A seawater-degradable PBAT polyester composition, preparation method and application

Abstract

The present invention belongs to the technical field of preparing polymer material composition films, and specifically relates to a method for preparing and applying a seawater-degradable PBAT composition film. The seawater-degradable PBAT composition film is composed of the following components by mass: PBAT (100 parts), polyoxalate (5-30 parts), oxalate monomer (0.5-3 parts), a terminal carboxyl removal agent (1-5 parts), an antioxidant (0.1-0.5 parts), a compatibilizer (0.2-0.5 parts), and an opening aid (0.1-1 parts). The film sample prepared by this technical solution also has good compatibility between the components, not only has a certain seawater degradation ability and excellent mechanical strength, but also has a wide range of applications.

Description

Technical Field

[0001] The present invention belongs to the technical field of preparing polymer material composition films, and specifically relates to a seawater-degradable PBAT polyester composition, a preparation method and applications. Background Art

[0002] Polybutylene terephthalate-adipate (PBAT) is widely used in daily life due to its good ductility and degradation properties, such as packaging bags, agricultural films and other fields. Although PBAT has a certain biodegradability under conditions such as composting, which can alleviate the environmental pollution caused by current non-degradable plastics, its degradation in seawater environments is extremely slow. With the large-scale application of PBAT materials, it has also caused a large amount of accumulation in the marine environment, so it is also identified as a pollutant in the marine environment. The content in the environment, especially in the marine environment, continues to increase, causing more and more environmental problems. In addition, PBAT has poor mechanical strength, which also limits its application in the market. Therefore, the design and development of marine-degradable high-performance PBAT materials has become a top priority to solve the marine environmental pollution caused by PBAT.

[0003] Literature reports suggest that improving polyester's seawater degradation performance can be achieved through the design and synthesis of novel seawater-degradable polymers, blending, or chemical modification. Blending is the most cost-effective approach to addressing polyester's difficulty in seawater degradation. The preferential hydrolysis of seawater-degradable components can lead to greater rupture of the blended material in the marine environment, creating conditions for further hydrolysis of the blend matrix.

[0004] Therefore, to give PBAT a certain degree of seawater degradation ability, improve its mechanical strength, and increase its economic efficiency, it still needs to be modified. However, how to select suitable materials under the condition of improving seawater degradation performance, solve the problems of poor compatibility and phase separation between the blended raw materials, and the problem that the blended composition cannot be smoothly blown into a film, while further improving the mechanical properties of the tough PBAT material, is the main problem to be solved by this application. Summary of the Invention

[0005] To address the shortcomings of existing PBAT materials, such as slow degradation in seawater, insufficient mechanical strength, and poor compatibility during blending, the present invention provides a seawater-degradable PBAT polyester composition, a preparation method, and its application fields.

[0006] In a first aspect, the present invention provides a seawater-degradable PBAT polyester composition, comprising the following components in parts by mass:

[0007]

[0008] The PBAT is polybutylene terephthalate adipate, and its structural formula is:

[0009]

[0010] Wherein, x is the number of butylene terephthalate structural units in PBAT, y is the number of butylene adipate structural units in PBAT, and n is the degree of polymerization of PBAT. x, y, and n are all natural numbers, 150<n<200;

[0011] The polyoxalate is selected from at least one of polyethylene oxalate (PEOx) and polybutylene oxalate (PBOx).

[0012] Preferably, the molar ratio of x to y is 6:(4-9), more preferably 45:55, 47:53, or 50:50.

[0013] Preferably, the PEOx structural formula is:

[0014]

[0015] Wherein, p is the number of structural units of ethylene glycol oxalate in PEOx, which is also the degree of polymerization of PEOx. p is a natural number and is greater than 400.

[0016] The PBOx structural formula is:

[0017]

[0018] Wherein, k is the number of structural units of butanediol oxalate in PBOx, and is also the degree of polymerization of PBOx. k is a natural number and is greater than 400.

[0019] Preferably, in the seawater-degradable PBAT polyester composition, by weight,

[0020]

[0021]

[0022] Preferably, the terminal carboxyl removal agent is at least one of erythritol, sorbitol, inositol, mannitol, and glycerol; preferably, the terminal carboxyl removal agent is inositol.

