A polybutylene sebacate terephthalate, polyester composition, and method of making and use thereof

Abstract

The application discloses a kind of polysebacic acid terephthalate, polyester composition and its preparation method and application.The weight average molecular weight of the polysebacic acid terephthalate is 70000~155000, and the intrinsic viscosity is 1.20~1.45 dL / g.The specific weight average molecular weight and intrinsic viscosity of the polysebacic acid terephthalate can significantly improve the deformation resistance and stiffness of the film made of polyester composition in the case of high addition amount in polyester composition.

Description

Technical Field

[0001] This invention belongs to the field of biodegradable materials technology, specifically relating to a polybutylene sebacate terephthalate, a polyester composition, its preparation method, and its application. Background Technology

[0003] Currently, the biodegradable materials used to prepare biodegradable film bags are mainly composed of polybutylene adipate terephthalate (PBAT), polylactic acid (PLA), starch, and other compounds, with PBAT primarily providing the material's flexibility. However, the bio-based carbon content of PBAT can theoretically only reach 35 wt%, preventing further increases in the bio-based carbon content of biodegradable materials.

[0004] The sebacic acid monomer in polybutylene terephthalate (PBSeT) can be derived from bio-based sources, resulting in a significantly higher bio-based carbon content for PBSeT compared to PBAT. For example, the bio-based carbon content of PBSeT developed by Kingfa Science & Technology is as high as 69%. Replacing a small portion of PBAT in current biodegradable materials with PBSeT can increase the bio-based carbon content of biodegradable materials. However, PBSeT suffers from insufficient rigidity and poor compatibility with components such as PBAT, PLA, and starch. When high levels of PBSeT are added to biodegradable materials to achieve a higher bio-based carbon content, it significantly affects the deformation resistance and stiffness of the product film / bag, mainly manifested in poor dart drop performance and low tensile strength, thus limiting its application in the packaging field. Summary of the Invention

[0005] To address the challenge of existing biodegradable materials simultaneously achieving high PBSeT content, high deformation resistance, and high stiffness, this invention provides a polybutylene sebacate terephthalate (PBSeT).

[0006] Another object of the present invention is to provide the use of the above-mentioned polybutylene sebacate in the preparation of biodegradable polyester compositions.

[0007] Another object of the present invention is to provide a polyester composition.

[0008] Another object of the present invention is to provide a method for preparing the above-mentioned polyester composition.

[0009] Another object of the present invention is to provide the use of the above-described polyester composition in the preparation of biodegradable film bags.

[0010] The above-mentioned objective of the present invention is achieved through the following technical solution: A polybutylene sebacic acid terephthalate, wherein the polybutylene sebacic acid terephthalate has a weight-average molecular weight of 70,000 to 155,000 and an intrinsic viscosity of 1.20 to 1.45 dL / g.

[0011] The inventors of this invention have discovered that the molecular weight and intrinsic viscosity of polybutylene terephthalate (PET) have a crucial impact on the deformation resistance and stiffness of biodegradable polyester compositions prepared using PET. The principle is that by controlling the weight-average molecular weight and intrinsic viscosity of PET within a specific range, the entanglement phenomenon of PET molecules can be rationally regulated, and the uniformity of the polyester composition after film formation can be improved. This, in turn, enhances the deformation resistance and stiffness of the film material even at high content levels (PET accounts for at least 25 wt% of the polyester composition).

[0012] If the weight-average molecular weight of polybutylene terephthalate sebacic acid is too large, the molecules become excessively entangled, making orientation difficult during film formation, resulting in poor stiffness and resistance to deformation of the polyester composition. If the weight-average molecular weight of polybutylene terephthalate sebacic acid is too small, the molecules become insufficiently entangled, resulting in poor resistance to deformation and stiffness of the polyester composition.

[0013] If the intrinsic viscosity of polybutylene terephthalate sebacic acid is too low, the stability of the polyester composition during film formation will be poor, and defects will easily occur; if the intrinsic viscosity of polybutylene terephthalate sebacic acid sebacic acid is too high, the uniformity of the film made from the polyester composition will be insufficient. Both will result in poor deformation resistance and stiffness of the polyester composition.

