PBS (Phosphate Buffer Solution) resin composition as well as preparation method and application thereof

Abstract

The invention provides a PBS resin composition and a preparation method and application thereof, the PBS resin composition comprises a combination of poly (butylene succinate), a cyclic oligomer and a linear oligomer, the mass content of the cyclic oligomer is 500-10000 ppm, and the mass content of the linear oligomer is 50-1000 ppm; the PBS resin composition has specific active end group content and molecular weight distribution through compounding and combined action of the cyclic oligomer, the straight-chain oligomer and the poly (butylene succinate) with specific content, the PBS resin composition has excellent mechanical property and hydrolysis aging resistance, and each component has excellent biodegradability, is good in safety and can be widely applied to the field of medical instruments, medical instruments, medical instruments, medical instruments, medical instruments, medical instruments, medical instruments, medical instruments, medical instruments, medical instruments, medical instruments, medical instruments, medical instruments, medical instruments, medical instruments, medical instruments and the like. The application requirements in food contact materials can be fully met.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and particularly relates to a PBS resin composition, a preparation method and an application thereof. Background Art

[0002] Polybutylene succinate (PBS) is an aliphatic biodegradable polyester whose final degradation products are carbon dioxide and water. It exhibits excellent biocompatibility, biodegradability, and processability. PBS also boasts a heat distortion temperature (HDT) exceeding 100°C, making it the most suitable biodegradable plastic for hot food applications. It is widely used in the production of milk tea straws, disposable knives, forks, and spoons, and drinking cups.

[0003] PBS preparation methods can be divided into direct esterification and transesterification. The direct esterification method uses succinic acid and 1,4-butanediol (BDO) as raw materials to undergo esterification and polycondensation. The transesterification method uses dimethyl succinate (DMS) and 1,4-butanediol (BDO) as raw materials to undergo transesterification and polycondensation. Due to the high cost of the transesterification method and the need for specialized recovery equipment to recover the by-product methanol, which results in higher equipment costs, the direct esterification method is currently the mainstream PBS preparation method.

[0004] Although the direct esterification method is widely used, there is still a lot of room for improvement. Since both the esterification stage and the polycondensation stage are accompanied by the generation of a large number of by-products, the molecular weight of the obtained PBS is low and the content of low molecular weight impurities is high, resulting in obvious deficiencies in its mechanical properties and water aging resistance. In order to increase the molecular weight of PBS and reduce low molecular weight impurities, researchers have improved the process from the perspectives of catalysts, reaction aids, and post-treatment. For example, CN104693428A discloses a high molecular weight polybutylene succinate, which uses succinic acid, succinic anhydride and 1,4-butanediol as raw materials, and undergoes esterification reaction and polycondensation reaction in sequence to finally obtain polybutylene succinate. The polycondensation reaction process uses titanium silicalite as a catalyst, which has a large specific surface area and can effectively increase the molecular weight of PBS; however, the preparation cost of titanium silicalite is high, which is not conducive to large-scale application. CN101077905A discloses a method for preparing high-molecular-weight poly (butylene succinate), which uses low-molecular-weight, double-terminated hydroxybutylene succinate as a prepolymer and undergoes a melt reaction with 0.1-13% of a chain extender, diisocyanate, to produce high-molecular-weight PBS. The chain extender used in this method poses a toxicity risk, limiting the application of PBS in the food industry. JP2006299161A discloses a method for refining polyester, which involves treating the polyester with a gaseous fluid such as CO2 and an extraction aid at room temperature and pressure to remove low-molecular-weight impurities from polyester products such as PBS. However, this method is costly, and the refined PBS has poor water aging resistance, resulting in insufficient product performance.

[0005] Therefore, there is an urgent need in this field to develop PBS products with excellent mechanical properties, water aging resistance and safety to meet their performance requirements in food-related materials. Summary of the Invention

[0006] In response to the deficiencies in the prior art, the present invention aims to provide a PBS resin composition, a preparation method thereof, and applications thereof. By compounding polybutylene succinate with specific contents of cyclic oligomers and linear oligomers, the PBS resin composition has significantly improved mechanical properties and resistance to water boiling aging, and is highly safe, fully meeting the application requirements of food contact materials.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a PBS resin composition, comprising a combination of polybutylene succinate, a cyclic oligomer, and a linear oligomer; the cyclic oligomer having a structure as shown in Formula I:

[0009]

[0010] In Formula I, n is selected from an integer of 1-10, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10.

[0011] The linear oligomer comprises a structural unit as shown in Formula II:

[0012]

[0013] The mass content of the cyclic oligomer in the PBS resin composition is 500-10000 ppm, and the mass content of the linear oligomer is 50-1000 ppm.

[0014] In the PBS resin composition provided by the present invention, the cyclic oligomer is as shown in Formula I, which is a cyclic structure formed by the esterification reaction between succinic acid and 1,4-butanediol, with functional groups connected end to end. The linear oligomer contains a structural unit as shown in Formula II, which is a chain product formed by the esterification of succinic acid and 1,4-butanediol, and both ends still retain activity (carboxyl and / or hydroxyl groups). The present invention compounded specific contents of cyclic oligomers, linear oligomers and polybutylene succinate (PBS) to exert appropriate lubricating and buffering effects between PBS macromolecules, regulate the interaction between PBS macromolecular segments, reduce spatial anomalies in the PBS molecular structure, and enable the PBS resin composition to have a specific molecular weight distribution and active end group content, increase intrinsic viscosity, and achieve both high strength and excellent flexibility, thereby significantly improving mechanical properties, thermal stability, durability and resistance to water boiling aging. Furthermore, the composition has higher processing fluidity, improved processing performance, higher gloss and excellent hue, and each component is biodegradable and safe, thus fully meeting application requirements in food contact materials.

[0015] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. Through the following preferred technical solutions, the objectives and beneficial effects of the present invention can be better achieved and realized.

[0016] In the present invention, "ppm" means parts per million, and 1 ppm means one part per million.

[0017] In the present invention, the structure of the cyclic oligomer is as shown in Formula I, wherein n represents the number of repeating units, which is an integer selected from 1-10; specifically, the cyclic oligomer includes any one or a combination of at least two of the following compounds:

[0018] (n is 1), (n is 2),

[0019]

[0020] Among them, R1 represents -(CH2)4-, and R2 represents -(CH2)2-.

