Aliphatic polyester and application thereof

Abstract

The invention provides aliphatic polyester and application thereof, the aliphatic polyester comprises dibasic acid residues and dihydric alcohol residues, the dibasic acid residues comprise the following residues: a1) 65-90 mol% of succinic acid residues based on 100 mol% of the total mole percentage of a1) and a2), and a2) 10-20 mol% of dihydric alcohol residues based on 100 mol% of the total mole percentage of a1) and a2); a2), 10-35 mol% of sebacic acid residues based on 100 mol% of the total mole percentage content of a1) and a2); the dihydric alcohol residues are selected from 1, 4-butanediol residues which are at least equal to the dibasic acid residues in molar weight; the aliphatic polyester contains an oligomer of which the number-average molecular weight measured by GPC is less than 1000, and the mass percentage content of the oligomer of which the number-average molecular weight measured by GPC is less than 1000 in the aliphatic polyester is 0.08-3.5 wt%. The packaging film prepared from the aliphatic polyester has good food contact performance and uncoiling performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of polyester materials, and particularly relates to an aliphatic polyester and its application. Background Art

[0002] A fresh-keeping film is a thin film plastic packaging product, which can not only extend the storage time of food, but also maintain the moisture of the stored food to maintain its freshness; more importantly, when it is used for opened beverages, fruits or dining utensils, it can also play a role in isolating bacteria and improve the hygienic safety. Therefore, the fresh-keeping film is widely used in fields such as household life, supermarkets or industrial food packaging. However, most traditional fresh-keeping films are made of polyethylene films, biaxially oriented polyester films (BOPET), biaxially oriented polypropylene films (BOPP) or chlorinated polypropylene films (CPP), etc. These fresh-keeping films cannot be biodegradable, and it is extremely easy to form "white pollution" after being discarded.

[0003] To solve the problem that traditional fresh-keeping films are not easily degradable, people have begun to use biodegradable polyesters, such as poly(butylene adipate-co-terephthalate) (PBAT) materials, to replace the above traditional film materials to improve the degradability of fresh-keeping films. However, the molecular chains of PBAT resin are entangled with each other, the material has a slow crystallization rate, and the film material has strong viscosity, resulting in easy adhesion to the stainless steel roller during the casting preparation of the fresh-keeping film, and frequent film breakage problems, which affect the processing stability. At the same time, the strong viscosity of the film material also causes the prepared fresh-keeping film to be unable to be effectively unrolled during use, reducing the customer experience. In order to reduce the viscosity of PBAT resin and increase the unrolling property, in the prior art, the method of blending PBAT with lubricants such as epoxidized soybean oil is mostly used to improve the unrolling performance of PBAT fresh-keeping films. However, due to the polarity difference between the lubricant and PBAT resin, it is easy to migrate and precipitate during use, increasing the food contact risk.

[0004] Based on this, developing a biodegradable fresh-keeping film with both good unrolling performance and low food contact risk is an urgent problem to be solved in this field. Summary of the Invention

[0005] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide an aliphatic polyester and its application. The aliphatic polyester is used to prepare a packaging film, especially a food-grade packaging film, which solves the problem that the packaging film in the prior art cannot have both good unrolling performance and food contact performance, and at the same time has good degradation performance and can meet the requirements of household composting, etc.

[0006] To achieve this purpose, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides an aliphatic polyester, which comprises dibasic acid residues and diol residues: the dibasic acid residues comprise the following residues: a1), based on the total molar percentage content of a1) and a2) being 100 mol%, 65 to 90 mol% of succinic acid residues; a2), based on the total molar percentage content of a1) and a2) being 100 mol%, 10 to 35 mol% of sebacic acid residues; the diol residues are selected from 1,4-butanediol residues in an amount of at least equimolar to the dibasic acid residues; the aliphatic polyester contains oligomers with a number average molecular weight < 1000 measured by GPC, and the mass percentage content of the oligomers with a number average molecular weight < 1000 in the aliphatic polyester is 0.08 to 3.5 wt%.

[0008] In the present invention, succinic acid and / or succinic acid derivatives are introduced into the polyester molecular chain through a polymerization reaction to form succinic acid residues; sebacic acid and / or sebacic acid derivatives are introduced into the polyester molecular chain through a polymerization reaction to form sebacic acid residues; the polybutylene succinate sebacate formed by using succinic acid and / or its derivatives, sebacic acid and / or its derivatives and 1,4-butanediol has good degradation performance and can meet the requirements of home composting degradation; however, when succinic acid and sebacic acid react with 1,4-butanediol, oligomers with a degree of polymerization of 1 to 8 are very likely to be generated, resulting in an excessively high content of oligomers (> 4 wt%) in the obtained aliphatic polyester. When in contact with acidic or alcohol-containing foods, the oligomers are likely to migrate and precipitate, triggering food contact risks; therefore, those skilled in the art tend to reduce the content of oligomers; however, the inventor found that during the processing, the presence of oligomers can play a good lubricating role, which is beneficial to reducing the viscosity of the system and making the prepared packaging film have good unwindability; therefore, the present invention controls the molar ratio of succinic acid residues and sebacic acid residues in the polybutylene succinate sebacate, and at the same time controls the content of oligomers in the aliphatic polyester within a specific range, so that the packaging film prepared from the aliphatic polyester has both good unwindability and food contact performance, and at the same time has good degradation performance and can meet the requirements of home composting and the like.

[0009] It should be noted that the "residue" refers to any organic structure introduced into the polymer molecular chain by the relevant monomer through polycondensation reaction, that is, the organic structure derived from the relevant monomer; for example, the dibasic acid residue refers to the structure derived from the dibasic acid monomer in the aliphatic polyester.

[0010] In the present invention, the succinic acid derivative includes alkyl succinates. Exemplarily, the alkyl succinate may be at least one of dimethyl succinate, diethyl succinate, di-n-propyl succinate, di-isopropyl succinate, di-n-butyl succinate, di-isobutyl succinate, di-tert-butyl succinate, di-n-pentyl succinate, di-isopentyl succinate, and di-n-hexyl succinate; the alkyl succinate may be an alkyl ester formed from succinic acid or an alkyl ester formed from succinic anhydride, and preferably dimethyl succinate formed from succinic anhydride is used.

[0011] In the present invention, the sebacic acid derivative includes alkyl sebacates; Exemplarily, the alkyl sebacate may be at least one of dimethyl sebacate, diethyl sebacate, di-n-propyl sebacate, di-isopropyl sebacate, di-n-butyl sebacate, di-isobutyl sebacate, di-tert-butyl sebacate, di-n-pentyl sebacate, di-isopentyl sebacate, and di-n-hexyl sebacate; the alkyl sebacate may be an alkyl ester formed from sebacic acid or an alkyl ester formed from sebacic anhydride.

[0012] In the present invention, the oligomer includes a linear or cyclic polyester oligomer formed by the reaction of a dibasic acid and a diol; it also includes a cyclic oligomer formed by the "back-biting" of end groups during the prepolymerization and polycondensation processes due to the thermal decomposition of the prepolymer or the condensate.

[0013] In the present invention, the content of the oligomer can be measured by a gel permeation chromatograph (GPC).

[0014] Preferably, the oligomer in the aliphatic polyester has the following characteristics: 0.05 wt% < q 1 < 1.0 wt%, 0.1 wt% < q 2 < 2.5 wt%, where q 1 is the mass percentage of oligomers with a number average molecular weight of less than 500 in the aliphatic polyester measured by GPC, and q 2 is the mass percentage of oligomers with a number average molecular weight of less than 1000 in the aliphatic polyester measured by GPC; more preferably, 0.08 wt% < q 1 < 0.8 wt%, 0.15 wt% < q 2 < 2.1 wt%.

[0015] Preferably, the q 1 is 0.1 - 0.6 wt%.

[0016] Preferably, the q 2 is 0.2 - 1.3 wt%.

[0017] Preferably, the q 2 and q 1The ratio of <2, and q is further preferably 2 and q 1 The ratio of <1.5, and it is more preferably q 2 and q 1 The ratio is 1.1 - 1.45.

[0018] Preferably, the dibasic acid residue comprises the following residues: a1), based on the total molar percentage content of a1) and a2) being 100 mol%, 70 - 87 mol% of succinic acid residues; a2), based on the total molar percentage content of a1) and a2) being 100 mol%, 13 - 30 mol% of sebacic acid residues; More preferably, the dibasic acid residue comprises the following residues: a1), based on the total molar percentage content of a1) and a2) being 100 mol%, 74 - 85 mol% of succinic acid residues; a2), based on the total molar percentage content of a1) and a2) being 100 mol%, 15 - 26 mol% of sebacic acid residues.

