel strength.

[0026] 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, or 150,000 g / mol.

[0027] Specifically, the weight average molecular weight of the polypropylene 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.

[0028] Specifically, the antioxidant is antioxidant 1010, and the anti-ultraviolet agent is anti-ultraviolet agent UV-622.

[0029] Another specific embodiment of the present invention discloses a method for preparing a stretch film using the above-mentioned material, comprising the following steps: (1) reacting rosin glycerol ester and guar gum in the presence of acid to obtain a tackifier; (2) According to the ratio of each raw material used in the biodegradable stretch film, weigh and set aside; (3) Blending polybutylene terephthalate, polybutylene succinate, polypropylene adipate, an antioxidant, an anti-ultraviolet agent and a tackifier, extruding and granulating, and casting to obtain the stretch film.

[0030] The tackifier of the present invention contains both the rigid structure of rosin and the flexible segments of guar gum. This synergistic 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 adhesion to improve peel strength. Furthermore, because the rosin glycerol ester and guar gum undergo an ester exchange reaction under acidic conditions, the ester exchange may introduce the hydrophobic ester groups of the rosin into the polysaccharide chains of the guar gum, forming a partially esterified or cross-linked structure. After the reaction, the advantages of both are combined. The resulting tackifier not only enhances the viscosity of the stretch film, but also improves its flexibility and mechanical properties, achieving synergistic performance enhancement.

[0031] Specifically, in step (1), the reaction comprises: dissolving rosin glycerol ester and guar gum in a solvent, and reacting them in the presence of an acid to obtain a tackifier.

[0032] Preferably, the acid is p-toluenesulfonic acid, and the solvent is ethyl acetate.

[0033] Preferably, the molar ratio of rosin glycerol ester and guar gum is 1:1.5-2 (for example, 1:1.6, 1:1.7, 1:1.8, 1:1.9), the mass of the acid is 0.6-1.0% (for example, 0.65%, 0.70%, 0.75%, 0.80%, 0.85%, 0.90%, 0.95%) of the total mass of rosin glycerol ester and guar gum, and the mass of the solvent is 4-8 times (for example, 4.5 times, 5.0 times, 5.5 times, 6.0 times, 6.5 times, 7.0 times, 7.5 times) of the total mass of rosin glycerol ester and guar gum.

[0034] Specifically, the reaction temperature is 60-80°C (for example, 62°C, 64°C, 66°C, 68°C, 70°C, 72°C, 74°C, 76°C, 78°C), and the reaction time is 2-4 h (for example, 2.2 h, 2.4 h, 2.6 h, 2.8 h, 3.0 h, 3.2 h, 3.4 h, 3.6 h, 3.8 h).

[0035] It should be noted that the reaction temperature of the present invention must be precisely controlled within a certain range. At this temperature, the rosin glycerol ester and guar gum can undergo an ester exchange reaction to produce 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 the peel strength.

[0036] The reaction time of the present invention is optimized after a large number of experiments. The tackifier generated within this time can effectively improve the viscosity and flexibility of the stretch film, enhance its adhesion to the goods, thereby improving the peel strength while maintaining good mechanical properties.

[0037] Specifically, a twin-screw extruder is used for extrusion granulation.

[0038] Preferably, the temperature of each zone of the twin-screw extruder is set as follows: 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℃.

[0039] 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.

[0040] The stretch film of the present invention has an elongation at break of 519-534%, a longitudinal tensile strength of 26.7-27.8 MPa, a peel strength of 2.17-2.23 N / m, and a relative biodegradability of 98.4-99.2%.

[0041] It should be noted that all raw materials in the present invention are commercially available raw materials or are prepared by existing methods. The technical solutions of the present invention are further explained below in conjunction with specific examples.

[0042] 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 Jinfa Biomaterial Co., Ltd.; polypropylene adipate: Wuhan Shuer Biotechnology Co., Ltd.; rosin glycerol ester manufacturer is Xi'an Dafengshou Biotechnology Co., Ltd., model 136; guar gum manufacturer is Xibao Biotechnology (Shanghai) Co., Ltd., model AJA0082F; antioxidant 1010 manufacturer is Tianjin Li'anlong New Materials Co., Ltd.; anti-ultraviolet agent UV-622 manufacturer is BASF.