[0023] Preferably, the antioxidant is at least one of trimethyl phosphate, triphenyl phosphate, triethyl phosphate, polyphosphoric acid, triethyl phosphoacetate, trimethyl phosphoacetate, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 2,6-di-tert-butyl-4-methylphenol, 4,4'-thiobis(6-tert-butyl-3-methylphenol), dilauryl thiodipropionate, and distearyl thiodipropionate; preferably, the antioxidant is 2,6-di-tert-butyl-4-methylphenol.

[0024] Preferably, the compatibilizer is an isocyanate compound, specifically at least one of isophorone diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, toluene diisocyanate, and dicyclohexylmethane diisocyanate; preferably, the compatibilizer is isophorone diisocyanate.

[0025] Preferably, the opening aid is at least one of behenamide, lauramide, erucamide, oleamide, stearamide, talc, silicon dioxide, and titanium dioxide; preferably, the opening aid is titanium dioxide.

[0026] Furthermore, a seawater-degradable PBAT polyester composition further comprises an oxalate monomer based on the above-mentioned seawater-degradable PBAT polyester composition, and each component is calculated in parts by mass.

[0027]

[0028] Preferably, the mass fraction of the oxalate monomer is 1-2 parts.

[0029] Preferably, the oxalate monomer is at least one of dimethyl oxalate, diethyl oxalate, dipropyl oxalate, dibutyl oxalate, diphenyl oxalate, monomethyl oxalate, and monoethyl oxalate; preferably, the oxalate monomer is diethyl oxalate.

[0030] In a second aspect, the present invention provides a method for preparing a seawater-degradable PBAT polyester composition, comprising the following steps:

[0031] 100 parts of dried PBAT, 5-30 parts of dried polyoxalate, 1-5 parts of a terminal carboxyl group removing agent, 0.1-0.5 parts of an antioxidant, 0.1-1 parts of an opening aid, and 0.2-0.5 parts of a compatibilizer are added into a high-pressure mixer, uniformly mixed for not less than 5 minutes in the high-pressure mixer, and then extruded and granulated in a twin-screw extruder to obtain seawater-degradable polyester composition pellets.

[0032] Preferably, the temperature of the mixed material from the feed inlet to the melt outlet is set to 160, 165, 170, 175 and 180° C. respectively.

[0033] Preferably, before blending, the PBAT and polyoxalate are dried at 80° C. for not less than 12 hours;

[0034] In a third aspect, the present invention provides a method for preparing a seawater-degradable polyester composition film. Based on the above method for preparing a seawater-degradable polyester composition, the obtained seawater-degradable polyester composition pellets are dried and then added to a high-speed mixer together with an oxalate monomer. The mixture is uniformly mixed in the high-speed mixer for not less than 5 minutes, and then the film is blown in a film blowing machine.

[0035] The amount of the oxalate monomer added is calculated as follows: in parts by mass, 0.5-3 parts of oxalate monomer are added to every 100 parts of PBAT.

[0036] Preferably, the temperature of the mixed material from the feed port to the die of the film blowing machine is set to 160, 165, 170, 175 and 180° C. respectively.

[0037] Preferably, the pellets are dried at 80° C. for no less than 12 hours.

[0038] According to the above preparation method, a seawater-degradable PBAT composition film of the present invention can be obtained.

[0039] A type of seawater-degradable PBAT composition is used in seawater-degradable plastic handbags.