[0014] In this invention, the weight-average molecular weight of the polybutylene sebacic acid terephthalate can specifically be 70,000, 75,000, 80,000, 85,000, 90,000, 95,000, 100,000, 105,000, 110,000, 112,000, 114,000, 115,000, 116,000, 118,000, 120,000, 122,000, 1... The intrinsic viscosity can be any two values ​​of 23000, 124000, 125000, 130000, 135000, 140000, 145000, 150000, 155000 or higher; the intrinsic viscosity can be any two values ​​of 1.20, 1.22, 1.25, 1.28, 1.30, 1.32, 1.35, 1.38, 1.40, 1.42, 1.45 dL / g or higher.

[0015] Preferably, in the polybutylene sebacate terephthalate, terephthalic acid residues account for 40-55% of the total molar amount of terephthalic acid residues and sebacate residues; specifically, it can be any two values ​​forming a range of 40%, 42%, 44%, 46%, 48%, 50%, 52%, 54%, 55% or more.

[0016] Preferably, the polybutylene sebacic acid terephthalate has a weight-average molecular weight of 110,000 to 122,000 and an intrinsic viscosity of 1.22 to 1.36 dL / g.

[0017] The polybutylene terephthalate (PET) of this invention can be obtained through conventional preparation methods. For example, terephthalic acid, sebacic acid, 1,4-butanediol, a catalyst, and other optional auxiliaries (such as chain extenders or branching agents) can be reacted in a one-step esterification reaction to obtain the PET. Alternatively, terephthalic acid, sebacic acid, 1,4-butanediol, and other optional auxiliaries (such as branching agents) can be reacted first at 180-200°C, followed by a compression polymerization reaction at 220-240°C under the action of a catalyst to obtain the PET. It can also be obtained by modifying existing PET products. The technical problem of this application can be solved as long as the weight-average molecular weight and intrinsic viscosity of the PET simultaneously meet the scope of this application.

[0018] The factors influencing the weight-average molecular weight and intrinsic viscosity of polybutylene terephthalate (PBDT) are well known in the art. Generally, under constant conditions, as the one-step esterification time or the decompression polymerization time increases, both the weight-average molecular weight and intrinsic viscosity of PBDT gradually increase, with the increase in weight-average molecular weight being more significant. Under constant conditions, increasing the reaction temperature of one-step esterification or the decompression polymerization temperature gradually increases both the weight-average molecular weight and intrinsic viscosity of PBDT, with the increase in weight-average molecular weight being more significant. Under constant conditions, adding a branching agent during the esterification process can improve the viscosity of PBDT. The intrinsic viscosity of polybutylene terephthalate (PET) increases significantly, while the weight-average molecular weight (MAM) increases only slightly. Under constant conditions, adding a chain extender during the compression polymerization process also significantly increases the intrinsic viscosity of PET, while the MAM increases only slightly. Similarly, adding a chain extender during melt extrusion in the modification stage also significantly increases the intrinsic viscosity of PET, while the MAM increases only slightly. Furthermore, by simultaneously adjusting the amount of branching agent added during esterification, as well as the esterification reaction time and the compression polymerization time, the intrinsic viscosity of PET remains relatively unchanged, while the MAM changes significantly. Those skilled in the art can select different process parameters based on the type and amount of raw materials used to obtain PET that meets the MAM and intrinsic viscosity requirements of this application.

[0019] For example, when the branching agent is selected from glycerol and its amount is 0.0005-0.00131 of the total molar amount of terephthalic acid and sebacic acid, the following process is applicable: terephthalic acid, sebacic acid, and 1,4-butanediol are mixed and reacted at 180-200°C for 2-4 hours; then a catalyst is added, and the mixture is reacted under vacuum and at 220-240°C for 8-10 hours to obtain the polybutylene sebacic acid terephthalate, wherein the molar ratio of the sum of the molar amounts of terephthalic acid and sebacic acid to the molar amount of 1,4-butanediol is 1:(1.05-1.3); the catalyst includes, but is not limited to, tetrabutyl titanate; the mass of the catalyst is 0.008-0.015% of the total mass of terephthalic acid, sebacic acid, and 1,4-butanediol; and the vacuum degree is 80-120 Pa.

[0020] The present invention also protects the use of the above-mentioned polybutylene sebacate terephthalate material in the preparation of biodegradable polyester compositions.

