A biodegradable aliphatic polyester composition, and a method for preparing and using the same

Abstract

The application provides a biodegradable aliphatic polyester composition, a preparation method thereof and application as a packaging film, and belongs to the technical field of degradable materials. The biodegradable aliphatic polyester composition comprises a biodegradable aliphatic polyester and a cyclic ester compound, wherein the biodegradable aliphatic polyester comprises: component A, a dicarboxylic acid compound, based on the total molar amount of component A, comprising a1, 65-95 mol% of succinic acid or a derivative thereof, or a mixture thereof, and a2, 5-35 mol% of adipic acid or a derivative thereof, or a mixture thereof; component B, at least 1,4-butanediol in an equimolar amount with component A; the cyclic ester compound comprises compounds represented by formula (I) and formula (II), the content of the cyclic ester compound represented by formula (I) and formula (II) is 538-1100 ppm based on the total weight of the biodegradable aliphatic polyester composition, and the TVOC content of the biodegradable aliphatic polyester composition is not higher than 157 ppm.

Description

Technical Field

[0001] The present invention relates to the technical field of biodegradable materials, in particular to a biodegradable aliphatic polyester composition and a preparation method and application thereof. Background Art

[0002] Polybutylene succinate-adipate (PBSA) is synthesized using 1,4-butanediol as raw material. PBSA has good processing properties and can be processed on common molding equipment using methods such as extrusion, injection molding, blow molding, spinning, blister molding, lamination, and foaming. The product has a wide range of uses and is mainly used in the packaging field, such as shrink film and food wrap.

[0003] During the synthesis of biodegradable polyesters, monomeric diacids and diols readily undergo esterification, producing small-molecule compounds such as cyclic esters or polyester oligomers. These cyclic esters and polyester oligomers are susceptible to migration and precipitation during use. The migration and precipitation of small-molecule compounds is particularly critical when biodegradable polyesters are used in packaging products, particularly food packaging.

[0004] When biodegradable polyester is used in packaging films, it is necessary to have good adhesion. That is, the film's ability to adhere to itself and other non-adhesive surfaces without adding an adhesive is essential. This characteristic allows users of such films to wrap one or more layers of film around an object (e.g., food on a plate), thus sealing it airtight. At the same time, for the convenience of consumers, it is necessary to clearly identify the object wrapped therein without opening the object. From a commercial perspective, it is highly desired that the product wrapped in the film should be as clearly visible as possible, so very high requirements are placed on the transparency of the film.

[0005] The purpose of the present invention is to develop a biodegradable aliphatic polyester material with low migration, high adhesion and high transparency to meet the needs of food contact packaging films. Summary of the Invention

[0006] The present invention aims to overcome the defects of the prior art, such as high migration, low adhesion and poor transparency, and to provide a biodegradable aliphatic polyester composition having a cyclic ester content of 538-1100 ppm and the characteristics of low migration, high adhesion and high transparency.

[0007] Another object of the present invention is to provide a method for preparing the biodegradable aliphatic polyester composition.

[0008] Another object of the present invention is to provide application of the biodegradable aliphatic polyester composition in the field of food packaging films.

[0009] To achieve the above object, the present invention adopts the following technical solutions:

[0010] A biodegradable aliphatic polyester composition comprising the following components:

[0011] i) biodegradable aliphatic polyester; the biodegradable aliphatic polyester comprises:

[0012] Component A, the dicarboxylic acid compound, based on the total molar amount of component A, comprises:

[0013] a1, 65 to 95 mol% of a derivative of succinic acid or its ester, or a mixture thereof,

[0014] a2, 5 to 35 mol% of adipic acid or its ester derivatives, or mixtures thereof;

[0015] Component B, 1,4-butanediol in an amount at least equimolar to that of component A;

[0016] ii) Cyclic esters, including compounds represented by formula (I) and formula (II):

[0017]

[0018] Based on the total weight of the biodegradable aliphatic polyester composition, the total content of the cyclic esters of the structures represented by formula (I) and formula (II) is 538-1100 ppm; it can be understood that, based on the total weight of the biodegradable aliphatic polyester composition, the total content of the cyclic esters of the structures represented by formula (I) and formula (II) includes but is not limited to: 538 ppm, 582 ppm, 600 ppm, 620 ppm, 700 ppm, 750 ppm, 850 ppm, 900 ppm, 1000 ppm, 1100 ppm;

[0019] The TVOC content of the biodegradable aliphatic polyester composition is not higher than 157 ppm.

[0020] Preferably, the component A, based on the total molar amount of component A, comprises:

[0021] a1, 72 to 82 mol% of a derivative of succinic acid or its ester, or a mixture thereof,

[0022] a2, 18 to 28 mol% of adipic acid or its ester derivative, or a mixture thereof.

[0023] Alternatively, the derivative of the succinate is at least one of dimethyl, diethyl, di-n-propyl, diisopropyl, di-n-butyl, diisobutyl, di-tert-butyl, di-n-pentyl, diisopentyl, and di-n-hexyl esters. Anhydrides of these dicarboxylic acids are also suitable derivatives for forming esters. Dimethyl succinate and succinic anhydride are preferably used, and succinic anhydride is particularly preferred.

[0024] Optionally, the derivative of the adipic acid ester is at least one of dimethyl, diethyl, di-n-propyl, diisopropyl, di-n-butyl, diisobutyl, di-tert-butyl, di-n-pentyl, diisopentyl, and di-n-hexyl ester. Anhydrides of these dicarboxylic acids are also suitable derivatives for forming esters.

[0025] The derivatives of dicarboxylic acids or esters thereof in the present invention may be used alone or in admixture of two or more.

[0026] Preferably, based on the total weight of the biodegradable aliphatic polyester composition, the total content of the cyclic esters of the structures represented by formula (I) and formula (II) is 538-850 ppm.

[0027] More preferably, based on the total weight of the biodegradable aliphatic polyester composition, the total content of the cyclic esters of the structures represented by formula (I) and formula (II) is 538-620 ppm.

[0028] Preferably, the biodegradable aliphatic polyester composition further comprises a chain extender, and the content of the chain extender is 0.05-2.0 wt.%, more preferably 0.1-1.5 wt.%, based on the total weight of the biodegradable aliphatic polyester composition.

[0029] Preferably, the chain extender comprises one or more of the following components:

[0030] c1, isocyanate,

[0031] c2, peroxide,

[0032] c3, epoxide,

[0033] c4, oxazoline, oxazine, caprolactam and / or carbodiimide.

[0034] The isocyanate described in the present invention can use aromatic diisocyanates or aliphatic diisocyanates. For example, the aromatic diisocyanate can 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.

[0035] Among them, diphenylmethane 2,2'-diisocyanate, 2,4'-diisocyanate, or 4,4'-diisocyanate is particularly preferably used.

[0036] Isocyanates that can also be used include tris(4-isocyanato-phenyl)methane having three rings. Such polynuclear aromatic diisocyanates can be formed, for example, during the production of diisocyanates having one or two rings.

[0037] For the purposes of the present invention, the aliphatic diisocyanate may be any linear or branched alkylene diisocyanate or cycloalkylene diisocyanate containing 2 to 20 carbon atoms, preferably 3 to 12 carbon atoms, such as hexamethylene diisocyanate, pentamethylene diisocyanate, isophorone diisocyanate, and methylene di(4-isocyanatocyclohexane) diisocyanate. Hexamethylene diisocyanate is particularly preferred.