[0019] In the present invention, considering the anti - aging performance, hydrolysis resistance, degradation performance and cost of the aliphatic polyester, etc.; preferably, according to GB / T 32366 - 2015, the carboxyl content of the aliphatic polyester <40 mol / t, further preferably the carboxyl content <30 mol / t, more preferably the carboxyl content <22 mol / t, and particularly preferably the carboxyl content is 8 - 20 mol / t.

[0020] In the present invention, the reaction degree can be regulated or thermal decomposition can be inhibited to control the carboxyl content by changing conditions such as the alcohol - acid ratio, polymerization temperature, polymerization time, etc.; in addition, the carboxyl content can also be controlled by inhibiting the types or amounts of impurities in raw materials such as nitrogen compounds and metal ions.

[0021] Based on considerations of production efficiency and the mechanical properties of the molded body, preferably, according to GB / T 17931 - 1999, the intrinsic viscosity of the aliphatic polyester is 1 - 3 dL / g, preferably the intrinsic viscosity is 1.5 - 2.2 dL / g, further preferably the intrinsic viscosity is 1.58 - 2.11 dL / g, more preferably the intrinsic viscosity is 1.67 - 2.02 dL / g, and particularly preferably the intrinsic viscosity is 1.82 - 1.95 dL / g.

[0022] In the present invention, the preparation method of the aliphatic polyester is not particularly limited, and any method that can prepare the aliphatic polyester with a specific oligomer content of the present invention is acceptable; preferably, the preparation method of the aliphatic polyester comprises the following steps:

[0023] (1) React a dibasic acid with a diol to obtain an esterification product;

[0024] (2) Carry out a prepolymerization reaction on the esterification product obtained in step (1) to obtain a prepolymerization product;

[0025] (3) Subject the prepolymer obtained in step (2) to a polycondensation reaction to obtain the polycondensate;

[0026] (4) Contact the polycondensate obtained in step (3) with an organic solvent to obtain the aliphatic polyester.

[0027] In the present invention, the dibasic acid in step (1) is succinic acid and / or succinic acid derivatives, and sebacic acid and / or sebacic acid derivatives; the dibasic acid can be used alone or as a mixture of at least two; the diol is 1,4-butanediol.

[0028] In the present invention, the source of the succinic acid and / or succinic acid derivatives is not particularly limited, and it can be succinic acid and / or succinic acid derivatives derived from bio-based (i.e., the preparation raw material is biomass resources), or succinic acid and / or succinic acid derivatives derived from petroleum-based (i.e., the preparation raw material is petroleum resources).

[0029] In the present invention, the molar ratio of the diol to the dibasic acid in step (1) is (1.2 - 3):1, for example, it can be 1.2:1, 1.5:1, 1.8:1, 2:1, 2.2:1, 2.5:1, 2.8:1, 3:1 or the range between any of the above values, and more preferably (1.4 - 2):1.

[0030] In the present invention, the raw materials for the reaction in step (1) further include a crosslinking agent; based on the total mass of the dibasic acid and the diol being 100 wt%, the mass of the crosslinking agent is 0 - 3 wt%; the crosslinking agent includes at least one of polyols, polyacids or polyanhydrides; exemplarily, the crosslinking agent includes but is not limited to tartaric acid, citric acid, malic acid, trimethylolpropane, trimethylolethane, pentaerythritol, polyether triol, glycerol, 1,3,5-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic anhydride, 1,2,4,5-benzenetetracarboxylic acid, pyromellitic dianhydride, etc.

[0031] In the present invention, the reaction in step (1) includes an esterification reaction and / or a transesterification reaction; the temperature of the reaction is 140 - 220 °C, the pressure is 0.7 - 1.4 bar, and the time is 2 - 5 h. Further preferably, the temperature of the reaction is 165 - 212 °C, the pressure is 0.78 - 1.2 bar, and the time is 2.4 - 4.5 h.

[0032] In the present invention, step (1) can be carried out in a mixing device, where the dibasic acid and the diol are mixed to obtain a slurry, and then the temperature is raised for the reaction.

[0033] In the present invention, the carboxyl content of the esterification product in step (1) is 245 - 575 mol / t, and more preferably 310 - 420 mol / t.

[0034] In the present invention, after the reaction in step (1), there is further a step of removing the excessive diol by distillation. The removed diol can be purified by distillation and reused as a raw material. The purity of the purified diol is ≥95%.

[0035] In the present invention, the temperature of the prepolymerization reaction in step (2) is 230 - 260 °C, the pressure is 0.3 - 0.8 bar, and the time is 70 - 200 min; more preferably, the temperature of the reaction is 235 - 246 °C, the pressure is 0.35 - 0.65 bar, and the time is 90 - 130 min.

[0036] In the present invention, step (2) can be carried out in a prepolymerization reactor.

[0037] In the present invention, the carboxyl content of the prepolymer product in step (2) is 40 - 90 mol / t, more preferably 60 - 80 mol / t.

[0038] In the present invention, the temperature of the polycondensation reaction in step (3) is 235 - 260 °C, the pressure is 0.2 - 5 mbar, and the time is 40 - 110 min; more preferably, the temperature of the reaction is 238 - 250 °C, the pressure is 0.5 - 2 mbar, and the time is 48 - 98 min.

[0039] In the present invention, the carboxyl content of the polycondensation product in step (3) is <50 mol / t, preferably the carboxyl content is <35 mol / t, and more preferably the carboxyl content is 10 - 25 mol / t.

[0040] In the present invention, step (3) can be carried out in a finishing machine suitable for polycondensation reaction, such as a rotary disk reactor, a cage reactor, a horizontal reactor, etc.

[0041] In the present invention, the reactions in step (1), step (2) and step (3) are each independently carried out in the presence of a catalyst; the catalysts in step (1), step (2) and step (3) can be the same or different; the catalyst can be an externally added catalyst or a catalyst existing in the system. The catalyst can be a tin compound, an antimony compound, a cobalt compound, a lead compound, a zinc compound, an aluminum compound or a titanium compound, more preferably a zinc compound, an aluminum compound or a titanium compound, and most preferably a titanium compound; the titanium compound can be tetrabutyl titanate or tetraisopropyl titanate; the titanium compound has less residue in the product or downstream products compared with other compounds and lower toxicity. It is especially suitable for preparing biodegradable polyesters and can directly enter the environment in the form of compost bags or covering films.

[0042] In the present invention, based on the total mass of the reaction raw materials (dicarboxylic acid, diol, and optional crosslinking agent) being 100 wt%, the total mass of the catalyst is 0.001 - 1 wt%.

[0043] In the present invention, according to actual needs, other additives can be added during the reaction in step (3); the other additives include but are not limited to catalyst passivators, color stabilizers, activators, etc.

[0044] The catalyst passivator includes but is not limited to phosphorus compounds; the phosphorus compounds include but are not limited to one or more of phosphorous acid and phosphoric acid; based on the mass of the prepolymer being 100 wt%, the mass of the catalyst passivator is 0.001 - 0.1 wt%, preferably 0.01 - 0.05 wt%. Exemplarily, when the catalyst is a highly active titanium compound, a catalyst passivator can be added, wherein the molar ratio of Ti to P is (1.1 - 1.5):1, and particularly preferably the molar ratio of Ti to P is (1.1 - 1.3):1.

[0045] The color stabilizer includes but is not limited to phosphorus compounds; the phosphorus compounds include but are not limited to one or more of phosphoric acid, phosphorous acid, triphenyl phosphite, triphenyl phosphate, sodium hypophosphite, and sodium phosphite; the use of a color stabilizer generally results in a decrease in the condensation rate. Therefore, triphenyl phosphate, which has no adverse effect on the condensation rate, is preferably used as the color stabilizer. Based on the mass of the prepolymer being 100 wt%, the mass of the color stabilizer is 0.001 - 1.5 wt%, preferably 0.01 - 1.0 wt%; when the catalyst is selected from titanium compounds, the molar ratio of Ti to P is 1:(0.3 - 1.0), and particularly preferably the molar ratio of Ti to P is 1:(0.5 - 1.0).