[0021] This invention also protects a polyester composition comprising the following components in parts by weight: 30-60 parts of the above-mentioned polybutylene sebacic acid terephthalate, 10-30 parts of polybutylene adipate terephthalate 5-10 parts of polylactic acid, 10-30 parts starch.

[0022] In the polyester composition of the present invention, the carbon in each polymer component can be derived from petroleum-based or bio-based sources. With the amounts of each component and the copolymer unit ratio of the copolymer remaining constant, the bio-based carbon content in each polymer component can be increased to enhance the bio-based carbon content of the polyester composition (wherein, the bio-based carbon content of starch and polylactic acid can reach up to 100%, the bio-based carbon content of polybutylene adipate terephthalate can reach up to 35% (when the molar ratio of adipate residues to terephthalic acid residues is 1:1), and the bio-based carbon content of polybutylene sebacate terephthalate can reach up to 69% (when the molar ratio of sebacate residues to terephthalic acid residues is 1:1)).

[0023] In this invention, the bio-based carbon content of the polyester composition is determined according to the method specified in ISO 16620-2:2019; the bio-based carbon content of starch, polylactic acid, butylene terephthalate adipic acid, and polybutylene terephthalate sebacic acid can be determined according to ISO... The method specified in standard 16620-2:2019 can be used for determination, or it can be calculated based on the source of its polymer raw materials. For example, the monomers of starch and polylactic acid are usually bio-based, and the bio-based carbon content can reach 100%. The phthalic acid in polybutylene terephthalate sebacic acid is petroleum-based, while sebacic acid and butanediol can be either petroleum-based or bio-based. When both sebacic acid and butanediol are bio-based, the terephthalic acid residues contribute 8 carbons, the butanediol residues contribute 8 carbons, and the sebacic acid residues contribute 10 carbons (when the molar ratio of sebacic acid residues to terephthalic acid residues is 1:1). Then the bio-based carbon content of polybutylene terephthalate sebacic acid ...

[0024] In this invention, polybutylene sebacic acid terephthalate is used as the main resin, accounting for at least 25 wt% of the polyester composition, preferably 45-70 wt%.

[0025] In this invention, the polybutylene adipate terephthalate can be either commercially available or prepared in-house.

[0026] Preferably, the method for preparing polybutylene adipate terephthalate is as follows: terephthalic acid, adipic acid and 1,4-butanediol are mixed and reacted at 180~200℃ for 2.5~4 hours, a catalyst is added, and then the mixture is reacted at 230~260℃ for 6~12 hours to obtain polybutylene adipate terephthalate.

[0027] More preferably, the molar ratio of phthalic acid to adipic acid is 18~22:19~23.

[0028] More preferably, the ratio of the sum of the molar amounts of phthalic acid and adipic acid to the molar amount of 1,4-butanediol is 1:(1.05~1.3).

[0029] More preferably, a branching agent is added during the mixing process, including but not limited to glycerol.

[0030] More preferably, the molar ratio of the sum of the molar amounts of phthalic acid and adipic acid to the molar ratio of the branching agent is 1:(0.0005~0.002).

[0031] Preferably, the weight-average molecular weight of the polybutylene adipate terephthalate is 90,000 to 160,000.

[0032] Preferably, the intrinsic viscosity of the polybutylene adipate terephthalate is 1.30~1.55 dL / g.

[0033] Preferably, in the polybutylene adipate terephthalate, terephthalic acid residues account for 45-55% of the total molar amount of terephthalic acid residues and adipic acid residues.

[0034] In this invention, polylactic acid can be either commercially available or prepared in-house. The in-house preparation method is as follows: polylactic acid is obtained by the ring-opening polymerization of lactide.

[0035] Preferably, the lactide includes L-lactide and meso-lactide.

[0036] More preferably, the mass ratio of L-lactide to meso-lactide is (78~92):(8~22).

[0037] More preferably, the ring-opening polymerization reaction is carried out in the presence of a catalyst, which includes, but is not limited to, stannous octoate.

[0038] More preferably, the ring-opening polymerization process is as follows: first, react at 130~145℃ and 1000~1400Pa for 2~4 hours, and then react at 160~180℃ and 300~500Pa for 4~6 hours.