[0038] The peroxide of the present invention can be one or more of the following compounds:

[0039] Benzoyl peroxide, 1,1-di(tert-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1-di(tert-butylperoxy)methylcyclododecane, n-butyl 4,4-di(butylperoxy)valerate, dicumyl peroxide, tert-butyl peroxybenzoate, dibutyl peroxide, α,α-di(tert-butylperoxy)diisopropylbenzene, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, 2,5-dimethyl-2,5-di(tert-butylperoxy)hex-3-yne, and tert-butylcumene peroxide.

[0040] The epoxide of the present invention 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, or a copolymer containing epoxy groups based on styrene, acrylate and / or methacrylate.

[0041] The dioxazoline of the present invention may preferably be 2,2′-di(2-oxazoline), di(2-oxazolinyl)methane, 1,2-di(2-oxazolinyl)ethane, 1,3-di(2-oxazolinyl)propane or 1,4-di(2-oxazolinyl)butane, in particular 1,4-di(2-oxazolinyl)benzene, 1,2-di(2-oxazolinyl)benzene or 1,3-di(2-oxazolinyl)benzene.

[0042] The dioxazine is preferably 2,2′-di(2-dioxazine), di(2-dioxazinyl)methane, 1,2-di(2-dioxazinyl)ethane, 1,3-di(2-dioxazinyl)propane or 1,4-di(2-dioxazinyl)butane, in particular 1,4-di(2-dioxazinyl)benzene, 1,2-di(2-dioxazinyl)benzene or 1,3-di(2-dioxazinyl)benzene.

[0043] The carbodiimide may be: 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 and di-tert-butylcarbodiimide.

[0044] Preferably, the biodegradable aliphatic polyester composition may further include, based on the total weight of the biodegradable aliphatic polyester composition, 0 to 3 wt.% of a crosslinking agent having at least three functional groups, preferably 0.01 to 2 wt.%, more preferably 0.05 to 1 wt.%, and particularly preferably 0.20 to 0.31 wt.%.

[0045] The cross-linking agent having at least three functional groups is particularly preferably a compound having 3 to 6 hydroxyl groups. Optionally, the cross-linking agent is at least one of tartaric acid, citric acid, malic acid, trimethylolpropane, trimethylolethane, pentaerythritol, polyether triol, glycerol, trimellitic acid, trimellitic acid, trimellitic anhydride, pyromellitic acid, and pyromellitic dianhydride. Polyols such as trimethylolpropane, pentaerythritol, and glycerol are preferred, with glycerol being particularly preferred.

[0046] The biodegradable aliphatic polyester composition of the present invention has a melt mass flow rate (MFR) of 1.0 to 40.0 g / 10 min, preferably 2.5 to 12 g / 10 min, and particularly preferably 3.5 to 8 g / 10 min at 190° C. and 2.16 kg according to the ISO 1133-2-2011 standard method.

[0047] The biodegradable aliphatic polyester composition of the present invention has a carboxyl content (AN) of 5 to 60 mol / t, preferably 10 to 40 mol / t, and particularly preferably 15 to 28 mol / t, according to the GB / T 32366-2015 standard method.

[0048] Total volatile organic compounds (TVOCs) in biodegradable aliphatic polyester compositions can produce unpleasant odors and affect human health. The TVOC content in the biodegradable aliphatic polyester composition of the present invention is preferably no greater than 89 ppm, particularly preferably no greater than 53 ppm, based on the total weight of the biodegradable aliphatic polyester composition.

[0049] According to the FLTM BO131-03 standard, the odor grade of the biodegradable aliphatic polyester composition is not higher than 5, preferably not higher than 3.5, and particularly preferably not higher than 2.0.

[0050] The present invention also protects a method for preparing the above-mentioned biodegradable aliphatic polyester composition, comprising the following steps:

[0051] S1. Component a1 is mixed with a portion of component B, with or without the addition of a catalyst to obtain slurry A, and slurry A is subjected to an esterification or transesterification reaction until the intrinsic viscosity of the esterified product is 0.05 to 0.12 dL / g as measured in accordance with GB / T 17931-1999;

[0052] S2. Component a2 is mixed with the remaining component B, with or without the addition of a catalyst to obtain a slurry B, and the slurry B is subjected to an esterification or transesterification reaction until the intrinsic viscosity of the esterified product is 0.05 to 0.14 dL / g as measured in accordance with GB / T 17931-1999;

[0053] S3. The esterification products obtained in steps S1 and S2 are mixed to obtain a mixture of esterification products, and the mixture is pre-condensed until the intrinsic viscosity of the prepolymer product is 0.30 to 0.55 dL / g as measured according to GB / T 17931-1999;

[0054] S4. The prepolymer obtained in step S3 is polycondensed until the intrinsic viscosity of the polycondensation product is 1.18 to 1.85 dL / g as measured in accordance with GB / T 17931-1999;

[0055] S5. The polycondensation product obtained in step S4 is sliced ​​to obtain polyester particles, which are contacted with an organic solvent or an aqueous solution thereof;

[0056] S6. Drying the product after the contact treatment in step S5, and performing solid phase polycondensation to obtain the biodegradable aliphatic polyester composition.

[0057] In the preparation method of the present invention, after esterification or transesterification reaction of succinic acid or its ester derivatives, or mixtures thereof, adipic acid or its ester derivatives, or mixtures thereof, the further obtained polycondensation product is sliced ​​and then sequentially subjected to contact treatment with an organic solvent or its aqueous solution and solid-phase polycondensation.

[0058] Preferably, in step S1, the ratio of component a1 to component B in slurry A is: 1.0 molar equivalent of component a1: 1.0 to 1.8 molar equivalents, preferably 1.05 to 1.60 molar equivalents, particularly preferably 1.15 to 1.50 molar equivalents of component B.

[0059] Preferably, in step S2, the ratio of component a2 to component B in slurry B is: 1.0 molar equivalent of component a2: 1.1 to 2.2 molar equivalents, preferably 1.2 to 1.8 molar equivalents, particularly preferably 1.3 to 1.6 molar equivalents of component B.

[0060] Preferably, in step S1 and / or step S2, all or part of the catalyst is metered in. The catalysts used typically include zinc, aluminum, and in particular titanium compounds. Another advantage of titanium catalysts such as tetrabutyl titanate or tetraisopropyl titanate over the tin compounds, antimony compounds, cobalt compounds, and lead compounds commonly used in the literature is that the residual amount of catalyst remaining in the product or downstream products is less toxic. This is particularly important in biodegradable polyesters because they enter the environment directly, for example, in the form of compost bags or mulch films. The catalyst is preferably a titanium catalyst.

[0061] Preferably, the addition amount of the titanium catalyst is 40-180 ppm (calculated as Ti element content) based on the total weight of the biodegradable aliphatic polyester composition.