[0021] n1 represents an integer from 1 to 8, for example, 1, 2, 3, 4, 5, 6, 7 or 8. When n1 is 1, n in Formula 1 is 3; when n1 is 2, n in Formula 1 is 4; and so on. For the sake of brevity, each of the above descriptions will not be repeated.

[0022] The mass content of the cyclic oligomer in the PBS resin composition is 500-10000 ppm, for example, 600 ppm, 800 ppm, 1000 ppm, 1500 ppm, 2000 ppm, 2500 ppm, 3000 ppm, 3500 ppm, 4000 ppm, 4500 ppm, 5000 ppm, 5500 ppm, 6000 ppm, 6500 ppm, 7000 ppm, 7500 ppm, 8000 ppm, 8500 ppm, 9000 ppm or 9500 ppm, as well as specific values between the above points. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively enumerates the specific points included in the range. It is further preferred that the range is 2000-8000 ppm, and even more preferably 4000-6000 ppm.

[0023] The mass content of the linear oligomer in the PBS resin composition is 50-1000 ppm, for example, 60 ppm, 80 ppm, 100 ppm, 150 ppm, 200 ppm, 250 ppm, 300 ppm, 350 ppm, 400 ppm, 450 ppm, 500 ppm, 550 ppm, 600 ppm, 650 ppm, 700 ppm, 750 ppm, 800 ppm, 850 ppm, 900 ppm or 950 ppm, as well as specific values between the above points. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively enumerates the specific points included in the range, and 100-500 ppm is further preferred.

[0024] The present invention designs and optimizes the content of the cyclic oligomer and the linear oligomer in the PBS resin composition, thereby enabling the PBS resin composition to have excellent mechanical properties, durability, resistance to water boiling aging, and thermal stability. If the content of the cyclic oligomer and the linear oligomer is too high, the content of low molecular weight components in the PBS resin composition will increase, resulting in insufficient mechanical properties and the risk of small molecule migration and precipitation, affecting the safety of the composition in food contact applications. If the mass content of the cyclic oligomer and the linear oligomer is too low, the aggregation of PBS macromolecules will be too high, thermal stability will be reduced, and resistance to water boiling aging will be insufficient.

[0025] Preferably, n is an integer selected from 2-9.

[0026] Preferably, the number average molecular weight of the cyclic oligomer is 172-1720, for example, it can be 180, 200, 300, 400, 500, 600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500, 1600 or 1700, as well as specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values included in the said range.

[0027] Preferably, the linear oligomer is selected from any one or a combination of at least two of the compound represented by formula II-1, the compound represented by formula II-2, and the compound represented by formula II-3;

[0028]

[0029] Wherein, m1, m2, and m3 are each independently selected from integers of 1-10, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10, more preferably 2-9.

[0030] Preferably, the number average molecular weight of the linear oligomer is 190-1838, for example, it can be 195, 200, 300, 400, 500, 600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700 or 1800, as well as specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values included in the range.

[0031] Exemplarily, the content of cyclic oligomers and linear oligomers in the PBS resin composition can be tested by high performance size exclusion chromatography-mass spectrometry (SEC-ESI-Q-TOF MS), specifically as follows: the sample to be tested is dissolved in a chloroform / trifluoroacetic acid TFA mixed solvent (the volume ratio of chloroform to TFA is 9:1), and tested by SEC-ESI-Q-TOF MS. In the obtained spectrum, the retention time of PBS is <10 min, and the retention time of the cyclic oligomer and the linear oligomer is 15-20 min. Furthermore, the cyclic oligomer has a structure of formula I, and its molecular weight satisfies the relationship M=172x; the molecular weight of the linear oligomer satisfies the relationship M=172x+18 (structure shown in formula II-1), M=172x+118 (structure shown in formula II-2), and M=172x+90 (structure shown in formula II-3), where the aforementioned x represents an integer of 1-10; the total ion current (TIC) of the mass spectrometer is extracted from the chromatographic peak in the 15-20min interval, the target peak is locked in combination with the ultraviolet signal, and the chromatographic peak in the 15-20min interval is resolved in combination with the x value, the chromatographic peaks of the linear oligomer and the cyclic oligomer are identified, and the chromatographic peaks in the 15-20min interval are integrated, and the contents of the cyclic oligomer and the linear oligomer are calculated respectively by the peak area normalization method.

[0032] Preferably, the number average molecular weight of the PBS resin composition is 4×10 4 -10×10 4 , for example, it can be 4.5×10 4 , 5×10 4 , 5.5×10 4 , 6×10 4 , 6.2×10 4 , 6.4×10 4 , 6.5×10 4 , 6.6×10 4 , 6.8×10 4 , 7×10 4 , 7.2×10 4 , 7.4×10 4 , 7.5×10 4 , 7.6×10 4 , 7.8×10 4 , 8×10 4 , 8.5×10 4 , 9×10 4 or 9.5×10 4 , and specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values included in the above range. It is further preferred that 6×10 4 -8×10 4 .

[0033] Preferably, the weight average molecular weight of the PBS resin composition is 5×10 4 -12×10 4 , for example, it can be 5.5×10 4 , 6×10 4 , 6.5×10 4 , 7×10 4 , 7.5×10 4 , 8×10 4 , 8.2×10 4 , 8.5×10 4 , 8.8×10 4 , 9×10 4 , 9.2×10 4 , 9.5×10 4 , 9.8×10 4 , 10×10 4 , 10.2×10 4 , 10.5×10 4 , 10.8×10 4 , 11×10 4 or 11.5×10 4 , and specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values included in the above range. 8×10 4 -11×10 4 .

[0034] Preferably, the Z average molecular weight of the PBS resin composition is 8×10 4 -16×10 4 , for example, it can be 8.5×10 4 , 9×10 4 , 9.5×10 4 , 10×10 4 , 10.5×10 4 , 11×10 4 , 11.5×10 4 , 12×10 4 , 12.2×10 4 , 12.5×10 4 , 12.8×10 4 , 13×10 4 , 13.2×10 4 、13.5×10 4 、13.8×10 4 , 14×10 4 、14.2×10 4 、14.5×10 4、14.8×10 4 , 15×10 4 or 15.5×10 4 , and specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values included in the above range. It is further preferred that 12×10 4 -15×10 4 .