[0043] Example 1

[0044] A material for preparing a biodegradable stretch film according to this embodiment includes the following raw materials, in parts by weight: 74.5 parts of polybutylene adipate terephthalate, 17 parts of polybutylene succinate, 1 part of polypropylene adipate, 0.6 parts of an antioxidant, 0.3 parts of an anti-ultraviolet agent, and 8 parts of a tackifier, wherein 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, the weight-average molecular weight of the polypropylene adipate is 2,700 g / mol, the antioxidant is antioxidant 1010, and the anti-ultraviolet agent is anti-ultraviolet agent UV-622.

[0045] A method for preparing a stretch film using the above-mentioned material in this embodiment includes the following steps: (1) Rosin glycerol ester and guar gum were dissolved in ethyl acetate and reacted for 4 h at 60°C with p-toluenesulfonic acid as the acid to obtain a tackifier, wherein the molar ratio of rosin glycerol ester to guar gum was 1:1.5, the mass of the acid was 0.6% of the total mass of the rosin glycerol ester and guar gum, and the mass of the solvent was 4 times the total mass of the rosin glycerol ester and guar gum; (2) According to the ratio of each raw material used in the biodegradable stretch film, weigh and set aside; (3) Polybutylene terephthalate, polybutylene succinate, polypropylene adipate, antioxidant, anti-ultraviolet agent and tackifier are blended and extruded into granules using a twin-screw extruder. The temperature settings of each zone of the twin-screw extruder are as follows: zone 1: 180°C, zone 2: 185°C, zone 3: 190°C, zone 4: 190°C, zone 5: 190°C, zone 6: 190°C, zone 7: 185°C, zone 8: 180°C, die head: 200°C, the screw speed of the twin-screw extruder is 100 rpm, and the stretch film is cast to obtain the stretch film.

[0046] Example 2

[0047] A material for preparing a biodegradable stretch film according to this embodiment includes the following raw materials, in parts by weight: 77 parts of polybutylene terephthalate, 15 parts of polybutylene succinate, 2 parts of polypropylene adipate, 0.4 parts of an antioxidant, 0.6 parts of an anti-ultraviolet agent, and 6.5 parts of a 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 100,000 g / mol, the weight average molecular weight of polybutylene succinate is 125,000 g / mol, the weight average molecular weight of the polypropylene adipate is 4,000 g / mol, the antioxidant is antioxidant 1010, and the anti-ultraviolet agent is anti-ultraviolet agent UV-622.

[0048] A method for preparing a stretch film using the above-mentioned material in this embodiment includes the following steps: (1) Rosin glycerol ester and guar gum were dissolved in ethyl acetate and reacted for 3 h at 70°C with p-toluenesulfonic acid as the acid to obtain a tackifier, wherein the molar ratio of rosin glycerol ester to guar gum was 1:1.75, the mass of the acid was 0.8% of the total mass of the rosin glycerol ester and guar gum, and the mass of the solvent was 6 times the total mass of the rosin glycerol ester and guar gum; (2) According to the ratio of each raw material used in the biodegradable stretch film, weigh and set aside; (3) Polybutylene terephthalate, polybutylene succinate, polypropylene adipate, antioxidant, anti-ultraviolet agent and tackifier are blended and extruded into granules using a twin-screw extruder. The temperature of each zone of the twin-screw extruder is set as follows: zone 1: 170°C, zone 2: 195°C, zone 3: 180°C, zone 4: 200°C, zone 5: 180°C, zone 6: 200°C, zone 7: 175°C, zone 8: 190°C, die head: 190°C, the screw speed of the twin-screw extruder is 150rpm, and the stretch film is cast to obtain the stretch film.

[0049] Example 3

[0050] A material for preparing a biodegradable stretch film according to this embodiment includes the following raw materials, in parts by weight: 79.5 parts of polybutylene adipate terephthalate, 13 parts of polybutylene succinate, 3 parts of polypropylene adipate, 0.2 parts of an antioxidant, 0.9 parts of an anti-ultraviolet agent, and 5 parts of a 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 110,000 g / mol, the weight average molecular weight of polybutylene succinate is 150,000 g / mol, the weight average molecular weight of the polypropylene adipate is 6,000 g / mol, the antioxidant is antioxidant 1010, and the anti-ultraviolet agent is anti-ultraviolet agent UV-622.