[0062] Preferably, in step S1, the esterification or transesterification reaction temperature is 140 to 220°C, preferably 155 to 205°C, and the pressure is 0.6 to 1.2 bar, preferably 0.8 to 1.0 bar. Step S1 can be carried out in a mixing device, with a typical reaction time of 2 to 4 hours, to produce an esterified product having an intrinsic viscosity of 0.05 to 0.12 dL / g, as measured in a phenol / o-cresol solution with a weight ratio of 1:1 in a constant temperature water bath at 25±0.05°C, as specified in GB / T 17931-1999.

[0063] Preferably, in step S2, the esterification or transesterification reaction is carried out at a temperature of 180 to 230°C, preferably 190 to 210°C, and at a pressure of 0.8 to 1.1 bar, preferably 0.9 to 1.0 bar. Step S2 can be carried out in a mixing device, with a typical reaction time of 3 to 5 hours, to produce an esterified product having an intrinsic viscosity of 0.05 to 0.14 dL / g, as measured in a phenol / o-cresol solution at a weight ratio of 1:1 in a constant temperature water bath at 25±0.05°C, as specified in GB / T 17931-1999.

[0064] Excess diol components are generally removed by distillation and returned to the circuit, for example after purification by distillation.

[0065] Preferably, in step S3, the mixture of the esterified products and the remaining catalyst are added to a reactor suitable for a pre-condensation reaction to carry out a pre-condensation reaction; the reaction temperature is 225-260°C, preferably 235-245°C; the pressure is 0.2-0.7 bar, preferably 0.35-0.55 bar; and the reaction time is 75-180 minutes, thereby producing a pre-polymerized product having an intrinsic viscosity of 0.30-0.55 dL / g as measured in a phenol / o-cresol solution with a weight ratio of 1:1 in a constant temperature water bath at 25±0.05°C in accordance with GB / T17931-1999. In a preferred embodiment, the intrinsic viscosity of the pre-polymerized product is controlled to be 0.35-0.48 dL / g.

[0066] Preferably, in step S4, a catalyst deactivator is mixed with the prepolymer product, if appropriate. Suitable deactivators are, in particular, phosphorus compounds: either organic phosphites such as phosphorous acid, or phosphoric acid. It should be noted that if a highly active titanium catalyst is used, a deactivator can be added. The amount of deactivator added can be 0.001 to 0.1 wt.%, preferably 0.01 to 0.05 wt.%, based on the amount of polymer after step S4. The Ti / P ratio (mol / mol) is preferably set at 1.1 to 1.5:1, particularly preferably 1.1 to 1.3:1.

[0067] If appropriate, a color stabilizer for the condensation process is mixed with the prepolymer product in step S4. Suitable color stabilizers are, in particular, phosphorus compounds, such as phosphoric acid, phosphorous acid, triphenyl phosphite, triphenyl phosphate, sodium hypophosphite, and sodium phosphite. These phosphorus compounds can also be used in the form of mixtures. The use of color stabilizers generally results in a reduced condensation rate. Triphenyl phosphate is a particularly suitable color stabilizer because it has no adverse effect on the condensation rate.

[0068] The amount of color stabilizer added may be 0.001 to 1.5 wt.%, preferably 0.01 to 1.0 wt.%, based on the amount of polymer after step S4. The Ti / P ratio (mol / mol) is preferably set to 1.0:0.3 to 1.0, particularly preferably 1.0:0.5 to 1.0.

[0069] In step S4, if appropriate, an activator for the condensation process is mixed with the prepolymer product. Suitable activators are particularly phosphorus compounds. For example, 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. These phosphorus compounds can also be used in the form of a mixture. Particularly suitable activators are disodium hydrogen phosphate and sodium phosphite.

[0070] The amount of the activator added may be 0.001 to 1.5 wt.%, preferably 0.01 to 1.0 wt.%, based on the amount of polymer after step S4. The Ti / P ratio (mol / mol) is preferably set to 1.0 to 1.5:1, particularly preferably 1.1 to 1.3:1.

[0071] The combination of color stabilizers and activators is of particular concern, an example being triphenyl phosphate / disodium hydrogen phosphate.

[0072] The polycondensation process described in step S4 occurs in a finisher. Reactors such as rotary disc reactors or cage reactors have proven particularly suitable. The reaction temperature is typically set at 235-260°C, preferably 240-255°C, and the pressure is typically set at 0.2-5 mbar, preferably 0.5-3 mbar. The typical reaction time is 45-110 minutes, preferably 60-90 minutes, producing a polycondensation product having an intrinsic viscosity of 1.18-1.85 dL / g, as measured in a phenol / o-cresol solution with a weight ratio of 1:1 in a constant temperature water bath at 25±0.05°C, as specified in GB / T 17931-1999.

[0073] If necessary, after step S4 and before step S5, step S4', a chain extension reaction, can also be carried out. The polycondensation product described in step S4 is added together with the chain extender (component C) to an extruder, or to a continuous kneader (List reactor), or to a static mixer. The static mixer can use SMR, SMX or SMXL components, or a combination thereof. Examples of List reactors are: single-shaft DISCOTHERM B or double-shaft CRP or ORP reactors. The extruder that can be used is a single-screw extruder or a twin-screw extruder. In the present invention, the chain extension reaction is preferably carried out in an extruder. After chain extension, the chain extension product finally obtained has an intrinsic viscosity of 1.30 to 1.92 dL / g measured in a phenol / o-cresol solution with a weight ratio of 1:1 in a constant temperature water bath at 25±0.05°C according to GB / T 17931-1999.

[0074] The chain extension reaction is carried out at a reaction temperature of 170-240°C, preferably 180-220°C, under superatmospheric or atmospheric pressure, depending on the system used, with a residence time of 2-15 minutes, preferably 4-10 minutes.

[0075] After the polycondensation product obtained in step S4 is sliced, polyester pellets are obtained. The polyester pellets are then subjected to a contact treatment step with an organic solvent or an aqueous solution thereof. To facilitate volatilization of the organic solvent in subsequent processes and minimize residual organic solvent in the polyester product, an organic solvent having a boiling point not exceeding 100°C is selected during the contact treatment step.

[0076] Preferably, in step S5, the organic solvent is at least one of ketone compounds, alcohol compounds, ether compounds, and aliphatic hydrocarbon compounds.

[0077] Preferably, the boiling point of the organic solvent is ≤100°C.

[0078] Optionally, the ketone compound is acetone and / or butanone, preferably acetone; optionally, the alcohol compound is methanol, ethanol and / or isopropanol; optionally, the ether compound is at least one of diethyl ether, propyl ether, and tetrahydrofuran, preferably tetrahydrofuran; optionally, the aliphatic hydrocarbon compound is at least one of n-hexane, n-heptane, and cyclohexane, preferably n-hexane and / or cyclohexane.

[0079] Preferably, in step S5, the temperature of the contact treatment is 35-50°C.

[0080] Preferably, in step S5, the contact treatment time is 5 to 20 hours; more preferably 8 to 16 hours.

[0081] Preferably, in step S5, the mass ratio of the polyester particles to the organic solvent or its aqueous solution is 1:(1-10), and the mass concentration of the organic solvent aqueous solution is 35-90 wt.%.

[0082] More preferably, in step S5, the mass ratio of the polyester particles to the organic solvent or its aqueous solution is 1:(2-5).