[0046] The activator includes but is not limited to phosphorus compounds; the phosphorus compounds include but are not limited to one or more of disodium hydrogen phosphate, calcium hypophosphite, calcium phosphite, calcium phosphate, sodium hypophosphite, sodium phosphite, triphenyl phosphite, triphenyl phosphate, trimethyl phosphate, triethyl phosphate, tripropyl phosphate, and tributyl phosphate. Based on the mass of the prepolymer being 100 wt%, the mass of the activator is 0.001 - 1.5 wt%, preferably 0.01 - 1.0 wt%; when the catalyst is selected from titanium compounds, the molar ratio of Ti to P is (1.0 - 1.5):1, and particularly preferably the molar ratio of Ti to P is (1.1 - 1.3):1.

[0047] More preferably, a color stabilizer and an activator are used in combination, for example, triphenyl phosphate and disodium hydrogen phosphate are used in combination.

[0048] In the present invention, after the polycondensation reaction, a chain growth reaction is further included, that is, the product obtained from the polycondensation reaction (polycondensate) is reacted with a chain extender to obtain a chain growth product.

[0049] In the present invention, the chain extender includes one or more of isocyanate, peroxide, epoxide, oxazoline, oxazine, caprolactam or carbodiimide.

[0050] In the present invention, the isocyanate may be an aromatic diisocyanate and / or an aliphatic diisocyanate. The aromatic diisocyanate may be toluene 2,4-diisocyanate, toluene 2,6-diisocyanate, diphenylmethane 2,2'-diisocyanate, diphenylmethane 2,4'-diisocyanate, diphenylmethane 4,4'-diisocyanate, naphthalene 1,5-diisocyanate or xylene diisocyanate; particularly preferably diphenylmethane 2,2'-diisocyanate, diphenylmethane 2,4'-diisocyanate or diphenylmethane 4,4'-diisocyanate. The aromatic diisocyanate may also be a polynuclear aromatic diisocyanate, such as tris(4-isocyanatophenyl)methane with three rings, which may be formed during the production of diisocyanates with one or two rings. The aliphatic diisocyanate may be a straight-chain or branched alkylene diisocyanate containing 2 to 20 carbon atoms or a cycloalkylene diisocyanate containing 3 to 20 carbon atoms; exemplarily, the aliphatic diisocyanate includes hexamethylene diisocyanate, pentamethylene diisocyanate, isophorone diisocyanate or the diisocyanate of methylene bis(4-isocyanatocyclohexane). Particularly preferred is hexamethylene diisocyanate.

[0051] In the present invention, based on the total mass of the polycondensation product, the mass of the isocyanate may be 0.05 to 2 wt%, particularly preferably 0.1 to 1.5 wt%.

[0052] In the present invention, the peroxide may be one or more of benzoyl peroxide, 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(tert-butylperoxy)methylcyclododecane, n-butyl 4,4-bis(butylperoxy)valerate, dicumyl peroxide, tert-butyl peroxybenzoate, dibutyl peroxide, α,α-bis(tert-butylperoxy)diisopropylbenzene, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hex-3-yne or cumene hydroperoxide.

[0053] In the present invention, based on the total mass of the polycondensation product, the mass of the peroxide may be 0.1 to 2 wt%, particularly preferably 0.2 to 1 wt%.

[0054] In the present invention, the epoxide may be one or more of diglycidyl ether, hexamethylene diglycidyl ether, sorbitol diglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether, glycerol polyglycidyl ether, trimethylolpropane polyglycidyl ether, resorcinol diglycidyl ether, neopentyl glycol diglycidyl ether, ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, dipropylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, and polybutylene glycol diglycidyl ether, and copolymers containing epoxy groups based on styrene, acrylate, and / or methacrylate.

[0055] In the present invention, based on the total mass of the polycondensation product, the mass of the epoxide may be 0.1 to 2 wt%, preferably 0.2 to 1 wt%.

[0056] In the present invention, the oxazoline may be selected from one or more of 2,2'-bis(2-oxazoline), bis(2-oxazolinyl)methane, 1,2-bis(2-oxazolinyl)ethane, 1,3-bis(2-oxazolinyl)propane, 1,4-bis(2-oxazolinyl)butane, 1,4-bis(2-oxazolinyl)benzene, 1,2-bis(2-oxazolinyl)benzene, or 1,3-bis(2-oxazolinyl)benzene. The oxazine may be selected from one or more of 2,2'-bis(2-dioxazine), bis(2-dioxazinyl)methane, 1,2-bis(2-dioxazinyl)ethane, 1,3-bis(2-dioxazinyl)propane, 1,4-bis(2-dioxazinyl)butane, 1,4-bis(2-dioxazinyl)benzene, 1,2-bis(2-dioxazinyl)benzene, or 1,3-bis(2-dioxazinyl)benzene. The carbodiimide may be selected from one or more of N,N'-di-2,6-diisopropylphenylcarbodiimide, N,N'-di-o-tolylcarbodiimide, N,N'-diphenylcarbodiimide, N,N'-dioctyldecylcarbodiimide, N,N'-di-2,6-dimethylphenylcarbodiimide, N-tolyl-N'-cyclohexylcarbodiimide, N,N'-di-2,6-di-tert-butylphenylcarbodiimide, N,N'-di-2,4,6-triisobutylphenylcarbodiimide, diisopropylcarbodiimide, dimethylcarbodiimide, diisobutylcarbodiimide, dioctylcarbodiimide, tert-butylisopropylcarbodiimide, di-β-naphthylcarbodiimide, or di-tert-butylcarbodiimide.

[0057] In the present invention, based on the total mass of the polycondensation product, the masses of the oxazoline, oxazine, caprolactam, and carbodiimide are each independently 0.1 to 2 wt%, preferably 0.2 to 1 wt%.

[0058] In the present invention, the chain growth reaction temperature is 170-245°C, more preferably 180-235°C; and it is carried out under superatmospheric pressure or atmospheric pressure, depending on the system used.

[0059] In the present invention, the chain growth reaction can be carried out in an extruder, a continuous kneader (List reactor) or a static mixer. The extruder can be a single screw extruder or a twin screw extruder; the static mixer can use SMR, SMX or SMXL components, or a combination thereof. Examples of List reactors are single-shaft DISCOTHERM B or twin-shaft CRP or ORP reactors. Preferably, the chain growth reaction is carried out in an extruder, and the residence time in the extruder is 2 to 15 minutes, more preferably 4 to 13 minutes.

[0060] In the present invention, the step (4) further includes slicing the polycondensation product before the contact treatment, and the slice size is limited by the weight of 100 particles (100-grain weight). The 100-grain weight of the polycondensation product after slicing is 2.2 to 6.0 g, and preferably 3.0 to 4.5 g.

[0061] In the present invention, the mass ratio of the polycondensation product to the organic solvent in step (4) is 1:(1-10), for example, it can be 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10 or a range between any of the above values; more preferably, it is 1:(2-6).

[0062] In the present invention, in order to facilitate the volatilization of the organic solvent in the subsequent process and reduce the residual organic solvent in the polyester product as much as possible, an organic solvent with a boiling point not exceeding 100° C. is preferably used.

[0063] Preferably, the organic solvent includes at least one of ketone compounds, alcohol compounds, ether compounds, and aliphatic hydrocarbon compounds; the ketone compounds include but are not limited to acetone and / or butanone, preferably acetone; the alcohol compounds include but are not limited to methanol, ethanol, isopropanol, etc.; the ether compounds include but are not limited to at least one of diethyl ether, propyl ether, and tetrahydrofuran, preferably tetrahydrofuran; the aliphatic hydrocarbon compounds include but are not limited to at least one of n-hexane, n-heptane, and cyclohexane, preferably n-hexane and / or cyclohexane.

[0064] In the present invention, the organic solvent may be a pure organic solvent or an organic solvent aqueous solution; when selected from an organic solvent aqueous solution, the mass concentration of the organic solvent aqueous solution is 35-90wt%.

[0065] In the present invention, the contact treatment temperature in step (4) is 35-80° C. and the time is 3-20 h; preferably, the contact treatment temperature is 40-55° C. and the time is 8-18 h.

[0066] In the present invention, the oligomer content in the aliphatic polyester can be regulated by contact treatment. Specifically, by controlling the temperature, time, and mass ratio of the polycondensation product to the organic solvent during contact treatment, etc., the oligomer content can be regulated. If the contact treatment temperature is too high, the organic solvent will volatilize quickly and there will be more losses. If the contact treatment temperature is too low, the elution effect cannot be effectively achieved, resulting in too high an oligomer content. If the contact treatment time is too long, the content of the organic solvent remaining in the polyester will be too high. If the contact treatment time is too short, the elution effect cannot be effectively achieved, resulting in too high an oligomer content. If the mass ratio of the polycondensation product to the organic solvent is not within the range, that is, the content of the organic solvent is too high, although the elution effect can be effectively improved, more solvents are consumed, more waste liquid is generated, the economic benefit is low, and the content of the organic solvent remaining in the polyester is too high. If the content is too low, the polyester cannot be uniformly dispersed in the solution, the elution effect is uneven, and the elution effect is poor.