[0035] Preferably, the molecular weight polydispersity index of the PBS resin composition is 1.2-1.6, for example, 1.22, 1.25, 1.28, 1.3, 1.32, 1.35, 1.38, 1.4, 1.42, 1.45, 1.48, 1.5, 1.52, 1.55 or 1.58, as well as specific values between the above points. Due to space limitations and for the sake of brevity, the present invention does not exhaustively enumerate the specific points included in the range.

[0036] In the present invention, the number average molecular weight (M n ), weight average molecular weight (M w ), Z average molecular weight (M z ) can be obtained by gel permeation chromatography (GPC) test, and the molecular weight polydispersity index (PDI) is M w / M n .

[0037] Exemplarily, the specific test method of the GPC is as follows: using a chromatography system at 35° C., using a set of 2 columns in series (particle diameter of 4-6 μm), using a refractive index detector, using tetrahydrofuran as the eluent (flow rate 0.1 mL / min), and using polystyrene as the reference standard.

[0038] Preferably, the terminal carboxyl value of the PBS resin composition is 5-80 mol / t, for example, it can be 8 mol / t, 10 mol / t, 15 mol / t, 20 mol / t, 25 mol / t, 30 mol / t, 35 mol / t, 40 mol / t, 45 mol / t, 50 mol / t, 55 mol / t, 60 mol / t, 65 mol / t, 70 mol / t or 75 mol / t, as well as specific values between the above points. Due to space limitations and for the sake of brevity, the present invention does not exhaustively enumerate the specific values included in the range.

[0039] For example, the terminal carboxyl value of the PBS resin composition can be measured according to the method in standard FZ / T 50012-2006.

[0040] Preferably, the intrinsic viscosity of the PBS resin composition is 1.40-1.65 dL / g, for example, 1.42 dL / g, 1.45 dL / g, 1.48 dL / g, 1.50 dL / g, 1.52 dL / g, 1.55 dL / g, 1.58 dL / g, 1.60 dL / g, 1.62 dL / g, or 1.64 dL / g, as well as specific values between the aforementioned values. Due to space limitations and for the sake of brevity, the present invention does not exhaustively enumerate the specific values included in the aforementioned range.

[0041] For example, the intrinsic viscosity of the PBS resin composition is tested using a fully automatic Ubbelohde viscometer, with a mixture of phenol and tetrachloroethane (phenol:tetrachloromethane=1:3, volume ratio) as a solvent.

[0042] In a second aspect, the present invention provides a method for preparing the PBS resin composition as described in the first aspect, the preparation method comprising the following steps:

[0043] Esterification reaction is carried out between succinic acid and 1,4-butanediol to obtain an esterified product;

[0044] The esterified product is subjected to a polycondensation reaction in the presence of a catalyst and a branching agent to obtain a polymer product;

[0045] The polymer product is extracted with a mixed solvent to obtain the PBS resin composition, wherein the mixed solvent comprises a combination of water, an alcohol solvent and a cycloalkane solvent.

[0046] Preferably, the molar ratio of succinic acid to 1,4-butanediol is 1:(1.2-1.6), for example, it can be 1:1.22, 1:1.25, 1:1.28, 1:1.3, 1:1.32, 1:1.35, 1:1.38, 1:1.4, 1:1.42, 1:1.45, 1:1.48, 1:1.5, 1:1.52, 1:1.55 or 1:1.58, etc.

[0047] Preferably, the temperature of the esterification reaction is 150-170°C, for example, it can be 152°C, 154°C, 155°C, 156°C, 158°C, 170°C, 172°C, 174°C, 175°C, 176°C or 178°C, as well as specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values included in the range.

[0048] Preferably, the esterification reaction time is 2-4 h, for example, it can be 2.2 h, 2.5 h, 2.8 h, 3 h, 3.2 h, 3.5 h or 3.8 h, as well as specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values included in the range.

[0049] As a preferred technical solution of the present invention, in the esterification reaction stage, the esterification condensation tower top temperature drops to ≤85°C and the esterification water yield is ≥95%, which is considered to be the end of the esterification reaction.

[0050] Preferably, the catalyst comprises a titanate catalyst, and more preferably comprises any one or a combination of at least two of tetramethyl titanate, tetraethyl titanate, tetraisopropyl titanate, tetra-n-butyl titanate, and tetraisooctyl titanate.

[0051] Preferably, based on the total mass of the succinic acid and 1,4-butanediol as 100%, the amount of the catalyst used is such that the mass of the Ti element is 50-200 ppm, for example, it can be 60 ppm, 80 ppm, 100 ppm, 120 ppm, 140 ppm, 150 ppm, 160 ppm or 180 ppm, as well as specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values included in the range.

[0052] Preferably, the branching agent includes a polyol (other than 1,4-butanediol), and more preferably includes any one or a combination of at least two of glycerol, trimethylolpropane, pentaerythritol, dipentaerythritol, and 2,2-dimethylolpropionic acid.

[0053] Preferably, based on the total mass of the succinic acid and 1,4-butanediol as 100%, the amount of the branching agent used is such that the mass of its hydroxyl group is 200-1000 ppm, for example, it can be 250 ppm, 300 ppm, 350 ppm, 400 ppm, 450 ppm, 500 ppm, 550 ppm, 600 ppm, 650 ppm, 700 ppm, 750 ppm, 800 ppm, 850 ppm, 900 ppm or 950 ppm, as well as specific values between the above points. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific points included in the range.

[0054] Preferably, the polycondensation reaction is carried out in the presence of a thermal stabilizer.

[0055] Preferably, the heat stabilizer includes a phosphate compound, and more preferably includes any one or a combination of at least two of trimethyl phosphate, triethyl phosphate, isopropyl phosphate, n-butyl phosphate, isooctyl phosphate, and triphenyl phosphate.

[0056] Preferably, based on the total mass of the succinic acid and 1,4-butanediol as 100%, the amount of the heat stabilizer is such that the mass of the P element is 5-100 ppm, for example, it can be 10 ppm, 20 ppm, 30 ppm, 40 ppm, 50 ppm, 60 ppm, 70 ppm, 80 ppm or 90 ppm, as well as specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values included in the range.