[0040] Beneficial effects:

[0041] ① Using low-cost and rapidly hydrolyzed PEOx and PBOx materials as the main seawater-degradable units to blend with PBAT can increase the seawater degradation ability of the PBAT matrix;

[0042] ② Oxalate monomer is added to the blend matrix as an auxiliary seawater-degradable unit, which can further improve the seawater hydrolysis efficiency of the blend material;

[0043] ③ The addition of a carboxyl-terminated reactant can effectively increase the stability and compatibility of the material during the blending process, and improve the processability of the blended material into a film;

[0044] ④ The compatibilizer can work synergistically with the end carboxyl removal agent to further improve the compatibility of the system;

[0045] ⑤ The obtained PBAT / PEOx blended film material has better mechanical properties than pure PBAT film, which expands the application field of PBAT materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1The scanning electron microscope images of Comparative Example 1, Example 1 and Example 2 during the seawater degradation process are shown;

[0047] Figure 2 This is a product picture of seawater-degradable PBAT composition film used as a plastic bag. DETAILED DESCRIPTION

[0048] In order to more clearly understand the above-mentioned objectives, features and advantages of the present invention, the scheme of the present invention will be further described below. It should be noted that, in the absence of conflict, the embodiments of the present invention and the features therein can be combined with each other.

[0049] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein; it is obvious that the embodiments in the specification are only part of the embodiments of the present invention, rather than all the embodiments.

[0050] The preferred embodiments of the present invention will be described in detail below with reference to the examples. It should be understood that the following examples are provided for illustrative purposes only and are not intended to limit the scope of the present invention. Those skilled in the art may make various modifications and substitutions to the present invention without departing from the purpose and spirit of the present invention.

[0051] In this example, mechanical properties were tested using an Instron (5567A, USA) instrument under a load of 100 N. The testing protocol was performed in accordance with GB / T 1040.3-2006. Specimens were cut into dumbbell shapes, 115 mm long and 25 mm wide, with a 6 mm narrow neck. The tensile rate was 100 mm / min. Each sample was repeated at least five times.

[0052] In this embodiment, the seawater in the seawater degradation performance characterization is artificial seawater, which is prepared by adding 35g of sea salt to 1000g of pure water to be consistent with the concentration of seawater. The seawater degradation experiment was carried out at 20°C. The blended membrane was cut into small pieces of 20mm×20mm, and then the specimens and artificial seawater were placed in a shaker and gently shaken. After a certain period of time, the sample was taken out, the residual test solution was washed with distilled water, and then placed in a 40°C vacuum oven for drying. In addition, the solution was replaced every 3 days. The percentage of weight loss was obtained according to the following formula to evaluate the level of seawater degradation.

[0053]

[0054] Where w0 and w1 represent the initial weight of the sample and the weight of the sample after regular sampling and drying, respectively.

[0055] The seawater degradation performance characterization in this embodiment also includes scanning electron microscopy characterization, using a QUANTA 450 manufactured by Thermo Fisher Scientific, USA. Before the test, the sample was subjected to gold spraying.

[0056] Example 1

[0057] A seawater-degradable PBAT composition comprising the following components in parts by mass:

[0058]

[0059] Prepare according to the following steps:

[0060] (1) Dry PBAT and PEOx at 80°C for 12 hours;

[0061] (2) 100 parts of PBAT, 10 parts of PEOx, 1.5 parts of inositol, 0.2 parts of 2,6-di-tert-butyl-4-methylphenol, 0.4 parts of isophorone diisocyanate, and 0.4 parts of titanium dioxide were uniformly mixed in a high-speed mixer for 5 minutes and then extruded into pellets in a twin-screw extruder. The temperatures from the feed port to the melt outlet were set to 160, 165, 170, 175, and 180° C., respectively; and PBAT polyester composition pellets were obtained;

[0062] (3) After the pellets obtained in step (2) were fully dried at 80°C for 12 hours, 114 parts of the pellets were taken and evenly mixed with 1.5 parts of diethyl oxalate in a high-speed mixer for 5 minutes, and then blown into a film in a film blowing machine. The temperatures from the feed port to the die were set to 160, 165, 170, 175, and 180°C, respectively. The seawater-degradable PBAT composition film was obtained.

[0063] The seawater-degradable PBAT composition film has a tensile strength of 42 MPa, an elongation at break of 1354%, and a weight loss rate of 6.5% after 30 days of seawater degradation.