[0051] A method for preparing a stretch film using the above-mentioned material in this embodiment includes the following steps: (1) Rosin glycerol ester and guar gum were dissolved in ethyl acetate and reacted for 2 h at 80°C with p-toluenesulfonic acid as the acid to obtain a tackifier, wherein the molar ratio of rosin glycerol ester to guar gum was 1:2, the mass of the acid was 1.0% of the total mass of the rosin glycerol ester and guar gum, and the mass of the solvent was 8 times the total mass of the rosin glycerol ester and guar gum; (2) According to the ratio of each raw material used in the biodegradable stretch film, weigh and set aside; (3) Polybutylene terephthalate, polybutylene succinate, polypropylene adipate, antioxidant, anti-ultraviolet agent and tackifier are blended and extruded into granules using a twin-screw extruder. The temperature settings of each zone of the twin-screw extruder are as follows: zone 1: 180°C, zone 2: 175°C, zone 3: 200°C, zone 4: 180°C, zone 5: 200°C, zone 6: 180°C, zone 7: 195°C, zone 8: 170°C, die head: 210°C, the screw speed of the twin-screw extruder is 200 rpm, and the stretch film is cast to obtain the stretch film.

[0052] Example 4

[0053] The material and preparation method for preparing biodegradable stretch film in this embodiment are the same as those in Example 2, except that the ratios of the raw materials are different, specifically as follows: polybutylene terephthalate: 72 parts, polybutylene succinate: 16 parts, polypropylene adipate: 1.5 parts, antioxidant: 0.5 parts, anti-ultraviolet agent: 0.5 parts and tackifier: 6 parts.

[0054] Comparative Example 1

[0055] The material and preparation method for preparing a biodegradable stretch film in this comparative example are the same as those in Example 2, except that the tackifier is rosin glycerol ester.

[0056] Comparative Example 2

[0057] The material and preparation method for preparing a biodegradable stretch film in this comparative example are the same as those in Example 2, except that the tackifier is guar gum.

[0058] Comparative Example 3

[0059] The material and preparation method for preparing a biodegradable stretch film in this comparative example are the same as those in Example 2, except that the weight-average molecular weight of polybutylene adipate terephthalate is 80,000 g / mol.

[0060] Comparative Example 4

[0061] The material and preparation method for preparing the biodegradable stretch film in this comparative example are the same as those in Example 2, except that the weight-average molecular weight of the polybutylene succinate is 90,000 g / mol.

[0062] Comparative Example 5

[0063] The material and preparation method for preparing a biodegradable stretch film in this comparative example are the same as those in Example 2, except that guar gum is replaced by sesbania gum.

[0064] Comparative Example 6

[0065] The material and preparation method for preparing a biodegradable stretch film in this comparative example are the same as those in Example 2, except that, in step (1), the reaction temperature is 55° C. and the reaction time is 5 h.

[0066] Comparative Example 7

[0067] The material and preparation method for preparing a biodegradable stretch film in this comparative example are the same as those in Example 2, except that the raw materials include 2 parts of tackifier and 81.5 parts of polybutylene adipate terephthalate.

[0068] Comparative Example 8

[0069] The material and preparation method for preparing a biodegradable stretch film in this comparative example are the same as those in Example 2, except that no polybutylene succinate is added to the raw materials, and the amount of polybutylene adipate terephthalate is 92 parts.

[0070] Comparative Example 9

[0071] The material and preparation method for preparing a biodegradable stretch film in this comparative example are the same as those in Example 2, except that no polypropylene adipate is added to the raw materials, and the amount of polybutylene adipate terephthalate is 79 parts.

[0072] Comparative Example 10

[0073] The material and preparation method for preparing a biodegradable stretch film in this comparative example are the same as those in Example 2, except that the molar ratio of rosin glycerol ester to guar gum is 1:1.

[0074] Test Example 1

[0075] Biodegradable stretch films were prepared using the methods of Examples 1-4 and Comparative Examples 1-10, respectively. The properties of the biodegradable stretch films obtained in each group were tested. The results are shown in Table 1.