[0039] Preferably, the polylactic acid is a copolymer of L-lactic acid and D-lactic acid, and the weight percentage of the D-lactic acid repeating unit is 3.0~12%.

[0040] Preferably, the polylactic acid has a weight-average molecular weight of 90,000 to 200,000.

[0041] More preferably, the content of dextrorotatory lactic acid units in the polylactic acid is 3.5% to 6.0%. Adjusting the content within this range results in films made from the obtained polyester composition with better stiffness.

[0042] Preferably, the starch is plasticized starch.

[0043] More preferably, the plasticizer in the plasticized starch is at least one of glycerol, diglycerol, triglycerol or sorbitol.

[0044] More preferably, the plasticizer content in the plasticized starch is 5-20 wt%.

[0045] Preferably, the starch is at least one of corn starch, tapioca starch, and potato starch.

[0046] Preferably, the density of the starch is 1.3~1.5 g / cm³. 3 .

[0047] Preferably, the above-mentioned polyester composition further comprises 0.1 to 2 parts of a compatibilizer and 0.1 to 2 parts of other additives.

[0048] More preferably, the compatibilizer is an epoxy functional group copolymer.

[0049] More preferably, the epoxy functional group copolymer is at least one of styrene-acrylonitrile-glycidyl methacrylate terpolymer or ethylene-methyl acrylate-glycidyl methacrylate.

[0050] More preferably, the other additives are at least one of lubricant, antioxidant or antistatic agent.

[0051] More preferably, the lubricant is at least one of ethylene bis-stearamide, monoglyceride, oleamide, and erucamide.

[0052] More preferably, the antioxidant is at least one of antioxidant 1010 or antioxidant 168.

[0053] More preferably, the antistatic agent is at least one of ethoxylated alkylamine, glycerol stearate, or ethoxylated alkylamine.

[0054] The present invention also protects the use of the above-described polyester composition in the preparation of biodegradable film bags.

[0055] The present invention also protects a film bag made from the above-described polyester composition.

[0056] Compared with the prior art, the beneficial effects of the present invention are: The polybutylene sebacate terephthalate of the present invention, with specific weight-average molecular weight and intrinsic viscosity, can significantly improve the deformation resistance and stiffness of films made from polyester compositions even when added in high amounts to polyester compositions. Detailed Implementation

[0057] The present invention will be further illustrated below with reference to specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in this technical field.

[0058] Unless otherwise specified, all reagents and materials used in the following examples are commercially available.

[0059] The reagents used in the various embodiments and comparative examples of this invention are described below: I. Polybutylene terephthalate sebate (hereinafter referred to as PBSeT) PBSeT1#: Prepared in-house, its preparation method is as follows: 20.5 mol of terephthalic acid, 20.8 mol of sebacic acid, 51 mol of 1,4-butanediol, and 0.033 mol of branching agent glycerol were added to a reaction vessel. The mixture was heated to 190°C (temperature T1) and stirred for 3 hours (time t1). Water generated during stirring was removed promptly. Then, 0.01% (by mass of the diacid and diol) of tetrabutyl titanate was added as a catalyst. The mixture was heated to 230°C (temperature T2), and a vacuum of 100 Pa was applied. The reaction was carried out for 9 hours (time t2) to obtain PBSeT1#. PBSeT1# has a weight-average molecular weight of 118220, an intrinsic viscosity of 1.35 dL / g, and a T content of 49%.

[0060] PBSeT2#: In-house prepared, its preparation method differs from PBSeT1# in that the amount of branching agent glycerol added is 0.022 mol. PBSeT2# has a weight-average molecular weight of 117470, an intrinsic viscosity of 1.22 dL / g, and a T content of 49%.

[0061] PBSeT3#: In-house prepared, its preparation method differs from PBSeT1# in that the amount of branching agent glycerol added is 0.054 mol. PBSeT3# has a weight-average molecular weight of 119320, an intrinsic viscosity of 1.48 dL / g, and a T content of 49%.

[0062] PBSeT4#: Prepared in-house, its preparation method differs from PBSeT1# in that: the amount of branching agent glycerol added is 0.065 mol, the time t1 is 2 hours, and the time t2 is 5 hours. PBSeT4# has a weight-average molecular weight of 72380, an intrinsic viscosity of 1.32 dL / g, and a T content of 49%.