[0064] Comparative Example 1 (Pure PBAT Film)

[0065] A seawater-degradable PBAT polyester composition comprising the following components in parts by mass:

[0066]

[0067] Prepare according to the following steps:

[0068] (1) Dry PBAT at 80°C for 12 hours;

[0069] (2) 100 parts of PBAT, 1.5 parts of inositol, 0.2 parts of 2,6-di-tert-butyl-4-methylphenol, 0.4 parts of isophorone diisocyanate, and 0.4 parts of titanium dioxide were uniformly mixed in a high-speed mixer for 5 minutes and then extruded into pellets in a twin-screw extruder. The temperatures from the feed port to the melt outlet were set to 160, 165, 170, 175, and 180°C, respectively;

[0070] (3) After the pellets obtained in step (2) were fully dried at 80°C for 12 hours, 102.5 parts of the pellets were taken and subjected to film blowing in a film blowing machine. The temperatures from the feed port to the die were set to 160, 165, 170, 175, and 180°C, respectively.

[0071] The seawater-degradable PBAT composition film has a tensile strength of 29 MPa, an elongation at break of 1487%, and a weight loss rate of 0.2% after 30 days of seawater degradation.

[0072] Comparative Example 2 (without diethyl oxalate)

[0073] A seawater-degradable PBAT polyester composition film product, comprising the following components in parts by mass:

[0074]

[0075] Prepare according to the following steps:

[0076] (1) Dry PBAT at 80°C for 12 hours;

[0077] (2) 100 parts of PBAT, 10 parts of PEOx, 1.5 parts of inositol, 0.2 parts of 2,6-di-tert-butyl-4-methylphenol, 0.4 parts of isophorone diisocyanate, and 0.4 parts of titanium dioxide were uniformly mixed in a high-speed mixer for 5 minutes and then extruded into pellets in a twin-screw extruder. The temperatures from the feed port to the melt outlet were set to 160, 165, 170, 175, and 180°C, respectively;

[0078] (3) After the pellets obtained in step (2) were fully dried at 80°C for 12 hours, 112.5 parts of the pellets were taken and subjected to film blowing in a film blowing machine. The temperatures from the feed port to the die were set to 160, 165, 170, 175, and 180°C, respectively.

[0079] The seawater-degradable PBAT composition film has a tensile strength of 41 MPa, an elongation at break of 1322%, and a weight loss rate of 4.1% after 30 days of seawater degradation.

[0080] Comparative Example 3 (without PEOx)

[0081] A seawater-degradable PBAT composition film, wherein the composition film product comprises the following components in parts by mass:

[0082]

[0083] Prepare according to the following steps:

[0084] (1) Dry PBAT at 80°C for 12 hours;

[0085] (2) 100 parts of PBAT, 1.5 parts of inositol, 0.2 parts of 2,6-di-tert-butyl-4-methylphenol, 0.4 parts of isophorone diisocyanate, and 0.4 parts of titanium dioxide were uniformly mixed in a high-speed mixer for 5 minutes and then extruded into pellets in a twin-screw extruder. The temperatures from the feed port to the melt outlet were set to 160, 165, 170, 175, and 180°C, respectively;

[0086] (3) After the pellets obtained in step (2) were fully dried at 80°C for 12 hours, 104 parts of the pellets and 1.5 parts of diethyl oxalate were taken and blown into a film in a film blowing machine. The temperatures from the feed port to the die were set to 160, 165, 170, 175, and 180°C, respectively.

[0087] The seawater-degradable PBAT composition film has a tensile strength of 29 MPa and a weight loss rate of 1.2% after 30 days of seawater degradation.

[0088] Comparative Example 4 (without addition of inositol and isocyanate)

[0089] A seawater-degradable PBAT composition film, wherein the composition film product comprises the following components in parts by mass:

[0090]

[0091] Prepare according to the following steps:

[0092] (1) Dry PBAT at 80°C for 12 hours;

[0093] (2) 100 parts of PBAT, 10 parts of PEOx, 0.2 parts of 2,6-di-tert-butyl-4-methylphenol, and 0.4 parts of titanium dioxide were uniformly mixed in a high-speed mixer for 5 minutes and then extruded into pellets in a twin-screw extruder. The temperatures from the feed port to the melt outlet were set at 160, 165, 170, 175, and 180°C, respectively;

[0094] (3) After the pellets obtained in step (2) were fully dried at 80°C for 12 hours, 112.1 parts of the pellets and 1.5 parts of diethyl oxalate were taken and blown into a film in a film blowing machine. The temperatures from the feed port to the die were set at 160, 165, 170, 175, and 180°C, respectively.