[0057] Preferably, the polycondensation reaction includes a prepolymerization reaction and a final polymerization reaction carried out sequentially.

[0058] Preferably, the temperature of the prepolymerization reaction is 180-240°C, for example, it can be 185°C, 190°C, 195°C, 200°C, 205°C, 210°C, 215°C, 220°C, 225°C, 230°C or 235°C, as well as specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values included in the range.

[0059] Preferably, the pressure of the prepolymerization reaction is 1-5 kPa, for example, it can be 1.5 kPa, 2 kPa, 2.5 kPa, 3 kPa, 3.5 kPa, 4 kPa or 4.5 kPa, as well as specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values included in the range.

[0060] Preferably, the prepolymerization reaction time is 1-3h, for example, it can be 1.2h, 1.5h, 1.8h, 2h, 2.2h, 2.5h or 2.8h, as well as specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values included in the range.

[0061] Preferably, the temperature of the final polymerization reaction is 220-260°C, for example, it can be 222°C, 225°C, 228°C, 230°C, 232°C, 235°C, 238°C, 240°C, 242°C, 245°C, 248°C, 250°C, 252°C, 255°C or 258°C, as well as specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values included in the range.

[0062] Preferably, the pressure of the final polymerization reaction is 20-100 Pa, for example, it can be 25 Pa, 30 Pa, 35 Pa, 40 Pa, 45 Pa, 50 Pa, 55 Pa, 60 Pa, 65 Pa, 70 Pa, 75 Pa, 80 Pa, 85 Pa, 90 Pa or 95 Pa, as well as specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values included in the range.

[0063] Preferably, the final polymerization reaction time is 2-6h, for example, it can be 2.2h, 2.5h, 2.8h, 3h, 3.2h, 3.5h, 3.8h, 4h, 4.2h, 4.5h, 4.8h, 5h, 5.2h, 5.5h or 5.8h, as well as specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values included in the range.

[0064] Preferably, after the final polymerization reaction is completed, the process further comprises the step of extrusion granulation.

[0065] Preferably, the 100-grain weight of the polymer product obtained by extrusion granulation is 1.2-1.32 g, for example, it can be 1.22 g, 1.25 g, 1.28 g or 1.30 g, as well as specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values included in the range, and 1.25-1.30 g is further preferred.

[0066] In the present invention, the term "100-grain weight" refers to the mass of 100 particles of the polymer product, which can be measured by weighing.

[0067] The present invention adopts a ternary mixed solvent including water, an alcohol solvent and a cycloalkane solvent to extract the polymer product, and can adjust the extraction effect to obtain a PBS resin composition containing a specific content of cyclic oligomers and linear oligomers.

[0068] Preferably, the mass percentage of water in the mixed solvent is 25-45%, for example, it can be 28%, 30%, 32%, 35%, 38%, 40%, 42% or 44%, as well as specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values included in the range, and 30-40% is further preferred.

[0069] Preferably, the alcohol solvent includes any one of methanol, ethanol, propanol, and butanol, or a combination of at least two thereof, and n-butanol is more preferred.

[0070] Preferably, the mass percentage of the alcohol solvent in the mixed solvent is 45-62%, for example, it can be 48%, 50%, 52%, 55%, 56%, 58% or 60%, as well as specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values included in the range, and 50-60% is further preferred.

[0071] Preferably, the cycloalkane solvent comprises cyclohexane.

[0072] Preferably, the mass percentage of the cycloalkane solvent in the mixed solvent is 8-25%, for example, it can be 10%, 12%, 14%, 15%, 16%, 18%, 20%, 20%, 22% or 24%, as well as specific values between the above points. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific points included in the range, and 10-20% is further preferred.

[0073] Preferably, the number of extractions is 1-3 times, for example, 1 time, 2 times or 3 times; when the number of extractions is ≥ 2, the organic solvent used in each extraction is the same or different, the time of each extraction is the same or different, the temperature of each extraction is the same or different, and the solid-liquid ratio (mass ratio of the polymer product to the organic solvent) of each extraction is the same or different.

[0074] Preferably, the mass ratio of the polymer product to the mixed solvent (the solid-liquid ratio of the extraction) is 1:(1.5-2), for example, it can be 1:1.55, 1:1.6, 1:1.65, 1:1.7, 1:1.75, 1:1.8, 1:1.85, 1:1.9 or 1:1.95, etc.

[0075] Preferably, the extraction temperature is 60-80°C, for example, 62°C, 65°C, 68°C, 70°C, 72°C, 75°C or 78°C, as well as specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values included in the range.

[0076] Preferably, the extraction time is 0.5-3h, for example, it can be 0.8h, 1h, 1.2h, 1.5h, 1.8h, 2h, 2.1h, 2.2h, 2.3h, 2.4h, 2.5h, 2.6h, 2.7h, 2.8h or 2.9h, as well as specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values included in the range.

[0077] Preferably, each extraction further includes the steps of solid-liquid separation and drying.

[0078] As a preferred technical solution of the present invention, the preparation method of the PBS resin composition comprises the following steps:

[0079] (1) Succinic acid and 1,4-butanediol are mixed at a molar ratio of 1:(1.2-1.6), and esterification reaction is carried out at 150-170° C. for 2-4 hours to obtain an esterified product;

[0080] (2) placing the esterified product obtained in step (1), a titanate catalyst, a polyol branching agent, and a phosphate thermal stabilizer in a reaction apparatus, and reacting them at 180-240° C. and 1-5 kPa for 1-3 hours to obtain a prepolymer;

[0081] Based on the total mass of the succinic acid and 1,4-butanediol as 100%, the titanate catalyst is used in an amount such that the mass of the Ti element is 50-200 ppm, the polyol branching agent is used in an amount such that the mass of the hydroxyl group is 200-1000 ppm, and the phosphate heat stabilizer is used in an amount such that the mass of the P element is 5-100 ppm;

[0082] (3) reacting the prepolymer obtained in step (2) at 220-260° C. and 20-100 Pa for 2-6 hours, extruding and granulating to obtain a polymer product;

[0083] (4) extracting the polymer product obtained in step (3) 1-3 times with a mixed solvent under stirring, performing solid-liquid separation and drying to obtain the PBS resin composition;

[0084] The mixed solvent comprises, by weight percentage, 25-45% water, 45-62% alcohol solvent, and 8-25% cycloalkane solvent;

[0085] The extraction temperature is independently 60-80° C., the extraction time is independently 0.5-3 h, and the solid-liquid ratio is independently 1:(1.5-2).