[0063] PBSeT5#: Prepared in-house, its preparation method differs from PBSeT1# in that it does not contain the branching agent glycerol, and the preparation time t1 is 4 hours and t2 is 13 hours. PBSeT5# has a weight-average molecular weight of 150,630, an intrinsic viscosity of 1.38 dL / g, and a T content of 49%.

[0064] PBSeT6#: In-house prepared, its preparation method differs from PBSeT1# in that it contains 18.7 mol of terephthalic acid and 22.3 mol of sebacic acid. PBSeT6# has a weight-average molecular weight of 117,430, an intrinsic viscosity of 1.33 dL / g, and a T content of 46%.

[0065] PBSeT7#: In-house prepared, its preparation method differs from PBSeT1# in that it contains 21.7 mol of terephthalic acid and 19.8 mol of sebacic acid. PBSeT7# has a weight-average molecular weight of 118,900, an intrinsic viscosity of 1.36 dL / g, and a T content of 52%.

[0066] PBSeT8#: In-house prepared, its preparation method differs from PBSeT1# in that the amount of branching agent glycerol added is 0.016 mol. PBSeT8# has a weight-average molecular weight of 114360, an intrinsic viscosity of 1.13 dL / g, and a T content of 49%.

[0067] PBSeT9#: In-house prepared, its preparation method differs from PBSeT1# in that the amount of branching agent glycerol added is 0.076 mol. PBSeT9# has a weight-average molecular weight of 120,660, an intrinsic viscosity of 1.72 dL / g, and a T content of 49%.

[0068] PBSeT10#: In-house prepared, its preparation method differs from PBSeT1# in that the amount of branching agent glycerol added is 0.071 mol, the time t1 is 2 hours, and the time t2 is 4 hours. PBSeT10# has a weight-average molecular weight of 62060, an intrinsic viscosity of 1.29 dL / g, and a T content of 49%.

[0069] PBSeT11#: In-house prepared, its preparation method differs from PBSeT1# in that the amount of branching agent glycerol added is 0.007 mol, the time t1 is 5 hours, and the time t2 is 15 hours. PBSeT11# has a weight-average molecular weight of 177,860, an intrinsic viscosity of 1.40 dL / g, and a T content of 49%.

[0070] PBSeT12#: Prepared in-house, the preparation method is as follows: 20.5 mol of terephthalic acid, 20.8 mol of sebacic acid, and 51 mol of 1,4-butanediol were added to a reaction vessel, heated to 190°C, and stirred for 6 hours. Water generated during stirring was removed promptly. Then, tetrabutyl titanate (0.01% of the total mass of the diacid and diol) was added as a catalyst, and the temperature was raised to 235°C. A vacuum of 100 Pa was applied, and the reaction was allowed to proceed for 10 hours. Then, a chain extender (0.05 wt% of the sum of the masses of terephthalic acid, sebacic acid, and 1,4-butanediol; epoxy-type chain extender, ADR-4468, purchased from BASF) was added, and the reaction was allowed to continue for 2 hours to obtain PBSeT12#. PBSeT12# has a weight-average molecular weight of 115230, an intrinsic viscosity of 1.32 dL / g, and a T content of 49%.

[0071] PBSeT-A#: ecoflex® F Blend C2200, BASF, weight-average molecular weight 148300, intrinsic viscosity 1.18 dL / g; PBSeT-B#: PBSeT8# is processed as follows: 99.9 parts by weight of PBSeT8# are mixed with 0.01 parts by weight of chain extender (epoxy chain extender, ADR-4468, purchased from BASF), melt extruded, and granulated to obtain PBSeT-B#. PBSeT-B# has a weight-average molecular weight of 120,300, an intrinsic viscosity of 1.33 dL / g, and a T content of 49%. The temperatures of each zone in the melt extrusion are 150℃, 150℃, 155℃, 160℃, 160℃, 160℃, 160℃, and 160℃, the screw length-to-diameter ratio is 48:1, and the screw speed is 250 rpm.

[0072] In this invention, the weight-average molecular weight of PBSeT resin can be determined by GPC. The specific operation is as follows: using a chromatographic system at 40°C, a set of three tandem columns (particle diameter 5 μm and porosities of 500 Å, 1000 Å and 10000 Å respectively), a refractive index detector, chloroform as eluent (flow rate 1 mL / min), and polystyrene as a reference standard are used for determination.