[0095] The seawater-degradable PBAT composition film has a tensile strength of 23 MPa, an elongation at break of 1263%, and a weight loss rate of 5.7% after 30 days of seawater degradation.

[0096] Comparative Example 5 (Inositol is added without isocyanate)

[0097] A seawater-degradable PBAT composition film, wherein the composition film product comprises the following components in parts by mass:

[0098]

[0099]

[0100] Prepare according to the following steps:

[0101] (1) Dry PBAT at 80°C for 12 hours;

[0102] (2) 100 parts of PBAT, 10 parts of PEOx, 1.5 parts of inositol, 0.2 parts of 2,6-di-tert-butyl-4-methylphenol, and 0.4 parts of titanium dioxide were uniformly mixed in a high-speed mixer for 5 minutes and then extruded into pellets in a twin-screw extruder. The temperatures from the feed port to the melt outlet were set to 160, 165, 170, 175, and 180°C, respectively;

[0103] (3) After the pellets obtained in step (2) were fully dried at 80°C for 12 hours, 113.6 parts of the pellets and 1.5 parts of diethyl oxalate were taken and blown into a film in a film blowing machine. The temperatures from the feed port to the die were set at 160, 165, 170, 175, and 180°C, respectively.

[0104] The seawater-degradable PBAT composition film has a tensile strength of 30 MPa, an elongation at break of 1386%, and a weight loss rate of 5.8% after 30 days of seawater degradation.

[0105] Comparative Example 6 (without adding inositol and adding isocyanate)

[0106] A seawater-degradable PBAT composition film, wherein the composition film product comprises the following components in parts by mass:

[0107]

[0108] Prepare according to the following steps:

[0109] (1) Dry PBAT at 80°C for 12 hours;

[0110] (2) 100 parts of PBAT, 10 parts of PEOx, 0.2 parts of 2,6-di-tert-butyl-4-methylphenol, 0.4 parts of isophorone diisocyanate, and 0.4 parts of titanium dioxide were uniformly mixed in a high-speed mixer for 5 minutes and then extruded into pellets in a twin-screw extruder. The temperatures from the feed port to the melt outlet were set at 160, 165, 170, 175, and 180°C, respectively;

[0111] (3) After the pellets obtained in step (2) were fully dried at 80°C for 12 hours, 112.5 parts of the pellets and 1.5 parts of diethyl oxalate were taken and blown into a film in a film blowing machine. The temperatures from the feed port to the die were set at 160, 165, 170, 175, and 180°C, respectively.

[0112] The seawater-degradable PBAT composition film has a tensile strength of 33 MPa, an elongation at break of 1335%, and a weight loss rate of 5.5% after 30 days of seawater degradation.

[0113] Comparative Example 7 (PEOx is replaced by polybutylene succinate (PBS))

[0114] A seawater-degradable PBAT composition comprising the following components in parts by mass:

[0115]

[0116] Prepare according to the following steps:

[0117] (1) Dry PBAT and PEOx at 80°C for 12 hours;

[0118] (2) 100 parts of PBAT, 10 parts of PBS, 1.5 parts of inositol, 0.2 parts of 2,6-di-tert-butyl-4-methylphenol, 0.4 parts of isophorone diisocyanate, and 0.4 parts of titanium dioxide were uniformly mixed in a high-speed mixer for 5 minutes and then extruded into pellets in a twin-screw extruder. The temperatures from the feed port to the melt outlet were set to 160, 165, 170, 175, and 180° C., respectively; and PBAT polyester composition pellets were obtained;

[0119] (3) After the pellets obtained in step (2) were fully dried at 80°C for 12 hours, 114 parts of the pellets were taken and evenly mixed with 1.5 parts of diethyl oxalate in a high-speed mixer for 5 minutes, and then blown into a film in a film blowing machine. The temperatures from the feed port to the die were set to 160, 165, 170, 175, and 180°C, respectively. The seawater-degradable PBAT composition film was obtained.