[0067] Except for the contact treatment in step (4), the polymerization conditions, the molar ratio of alcohol to acid, etc. in steps (1) to (3) will also affect the oligomer content.

[0068] In the present invention, the preparation method of the aliphatic polyester can be obtained by subjecting the polycondensation product to contact treatment, or by subjecting the polycondensation product to a chain extension reaction (i.e., a chain growth reaction); it can also be obtained by first subjecting the polycondensation product to chain extension and then performing contact treatment.

[0069] In the present invention, the aliphatic polyester can also be prepared by the following method, that is, in step (1), succinic acid and / or succinic acid derivatives and sebacic acid and / or sebacic acid derivatives are respectively reacted with 1,4-butanediol to obtain two esterification products, and then the two esterification products are subjected to subsequent prepolymerization reaction, polycondensation reaction, and optional chain growth reaction and contact treatment.

[0070] Exemplarily, the preparation method specifically includes the following steps:

[0071] Step (1-1): React succinic acid and / or succinic acid derivatives, 1,4-butanediol with an optional crosslinking agent at a temperature of 150-195°C and a pressure of 0.7-1.2 bar for 2-6 h to obtain an esterification product A;

[0072] Step (1-2): React sebacic acid and / or sebacic acid derivatives with 1,4-butanediol at a temperature of 180-220°C and a pressure of 0.6-1.1 bar for 2-6 h to obtain an esterification product B; then mix the esterification product A with the esterification product B and perform a prepolymerization reaction, a polycondensation reaction, and an optional chain growth reaction and contact treatment; wherein, the conditions of the prepolymerization reaction, the polycondensation reaction, and the optional chain growth reaction and contact treatment are selected from the same ranges as those in step (2), step (3), and the aforementioned chain growth reaction, step (4).

[0073] In a second aspect, the present invention provides a polyester composition, and the polyester composition includes the aliphatic polyester described in the first aspect.

[0074] Preferably, the polyester composition further includes at least one of a second polyester, a third polymer, and an additive.

[0075] Preferably, the second polyester includes at least one of polylactic acid, an aliphatic-aromatic polyester, or other aliphatic polyesters.

[0076] Preferably, the second polyester includes at least one of polylactic acid (PLA), an aliphatic-aromatic polyester, or other aliphatic polyesters.

[0077] Preferably, the aromatic polyester includes at least one of polybutylene succinate terephthalate (PBST), polybutylene adipate terephthalate (PBAT), polybutylene sebacate terephthalate (PBSeT), or polybutylene adipate furandicarboxylate (PBAF).

[0078] Preferably, the other aliphatic polyesters include at least one of polybutylene succinate (PBS), polybutylene adipate succinate (PBSA), or polybutylene sebacate (PBSe).

[0079] In the present invention, according to standard ISO 1133-2-2012, at 190°C and 2.16 kg, the melt flow rate of the second polyester is 0.5-50 g / 10 min.

[0080] In the present invention, the second polyester can select the corresponding polyester according to actual needs, not limited to the polyesters mentioned above.

[0081] Preferably, the third polymer includes at least one of starch, cellulose, chitin, chitosan, alginate, protein, gelatin, natural rubber, lignin, or derivatives of the aforementioned substances.

[0082] In the present invention, the proteins include, but are not limited to, gluten, zein, casein, collagen, etc.; the lignins include unpurified lignin, purified hydrolyzed lignin, alkalized lignin, etc. Starch can also be used in the form of allosteric and gelatinized forms or as a filler. The starch can represent the continuous phase or the dispersed phase, or can be in a co-continuous form.

[0083] In the present invention, the additives can be added according to actual needs, including but not limited to at least one of antioxidants, lubricants, light stabilizers, mold release agents or antistatic agents.

[0084] In the present invention, the types of additives are not overly limited, and conventional additives can be used. Exemplarily, the antioxidant includes but is not limited to any one of antioxidant 1010, antioxidant 1076, antioxidant 168, antioxidant 164, antioxidant DLTP or antioxidant TPP.

[0085] The light stabilizer includes but is not limited to at least one of hindered amine light stabilizers (such as light stabilizer 770, light stabilizer 622, light stabilizer 944, etc.), benzophenone light stabilizers (such as UV531) or benzotriazole light stabilizers.

[0086] The lubricant includes but is not limited to at least one of esters (such as polyethylene glycol esters, polyol esters), lignite salts, ethylene bisstearamide or polyethylene wax.

[0087] The mold release agent includes but is not limited to at least one of inorganic mold release agents (such as talc powder, mica powder, clay, etc.), organic mold release agents (such as fatty acids, paraffin wax, glycerin, petrolatum, etc.) or polymer mold release agents (such as silicone oil, polyethylene glycol, low molecular weight polyethylene, etc.).

[0088] The antistatic agent includes but is not limited to at least one of cationic antistatic agents (such as quaternary ammonium salts), anionic antistatic agents (such as alkyl sulfonates, phosphates), amphoteric antistatic agents (such as amphoteric imidazoline compounds), non-ionic antistatic agents (such as hydroxyethyl alkylamines, fatty acid amides, polyoxyethylene types, polyol esters) or polymer antistatic agents (such as polyethers).

[0089] As a preferred technical solution of the present invention, based on parts by weight, the polyester composition comprises 50 to 95 parts of an aliphatic polyester (for example, it can be 50 parts, 55 parts, 60 parts, 65 parts, 70 parts, 75 parts, 80 parts, 85 parts, 90 parts, 95 parts or the range between any of the above values, preferably 52 to 92 parts, more preferably 56 to 82 parts), 1 to 20 parts of a second polyester (for example, it can be 1 part, 2 parts, 4 parts, 6 parts, 8 parts, 10 parts, 12 parts, 14 parts, 16 parts, 18 parts, 20 parts or the range between any of the above values, preferably 1.5 to 15 parts, more preferably 2.5 to 8.5 parts), 1 to 30 parts of a third polymer (for example, it can be 1 part, 2 parts, 4 parts, 6 parts, 8 parts, 10 parts, 12 parts, 14 parts, 16 parts, 18 parts, 20 parts, 22 parts, 24 parts, 25 parts, 26 parts, 28 parts, 30 parts or the range between any of the above values, preferably 9 to 27 parts, more preferably 21 to 26.5 parts) and 0 to 15 parts of an additive (for example, it can be 1 part, 2 parts, 4 parts, 6 parts, 8 parts, 10 parts, 12 parts, 14 parts, 15 parts or the range between any of the above values).

[0090] In the present invention, the preparation method of the polyester composition comprises: mixing the aliphatic polyester with an optional second polyester, a third polymer and an additive, and extruding to obtain the polyester composition; the extruder comprises a reactive extruder, and the extruder can be a single-screw extruder, a twin-screw extruder or a multi-screw extruder; the extrusion temperature is 140 to 220 °C, and the rotational speed of the screw during extrusion is 200 to 500 rpm.

[0091] In a third aspect, the present invention provides a packaging film, and the raw materials for preparing the packaging film comprise the aliphatic polyester described in the first aspect or the polyester composition described in the second aspect.

[0092] In the present invention, other substances can also be added to the raw materials for preparing the packaging film according to actual needs, such as colorants, pigments, inorganic fillers, etc.; the pigments include but are not limited to titanium dioxide, etc.; the inorganic fillers include but are not limited to talc, calcium carbonate, kaolin, etc.

[0093] Preferably, the unwind index of the packaging film ≤ 3, more preferably the unwind index ≤ 2.5, still more preferably the unwind index ≤ 2, and particularly preferably the unwind index ≤ 1.5.

[0094] Preferably, according to the EU10-2011 standard, under the OM6 test conditions, with 10% ethanol as the simulation liquid, when the thickness of the packaging film is 18 ± 2 μm, the overall migration amount of the packaging film ≤ 10 mg / dm 2 and more preferably the overall migration amount ≤ 5 mg / dm 2 .

[0095] In the present invention, the packaging film includes fresh-keeping film, shrink film, winding film, etc.

[0096] The aliphatic polyester, polyester composition containing the aliphatic polyester, and packaging film prepared therefrom according to the present invention are all biodegradable.