[0073] In this invention, the intrinsic viscosity of PBSeT resin can be measured using an Ubbelohde viscometer. The specific operation is as follows: chloroform is used as the solvent, and an Ubbelohde viscometer is used under constant temperature conditions (e.g., 25°C). The intrinsic viscosity (η) of a PBSeT resin solution (concentration 0.005 g / mL) was measured at 0.1℃, and the average value of three measurements was taken.

[0074] In this invention, the specific operation of the T content detection method for PBSeT resin is as follows: 20 mg of PBSeT resin sample is dissolved in 0.6 mL of deuterated chloroform, and then 1H NMR is measured at room temperature using a Bruker AV 500 nuclear magnetic resonance spectrometer to determine the molar content (T content) of aromatic dicarboxylic acid in PBSeT resin near the chloroform solvent peak of 7.26 ppm. The T content can be expressed by the integral area (IT and IA) of the two peaks at 8.10 ppm and 2.30 ppm: T content = IT / (IT+IA)×100%.

[0075] II. Polybutylene adipate terephthalate (hereinafter referred to as PBAT) PBAT1#: Self-made, its preparation method is as follows: 3.4 kg of terephthalic acid, 3.4 kg of adipic acid, and 4.6 kg of 1,4-butanediol (in excess), along with 0 g of glycerol (i.e., no glycerol added), were added to a reaction vessel. The mixture was stirred at 195°C for 3 hours (time t3), with water removed during stirring. Then, 0.01% tetrabutyl titanate (TIA) was added as a catalyst, based on the total mass of the diacid and diol. The temperature was raised to 238°C, a vacuum of 200 Pa was applied, and the reaction was continued for 8 hours (time t4) to obtain PBAT1#. PBAT1# has a weight-average molecular weight of 139,220, an intrinsic viscosity of 1.32 dL / g, and a T content of 47%.

[0076] PBAT2#: Self-made, its preparation method differs from PBAT resin 1# in that: 3.6 kg of terephthalic acid, 3.2 kg of adipic acid, 1.0 g of glycerol, time t3 is 4 hours, and time t4 is 12 hours. PBAT resin 2# has a weight-average molecular weight of 156,970 and a terephthalic acid content of 48%. PBAT2# has a weight-average molecular weight of 157,290, an intrinsic viscosity of 1.51 dL / g, and a T content of 50%.

[0077] In this invention, the molecular weight of PBAT resin can be determined by GPC. The specific operation is as follows: using a chromatographic system at 40°C, a set of three tandem columns (particle diameter 5 μm and porosities of 500 Å, 1000 Å and 10000 Å respectively), a refractive index detector, chloroform as eluent (flow rate 1 mL / min), and polystyrene as a reference standard are used for determination.

[0078] In this invention, the intrinsic viscosity of PBAT resin can be measured using an Ubbelohde viscometer. The specific operation is as follows: chloroform is used as the solvent, and an Ubbelohde viscometer is used under constant temperature conditions (e.g., 25°C). The intrinsic viscosity (η) of a PBAT resin solution (concentration 0.005 g / mL) was measured at 0.1℃, and the average value of three measurements was taken.

[0079] The specific operation of the T content detection method for PBAT resin in this invention is as follows: 20 mg of PBAT resin sample is dissolved in 0.6 mL of deuterated chloroform, and then 1H NMR is measured at room temperature using a Bruker AV 500 nuclear magnetic resonance spectrometer, calibrating the chloroform solvent peak around 7.26 ppm. The molar content of aromatic dicarboxylic acid (T content) in PBAT resin can be expressed by the integrated areas (IT and IA) of the two peaks at 8.10 ppm and 2.33 ppm: T content = IT / (IT+IA)×100%.