[0120] The seawater-degradable PBAT composition film has a tensile strength of 26 MPa, an elongation at break of 1342%, and a weight loss rate of 0.2% after 30 days of seawater degradation.

[0121] Example 2 (Increasing the content of PEOx)

[0122] A seawater-degradable PBAT composition film, wherein the composition film product comprises the following components in parts by mass:

[0123]

[0124]

[0125] Prepare according to the following steps:

[0126] (1) Dry PBAT and PEOx at 80°C for 12 hours;

[0127] (2) 100 parts of PBAT, 15 parts of PEOx, 1.5 parts of inositol, 0.2 parts of 2,6-di-tert-butyl-4-methylphenol, 0.4 parts of isophorone diisocyanate, and 0.4 parts of titanium dioxide were uniformly mixed in a high-speed mixer for 5 minutes and then extruded into pellets in a twin-screw extruder. The temperatures from the feed port to the melt outlet were set to 160, 165, 170, 175, and 180°C, respectively;

[0128] (3) After the pellets obtained in step (2) were fully dried at 80°C for 12 hours, 119 parts of the pellets were taken and evenly mixed with 1.5 parts of diethyl oxalate in a high-speed mixer for 5 minutes, and then blown into a film in a film blowing machine. The temperatures from the feed port to the die were set to 160, 165, 170, 175, and 180°C, respectively. The seawater-degradable PBAT composition film described in the present disclosure was obtained.

[0129] The seawater-degradable PBAT composition film has a tensile strength of 44 MPa, an elongation at break of 1258%, and a weight loss rate of 11.8% after 30 days of seawater degradation.

[0130] Example 3 (increasing the content of diethyl oxalate)

[0131] A seawater-degradable PBAT composition film, wherein the composition film product comprises the following components in parts by mass:

[0132]

[0133] Prepare according to the following steps:

[0134] (1) Dry PBAT and PEOx at 80°C for 12 hours;

[0135] (2) 100 parts of PBAT, 10 parts of PEOx, 1.5 parts of inositol, 0.2 parts of 2,6-di-tert-butyl-4-methylphenol, 0.4 parts of isophorone diisocyanate, and 0.4 parts of titanium dioxide were uniformly mixed in a high-speed mixer for 5 minutes and then extruded into pellets in a twin-screw extruder. The temperatures from the feed port to the melt outlet were set to 160, 165, 170, 175, and 180°C, respectively;

[0136] (3) After the pellets obtained in step (2) were fully dried at 80°C for 12 hours, 115.5 parts of the pellets were taken and mixed with 3 parts of diethyl oxalate in a high-speed mixer for 5 minutes, and then blown into a film in a film blowing machine. The temperatures from the feed port to the die were set to 160, 165, 170, 175, and 180°C, respectively. The seawater-degradable PBAT composition film described in the present disclosure was obtained.

[0137] The seawater-degradable PBAT composition film has a tensile strength of 42 MPa, an elongation at break of 1397%, and a weight loss rate of 8.3% after 30 days of seawater degradation.

[0138] Example 4 (Increasing the content of PEOx)

[0139] A seawater-degradable PBAT composition film, wherein the composition film product material comprises the following components in parts by mass:

[0140]

[0141] Prepare according to the following steps:

[0142] (1) Dry PBAT and PEOx at 80°C for 12 hours;

[0143] (2) 100 parts of PBAT, 20 parts of PEOx, 1.5 parts of inositol, 0.2 parts of 2,6-di-tert-butyl-4-methylphenol, 0.4 parts of isophorone diisocyanate, and 0.4 parts of titanium dioxide were uniformly mixed in a high-speed mixer for 5 minutes and then extruded into pellets in a twin-screw extruder. The temperatures from the feed port to the melt outlet were set to 160, 165, 170, 175, and 180°C, respectively;

[0144] (3) After the pellets obtained in step (2) were fully dried at 80°C for 12 hours, 124 parts of the pellets were taken and evenly mixed with 1.5 parts of diethyl oxalate in a high-speed mixer for 5 minutes, and then blown into a film in a film blowing machine. The temperatures from the feed port to the die were set to 160, 165, 170, 175, and 180°C, respectively. The seawater-degradable PBAT composition film described in the present disclosure was obtained.