[0083] The contact treatment temperature and time of the polyester particles and the organic solvent or its aqueous solution, as well as the mass ratio of the polyester particles to the organic solvent or its aqueous solution, will affect the final elution effect and the content of cyclic esters and TVOC content in the prepared biodegradable aliphatic polyester composition.

[0084] If the contact treatment temperature is too high, the organic solvent will evaporate faster and the loss will be greater. If the contact treatment temperature is too low, the elution effect cannot be effectively achieved.

[0085] If the contact treatment time is too long, the organic solvent content remaining in the polyester will be too high; if the contact treatment time is too short, the elution effect cannot be effectively achieved.

[0086] If the mass ratio of polyester particles to organic solvent or its aqueous solution is too high, although it can effectively improve the elution effect, it requires more solvent, generates a lot of waste liquid, has low economic benefits, and the organic solvent content remaining in the polyester composition is too high; if the mass ratio of polyester particles to organic solvent or its aqueous solution is too low, the polyester particles cannot be evenly dispersed in the solution, the elution effect is uneven, and the elution effect is poor.

[0087] The product after the contact treatment is filtered and the washing liquid is separated and recovered, and the wet particles and the washing filtrate are dried to a moisture content of less than 800 ppm and solid phase polycondensation is performed.

[0088] Preferably, in step S6, the solid phase polycondensation process can be carried out in a rotary drum reactor, the solid phase polycondensation temperature is 65 to 95° C., preferably 75 to 85° C.; the solid phase polycondensation reaction pressure is 0.3 to 6 mbar, preferably 0.5 to 3 mbar; and the solid phase polycondensation reaction time is 8 to 16 hours, preferably 10 to 16 hours.

[0089] The present invention also protects a biodegradable mixture comprising the following components:

[0090] I) based on the total weight of components I) and II), 5 to 95 wt.% of the biodegradable aliphatic polyester composition,

[0091] II) 5 to 95 wt.% of at least one or more components selected from aliphatic-aromatic copolyesters, aliphatic polyesters, starch, cellulose, polyhydroxyalkanoates, polyglycolic acid and polylactic acid, based on the total weight of components I) and II),

[0092] III) 0 to 35 wt.% of talc, based on the total weight of components I) to IV),

[0093] IV) 0 to 20 wt.% of calcium carbonate, based on the total weight of components I) to IV).

[0094] The biodegradable aliphatic polyester composition and biodegradable mixture of the present invention are both biodegradable.

[0095] For the purposes of the present invention, a substance or a mixture of substances is characterized as "biodegradable" if it shows a percentage degree of biodegradation as defined in DIN EN 13432 of at least 90%.

[0096] According to DIN EN 13432, during the composting process, CO2-free air is introduced into mature compost and the compost is subjected to a specific temperature profile. Biodegradability is defined as the percentage of biodegradation expressed as the ratio of the net amount of CO2 released by the sample (after subtracting the amount of CO2 released by the compost without the sample) to the maximum amount of CO2 that the sample could release (calculated from the carbon content of the sample). After only a few days of composting, biodegradable polyesters and biodegradable polyester blends often show visible signs of degradation, such as fungal growth, cracking, and perforation.

[0097] Other methods for determining biodegradability are described, for example, in ASTM D5338 and ASTM D6400.

[0098] The present invention also protects the use of the biodegradable mixture in the field of preparing food packaging films and food packaging bags.

[0099] The biodegradable aliphatic polyester composition of the present invention can be used to prepare packaging films, in particular to produce food packaging films with a thickness of 8 μm to 50 μm, preferably 10 μm to 25 μm.

[0100] By controlling the content of cyclic esters to 538-1100 ppm, the risk of cyclic ester migration and precipitation during use of food packaging films prepared with biodegradable aliphatic polyester compositions is greatly reduced, the precipitation resistance of the food packaging films is improved, and a high transparency is maintained.

[0101] The food packaging film with a thickness of 8 μm to 50 μm of the present invention has a precipitation resistance grade of no higher than 4, preferably no higher than 2.

[0102] The precipitation resistance grade of the present invention is evaluated according to the following method:

[0103] A film of 8 μm to 50 μm, preferably 10 μm to 25 μm, prepared from the biodegradable aliphatic polyester composition was stored at 60° C. and 60% humidity for 2 weeks. The surface appearance of the film was visually inspected and evaluated according to the following criteria:

[0104] Level 1: No white precipitate is found on the surface of the film by visual inspection;

[0105] Level 2: White precipitates are found on the surface of the membrane by visual inspection, and the area of ​​the white precipitates does not exceed 10% of the membrane area;

[0106] Level 3: White precipitates are found on the surface of the membrane by visual inspection, and the area of ​​the white precipitates is between 10% and 25% (excluding 10%) of the membrane area;

[0107] Level 4: White precipitates are found on the surface of the membrane by visual inspection. The area of ​​the white precipitates is between 25% and 45% (excluding 25%) of the membrane area.

[0108] Level 5: White precipitates are found on the surface of the membrane by visual inspection, and the area of ​​the white precipitates is between 45% and 75% (excluding 45%) of the membrane area;

[0109] Level 6: White precipitates are visually observed on the surface of the film, and the area of ​​the white precipitates exceeds 75% of the film area.

[0110] Preferably, the food packaging film with a thickness of 8 μm to 50 μm of the present invention has a static friction coefficient (COF) of ≥6.2, more preferably COF ≥8.8, and particularly preferably COF ≥11.3, and has high adhesion ability.

[0111] The test method of the static friction coefficient is carried out with reference to AS TMD 1 8 9 4 "Static and dynamic friction coefficients of plastic films and sheets". In the present invention, the static friction coefficient is measured in the following manner.

[0112] A sample of a film having a thickness of 8 μm to 50 μm, preferably 10 μm to 25 μm, is wrapped around a glass plate support surface of approximately 150×300 mm×2 mm thickness. The film material is fully adhered to the glass plate and must have a smooth, wrinkle-free surface. The plate is placed in a horizontal position and a stainless steel slide weighing 200 ± 5 grams and measuring 63.5 × 5 mm thick is placed on it. Moderate pressure is manually applied to its surface to improve the adhesion of the slide to the surface of the film. The load sensor is connected to one end of the slide via a nylon wire. The load sensor is positioned on the moving crossbar of the dynamometer and can move at a constant speed of 10 mm / min. The static friction coefficient is defined as the ratio of the force (F) recorded by the dynamometer at the moment when the slide no longer adheres to the film (the tangential friction force that hinders sliding) to the weight (Fg) (the weight of the steel slide) acting perpendicularly on the two contact surfaces.

[0113] Preferably, the food packaging film of the present invention having a thickness of 8 μm to 50 μm has a haze of ≤18%, more preferably ≤15%, and particularly preferably ≤11%, as tested according to standard ASTM D1003, and the film has high transparency.

[0114] The packaging film can be formed by extrusion blown film or cast film. Taking the extrusion blown film method as an example, the commonly used processing parameters are as follows:

[0115] Film blowing machine: adopts the universal LDPE / LLDPE low bubble method for extrusion and blowing.

[0116] Extruder screw: It is recommended to use a screw with a small number of mixing units to enhance the plasticizing and melting effect. The recommended screw length-to-diameter ratio is 30-32:1.

[0117] Die head: To ensure uniform distribution of the melt after extrusion, it is recommended to use a spiral flow channel die head.