[0097] For the present invention, if a substance or mixture of substances shows a biodegradation percentage degree of at least 90%, as defined in DIN EN 13432, then the substance or mixture of substances has the characteristic of "biodegradable".

[0098] According to DIN EN 13432, during the composting process, air without CO 2 is introduced into the mature compost, and the compost is subjected to a specific temperature process. Here, biodegradability is defined as: the net amount of CO 2 released by the sample (after subtracting the amount of CO 2 released by the compost without the sample) and the maximum amount of CO 2 that the sample can release (calculated from the carbon content in the sample), expressed as the percentage degree of biodegradation. Only a few days after composting, biodegradable polyesters and biodegradable polyester compositions usually show obvious signs of degradation, such as fungal growth, cracking, and perforation.

[0099] Other methods for determining biodegradability are also described in ASTM D5338 and ASTM D6400.

[0100] The numerical ranges described in the present invention not only include the point values listed above, but also include any point values between the above numerical ranges not listed. Due to space limitations and for the sake of simplicity, the specific point values included in the ranges of the present invention are not exhaustively listed.

[0101] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0102] The aliphatic polyester provided by the present invention controls the molar ratio of succinic acid and sebacic acid within a specific range, and at the same time controls the oligomer content in the aliphatic polyester within a specific range, so that the packaging film including the aliphatic polyester has both good unwindability and food contact performance, and at the same time has good degradation performance, and can meet the requirements of home composting, etc. Detailed Embodiments

[0103] The technical solutions of the present invention will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations to the present invention.

[0104] In the present invention, all materials used can be purchased from the market or prepared by conventional methods. Unless otherwise specified, the materials used in the present invention are as follows.

[0105] 1,4-Butanediol: purchased from Xinjiang Meike Chemical Co., Ltd.

[0106] Succinic acid: purchased from Shandong Landian Biotechnology Co., Ltd.

[0107] Sebacic acid: purchased from Hengshui Jinghua Chemical Co., Ltd.

[0108] Glycerin: Purchased from Aladdin.

[0109] Tetrabutyl titanate: purchased from Jianyi Chemical Import & Export Co., Ltd.

[0110] Hexamethylene diisocyanate: Purchased from Aladdin.

[0111] In the present invention, the testing methods for the molar content of succinic acid residues and sebacic acid residues, number average molecular weight (Mn), oligomer content, intrinsic viscosity, and carboxyl content in the aliphatic polyester are as follows.

[0112] 1. The molar content of succinic acid residues and sebacic acid residues in aliphatic polyesters is determined by 1 The test was carried out by the HNMR method; specifically, 20 mg of the aliphatic polyester sample was dissolved in 0.6 mL of deuterated chloroform, and then the 1HNMR thereof was determined at room temperature using a Bruker AV 500 nuclear magnetic resonance spectrometer; the characteristic peaks of succinic acid residues and sebacic acid residues were integrated, and the respective molar contents of succinic acid residues and sebacic acid residues in the aliphatic polyester were obtained by the proportion of the peak areas; it should be noted that the contents of succinic acid residues and sebacic acid residues in the aliphatic polyester in Table 1 are based on the total molar amount of succinic acid residues and sebacic acid residues as 100 mol%; for example, the integral area of ​​succinic acid residues is I1, and the integral area of ​​sebacic acid residues is I2, then the molar percentage of succinic acid in the aliphatic polyester is I1 / (I1+I2)×100%; wherein the characteristic chemical shift of succinic acid residues is about 2.63 ppm, representing two methylene groups -CH 2 -CH 2 -4 hydrogens on the bottom; the characteristic chemical shift of the sebacic acid residue is about 1.30ppm, representing the four methylene groups in the middle of sebacic acid -CH 2 -CH 2 -CH 2 -CH 2 -8 hydrogens.

[0113] 2. Mn and oligomer content were tested by gel permeation chromatography (GPC): a chromatographic system was used at 40°C, using a set of three columns in series (particle diameter of 5 μm and porosity of and ) and a refractive index detector, chloroform as the eluent (elution flow rate of 1 mL / min), and polystyrene as the reference standard for determination; the instrument model is: Waters 1515GPC, and the sample preparation method is: directly dissolve the aliphatic polyester in chromatographic grade THF to prepare a 1 mg / mL solution for testing. .

[0114] 3. The test of intrinsic viscosity is carried out in accordance with standard GB / T 17931-1999, specifically including: adding 0.1250±0.0002g of sample into 25mL of phenol / o-dichlorobenzene mixed solution with a weight ratio of 1:1, heating until the sample is completely dissolved, and after the sample is completely dissolved, using Ubbelohde viscometer for testing at a test temperature of 25±0.05℃.

[0115] 4. The test of carboxyl content is carried out in accordance with the standard GB / T 32366-2015, as follows: 1g of sample is dissolved in 50mL of a mixed solvent of phenol and chloroform in a volume ratio of 2:3; 0.01mol / L potassium hydroxide ethanol solution is used as the standard titration solution, and 0.2% bromophenol blue solution is used as the indicator; a blank test is performed according to the above method for testing the carboxyl content of the sample; the sample is tested twice in parallel, and the difference between the two test results is required to be less than or equal to 2mol / t, and the final result is the average of the two test results.

[0116] Examples 1 to 16, Comparative Examples 1 to 6

[0117] Examples 1 to 16 and Comparative Examples 1 to 6 respectively provide an aliphatic polyester, the molecular structure composition, q1, q2 values, carboxyl content and intrinsic viscosity of the aliphatic polyester are shown in Table 1.

[0118] Table 1

[0119]

[0120] The preparation methods of the aliphatic polyesters provided in Examples 1 to 16 and Comparative Examples 1 to 6 are as follows.

[0121] Example 1

[0122] A method for preparing the aliphatic polyester is provided, which specifically comprises the following steps:

[0123] (1) 479 kg of succinic acid, 116 kg of sebacic acid, 560 kg of 1,4-butanediol and 2.46 kg of glycerol were physically mixed. After the mixing was completed, the mixture was transferred to an esterification reactor and esterified for 3.5 hours at a temperature of 200° C. and a pressure of 1.1 bar to obtain an esterified product;

[0124] (2) transferring the esterification product obtained in step (1) to a vertical reactor with stirring, adding 0.48 kg of tetrabutyl titanate, and carrying out a prepolymerization reaction at a temperature of 240° C. and a pressure of 0.52 bar for 120 minutes to obtain a prepolymerized product;

[0125] (3) transferring the prepolymer product obtained in step (2) to a horizontal reactor with stirring, and performing polycondensation reaction at a temperature of 243° C. and a pressure of 1.3 mbar for 90 minutes to obtain a polycondensation product;

[0126] (4) Slicing the polycondensation product obtained in step (3), wherein the weight of 100 slices is about 3.7 g, and contacting with a tetrahydrofuran aqueous solution; wherein the mass ratio of the polycondensation product to the tetrahydrofuran aqueous solution is 1:5, the mass concentration of the tetrahydrofuran aqueous solution is 70%, the contact treatment temperature is 50° C., and the contact treatment time is 14 h, to obtain the aliphatic polyester.

[0127] Example 2

[0128] A method for preparing the aliphatic polyester is provided, which specifically comprises the following steps:

[0129] (1) 433 kg of succinic acid, 162 kg of sebacic acid, 570 kg of 1,4-butanediol and 2.46 kg of glycerol were physically mixed. After the mixing was completed, the mixture was transferred to an esterification reactor and esterified for 4 hours at a temperature of 190° C. and a pressure of 0.9 bar to obtain an esterified product;

[0130] (2) transferring the esterification product obtained in step (1) to a vertical reactor with stirring, adding 0.48 kg of tetrabutyl titanate, and carrying out a prepolymerization reaction at a temperature of 243° C. and a pressure of 0.45 bar for 110 minutes to obtain a prepolymerized product;

[0131] (3) transferring the prepolymer product obtained in step (2) to a horizontal reactor with stirring, and performing polycondensation reaction at a temperature of 243° C. and a pressure of 1.1 mbar for 80 minutes to obtain a polycondensation product;

[0132] (4) Slicing the polycondensation product obtained in step (3), wherein the weight of 100 slices is about 3.7 g, and contacting with a tetrahydrofuran aqueous solution; wherein the mass ratio of the polycondensation product to the tetrahydrofuran aqueous solution is 1:5, the mass concentration of the tetrahydrofuran aqueous solution is 65%, the contact treatment temperature is 55° C., and the contact treatment time is 14 h, to obtain the aliphatic polyester.