[0145] The seawater-degradable PBAT composition film has a tensile strength of 34 MPa, an elongation at break of 1223%, and a weight loss rate of 15.4% after 30 days of seawater degradation.

[0146] Example 5 (PBAT / PBOx composition)

[0147] A seawater-degradable PBAT composition comprising the following components in parts by mass:

[0148]

[0149] Prepare according to the following steps:

[0150] (1) Dry PBAT and PBOx at 80°C for 12 hours;

[0151] (2) 100 parts of PBAT, 10 parts of PBOx, 1.5 parts of inositol, 0.2 parts of 2,6-di-tert-butyl-4-methylphenol, 0.4 parts of isophorone diisocyanate, and 0.4 parts of titanium dioxide were uniformly mixed in a high-speed mixer for 5 minutes and then extruded into pellets in a twin-screw extruder. The temperatures from the feed port to the melt outlet were set to 160, 165, 170, 175, and 180° C., respectively; and PBAT polyester composition pellets were obtained;

[0152] (3) After the pellets obtained in step (2) were fully dried at 80°C for 12 hours, 114 parts of the pellets were taken and evenly mixed with 1.5 parts of diethyl oxalate in a high-speed mixer for 5 minutes, and then blown into a film in a film blowing machine. The temperatures from the feed port to the die were set to 160, 165, 170, 175, and 180°C, respectively. The seawater-degradable PBAT composition film was obtained.

[0153] The seawater-degradable PBAT composition film has a tensile strength of 40 MPa, an elongation at break of 1404%, and a weight loss rate of 5.7% after 30 days of seawater degradation.

[0154] It can be seen from Example 1, Comparative Example 1, Comparative Example 2 and Comparative Example 3 that the pure PBAT film has low mechanical strength and degrades slowly in seawater. After adding PEOx and diethyl oxalate, its seawater hydrolysis efficiency is significantly improved, and the effect of adding PEOx or diethyl oxalate alone is not as high as the seawater degradation efficiency of adding both at the same time.

[0155] As can be seen from Example 1, Comparative Example 4, Comparative Example 5, and Comparative Example 6, the mechanical strength of the pure PBAT film is low, but the addition of inositol and isophorone diisocyanate significantly improves its mechanical strength. Furthermore, the effect of adding either inositol or isophorone diisocyanate alone is not as significant as the mechanical strength improvement achieved by adding both simultaneously. This suggests that the simultaneous addition of both enhances the system's compatibility and suggests a synergistic effect.

[0156] It can be seen from Example 5 that after adding PBOx to replace PEOx, the composite film can also achieve the same technical effect as PBAT / PEOx, and significantly improve the mechanical properties and seawater degradation ability of PBAT.

[0157] After research, oxalic acid esters, particularly diethyl oxalate, as small molecule auxiliary agents, can be better dispersed in the polymer matrix during the blending process, and will not affect the compatibility between the blend matrices. Diethyl oxalate, as a seawater degradation auxiliary unit, can be rapidly hydrolyzed in an aqueous environment to generate oxalic acid. On the one hand, the two carboxyl groups in the oxalic acid monomer can provide enough hydrogen ions to promote the hydrolysis of the blend matrix. On the other hand, oxalic acid, as a bulk green monomer from plant sources, will not cause secondary pollution in an aqueous environment, which also avoids the situation of aggravating marine pollution. In addition to containing six hydroxyls, the terminal carboxyl agent has a polyhydroxy structure that can react with the carboxyl group to a greater extent, can effectively react with the terminal carboxyl group of each component in the blend, can improve the compatibility between the blends, and also facilitates the processing and storage of the blends. The compatibilizer can react with the terminal hydroxyl group of each component of the blend, not only can play the role of chain extension, but also can increase the compatibility between the components. The addition of materials such as opening aids can not only make the film products of the blend easier to separate after film blowing, facilitating subsequent applications, but the addition of titanium dioxide in the more preferred solution can also act as a nucleating agent, accelerate the crystallization of the PBAT main matrix, shorten the cooling cycle of the film during the film blowing process, and reduce industrial energy consumption.