[0118] Air ring: It is recommended to use double or multi-port air ring instead of the traditional single air ring to improve cooling efficiency and increase the cooling effect and stability of the film bubble.

[0119] Film blowing process: The recommended extrusion melt temperature setting value is 115-150°C. The recommended blow-up ratio is 3.5-4.0.

[0120] Compared with the prior art, the present invention has the following beneficial effects:

[0121] The present invention develops a biodegradable aliphatic polyester composition having excellent precipitation resistance, adhesion and transparency while maintaining good biodegradability. DETAILED DESCRIPTION

[0122] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below with reference to specific embodiments, but the embodiments do not limit the present invention in any form.

[0123] The raw materials in the examples and comparative examples can all be obtained commercially;

[0124] In this application, the content of cyclic esters is detected by the following method:

[0125] (1) Preparation of standard working curves for compounds represented by formula (I) and formula (II):

[0126] Standard working solutions of the compounds represented by formula (I) and formula (II) were prepared at concentrations of 0.1 mg / L, 1 mg / L, 5 mg / L, 10 mg / L, 20 mg / L, 50 mg / L, 100 mg / L, 200 mg / L, 500 mg / L, 1 g / L, and 2 g / L, respectively. Butyl acetate was used as the internal standard, and the internal standard concentration was 1 g / L. The internal standard method was adopted, and an Agilent 7820A gas chromatograph was used as the testing equipment. Standard working curves of the compounds represented by formula (I) and formula (II) were prepared respectively with the peak area ratio of the compounds represented by formula (I) and formula (II) to butyl acetate as the ordinate and the concentration ratio of the compounds represented by formula (I) and formula (II) to butyl acetate as the abscissa.

[0127] (2) Sample cyclic ester content test:

[0128] Quantitatively weigh 1.0 g of sample, dissolve it in 10 ml of dichloromethane, and filter to remove the insoluble components in dichloromethane;

[0129] Slowly add 10 ml of methanol to the dichloromethane solution to reprecipitate the polymer, centrifuge and separate, and retain the supernatant as the sample to be tested;

[0130] Take 1 ml of the supernatant and add it to a 10 ml volumetric flask. Add 1 ml of 1 g / L butyl acetate internal standard solution and make up to volume with methanol.

[0131] The peak areas of the compounds represented by formula (I) and formula (II) in the sample are measured using the same gas chromatography equipment and testing method as used to prepare the standard working curves of the compounds represented by formula (I) and formula (II);

[0132] The contents of the compounds represented by formula (I) and formula (II) in the sample were calculated using the peak area ratio of the compound represented by formula (I) to butyl acetate and the peak area ratio of the compound represented by formula (II) to butyl acetate in the sample, respectively, in combination with the standard working curve of cyclic esters;

[0133] The sum of the contents of the compounds represented by formula (I) and formula (II) is the total amount of cyclic esters in the biodegradable aliphatic polyester composition.

[0134] (3) Agilent 7820A test parameters and gas chromatography test methods

[0135] Table 1 Aglient 7820A test parameters

[0136]

[0137] Gas chromatography temperature program:

[0138] Initial value 60℃, holding time: 1min,

[0139] Heating rate: 8℃ / min, heating to 180℃, holding time 2min,

[0140] Heating rate: 15℃ / min, heating to 250℃, holding time 5min.

[0141] In this application, the TVOC content test method of the biodegradable aliphatic polyester composition is:

[0142] The PV-3341 method was used, with a sample weight of 1.2000 ± 0.0200 g, a headspace temperature of 120°C, and a headspace time of 5 hours. The test was performed using an Agilent 7697A-7890A instrument.

[0143] Agilent 7697A-7890A test parameters and test methods are shown in Tables 2 and 3:

[0144] Table 2 Aglient 7697A test parameters

[0145]

[0146]

[0147] Table 3 Aglient 7890A test parameters

[0148]

[0149] GC temperature program:

[0150] Initial value 50℃, holding time: 3 minutes;

[0151] The temperature was raised to 200°C at a rate of 12°C / min and the holding time was 4 minutes.

[0152] Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in this technical field.

[0153] Example 1

[0154] Example 1 provides a biodegradable aliphatic polyester composition, the preparation method of which is as follows:

[0155] S1. 187.9 kg of succinic acid, 205 kg of 1,4-butanediol, and 0.85 kg of glycerol were physically mixed and transferred to a multi-stage stirred tank cascade reactor. The reaction mixture was esterified at 180°C and 1.0 bar for 3 hours. The resulting esterified product had an intrinsic viscosity of 0.08 dL / g.

[0156] S2. 73.1 kg of adipic acid, 60 kg of 1,4-butanediol, and 0.22 kg of tetrabutyl titanate were physically mixed and then transferred to a multi-stage stirred tank cascade reactor. The reaction mixture was esterified at 200°C and 0.9 bar for 3 hours, resulting in an esterified product with an intrinsic viscosity of 0.09 dL / g.

[0157] S3. The esterified products obtained in steps S1 and S2 were mixed to obtain a mixture of esterified products. The mixture was transferred to a stirred vertical reactor, 0.10 kg of tetrabutyl titanate was added, and the reaction mixture was pre-polycondensed at 240° C. and a pressure of 0.35 bar in the reactor for 120 minutes. The resulting prepolymer had an intrinsic viscosity of 0.42 dL / g.

[0158] S4. The prepolymer obtained in step S3 was transferred to a horizontal reactor with stirring and polycondensed at 243°C and a pressure of 2.0 mbar for 85 minutes. The intrinsic viscosity of the polycondensation product was 1.62 dL / g.

[0159] S5. After slicing the polycondensation product obtained in step S4, the polyester particles were contacted with an aqueous tetrahydrofuran solution. The mass ratio of polyester particles to aqueous tetrahydrofuran solution was 1:5, the mass concentration of the aqueous tetrahydrofuran solution was 70%, the contact treatment temperature was 50°C, and the contact treatment time was 14 hours. The resulting product had an intrinsic viscosity of 1.59 dL / g.

[0160] S6. The product after the contact treatment in step S5 was dried and transferred to a rotary drum reactor for solid phase polycondensation at a solid phase polycondensation temperature of 75° C., a reaction pressure of 3.0 mbar, and a reaction time of 16 hours. The resulting biodegradable aliphatic polyester composition had an intrinsic viscosity of 1.65 dL / g.

[0161] The contents of the compounds represented by formula (I) and formula (II) in the biodegradable aliphatic polyester composition are shown in Table 4.

[0162] Example 2

[0163] Example 2 provides a biodegradable aliphatic polyester composition, the preparation method of which is as follows:

[0164] S1. 187.9 kg of succinic acid, 215 kg of 1,4-butanediol, and 0.9 kg of glycerol were physically mixed and transferred to a multi-stage stirred tank cascade reactor. The reaction mixture was esterified at 155°C and 1.1 bar for 2 hours to obtain an esterified product with an intrinsic viscosity of 0.05 dL / g.

[0165] S2. 125.0 kg of adipic acid, 100 kg of 1,4-butanediol, and 0.28 kg of tetrabutyl titanate were physically mixed and then transferred to a multi-stage stirred tank cascade reactor. The reaction mixture was esterified at 210°C and 0.80 bar for 4 hours, resulting in an esterified product with an intrinsic viscosity of 0.14 dL / g.