[0133] Example 3

[0134] A method for preparing the aliphatic polyester is provided, which specifically comprises the following steps:

[0135] (1) 388 kg of succinic acid, 215 kg of sebacic acid, 560 kg of 1,4-butanediol and 2.46 kg of glycerol were physically mixed. After the mixing was completed, the mixture was transferred to an esterification reactor, and the esterification reaction was carried out at a temperature of 205° C. and a pressure of 1.0 bar for 4 hours to obtain an esterified product;

[0136] (2) transferring the esterification product obtained in step (1) to a vertical reactor with stirring, adding 0.48 kg of tetrabutyl titanate, and carrying out a prepolymerization reaction at a temperature of 238° C. and a pressure of 0.40 bar for 95 minutes to obtain a prepolymerized product;

[0137] (3) transferring the prepolymer product obtained in step (2) to a horizontal reactor with stirring, and performing polycondensation reaction at a temperature of 242° C. and a pressure of 1.0 mbar for 80 min to obtain a polycondensation product;

[0138] (4) Slicing the polycondensation product obtained in step (3), wherein the weight of 100 slices is about 3.7 g, and contacting with a tetrahydrofuran aqueous solution; wherein the mass ratio of the polycondensation product to the tetrahydrofuran aqueous solution is 1:5, the mass concentration of the tetrahydrofuran aqueous solution is 70%, the contact treatment temperature is 50° C., and the contact treatment time is 14 h, to obtain the aliphatic polyester.

[0139] Example 4

[0140] A method for preparing the aliphatic polyester is provided, which specifically comprises the following steps:

[0141] (1) 350 kg of succinic acid, 250 kg of sebacic acid, 534 kg of 1,4-butanediol and 2.46 kg of glycerol were physically mixed. After the mixing was completed, the mixture was transferred to an esterification reactor, and the esterification reaction was carried out at a temperature of 200° C. and a pressure of 1.1 bar for 3.5 hours to obtain an esterified product;

[0142] (2) transferring the esterification product obtained in step (1) to a vertical reactor with stirring, adding 0.48 kg of tetrabutyl titanate, and carrying out a prepolymerization reaction at a temperature of 242° C. and a pressure of 0.4 bar for 100 minutes to obtain a prepolymerized product;

[0143] (3) transferring the prepolymer product obtained in step (2) to a horizontal reactor with stirring, and performing polycondensation reaction at a temperature of 242° C. and a pressure of 1.1 mbar for 85 minutes to obtain a polycondensation product;

[0144] (4) Slicing the polycondensation product obtained in step (3), wherein the weight of 100 slices is about 3.7 g, and contacting with a tetrahydrofuran aqueous solution; wherein the mass ratio of the polycondensation product to the tetrahydrofuran aqueous solution is 1:5, the mass concentration of the tetrahydrofuran aqueous solution is 70%, the contact treatment temperature is 50° C., and the contact treatment time is 14 h, to obtain the aliphatic polyester.

[0145] Example 5

[0146] A method for preparing the aliphatic polyester is provided, which specifically comprises the following steps:

[0147] (1) 320 kg of succinic acid, 280 kg of sebacic acid, 534 kg of 1,4-butanediol and 2.46 kg of glycerol were physically mixed. After the mixing was completed, the mixture was transferred to an esterification reactor, and the esterification reaction was carried out at a temperature of 180° C. and a pressure of 0.8 bar for 3 hours to obtain an esterified product;

[0148] (2) transferring the esterification product obtained in step (1) to a vertical reactor with stirring, adding 0.48 kg of tetrabutyl titanate, and carrying out a prepolymerization reaction at a temperature of 243° C. and a pressure of 0.60 bar for 110 minutes to obtain a prepolymerized product;

[0149] (3) transferring the prepolymer product obtained in step (2) to a horizontal reactor with stirring, and performing polycondensation reaction at a temperature of 243° C. and a pressure of 1.3 mbar for 90 minutes to obtain a polycondensation product;

[0150] (4) Slicing the polycondensation product obtained in step (3), wherein the weight of 100 slices is about 3.7 g, and contacting with a tetrahydrofuran aqueous solution; wherein the mass ratio of the polycondensation product to the tetrahydrofuran aqueous solution is 1:4, the mass concentration of the tetrahydrofuran aqueous solution is 60%, the contact treatment temperature is 45° C., and the contact treatment time is 12 h, to obtain the aliphatic polyester.

[0151] Example 6

[0152] Provided is a method for preparing the aliphatic polyester, which differs from Example 4 in that, in step (3), the prepolymer product obtained in step (2) is transferred to a horizontal reactor with stirring, and polycondensed for 60 minutes at a temperature of 240° C. and a pressure of 1.4 mbar to obtain a polycondensation product; then the polycondensation product and hexamethylene diisocyanate (the content is 0.20wt% of the mass of the polycondensation product) are extruded in a reactive extruder at a temperature of 200° C. for a residence time of 7 minutes to obtain chain-extended product slices, the slices weighing about 3.7 g per 100 grains; in step (4), the obtained chain-extended product slices are subjected to a contact treatment process with a tetrahydrofuran aqueous solution; wherein the mass ratio of the chain-extended product slices to the tetrahydrofuran aqueous solution is 1:6, the mass concentration of the tetrahydrofuran aqueous solution is 80%, the contact treatment temperature is 50° C., and the contact treatment time is 15 hours to obtain the aliphatic polyester; other raw materials, amounts and preparation methods are the same as those in Example 4.

[0153] Example 7

[0154] A method for preparing the aliphatic polyester is provided, which differs from Example 4 in that, in step (4), the condensation product obtained in step (3) is sliced, the slices have a weight of about 3.7 g per 100 grains, and are contacted with a tetrahydrofuran aqueous solution; wherein the mass ratio of the condensation product slices to the tetrahydrofuran aqueous solution is 1:8, the mass concentration of the tetrahydrofuran aqueous solution is 85%, the contact treatment temperature is 55°C, and the contact treatment time is 16 hours to obtain the aliphatic polyester; and other raw materials, amounts and preparation methods are the same as those in Example 4.

[0155] Example 8

[0156] A method for preparing the aliphatic polyester is provided, which differs from Example 4 in that, in step (4), the condensation product obtained in step (3) is sliced, the slices have a weight of about 3.7 g per 100 slices, and are contacted with an acetone aqueous solution; wherein the mass ratio of the condensation product to the acetone aqueous solution is 1:5, the mass concentration of the acetone aqueous solution is 75%, the contact treatment temperature is 45°C, and the contact treatment time is 12 hours to obtain the aliphatic polyester; and other raw materials, amounts and preparation methods are the same as those in Example 4.

[0157] Example 9

[0158] A method for preparing the aliphatic polyester is provided, which differs from Example 4 in that, in step (4), the condensation product obtained in step (3) is sliced, the slices have a weight of about 3.7 g per 100 grains, and are contacted with an ethanol aqueous solution; wherein the mass ratio of the condensation product to the ethanol aqueous solution is 1:5, the mass concentration of the ethanol aqueous solution is 80%, the contact treatment temperature is 70°C, and the contact treatment time is 18 hours to obtain the aliphatic polyester; other raw materials, amounts and preparation methods are the same as those in Example 4.

[0159] Example 10

[0160] A method for preparing the aliphatic polyester is provided, comprising the following steps:

[0161] (1) 350 kg of succinic acid, 250 kg of sebacic acid, 534 kg of 1,4-butanediol and 2.46 kg of glycerol were physically mixed. After the mixing was completed, the mixture was transferred to an esterification reactor and esterified for 2.5 hours at a temperature of 180° C. and a pressure of 1.1 bar to obtain an esterified product;

[0162] (2) transferring the esterification product obtained in step (1) to a vertical reactor with stirring, adding 0.48 kg of tetrabutyl titanate, and carrying out a prepolymerization reaction at a temperature of 240° C. and a pressure of 0.45 bar for 100 min to obtain a prepolymerized product;

[0163] (3) transferring the prepolymer product obtained in step (2) to a horizontal reactor with stirring, and performing polycondensation reaction at a temperature of 245° C. and a pressure of 1.3 mbar for 95 minutes to obtain a polycondensation product;

[0164] (4) Slicing the polycondensation product obtained in step (3), wherein the weight of 100 slices is about 4.4 g, and contacting with a tetrahydrofuran aqueous solution; wherein the mass ratio of the polycondensation product to the tetrahydrofuran aqueous solution is 1:3, the mass concentration of the tetrahydrofuran aqueous solution is 75%, the contact treatment temperature is 55° C., and the contact treatment time is 12 h, to obtain the aliphatic polyester.