[0086] In a preferred technical solution of the present invention, the PBS resin composition is prepared by a polymerization reaction method, that is, using succinic acid and 1,4-butanediol as main raw materials, obtaining a polymerization product through esterification reaction, prepolymerization reaction and final polymerization reaction, and then subjecting the polymerization product to extraction and mass transfer. Through the design and optimization of the process route, especially through the setting of the extraction solvent, the PBS resin composition containing specific amounts of cyclic oligomers, linear oligomers and PBS is obtained.

[0087] In another technical solution of the present invention, the PBS resin composition can be prepared by a blending method, that is, PBS, cyclic oligomers and linear oligomers are uniformly mixed in a specific ratio to obtain the PBS resin composition.

[0088] In a third aspect, the present invention provides a use of the PBS resin composition as described in the first aspect in food contact materials.

[0089] Optionally, the food contact material comprises a straw, cutlery (eg, knife, fork, spoon) or cup.

[0090] Compared with the prior art, the present invention has the following beneficial effects:

[0091] The PBS resin composition provided by the present invention utilizes specific amounts of cyclic oligomers, linear oligomers, and polybutylene succinate to compound and interact with each other, thereby regulating the interactions between PBS macromolecular segments, resulting in a specific active end group content and molecular weight distribution, and improving the intrinsic viscosity. The PBS resin composition exhibits excellent mechanical properties, thermal stability, durability, and resistance to water boiling aging, and also has improved processing fluidity. Each component exhibits excellent biodegradability, resulting in good safety, and fully meeting the application requirements of food contact materials. DETAILED DESCRIPTION

[0092] The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0093] As used herein, the terms "comprises," "including," "having," "containing" or any other variations thereof, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises a listed element is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.

[0094] In the following specific embodiments of the present invention, the testing methods for various properties are as follows:

[0095] (1) The content of cyclic oligomers and linear oligomers in the PBS resin composition was determined by high performance size exclusion chromatography coupled to mass spectrometry (SEC-ESI-Q-TOF MS). The specific method is as follows:

[0096] 1. Sample preparation

[0097] Weigh 5 mg of the PBS resin composition sample to be tested, add 5 mL of preheated chloroform / trifluoroacetic acid TFA mixed solvent (chloroform: TFA = 9:1, volume ratio), and sonicate in a 90°C water bath for 30 min; then filter using a 0.22 μm PTFE needle filter to remove undissolved PBS macromolecules and impurities, and transfer the filtrate to a 2 mL brown injection bottle for later use.

[0098] 2. Instruments and Analytical Conditions

[0099] 2.1 Chromatographic system

[0100] Chromatographic column: TSKgel Super Multipore HZ-M (4.6 × 150 mm, particle size 3 μm);

[0101] Mobile phase: a mixture of chloroform and TFA (TFA content: 0.1 wt %, degassed through a 0.22 μm filter membrane);

[0102] Flow rate: 0.5 mL / min, column temperature: 40 °C, detection wavelength: 220 nm;

[0103] Injection volume: 20 μL, run time: 25 min.

[0104] 2.2 Mass spectrometry system (SEC-ESI-Q-TOF MS)

[0105] Ion source: electrospray ionization (ESI), negative ion mode (carboxylic acid groups are easily deprotonated);

[0106] Parameter settings: capillary voltage: -3.0 kV; cone voltage: -40 V; desolvation temperature: 300 °C; nebulizer gas flow rate: 8 L / min;

[0107] Mass scan range: m / z 100-2000, resolution >30000 (FWHM).

[0108] 3. Separation and Detection Principles

[0109] 3.1 Relationship between retention time and molecular weight

[0110] PBS (weight average molecular weight M w >10000): Large hydrodynamic volume, retention time <10min;

[0111] Linear oligomers (number average molecular weight M n 190-1838): retention time 15-20min, the difference in terminal groups leads to different molecular formulas:

[0112] Double-terminal hydroxyl group (structure shown in formula II-3): molecular weight M = 172x + 90;

[0113] Double-terminal carboxyl group (structure shown in formula II-2): M = 172x + 118;

[0114] One end hydroxyl group and one end carboxyl group (structure shown in formula II-1): M = 172x + 18;

[0115] Circular oligomer (M n 172-1720): retention time 15-20min, its structure is compact, later than the linear oligomer of the same molecular weight, M = 172x;

[0116] The aforementioned x represents an integer from 1 to 10;

[0117] Molecular weight matching: The oligomer type was determined by accurate mass (error < 5 ppm).

[0118] 3. Data Analysis and Quantitative Methods

[0119] Chromatographic peak attribution:

[0120] PBS main peak: retention time <10min;

[0121] Oligomer peak: Extract the total ion current (TIC) of the chromatographic peak within the 15-20 min interval and lock the target peak in combination with the UV signal;

[0122] 3.2 Mass Spectrometry Data Interpretation

[0123] Deconvolution: MassLynx instrument software was used to deconvolute the multiply charged ion peaks to obtain the neutral molecular weight;

[0124] x value calculation:

[0125] Linear oligomer: x = (M-terminal group mass) / 172 (rounded);

[0126] Circular oligomer: x = M / 172 (rounded);

[0127] The chromatographic peaks in the 15-20 min interval were resolved by combining the x value to identify the chromatographic peaks of linear oligomers and circular oligomers;

[0128] 3.3 Quantitative calculation

[0129] UV detector quantification: The chromatographic peaks in the 15-20 min interval were integrated and the content of each oligomer was calculated by peak area normalization.