[0166] S3. The esterified products obtained in steps S1 and S2 were mixed to obtain a mixture of esterified products. The mixture was transferred to a stirred vertical reactor, 0.12 kg of tetrabutyl titanate was added, and the reaction mixture was pre-polycondensed at 245° C. and a pressure of 0.55 bar in the reactor for 75 minutes. The resulting pre-polyester had an intrinsic viscosity of 0.35 dL / g.

[0167] S4. The prepolymer obtained in step S3 was transferred to a horizontal reactor with stirring and polycondensed at 250°C and a pressure of 2.0 mbar for 90 minutes. The intrinsic viscosity of the polycondensation product was 1.56 dL / g.

[0168] S5. After slicing the polycondensation product obtained in step S4, the polyester pellets were subjected to a contact treatment step with an n-hexane solution. The mass ratio of polyester pellets to n-hexane solution was 1:2, the contact treatment temperature was 50°C, and the contact treatment time was 16 hours. The resulting product had an intrinsic viscosity of 1.54 dL / g.

[0169] S6. The product after the contact treatment in step S5 was dried and transferred to a rotary drum reactor for solid phase polycondensation at a solid phase polycondensation temperature of 65° C., a reaction pressure of 0.5 mbar, and a reaction time of 12 hours. The resulting biodegradable aliphatic polyester composition had an intrinsic viscosity of 1.57 dL / g.

[0170] The contents of the compounds represented by formula (I) and formula (II) in the biodegradable aliphatic polyester composition are shown in Table 4.

[0171] Example 3

[0172] Example 3 provides a biodegradable aliphatic polyester composition, the preparation method of which is as follows:

[0173] S1. 187.9 kg of succinic acid, 215 kg of 1,4-butanediol, and 0.90 kg of glycerol were physically mixed and transferred to a multi-stage stirred tank cascade reactor. The reaction mixture was esterified at 190°C and 0.9 bar for 4 hours. The resulting esterified product had an intrinsic viscosity of 0.12 dL / g.

[0174] S2. 73.1 kg of adipic acid, 60 kg of 1,4-butanediol, and 0.22 kg of tetrabutyl titanate were physically mixed and then transferred to a multi-stage stirred tank cascade reactor. The reaction mixture was esterified at 200°C and 0.90 bar for 3 hours, resulting in an esterified product with an intrinsic viscosity of 0.09 dL / g.

[0175] S3. The esterified products obtained in steps S1 and S2 were mixed to obtain a mixture of esterified products. The mixture was transferred to a stirred vertical reactor, 0.12 kg of tetrabutyl titanate was added, and the reaction mixture was pre-polycondensed at 235° C. and a pressure of 0.7 bar in the reactor for 90 minutes. The resulting pre-polyester had an intrinsic viscosity of 0.32 dL / g.

[0176] S4. The prepolymer obtained in step S3 was transferred to a horizontal reactor with stirring and polycondensed at 252°C and a pressure of 2.2 mbar for 96 minutes. The intrinsic viscosity of the polycondensation product was 1.53 dL / g.

[0177] S5. After slicing the polycondensation product obtained in step S4, the polyester particles were contacted with a cyclohexane solution. The mass ratio of polyester particles to cyclohexane solution was 1:5, the contact treatment temperature was 45°C, and the contact treatment time was 8 hours. The resulting product had an intrinsic viscosity of 1.50 dL / g.

[0178] S6. The product after the contact treatment in step S5 was dried and transferred to a rotary drum reactor for solid phase polycondensation at a solid phase polycondensation temperature of 75° C., a reaction pressure of 2.0 mbar, and a reaction time of 14 hours. The resulting biodegradable aliphatic polyester composition had an intrinsic viscosity of 1.52 dL / g.

[0179] The contents of the compounds represented by formula (I) and formula (II) in the biodegradable aliphatic polyester composition are shown in Table 4.

[0180] Example 4

[0181] Example 4 provides a biodegradable aliphatic polyester composition, which is prepared as follows:

[0182] S1. 152 kg of succinic acid, 185 kg of 1,4-butanediol, and 0.90 kg of glycerol were physically mixed and transferred to a multi-stage stirred tank cascade reactor. The reaction mixture was esterified at 170°C and 1.0 bar for 4 hours. The resulting esterified product had an intrinsic viscosity of 0.10 dL / g.

[0183] S2. 73.1 kg of adipic acid, 60 kg of 1,4-butanediol, and 0.22 kg of tetrabutyl titanate were physically mixed and then transferred to a multi-stage stirred tank cascade reactor. The reaction mixture was esterified at 220°C and 0.9 bar for 4 hours to obtain an esterified product with an intrinsic viscosity of 0.13 dL / g.

[0184] S3. The esterified products obtained in steps S1 and S2 were mixed to obtain a mixture of esterified products. The mixture was transferred to a stirred vertical reactor, 0.12 kg of tetrabutyl titanate was added, and the reaction mixture was pre-polycondensed at 245° C. and a pressure of 0.30 bar in the reactor for 140 minutes. The resulting pre-polyester had an intrinsic viscosity of 0.48 dL / g.

[0185] S4. The prepolymer obtained in step S3 was transferred to a horizontal reactor with stirring and polycondensed at 250°C and a pressure of 1.6 mbar for 100 minutes. The intrinsic viscosity of the polycondensation product was 1.66 dL / g.

[0186] S5. After slicing the polycondensation product obtained in step S4, the polyester particles were contacted with an acetone aqueous solution. The mass ratio of polyester particles to acetone aqueous solution was 1:4, the mass concentration of the acetone aqueous solution was 75%, the contact treatment temperature was 40°C, and the contact treatment time was 5 hours. The resulting product had an intrinsic viscosity of 1.64 dL / g.

[0187] S6. The product after the contact treatment in step S5 was dried and transferred to a rotary drum reactor for solid phase polycondensation at a solid phase polycondensation temperature of 75° C., a reaction pressure of 2.0 mbar, and a reaction time of 8 hours. The resulting biodegradable aliphatic polyester composition had an intrinsic viscosity of 1.66 dL / g.

[0188] The contents of the compounds represented by formula (I) and formula (II) in the biodegradable aliphatic polyester composition are shown in Table 4.

[0189] Example 5

[0190] Example 5 provides a biodegradable aliphatic polyester composition, the preparation method of which is as follows:

[0191] S1. 246 kg of succinic acid, 280 kg of 1,4-butanediol, and 1.1 kg of glycerol were physically mixed and transferred to a multi-stage stirred tank cascade reactor. The reaction mixture was esterified at 190°C and 0.8 bar for 3 hours. The resulting esterified product had an intrinsic viscosity of 0.12 dL / g.

[0192] S2. 67 kg of adipic acid, 65 kg of 1,4-butanediol, and 0.30 kg of tetrabutyl titanate were physically mixed and then transferred to a multi-stage stirred tank cascade reactor. The reaction mixture was esterified at 210°C and 0.8 bar for 5 hours, resulting in an esterified product with an intrinsic viscosity of 0.14 dL / g.