[0165] Embodiment 11

[0166] A method for preparing the aliphatic polyester is provided, which differs from Example 4 only in that, in step (3), the prepolymer product obtained in step (2) is transferred to a horizontal reactor with stirring, and polycondensation reaction is carried out for 85 minutes at a temperature of 242° C. and a pressure of 1.1 mbar to obtain a polycondensation product; in step (4), the polycondensation product obtained in step (3) is sliced, the weight of 100 slices is about 3.7 g, and a contact treatment process is carried out with a tetrahydrofuran aqueous solution; wherein the mass ratio of the polycondensation product to the tetrahydrofuran aqueous solution is 1:7, the mass concentration of the tetrahydrofuran aqueous solution is 75%, the contact treatment temperature is 55° C., and the contact treatment time is 14 hours to obtain the aliphatic polyester, and other raw materials, amounts and preparation methods are the same as those in Example 4.

[0167] Example 12

[0168] Provided is a method for preparing the aliphatic polyester, which differs from Example 4 only in that, in step (3), the prepolymer product obtained in step (2) is transferred to a horizontal reactor with stirring, and polycondensed for 50 minutes at a temperature of 246° C. and a pressure of 1.4 mbar to obtain a polycondensation product; the polycondensation product and hexamethylene diisocyanate (the content is 0.55wt% of the mass of the polycondensation product) are extruded in a reactive extruder at a temperature of 210° C. for a residence time of 9 minutes to obtain chain extension product slices; in step (4), the chain extension product obtained in step (3) is sliced, the slices weighing about 4.0g per 100 grains, and contacted with an ethanol aqueous solution; wherein the mass ratio of the chain extension product slices to the ethanol aqueous solution is 1:4, the mass concentration of the tetrahydrofuran aqueous solution is 70%, the contact treatment temperature is 50° C., and the contact treatment time is 12h to obtain the aliphatic polyester; other raw materials, amounts and preparation methods are the same as those in Example 4.

[0169] Embodiment 13

[0170] A method for preparing the aliphatic polyester is provided, which differs from Example 4 in that:

[0171] (1-1) 350 kg of succinic acid, 290 kg of 1,4-butanediol and 2.76 kg of glycerol were physically mixed. After the mixing was completed, the mixture was transferred to an esterification reactor and esterified for 4 hours at a temperature of 170° C. and a pressure of 1.1 bar to obtain an esterification product A;

[0172] (1-2) 245 kg of sebacic acid and 260 kg of 1,4-butanediol were physically mixed. After the mixing was completed, the mixture was transferred to an esterification reactor and esterified for 3 hours at a temperature of 210° C. and a pressure of 1.0 bar to obtain an esterified product B. After the esterified product A was mixed with the esterified product B, step (2), step (3), and step (4) were performed. Other raw materials, amounts, and preparation methods were the same as those in Example 4.

[0173] Embodiment 14

[0174] A method for preparing the aliphatic polyester is provided, which differs from Example 4 in that, in step (4), the condensation product obtained in step (3) is sliced, the slice weight is about 3.7 g, and the slice is contacted with a cyclohexane solution; wherein the mass ratio of the condensation product to the cyclohexane solution is 1:8, the mass concentration of the cyclohexane solution is 100%, the contact treatment temperature is 70°C, and the contact treatment time is 16 hours. The other raw materials, dosage and preparation method of the aliphatic polyester are the same as those in Example 4.

[0175] Embodiment 15

[0176] A method for preparing the aliphatic polyester is provided, comprising the following steps:

[0177] (1-1) 350 kg of succinic acid, 310 kg of 1,4-butanediol and 3.25 kg of glycerol were physically mixed. After the mixing was completed, the mixture was transferred to an esterification reactor and esterified for 4 hours at a temperature of 190° C. and a pressure of 0.9 bar to obtain an esterification product A;

[0178] (1-2) 245 kg of sebacic acid and 290 kg of 1,4-butanediol were physically mixed. After the mixing was completed, the mixture was transferred to an esterification reactor and esterified for 4 hours at a temperature of 210° C. and a pressure of 0.8 bar to obtain an esterification product B;

[0179] (2) transferring the esterification product A obtained in step (1-1) and the esterification product B obtained in step (1-2) to a vertical reactor with stirring, adding 0.48 kg of tetrabutyl titanate, and performing a prepolymerization reaction at a temperature of 240° C. and a pressure of 0.5 bar for 100 minutes to obtain a prepolymerized product;

[0180] (3) transferring the prepolymer product obtained in step (2) to a horizontal reactor with stirring, and performing polycondensation reaction at a temperature of 245° C. and a pressure of 1.0 mbar for 90 minutes to obtain a polycondensation product;

[0181] (4) Slicing the polycondensation product obtained in step (3), wherein the weight of 100 slices is about 3.2 g, and contacting with a tetrahydrofuran solution; wherein the mass ratio of the polycondensation product to the tetrahydrofuran solution is 1:6, the mass concentration of the tetrahydrofuran solution is 100%, the contact treatment temperature is 55° C., and the contact treatment time is 18 h, to obtain the aliphatic polyester.

[0182] Example 16

[0183] A method for preparing the aliphatic polyester is provided, which differs from Example 4 only in that, in step (3), the pre-condensation product obtained in step (2) is transferred to a horizontal reactor with stirring, and a condensation reaction is carried out for 70 minutes at a temperature of 242° C. and a pressure of 1.4 mbar to obtain a condensation product; the condensation product and hexamethylene diisocyanate (the content is 0.72wt% of the mass of the condensation product) are extruded in a reactive extruder at a temperature of 230° C. for a residence time of 12 minutes to obtain chain extension product slices; in step (4), the obtained chain extension product slices are sliced, the slices have a 100-grain weight of about 4.4g, and are contacted with an ethanol aqueous solution; wherein the mass ratio of the chain extension product slices to the ethanol aqueous solution is 1:4, the mass concentration of the ethanol aqueous solution is 65%, the contact treatment temperature is 65° C., and the contact treatment time is 10 hours to obtain the aliphatic polyester, and other raw materials, amounts and preparation methods are the same as those in Example 4.

[0184] Comparative Example 1

[0185] A method for preparing the aliphatic polyester is provided, which differs from Example 4 in that step (4) is not performed; other raw materials, amounts used and preparation methods are the same as those in Example 4.

[0186] Comparative Example 2

[0187] A method for preparing the aliphatic polyester is provided, which differs from Example 4 in that, in step (4), the condensation product obtained in step (3) is sliced, the slices have a weight of about 3.7 g per 100 slices, and are contacted with a tetrahydrofuran aqueous solution; wherein the mass ratio of the condensation product to the tetrahydrofuran aqueous solution is 1:10, the mass concentration of the tetrahydrofuran aqueous solution is 85%, the contact treatment temperature is 55°C, and the contact treatment time is 20 hours to obtain the aliphatic polyester, and other raw materials, amounts and preparation methods are the same as those in Example 4.

[0188] Comparative Example 3

[0189] A method for preparing the aliphatic polyester is provided, which specifically comprises the following steps:

[0190] (1) 275 kg of succinic acid, 315 kg of sebacic acid, 534 kg of 1,4-butanediol and 2.46 kg of glycerol were physically mixed. After the mixing was completed, the mixture was transferred to an esterification reactor, and the esterification reaction was carried out at a temperature of 200° C. and a pressure of 1.0 bar for 3 hours to obtain an esterification product;

[0191] (2) transferring the esterification product obtained in step (1) to a vertical reactor with stirring, adding 0.48 kg of tetrabutyl titanate, and carrying out a prepolymerization reaction at a temperature of 240° C. and a pressure of 0.70 bar for 115 minutes to obtain a prepolymerized product;

[0192] (3) transferring the prepolymer product obtained in step (2) to a horizontal reactor with stirring, and performing polycondensation reaction at a temperature of 246° C. and a pressure of 1.1 mbar for 100 min to obtain a polycondensation product;

[0193] (4) Slicing the polycondensation product obtained in step (3), wherein the weight of 100 slices is about 3.7 g, and contacting with a tetrahydrofuran aqueous solution; wherein the mass ratio of the polycondensation product to the tetrahydrofuran aqueous solution is 1:5, the mass concentration of the tetrahydrofuran aqueous solution is 70%, the contact treatment temperature is 50° C., and the contact treatment time is 14 h, to obtain the aliphatic polyester.