[0080] III. Polylactic acid Polylactic acid 1#: Self-made, prepared as follows: PLLA / PDLA copolymer, self-made, using 88 parts by weight of L-type lactide (purity ≥99.5%, the same below) and 12 parts by weight of meso-lactide (purity ≥99.5%, the same below). L-lactide was dissolved in hexanediol, and stannous octoate (0.1 wt% relative to the total amount of lactide) was added for ring-opening polymerization. The reaction was first carried out at 138℃ and 1300 Pa for 4 hours (time t5), and then at 170℃ and 400 Pa for 6 hours (time t6). Underwater pelletizing, crystallization, and drying yielded polylactic acid 1#. The weight-average molecular weight of polylactic acid 1# was 186,700, and the molar content of dextrorotatory lactic acid was 5.9%.

[0081] Polylactic acid 2#: Prepared in-house, its preparation method differs from that of polylactic acid 1# in that t5 is 2 hours and t6 is 4 hours. The weight-average molecular weight of polylactic acid 2# is 144,300, and the molar content of dextrorotatory lactic acid is 5.8%.

[0082] Polylactic acid 3#: Self-made, its preparation method differs from that of polylactic acid 1# in that: the amount of L-type lactide is 78 parts by weight, and the amount of meso-lactide is 22 parts by weight. The weight-average molecular weight of polylactic acid 3# is 184,800, and the molar content of dextro-lactic acid is 11.3%.

[0083] Polylactic acid 4#: Self-made, its preparation method differs from that of polylactic acid 1# in that: the amount of L-lactide is 92 parts by weight, and the amount of meso-lactide is 8 parts by weight. The weight-average molecular weight of polylactic acid 4# is 184,200, and the molar content of dextro-lactic acid is 3.6%.

[0084] In this invention, the weight-average molecular weight of polylactic acid can be determined by GPC. The specific operation is as follows: a chromatographic system can be used at 40°C, with a set of three tandem columns (particle diameter 5 μm and porosities of 500 Å, 1000 Å and 10000 Å, respectively), a refractive index detector, chloroform as eluent (flow rate 1 mL / min), and polystyrene as a reference standard.

[0085] In this invention, the dextrorotatory lactic acid (D-lactic acid) content of polylactic acid (PLA) can be determined by gas chromatography. The specific process is as follows: 100 mg of PLA sample is placed in a hydrothermal reactor, 10 ml of methanol is added, and 1 drop of NaOH aqueous solution is added. The hydrothermal reactor is then sealed. The hydrothermal reactor is placed in a 150°C forced-air oven for 60 min. After 60 min, the hydrothermal reactor is removed and cooled to room temperature by running water. The filtered sample solution is transferred to a gas chromatograph (Agilent 8860 gas chromatograph, CP7502 column). The peaks corresponding to D-lactic acid methyl ester and L-lactic acid methyl ester are determined based on the retention time, and the peak areas of D-lactic acid methyl ester and L-lactic acid methyl ester are recorded. The content of dextrorotatory lactic acid (D-lactic acid) in PLA is obtained by dividing the peak area of ​​D-lactic acid methyl ester by the sum of the peak areas of D-lactic acid methyl ester and L-lactic acid methyl ester.

[0086] IV. Starch Starch 1#: Plasticized corn starch, Jinyuandong, TPS-A315; Starch 2#: Plasticized tapioca starch, Thai Wah, TPS-S1; V. Other Raw Materials Compatibilizer 1#: Styrene-glycidyl methacrylate copolymer, Jia Yi Rong, HPC-3510P; Other additives #1: Lubricant, Fischer-Tropsch wax, YT-90; The polyester compositions of the embodiments and comparative examples of the present invention were prepared by the following method: Each component was weighed according to the formula, mixed evenly, and then fed into a twin-screw extruder for melt extrusion and granulation to obtain the polyester composition. The temperatures of the twin-screw extruder from zone one to zone ten were 100℃, 130℃, 150℃, 170℃, 170℃, 170℃, 170℃, 170℃, and 170℃ respectively; the screw length-to-diameter ratio was 40:1; and the screw speed was 350 rpm.

[0087] Examples 1-16 Examples 1-16 provide a series of polyester compositions, the formulations of which are shown in Tables 1 and 2 (unit: parts by weight).

[0088] Table 1 Formulations of the polyester compositions in Examples 1-9

[0089] Table 2 Formulations of the polyester compositions in Examples 10-16

[0090] Comparative Examples 1-5 Comparative Examples 1-5 provide a series of polyester compositions, the formulations of which are shown in Table 3 (unit: parts by weight).