[0193] S3. The esterified products obtained in steps S1 and S2 were mixed to obtain a mixture of esterified products. The mixture was transferred to a stirred vertical reactor, 0.15 kg of tetrabutyl titanate was added, and the reaction mixture was pre-polycondensed at 245° C. and a pressure of 0.2 bar in the reactor for 160 minutes. The resulting pre-polyester had an intrinsic viscosity of 0.55 dL / g.

[0194] S4. The prepolymer obtained in step S3 was transferred to a horizontal reactor with stirring and polycondensed at 248°C and a pressure of 1.0 mbar for 110 minutes. The intrinsic viscosity of the polycondensation product was 1.74 dL / g.

[0195] S5. After slicing the polycondensation product obtained in step S4, the polyester particles were contacted with an aqueous tetrahydrofuran solution. The mass ratio of polyester particles to aqueous tetrahydrofuran solution was 1:10, the mass concentration of the aqueous tetrahydrofuran solution was 70%, the contact treatment temperature was 45°C, and the contact treatment time was 6 hours. The resulting product had an intrinsic viscosity of 1.70 dL / g.

[0196] S6. The product after the contact treatment in step S5 was dried and transferred to a rotary drum reactor for solid phase polycondensation at a solid phase polycondensation temperature of 80° C., a reaction pressure of 1.0 mbar, and a reaction time of 10 hours. The resulting biodegradable aliphatic polyester composition had an intrinsic viscosity of 1.75 dL / g.

[0197] The contents of the compounds represented by formula (I) and formula (II) in the biodegradable aliphatic polyester composition are shown in Table 4.

[0198] Example 6

[0199] Example 6 provides a biodegradable aliphatic polyester composition, the preparation method of which is as follows:

[0200] S1. 246 kg of succinic acid, 280 kg of 1,4-butanediol, and 0.92 kg of glycerol were physically mixed and transferred to a multi-stage stirred tank cascade reactor. The reaction mixture was esterified at 160°C and 1.2 bar for 2 hours. The resulting esterified product had an intrinsic viscosity of 0.06 dL / g.

[0201] S2. 16 kg of adipic acid, 14 kg of 1,4-butanediol, and 0.20 kg of tetrabutyl titanate were physically mixed and then transferred to a multi-stage stirred tank cascade reactor. The reaction mixture was esterified at 190°C and 1.1 bar for 3 hours, resulting in an esterified product with an intrinsic viscosity of 0.05 dL / g.

[0202] S3. The esterified products obtained in steps S1 and S2 were mixed to obtain a mixture of esterified products. The mixture was transferred to a stirred vertical reactor, 0.17 kg of tetrabutyl titanate was added, and the reaction mixture was pre-polycondensed at 248° C. and a pressure of 0.3 bar in the reactor for 120 minutes. The resulting pre-polyester had an intrinsic viscosity of 0.30 dL / g.

[0203] S4. The prepolymer obtained in step S3 was transferred to a horizontal reactor with stirring and polycondensed at 250°C and a pressure of 1.4 mbar for 60 minutes. The intrinsic viscosity of the polycondensation product was 1.18 dL / g.

[0204] S4 '. The final polymerization product in step S4 was passed through a static mixer, 1.1kg of hexamethylene diisocyanate was added, and the mixture was mixed at 200 ℃ for 8 minutes to obtain a chain-extended product having an intrinsic viscosity of 1.85 dL / g.

[0205] S5. After slicing the chain-extended product obtained in step S4', the polyester particles were contacted with an aqueous tetrahydrofuran solution. The mass ratio of polyester particles to aqueous tetrahydrofuran solution was 1:1, the mass concentration of the aqueous tetrahydrofuran solution was 70%, the contact treatment temperature was 35°C, and the contact treatment time was 20 hours. The resulting product had an intrinsic viscosity of 1.83 dL / g.

[0206] S6. The product after the contact treatment in step S5 was dried and transferred to a rotary drum reactor for solid phase polycondensation at a solid phase polycondensation temperature of 95° C., a reaction pressure of 2.0 mbar, and a reaction time of 12 hours. The resulting biodegradable aliphatic polyester composition had an intrinsic viscosity of 1.88 dL / g.

[0207] The contents of the compounds represented by formula (I) and formula (II) in the biodegradable aliphatic polyester composition are shown in Table 4.

[0208] Table 4 Content of cyclic esters in the biodegradable aliphatic polyester compositions of Examples

[0209]

[0210] Comparative Example 1

[0211] Comparative Example 1 provides a biodegradable aliphatic polyester composition, the preparation method of which differs from that of Example 1 in that:

[0212] Step S5 and step S6 are not included.

[0213] That is, the polycondensation product obtained in step S4 is a biodegradable aliphatic polyester composition.

[0214] The contents of the compounds represented by formula (I) and formula (II) in the biodegradable aliphatic polyester composition are shown in Table 5.

[0215] Comparative Example 2

[0216] Comparative Example 2 provides a biodegradable aliphatic polyester composition. Steps S1 to S4 of the preparation method are the same as those in Example 1, and step S5 is:

[0217] After the polycondensation product obtained in step S4 was sliced, the polyester particles were then subjected to a contact treatment process with an acetone aqueous solution. The mass ratio of polyester particles to acetone aqueous solution was 1:5, the mass concentration of the acetone aqueous solution was 70%, the contact treatment temperature was 50°C, and the contact treatment time was 14 hours. The resulting product had an intrinsic viscosity of 1.59 dL / g.

[0218] Step S6 is not included.

[0219] That is, the product after the contact treatment obtained in step S5 is the biodegradable aliphatic polyester composition.

[0220] The contents of the compounds represented by formula (I) and formula (II) in the biodegradable aliphatic polyester composition are shown in Table 5.

[0221] Comparative Example 3

[0222] Comparative Example 3 provides a biodegradable aliphatic polyester composition. Steps S1 to S4 of the preparation method are the same as those in Example 1, excluding step S5, and proceeding directly to step S6:

[0223] The polycondensation product obtained in step S4 was transferred to a rotary drum reactor for solid phase polycondensation at a solid phase polycondensation temperature of 75° C., a reaction pressure of 3.0 mbar, and a reaction time of 13 hours. The intrinsic viscosity of the obtained biodegradable aliphatic polyester composition was 1.67 dL / g.

[0224] The contents of the compound represented by formula (I) and the compound represented by formula (II) in the biodegradable aliphatic polyester composition are shown in Table 5.

[0225] Comparative Example 4

[0226] Comparative Example 4 provides a biodegradable aliphatic polyester composition, the preparation method of which is as follows:

[0227] S1. 187.9 kg of succinic acid, 220 kg of 1,4-butanediol, and 0.85 kg of glycerol were physically mixed and transferred to a multi-stage stirred tank cascade reactor. The reaction mixture was esterified at 230°C and 1.0 bar for 5 hours. The resulting esterified product had an intrinsic viscosity of 0.16 dL / g.

[0228] S2. 73.1 kg of adipic acid, 48 kg of 1,4-butanediol, and 0.22 kg of tetrabutyl titanate were physically mixed and then transferred to a multi-stage stirred tank cascade reactor. The reaction mixture was esterified at 200°C and 1.0 bar for 2 hours to obtain an esterified product with an intrinsic viscosity of 0.04 dL / g.