[0130] (2) The number average molecular weight (M) of the PBS resin composition n ), weight average molecular weight (M w ), Z average molecular weight (M z ) and molecular weight polydispersity index (PDI): Molecular weights were determined by gel permeation chromatography (GPC) using a chromatographic system at 35°C with a set of two columns in series (particle diameter 4-6 μm), a refractive index detector, tetrahydrofuran as the eluent (flow rate 0.1 mL / min), and polystyrene as the reference standard. PDI = M w / M n .

[0131] (3) Terminal carboxyl value: obtained by acid-base neutralization titration according to the method in standard FZ / T 50012-2006.

[0132] (4) Intrinsic viscosity: The test was performed using a fully automatic Ubbelohde viscometer, with a mixture of phenol and tetrachloroethane (phenol:tetrachloromethane = 1:3, volume ratio) as the solvent.

[0133] (5) Water boiling aging resistance: The PBS resin composition to be tested was placed in a 95°C water bath for aging for 24 h, taken out and dried at 80°C, and then its intrinsic viscosity was measured according to the above method, and the change range was calculated; the smaller the absolute value of the change range, the better the hydrolysis aging resistance;

[0134] Variation range = 100% × (test value after water boiling aging - initial test value) / initial test value; the initial test value is the test value of the PBS resin composition before water boiling aging.

[0135] (6) Mechanical properties: The PBS to be tested was injection molded into specimens and tested according to the method in standard ISO 527-2-2012 at a test condition of 50 mm / min;

[0136] (7) Hundred-grain weight: Take 100 granular polymer products and weigh them to obtain the hundred-grain weight in g.

[0137] In the following specific embodiments of the present invention, reagents for which the preparation methods are not specified are all conventional commercially available chemicals.

[0138] Example 1

[0139] A PBS resin composition comprises a combination of PBS, a cyclic oligomer and a linear oligomer; the preparation method comprises the following steps:

[0140] (1) Succinic acid and 1,4-butanediol were mixed at a molar ratio of 1:1.4, and esterification reaction was carried out at 155°C for 3 hours to obtain an esterified product;

[0141] (2) placing the esterified product obtained in step (1), a catalyst (tetra-n-butyl titanate), a branching agent (dipentaerythritol) and a thermal stabilizer (trimethyl phosphate) in a prepolymerization reactor, and reacting them at 220° C. and 1 kPa for 1 hour to obtain a prepolymer;

[0142] Based on the total mass of the succinic acid and 1,4-butanediol as 100%, the amount of the catalyst used is such that the mass of the Ti element is 80 ppm, the amount of the branching agent used is such that the mass of the hydroxyl group is 400 ppm, and the amount of the heat stabilizer used is such that the mass of the P element is 50 ppm;

[0143] (3) transferring the prepolymer obtained in step (2) to a final polymerization reactor, reacting at 240° C. and 30 Pa for 2 h, and extruding the obtained polycondensate into pellets in a screw extruder, wherein the feed section temperature is 110° C., the melting section temperature is 140° C., the aspect ratio is 20:1, and the screw speed is 100 rpm; obtaining a polymer product with a 100-pellet weight of 1.26 g;

[0144] (4) preparing a mixed solvent according to the following mass contents: 30% water, 50% n-butanol, and 20% cyclohexane;

[0145] The polymer product obtained in step (3) was dispersed in a mixed solvent so that the mass ratio of the polymer product to the mixed solvent was 1:2, and extracted at 75° C. for 2 h under stirring conditions, followed by solid-liquid separation and drying to obtain the PBS resin composition, the specific components and test data of which are shown in Table 1.

[0146] Example 2

[0147] A PBS resin composition comprises a combination of PBS, a cyclic oligomer and a linear oligomer; the preparation method comprises the following steps:

[0148] (1) Succinic acid and 1,4-butanediol were mixed at a molar ratio of 1:1.5, and esterification reaction was carried out at 160°C for 3.5 hours to obtain an esterified product;

[0149] (2) placing the esterified product obtained in step (1), a catalyst (tetraethyl hexyl titanate), a branching agent (propylene glycol) and a thermal stabilizer (triethyl phosphate) in a prepolymerization reactor, and reacting them at 230° C. and 2 kPa for 2 h to obtain a prepolymer;

[0150] Based on the total mass of the succinic acid and 1,4-butanediol as 100%, the amount of the catalyst used is such that the mass of the Ti element is 120 ppm, the amount of the branching agent used is such that the mass of the hydroxyl group is 600 ppm, and the amount of the heat stabilizer used is such that the mass of the P element is 75 ppm;

[0151] (3) The prepolymer obtained in step (2) was transferred to a final polymerization reactor, reacted at 230° C. and 20 Pa for 3 h, and then extruded and granulated according to the same process as in Example 1 to obtain a polymer product;

[0152] (4) preparing a mixed solvent according to the following mass contents: 35% water, 55% n-butanol, and 10% cyclohexane;

[0153] The polymer product obtained in step (3) was dispersed in a mixed solvent so that the mass ratio of the polymer product to the mixed solvent was 1:1.5, and extracted at 70°C for 40 minutes under stirring conditions, followed by solid-liquid separation. The above extraction process was repeated twice (a total of 3 extractions), and dried to obtain the PBS resin composition. Its specific components and test data are shown in Table 1.

[0154] Example 3

[0155] A PBS resin composition comprises a combination of PBS, a cyclic oligomer and a linear oligomer; the preparation method comprises the following steps:

[0156] (1) Succinic acid and 1,4-butanediol were mixed at a molar ratio of 1:1.25, and esterification reaction was carried out at 165°C for 3 hours to obtain an esterified product;

[0157] (2) placing the esterified product obtained in step (1), a catalyst (tetraethyl titanate), a branching agent (2,2-dihydroxymethylpropionic acid) and a thermal stabilizer (n-butyl phosphate) in a prepolymerization reactor, and reacting them at 210° C. and 3 kPa for 2.5 hours to obtain a prepolymer;

[0158] Based on the total mass of the succinic acid and 1,4-butanediol as 100%, the amount of the catalyst used is such that the mass of the Ti element is 160 ppm, the amount of the branching agent used is such that the mass of the hydroxyl group is 700 ppm, and the amount of the heat stabilizer used is such that the mass of the P element is 60 ppm;

[0159] (3) The prepolymer obtained in step (2) was transferred to a final polymerization reactor, reacted at 245° C. and 50 Pa for 4 h, and then extruded and granulated according to the same process as in Example 1 to obtain a polymer product;

[0160] (4) preparing a mixed solvent according to the following mass contents: water 40%, n-butanol 50%, and cyclohexane 10%;

[0161] The polymer product obtained in step (3) was dispersed in a mixed solvent so that the mass ratio of the polymer product to the mixed solvent was 1:1.8, and extracted at 65° C. for 3 h under stirring conditions, followed by solid-liquid separation and drying to obtain the PBS resin composition. The specific components and test data of the PBS resin composition are shown in Table 1.