[0158] 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 seawater-degradable PBAT polyester composition, characterized in that: Calculated by mass, it contains the following components: The PBAT is polybutylene terephthalate adipate, and its structural formula is: Wherein, x is the number of butylene terephthalate structural units in PBAT, y is the number of butylene adipate structural units in PBAT, and n is the degree of polymerization of PBAT. x, y, and n are all natural numbers, 150<n<200; The polyoxalate is selected from at least one of polyethylene oxalate (PEOx) and polybutylene oxalate (PBOx); The structural formula of the polyethylene oxalate is: Wherein, p is the number of structural units of polyethylene oxalate in polyethylene oxalate, and is also the degree of polymerization of polyethylene oxalate, and p is a natural number and is greater than 400; The structural formula of polybutylene oxalate is: Wherein, k is the number of structural units of polybutylene oxalate in polybutylene oxalate, and is also the degree of polymerization of polybutylene oxalate, and k is a natural number and is greater than 400; The terminal carboxyl group removing agent is at least one of erythritol, sorbitol, inositol, mannitol, and glycerol; The compatibilizer is selected from at least one of isophorone diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, toluene diisocyanate and dicyclohexylmethane diisocyanate.

2. The seawater-degradable PBAT polyester composition according to claim 1, characterized in that: The molar ratio of x to y is 6:(4-9).

3. The seawater-degradable PBAT polyester composition according to claim 1, characterized in that: The antioxidant is at least one of trimethyl phosphate, triphenyl phosphate, triethyl phosphate, polyphosphoric acid, triethyl phosphoacetate, trimethyl phosphoacetate, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 2,6-di-tert-butyl-4-methylphenol, 4,4'-thiobis(6-tert-butyl-3-methylphenol), dilauryl thiodipropionate, and distearyl thiodipropionate; The opening aid is at least one of behenamide, lauramide, erucamide, oleamide, stearamide, talc, silicon dioxide and titanium dioxide.

4. The seawater-degradable PBAT polyester composition according to claim 1, characterized in that: Calculated by mass, it contains the following components:

5. The seawater-degradable PBAT polyester composition according to claim 1, characterized in that: Also contains oxalate monomer; in parts by mass, 6. The seawater-degradable PBAT polyester composition according to claim 5, characterized in that: The oxalate monomer is at least one of dimethyl oxalate, diethyl oxalate, dipropyl oxalate, dibutyl oxalate, diphenyl oxalate, monomethyl oxalate and monoethyl oxalate.

7. The seawater-degradable PBAT polyester composition according to claim 5, characterized in that: The mass fraction of the oxalate monomer is 1-2 parts.

8. A method for preparing a seawater-degradable PBAT polyester composition according to any one of claims 1 to 4, characterized in that: The steps include: The measured dried PBAT and polyoxalate, together with the end carboxyl removal agent, antioxidant, opening aid and compatibilizer, are put into a high-speed mixer in parts by mass, uniformly mixed in the high-speed mixer, and then extruded into granules in a twin-screw extruder to obtain seawater-degradable PBAT polyester composition pellets.

9. A method for preparing the seawater-degradable PBAT polyester composition according to claim 8, characterized in that: The method comprises the following steps: drying the seawater-degradable polyester composition pellets prepared according to claim 8, adding the pellets together with the oxalate monomer into a high-speed mixer, uniformly mixing them in the high-speed mixer, and then performing film blowing processing in a film blowing machine to obtain the seawater-degradable PBAT polyester composition in the form of a film product; The amount of the oxalate monomer added is calculated as follows: in parts by mass, 0.5-3 parts of oxalate monomer are added to every 100 parts of PBAT.

10. Use of the seawater-degradable PBAT polyester composition according to any one of claims 5 to 7 in seawater-degradable plastic handbags.

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