[0076] The tensile performance test refers to the standard GB / T 1040-2018, the peel strength test refers to the standard GB / T 2792-1998, and the biodegradability test refers to the standard GB / T 35795-2017.

[0077] Table 1 ; As shown in Table 1, when the tackifier used in Comparative Examples 1 and 2 is rosin glycerol ester or guar gum, the mechanical properties and peel strength of the stretch film are reduced compared to Example 2. This is because the tackifier obtained through transesterification contains both the rigid structure of rosin and the flexible chain segments of guar gum. This synergistic rigidity and flexibility in the stretch film allows the tackifier to provide sufficient rigidity and enhance mechanical properties while maintaining a certain degree of flexibility and viscosity to improve peel strength.

[0078] Compared with Example 2, in Comparative Examples 3 and 4, the mechanical properties and peel strength of the prepared stretch films were reduced because the molecular weights of the polybutylene adipate terephthalate and the polybutylene succinate were outside the range of the present invention.

[0079] Comparative Example 5 Compared with Example 2, when guar gum was replaced with sesbania gum, the mechanical properties and peel strength of the stretch film were reduced.

[0080] Compared with Example 2, in Comparative Example 6, the transesterification conditions were not within the scope of the present invention, and the mechanical properties and peel strength of the prepared stretch film were reduced.

[0081] Compared with Example 2, in Comparative Examples 7-10, the raw materials or proportions of the stretch films are not within the scope of the present invention, and the mechanical properties and peel strength of the prepared stretch films are reduced.

[0082] The above description is only a preferred specific 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 thought of by any technician familiar with this technical field within the technical scope disclosed by the present invention should be covered by the scope of protection of the present invention.

Claims

1. A material used in the preparation of biodegradable stretch film, characterized in that: The material includes the following raw materials in parts by weight: 74.5 to 79.5 parts of polybutylene adipate terephthalate, 13 to 17 parts of polybutylene succinate, 1 to 3 parts of polypropylene adipate, 0.2 to 0.6 parts of antioxidant, 0.3 to 0.9 parts of anti-ultraviolet agent and 5 to 8 parts of tackifier, wherein the tackifier is prepared by reacting rosin glycerol ester and guar gum under acidic conditions.

2. The material for preparing biodegradable stretch film according to claim 1, characterized in that: The weight average molecular weight of the polybutylene adipate terephthalate is 90,000-110,000 g / mol.

3. The material for preparing biodegradable stretch film according to claim 1, characterized in that: The weight average molecular weight of the polybutylene succinate is 100,000-150,000 g / mol.

4. The material for preparing biodegradable stretch film according to claim 1, characterized in that: The weight average molecular weight of the polypropylene adipate is 2700-6000 g / mol.

5. The material for preparing biodegradable stretch film according to any one of claims 1 to 4, characterized in that: The antioxidant is antioxidant 1010, and the anti-ultraviolet agent is anti-ultraviolet agent UV-622.

6. A method for preparing a stretch film using the material according to any one of claims 1 to 5, characterized in that: The steps include: (1) reacting rosin glycerol ester and guar gum in the presence of acid to obtain a tackifier; (2) According to the ratio of each raw material used in the biodegradable stretch film, weigh and set aside; (3) Blending polybutylene terephthalate, polybutylene succinate, polypropylene adipate, an antioxidant, an anti-ultraviolet agent and a tackifier, extruding and granulating, and casting to obtain the stretch film.

7. The method for preparing a stretch film according to claim 6, wherein: In step (1), the reaction comprises: dissolving rosin glycerol ester and guar gum in a solvent, and reacting in the presence of an acid to obtain a tackifier.

8. The method for preparing a stretch film according to claim 7, wherein: The acid is p-toluenesulfonic acid, and the solvent is ethyl acetate.

9. The method for preparing a stretch film according to claim 7, wherein: The molar ratio of rosin glycerol ester and guar gum is 1:1.5-2, the mass of the acid is 0.6-1.0% of the total mass of the rosin glycerol ester and guar gum, and the mass of the solvent is 4-8 times the total mass of the rosin glycerol ester and guar gum.

10. The method for preparing a stretch film according to any one of claims 6 to 9, characterized in that: The reaction temperature is 60~80℃ and the reaction time is 2~4h.