[0194] Comparative Example 4

[0195] A method for preparing the aliphatic polyester is provided, which specifically comprises the following steps:

[0196] (1) 535 kg of succinic acid, 60 kg of sebacic acid, 534 kg of 1,4-butanediol and 2.46 kg of glycerol were physically mixed. After the mixing was completed, the mixture was transferred to an esterification reactor and subjected to an esterification reaction at a temperature of 200° C. and a pressure of 1.1 bar for 3.5 hours to obtain an esterified product;

[0197] (2) transferring the esterification product obtained in step (1) to a vertical reactor with stirring, adding 0.48 kg of tetrabutyl titanate, and carrying out a prepolymerization reaction at a temperature of 243° C. and a pressure of 0.50 bar for 120 min to obtain a prepolymerized product;

[0198] (3) transferring the prepolymer product obtained in step (2) to a horizontal reactor with stirring, and performing polycondensation reaction at a temperature of 245° C. and a pressure of 1.2 mbar for 90 minutes to obtain a polycondensation product;

[0199] (4) Slicing the polycondensation product obtained in step (3), wherein the weight of 100 slices is about 3.7 g, and contacting with a tetrahydrofuran aqueous solution; wherein the mass ratio of the polycondensation product to the tetrahydrofuran aqueous solution is 1:5, the mass concentration of the tetrahydrofuran aqueous solution is 70%, the contact treatment temperature is 50° C., and the contact treatment time is 14 h, to obtain the aliphatic polyester.

[0200] Comparative Example 5

[0201] A method for preparing the aliphatic polyester is provided, which differs from Comparative Example 3 in that, in step (4), the polycondensation product obtained in step (3) is sliced, the weight of 100 slices is about 3.2 g, and the slices are contacted with a tetrahydrofuran aqueous solution; wherein the mass ratio of the polycondensation product to the tetrahydrofuran aqueous solution is 1:8, the mass concentration of the tetrahydrofuran aqueous solution is 90%, the contact treatment temperature is 55°C, and the contact treatment time is 16 hours to obtain the aliphatic polyester, and other raw materials, dosages and preparation methods are the same as those in Comparative Example 3.

[0202] Comparative Example 6

[0203] A method for preparing the aliphatic polyester is provided, which differs from comparative example 4 in that, in step (4), the condensation product obtained in step (3) is sliced, the slices have a weight of about 3.0 g per 100 grains, and are contacted with an ethanol aqueous solution; wherein the mass ratio of the condensation product to the ethanol aqueous solution is 1:8, the mass concentration of the ethanol aqueous solution is 70%, the contact treatment temperature is 70°C, and the contact treatment time is 18 hours to obtain the aliphatic polyester, and other raw materials, dosages and preparation methods are the same as those in comparative example 4.

[0204] Performance Testing

[0205] The aliphatic polyesters provided in Examples 1 to 16 and Comparative Examples 1 to 6 were cast in the following manner to prepare fresh-keeping films.

[0206] Screw temperature: 145-150℃; die temperature: 165℃; cooling temperature: 10℃; main machine feeding speed: 27.2kg / h, traction roller: 11.5Hz; winding roller: 11.8-13.2Hz.

[0207] The unwinding performance, food contact performance and disintegration cycle of the cling film were tested.

[0208] In the present invention, the unwinding index evaluation method is: tear off about 10 cm of the fully rolled cling film (width 30 cm, thickness 10±2 μm), hold the film with both hands to a height of 1 m, let the rolled film fall freely, and evaluate the unwinding index of the cling film according to the time it takes for the rolled film to fall to the ground, wherein the unwinding index is 1.0: free fall within 1 s; the unwinding index is 1.5: free fall within 3 s; the unwinding index is 2.0: free fall within 5 s; the unwinding index is 2.5: free fall within 7 s; the unwinding index is 3.0: free fall within 10 s; the unwinding index is 4.0: free fall within 15 s; the unwinding index is 5.0: free fall within 20 s. The lower the unwinding index, the better the unwinding performance.

[0209] In the present invention, the food contact performance is characterized by the migration amount of the cling film oligomers, specifically: according to the EU10-2011 standard, according to the OM6 test conditions, with 10% ethanol as the simulated liquid and the cling film thickness of 18±2μm, the migration amount is tested.

[0210] Disintegration cycle:

[0211] The aliphatic polyester was molded into a product with a size of 10 cm×10 cm and a thickness of 18±2 μm, and a home composting test was performed according to standard AS5810-2010, and the biodisintegration rate after 16 weeks of composting was recorded.

[0212] The specific test results are shown in Table 2.

[0213] Table 2

[0214]

[0215] As can be seen from Table 2, the aliphatic polyester of the present invention, by adjusting the ratio of succinic acid residues to sebacic acid residues and controlling the oligomer content within a specific range, can have a packaging film comprising the aliphatic polyester with good food contact performance and unwinding performance, and has a high biodisintegration rate under home composting conditions, thus meeting the requirements of home composting.

[0216] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An aliphatic polyester, characterized in that The aliphatic polyester comprises a dibasic acid residue and a diol residue: The dibasic acid residues include the following residues: a1) 65 to 90 mol % of succinic acid residues, based on the total molar percentage of a1) and a2) being 100 mol %; a2) 10 to 35 mol % of sebacic acid residues, based on the total molar percentage content of a1) and a2) being 100 mol %; The diol residues are selected from 1,4-butanediol residues in at least an equimolar amount to the dibasic acid residues; The aliphatic polyester contains oligomers with a number average molecular weight of less than 1000 as measured by GPC, and the mass percentage of the oligomers with a number average molecular weight of less than 1000 as measured by GPC in the aliphatic polyester is 0.08 to 3.45 wt %.

2. The aliphatic polyester according to claim 1, characterized in that The oligomers with a number average molecular weight of less than 1000 in the aliphatic polyester measured by GPC have the following characteristics: 0.05wt% <q1<1.0wt%; 0.1wt% <q2<2.5wt%; in, q1 is the mass percentage of oligomers with a number average molecular weight less than 500 in the aliphatic polyester measured by GPC; q2 is the mass percentage of oligomers with a number average molecular weight less than 1000 in the aliphatic polyester measured by GPC; Preferably, the q1 is 0.1-0.6wt%; Preferably, the q2 is 0.2-1.3 wt%.

3. The aliphatic polyester according to claim 2, characterized in that The ratio of q2 to q1 is less than 2, preferably the ratio of q2 to q1 is less than 1.

5.

4. The aliphatic polyester according to any one of claims 1 to 3, characterized in that The dibasic acid residues include the following residues: a1) 74 to 85 mol % of succinic acid residues, based on the total molar percentage of a1) and a2) being 100 mol %; a2) 15 to 26 mol % of sebacic acid residues, based on the total molar percentage of a1) and a2) being 100 mol %.

5. The aliphatic polyester according to any one of claims 1 to 4, characterized in that According to GB / T32366-2015, the carboxyl content of the aliphatic polyester is less than 40 mol / t, more preferably less than 30 mol / t, and more preferably less than 22 mol / t.

6. The aliphatic polyester according to any one of claims 1 to 5, characterized in that According to GB / T17931-1999, the intrinsic viscosity of the aliphatic polyester is 1 to 3 dL / g.

7. A polyester composition, characterized in that The polyester composition comprises the aliphatic polyester according to any one of claims 1 to 6.

8. The polyester composition according to claim 7, characterized in that The polyester composition further comprises at least one of a second polyester, a third polymer and an auxiliary agent; Preferably, the second polyester comprises at least one of polylactic acid, aliphatic-aromatic polyester or other aliphatic polyester; Preferably, the aliphatic-aromatic polyester comprises at least one of polybutylene terephthalate succinate, polybutylene terephthalate adipate, polybutylene terephthalate sebacate or polybutylene furandicarboxylate adipate; Preferably, the other aliphatic polyester comprises at least one of polybutylene succinate, polybutylene succinate adipate or polybutylene sebacate; Preferably, the third polymer comprises at least one of starch, cellulose, chitin, chitosan, alginate, protein, gelatin, natural rubber, lignin or derivatives thereof.

9. A packaging film, characterized in that: The raw material for preparing the packaging film comprises the aliphatic polyester according to any one of claims 1 to 6 or the polyester composition according to claim 7 or 8.

10. The packaging film according to claim 9, characterized in that: The unwinding index of the packaging film is ≤3; Preferably, according to the EU10-2011 standard, in accordance with the OM6 test conditions, with 10% ethanol as the simulated liquid and a packaging film thickness of 18±2 μm, the total migration amount of the packaging film is ≤10 mg / dm 2 .

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