[0162] Example 4

[0163] A PBS resin composition comprises a combination of PBS, a cyclic oligomer and a linear oligomer; the preparation method comprises the following steps:

[0164] (1) Succinic acid and 1,4-butanediol were mixed at a molar ratio of 1:1.3, and esterification reaction was carried out at 165°C for 3 hours to obtain an esterified product;

[0165] (2) placing the esterified product obtained in step (1), a catalyst (tetraethyl titanate), a branching agent (2,2-dihydroxymethylpropionic acid) and a thermal stabilizer (n-butyl phosphate) in a prepolymerization reactor, and reacting them at 210° C. and 3 kPa for 2.5 hours to obtain a prepolymer;

[0166] Based on the total mass of the succinic acid and 1,4-butanediol as 100%, the amount of the catalyst used is such that the mass of the Ti element is 90 ppm, the amount of the branching agent used is such that the mass of the hydroxyl group is 500 ppm, and the amount of the heat stabilizer used is such that the mass of the P element is 20 ppm;

[0167] (3) The prepolymer obtained in step (2) was transferred to a final polymerization reactor, reacted at 245° C. and 50 Pa for 4 h, and then extruded and granulated according to the same process as in Example 1 to obtain a polymer product;

[0168] (4) preparing a mixed solvent according to the following mass contents: 30% water, 55% n-butanol, and 15% cyclohexane;

[0169] The polymer product obtained in step (3) was dispersed in a mixed solvent so that the mass ratio of the polymer product to the mixed solvent was 1:1.8, and extracted at 65°C for 1 hour under stirring conditions, followed by solid-liquid separation. The above extraction process was repeated once (a total of 2 extractions), and dried to obtain the PBS resin composition. Its specific components and test data are shown in Table 1.

[0170] Example 5

[0171] A PBS resin composition comprises a combination of PBS, a cyclic oligomer and a linear oligomer; the preparation method comprises the following steps:

[0172] (1) Succinic acid and 1,4-butanediol were mixed at a molar ratio of 1:1.5, and esterification reaction was carried out at 165°C for 3 hours to obtain an esterified product;

[0173] (2) placing the esterified product obtained in step (1), a catalyst (tetraethyl titanate), a branching agent (2,2-dihydroxymethylpropionic acid) and a thermal stabilizer (n-butyl phosphate) in a prepolymerization reactor, and reacting them at 210° C. and 3 kPa for 2.5 hours to obtain a prepolymer;

[0174] Based on the total mass of the succinic acid and 1,4-butanediol as 100%, the amount of the catalyst used is such that the mass of the Ti element is 100 ppm, the amount of the branching agent used is such that the mass of the hydroxyl group is 500 ppm, and the amount of the heat stabilizer used is such that the mass of the P element is 50 ppm;

[0175] (3) The prepolymer obtained in step (2) was transferred to a final polymerization reactor, reacted at 245° C. and 50 Pa for 4 h, and then extruded and granulated according to the same process as in Example 1 to obtain a polymer product;

[0176] (4) preparing a mixed solvent according to the following mass contents: 33% water, 52% n-butanol, and 15% cyclohexane;

[0177] The polymer product obtained in step (3) was dispersed in a mixed solvent so that the mass ratio of the polymer product to the mixed solvent was 1:1.8, and extracted at 65° C. for 3 h under stirring conditions, followed by solid-liquid separation and drying to obtain the PBS resin composition. The specific components and test data of the PBS resin composition are shown in Table 1.

[0178] Comparative Example 1

[0179] A PBS resin composition comprises a combination of PBS, a cyclic oligomer, and a linear oligomer. The preparation method differs from that of Example 1 only in that the mass ratio of the mixed solvent in step (4) is as follows: 30% water and 70% n-butanol. Other materials, amounts, and processes are the same as those of Example 1. The specific components and test data of the obtained PBS resin composition are shown in Table 1.

[0180] Comparative Example 2

[0181] A PBS resin composition comprises a combination of PBS, a cyclic oligomer, and a linear oligomer. The preparation method differs from that of Example 1 only in that the mass ratio of the mixed solvent in step (4) is as follows: 30% water and 70% cyclohexane. Other materials, amounts, and processes are the same as those of Example 1. The specific components and test data of the obtained PBS resin composition are shown in Table 1.

[0182] Comparative Example 3

[0183] A PBS resin composition comprises a combination of PBS, a cyclic oligomer, and a linear oligomer. The preparation method differs from that of Example 1 only in that the mass ratio of the mixed solvent in step (4) is as follows: 70% n-butanol and 30% cyclohexane. Other materials, amounts, and processes are the same as those of Example 1. The specific components and test data of the obtained PBS resin composition are shown in Table 1.

[0184] Comparative Example 4

[0185] A PBS resin composition comprises a combination of PBS, a cyclic oligomer, and a linear oligomer. The preparation method differs from that of Example 1 only in that the mass ratio of the mixed solvent in step (4) is as follows: 30% n-butanol and 70% cyclohexane. Other materials, amounts, and processes are the same as those of Example 1. The specific components and test data of the obtained PBS resin composition are shown in Table 1.

[0186] Table 1

[0187]

[0188]

[0189] According to the data in Table 1, the PBS resin composition provided by the present invention has a specific active end group content and molecular weight distribution by designing the mass content of the cyclic oligomer to be 500-10000 ppm and the mass content of the linear oligomer to be 50-1000 ppm. The components are compounded and act together to provide the PBS resin composition with a PDI of 1.25-1.45 and a terminal carboxyl group value of 25-39 mol / t. The composition exhibits excellent mechanical properties such as tensile strength and flexibility, with a tensile strength of ≥38.1 MPa and an elongation at break of ≥218%. The composition also exhibits significantly improved resistance to water boiling aging, with a decrease in intrinsic viscosity of ≤22% after aging in a 95°C water bath for 24 hours.