[0091] Table 3 Formulations of polyester compositions in Comparative Examples 1-5

[0092] Performance testing The polyester compositions provided in the embodiments and comparative examples of the present invention were subjected to performance testing according to the following test methods: (1) 10% fixed-value tensile strength in the longitudinal and transverse directions: The polyester composition was prepared into a film with a thickness of 10 μm by a blown film machine. The 10% fixed-value tensile strength of the film bag was tested using a universal film testing machine according to GB / T 1040.3-2006. The film was fixed on the universal film testing machine and tested at a speed of 100 mm / min. The tensile strength at 10% elongation at break was recorded. The average value of 5 tests was taken. (2) 10μm dart strength: The impact resistance of the plastic film was tested using a dart impact tester according to ISO 7765-1:2004. The sample (≥150 mm × 150 mm) was placed in an inner diameter 125 mm... The ring clamp is secured with rubber washers (Shore hardness A 50-60) in a 2 mm diameter ring to ensure a wrinkle-free fit. Test method A is selected: diameter 38 mm. A 1 mm hemispherical dart, from 0.66 The darts were dropped freely from a height of 0.01 m, and the mass of the falling darts was adjusted using a step-by-step method: if the specimen broke, the mass was reduced; if it did not break, the mass was increased (the step size Δm was 5-15% of the estimated value), until 20 sets of effective impacts were completed and 10 specimens broke. The critical impact mass (F50) at which 50% of the specimens broke was recorded. The final result was the average F50 of the effective specimens, accurate to 0.1 g.

[0093] The properties of the polyester compositions of each embodiment and comparative example were determined according to the test methods described above, and the test results are shown in Table 4.

[0094] Table 4 Performance test results of polyester compositions in each example and comparative example

[0095] As can be seen from Table 4, the longitudinal 10% fixed value tensile strength of the polyester composition samples obtained in Examples 1 to 16 is not less than 7.9 MPa, the longitudinal 10% fixed value tensile strength is not less than 6.5 MPa, and the 10 μm dart strength is not less than 109 g, indicating that the polyester composition provided by the present invention has good resistance to deformation and stiffness.

[0096] In Comparative Examples 1-4, the weight-average molecular weight or intrinsic viscosity of the PBSeT resin was not properly selected. The resulting polyester compositions had significantly lower longitudinal and transverse 10% tensile strength and 10μm dart strength, indicating poor resistance to deformation and stiffness.

[0097] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A polybutylene sebacic acid terephthalate, characterized in that, The polybutylene sebacic acid terephthalate has a weight-average molecular weight of 70,000 to 155,000 and an intrinsic viscosity of 1.20 to 1.45 dL / g.

2. The polybutylene sebacic acid terephthalate according to claim 1, characterized in that, In the polybutylene sebacate terephthalate, terephthalic acid residues account for 40-55% of the total molar amount of terephthalic acid residues and sebacate residues.

3. The polybutylene sebacic acid terephthalate according to claim 1, characterized in that, The polybutylene sebacic acid terephthalate has a weight-average molecular weight of 110,000 to 122,000 and an intrinsic viscosity of 1.22 to 1.36 dL / g.

4. The use of polybutylene sebacate according to any one of claims 1 to 3 in the preparation of biodegradable polyester compositions.

5. A polyester composition, characterized in that, The components include the following parts by weight: 30-60 parts of the polybutylene sebacic acid terephthalate as described in any one of claims 1-3 10-30 parts of polybutylene adipate terephthalate 5-10 parts of polylactic acid, 10-30 parts starch.

6. The polyester composition according to claim 5, characterized in that, The weight-average molecular weight of the polybutylene adipate terephthalate is 90,000 to 160,000.

7. The polyester composition according to claim 5, characterized in that, The molecular weight of the polylactic acid is 90,000 to 200,000.

8. The polyester composition according to claim 5, characterized in that, The polyester composition further comprises 0.1 to 2 parts of a compatibilizer and 0.1 to 2 parts of other additives.

9. A method for preparing the polyester composition according to any one of claims 5 to 8, characterized in that, The process includes the following steps: mixing the components, melt extruding, and granulating to obtain the biodegradable composite material.

10. A membrane bag, characterized in that, It is prepared from the polyester composition according to any one of claims 5 to 8.

Images