[0190] The present invention combines cyclic oligomers and linear oligomers with PBS in a specific ratio. The two oligomers synergize to regulate interactions between PBS molecules, reduce spatial anomalies in the PBS molecular structure, and impart excellent mechanical properties, thermal stability, and resistance to water-boiling aging to the PBS resin composition. In Comparative Example 1, the low linear oligomer content resulted in reduced elongation at break and decreased flexibility. In Comparative Example 3, the low cyclic oligomer content affected the tensile strength of the material. In Comparative Example 2, the high linear oligomer content significantly reduced the intrinsic viscosity after water-boiling aging, resulting in insufficient thermal stability and decreased tensile strength. In Comparative Example 4, the high cyclic oligomer content reduced elongation at break and worsened flexibility.

[0191] The applicant states that while the above-described embodiments illustrate the PBS resin composition, its preparation method, and its application, the present invention is not limited to these embodiments, nor does it necessarily rely on these embodiments for implementation. Those skilled in the art will appreciate that any improvements to the present invention, equivalent substitutions for raw materials in the present invention, addition of auxiliary ingredients, and selection of specific methods, etc., fall within the scope of protection and disclosure of the present invention.

Claims

1. A PBS resin composition, characterized in that The PBS resin composition comprises a combination of polybutylene succinate, a cyclic oligomer and a linear oligomer; The cyclic oligomer has a structure as shown in Formula I: wherein n is selected from an integer of 1 to 10; The linear oligomer comprises a structural unit as shown in Formula II: The mass content of the cyclic oligomer in the PBS resin composition is 500-10000 ppm, and the mass content of the linear oligomer is 50-1000 ppm.

2. PBS resin composition according to claim 1, is characterized in that, Said n is selected from an integer of 2-9; Preferably, the number average molecular weight of the cyclic oligomer is 172-1720; Preferably, the mass content of the cyclic oligomer in the PBS resin composition is 2000-8000 ppm, more preferably 4000-6000 ppm.

3. PBS resin composition according to claim 1, is characterized in that, The linear oligomer is selected from any one or a combination of at least two of the compound represented by formula II-1, the compound represented by formula II-2, and the compound represented by formula II-3; wherein m1, m2, and m3 are each independently selected from an integer of 1-10, more preferably 2-9; Preferably, the number average molecular weight of the linear oligomer is 190-1838; Preferably, the mass content of the linear oligomer in the PBS resin composition is 100-500 ppm.

4. PBS resin composition according to claim 1, is characterized in that, The number average molecular weight of the PBS resin composition is 4×10 4 -10×10 4 ; Preferably, the weight average molecular weight of the PBS resin composition is 5×10 4 -12×10 4 ; Preferably, the molecular weight polydispersity index of the PBS resin composition is 1.2-1.

6.

5. PBS resin composition according to claim 1, is characterized in that, The terminal carboxyl value of the PBS resin composition is 5-80 mol / t; Preferably, the intrinsic viscosity of the PBS resin composition is 1.40-1.65 dL / g.

6. A method for preparing a PBS resin composition according to any one of claims 1 to 5, characterized in that: The preparation method comprises the following steps: Esterification reaction is carried out between succinic acid and 1,4-butanediol to obtain an esterified product; The esterified product is subjected to a polycondensation reaction in the presence of a catalyst and a branching agent to obtain a polymer product; The polymer product is extracted with a mixed solvent to obtain the PBS resin composition, wherein the mixed solvent comprises a combination of water, an alcohol solvent and a cycloalkane solvent.

7. The preparation method according to claim 6, characterized in that The molar ratio of succinic acid to 1,4-butanediol is 1:(1.2-1.6); Preferably, the esterification reaction temperature is 150-170° C., and the time is 2-4 hours.

8. The preparation method according to claim 6, characterized in that The catalyst comprises any one of tetramethyl titanate, tetraethyl titanate, tetraisopropyl titanate, tetra-n-butyl titanate, and tetraisooctyl titanate, or a combination of at least two thereof; Preferably, based on the total mass of the succinic acid and 1,4-butanediol as 100%, the amount of the catalyst used is such that the mass of the Ti element is 50-200 ppm; Preferably, the branching agent includes any one of glycerol, trimethylolpropane, pentaerythritol, dipentaerythritol, and 2,2-dimethylolpropionic acid, or a combination of at least two thereof; Preferably, based on the total mass of the succinic acid and 1,4-butanediol as 100%, the amount of the branching agent used is such that the mass of its hydroxyl groups is 200-1000 ppm; Preferably, the polycondensation reaction is carried out in the presence of a thermal stabilizer; Preferably, the heat stabilizer comprises any one or a combination of at least two of trimethyl phosphate, triethyl phosphate, isopropyl phosphate, n-butyl phosphate, isooctyl phosphate, and triphenyl phosphate; Preferably, based on the total mass of the succinic acid and 1,4-butanediol as 100%, the amount of the heat stabilizer is such that the mass of the P element is 5-100 ppm; Preferably, the polycondensation reaction includes a prepolymerization reaction and a final polymerization reaction carried out in sequence; Preferably, the prepolymerization reaction temperature is 180-240°C, the pressure is 1-5kPa, and the time is 1-3h; Preferably, the temperature of the final polymerization reaction is 220-260° C., the pressure is 20-100 Pa, and the time is 2-6 hours.

9. The preparation method according to claim 6, characterized in that The alcohol solvent includes any one of methanol, ethanol, propanol, butanol or a combination of at least two thereof, preferably n-butanol; Preferably, the mass percentage of the alcohol solvent in the mixed solvent is 45-62%; Preferably, the cycloalkane solvent comprises cyclohexane; Preferably, the mass percentage of the cycloalkane solvent in the mixed solvent is 8-25%; Preferably, the extraction is performed 1-3 times; Preferably, the mass ratio of the polymer product to the mixed solvent is 1:(1.5-2); Preferably, the extraction temperature is 60-80° C. and the extraction time is 0.5-3 h.

10. Use of the PBS resin composition according to any one of claims 1 to 5 in food contact materials.

Images