[0229] S3. The esterified products obtained in steps S1 and S2 were mixed to obtain a mixture of esterified products. The mixture was transferred to a stirred vertical reactor, 0.10 kg of tetrabutyl titanate was added, and the reaction mixture was pre-polycondensed at 220° C. and a pressure of 0.85 bar in the reactor for 80 minutes. The resulting pre-polyester had an intrinsic viscosity of 0.28 dL / g.

[0230] S4. The prepolymer obtained in step S3 was transferred to a horizontal reactor with stirring and polycondensed at 252°C and a pressure of 2.0 mbar for 180 minutes. The intrinsic viscosity of the polycondensation product was 1.53 dL / g.

[0231] S5. After slicing the polycondensation product obtained in step S4, the polyester particles were contacted with an aqueous tetrahydrofuran solution. The mass ratio of polyester particles to aqueous tetrahydrofuran solution was 1:4, the mass concentration of the aqueous tetrahydrofuran solution was 75%, the contact treatment temperature was 50°C, and the contact treatment time was 8 hours. The resulting product had an intrinsic viscosity of 1.50 dL / g.

[0232] S6. The product after the contact treatment in step S5 was dried and transferred to a rotary drum reactor for solid phase polycondensation at a solid phase polycondensation temperature of 75° C., a reaction pressure of 1.5 mbar, and a reaction time of 16 hours. The resulting biodegradable aliphatic polyester composition had an intrinsic viscosity of 1.54 dL / g.

[0233] The contents of the compounds represented by formula (I) and formula (II) in the biodegradable aliphatic polyester composition are shown in Table 5.

[0234] Comparative Example 5

[0235] Comparative Example 5 provides a biodegradable aliphatic polyester composition. Steps S1 to S4 of the preparation method are the same as those in Example 1, except that:

[0236] Step S5 involves slicing the polycondensation product obtained in step S4, and then contacting the polyester particles with a tetrahydrofuran aqueous solution. The mass ratio of polyester particles to tetrahydrofuran aqueous solution is 1:1, the mass concentration of the tetrahydrofuran aqueous solution is 70%, the contact treatment temperature is 25°C, and the contact treatment time is 3 hours. The resulting product has an intrinsic viscosity of 1.60 dL / g.

[0237] Step S6 involves drying the product after the contact treatment in step S5 and transferring it to a rotary drum reactor for solid-state polycondensation at a temperature of 75°C, a pressure of 2.0 mbar, and a reaction time of 14 hours. The resulting biodegradable aliphatic polyester has an intrinsic viscosity of 1.66 dL / g.

[0238] The contents of the compounds represented by formula (I) and formula (II) in the biodegradable aliphatic polyester composition are shown in Table 5.

[0239] Comparative Example 6

[0240] Comparative Example 6 provides a biodegradable aliphatic polyester composition. Steps S1 to S4 of the preparation method are the same as those in Example 1, except that:

[0241] Step S5 involves slicing the polycondensation product obtained in step S4, and then contacting the polyester particles with a tetrahydrofuran aqueous solution. The mass ratio of polyester particles to tetrahydrofuran 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 8 hours. The resulting product has an intrinsic viscosity of 1.59 dL / g.

[0242] Step S6 involves drying the product after the contact treatment in step S5 and transferring it to a rotary drum reactor for solid-state polycondensation at a temperature of 60° C., a pressure of 10.0 mbar, and a reaction time of 8 hours. The resulting biodegradable aliphatic polyester has an intrinsic viscosity of 1.60 dL / g.

[0243] The contents of the compounds represented by formula (I) and formula (II) in the biodegradable aliphatic polyester composition are shown in Table 5.

[0244] Comparative Example 7

[0245] Comparative Example 7 provides a biodegradable aliphatic polyester composition. Steps S1 to S4 of the preparation method are the same as those in Example 1, except that:

[0246] Step S5 is: after slicing the polycondensation product obtained in step S4, the polyester particles are subjected to a contact treatment process with a tetrahydrofuran aqueous solution. The contact treatment process is carried out twice. In the first contact treatment process, the mass ratio of the polyester particles to the tetrahydrofuran aqueous solution is 1:15, the mass concentration of the tetrahydrofuran aqueous solution is 75%, the contact treatment temperature is 60°C, and the contact treatment time is 30 hours. The polyester particles after the first contact treatment are then subjected to a second contact treatment process. In the second contact treatment process, the mass ratio of the polyester particles to the tetrahydrofuran aqueous solution is 1:12, the mass concentration of the tetrahydrofuran aqueous solution is 75%, the contact treatment temperature is 60°C, and the contact treatment time is 22 hours. The intrinsic viscosity of the product obtained from the polyester particles is 1.51 dL / g;

[0247] Step S6 is not included.

[0248] That is, the product obtained in step S5 is a biodegradable aliphatic polyester composition.

[0249] The contents of the compounds represented by formula (I) and formula (II) in the biodegradable aliphatic polyester composition are shown in Table 5.

[0250] Comparative Example 8

[0251] Comparative Example 8 provides a biodegradable aliphatic polyester composition, the preparation method of which is as follows:

[0252] S1. 187.9 kg of succinic acid, 205 kg of 1,4-butanediol, and 0.85 kg of glycerol were physically mixed and transferred to a multi-stage stirred tank cascade reactor. The reaction mixture was esterified at 205°C and 0.80 bar for 4 hours. The resulting esterified product had an intrinsic viscosity of 0.12 dL / g.

[0253] S3. The esterified product obtained in step S1 was transferred to a stirred vertical reactor, 0.10 kg of tetrabutyl titanate was added, and the reaction mixture was pre-polycondensed at 245 ° C and a pressure of 0.50 bar in the reactor for 110 minutes, and 0.22 kg of tetrabutyl titanate was added. The resulting prepolymer had an intrinsic viscosity of 0.43 dL / g;

[0254] S4. The prepolymer obtained in step S3 was transferred to a horizontal reactor with stirring and polycondensed at 250°C and a pressure of 1.5 mbar for 90 minutes. The intrinsic viscosity of the polycondensation product was 1.68 dL / g.

[0255] S5. After slicing the polycondensation product obtained in step S4, the polyester particles were contacted with an aqueous tetrahydrofuran solution. The mass ratio of polyester particles to aqueous tetrahydrofuran solution was 1:8, the mass concentration of the aqueous tetrahydrofuran solution was 70%, the contact treatment temperature was 50°C, and the contact treatment time was 12 hours. The resulting biodegradable aliphatic polyester had an intrinsic viscosity of 1.65 dL / g.

[0256] S6. The product after the contact treatment in step S5 was dried and transferred to a rotary drum reactor for solid phase polycondensation at a solid phase polycondensation temperature of 100° C., a reaction pressure of 3.0 mbar, and a reaction time of 10 hours. The resulting biodegradable aliphatic polyester composition had an intrinsic viscosity of 1.70 dL / g.

[0257] The contents of the compound represented by formula (I) and the compound represented by formula (II) in the biodegradable aliphatic polyester composition are shown in Table 5.

[0258] Table 5 Content of cyclic esters in the biodegradable aliphatic polyester compositions of the comparative examples

[0259]

[0260] Performance Testing

[0261] The biodegradable aliphatic polyester compositions prepared in the above examples and comparative examples were subjected to performance tests, including the precipitation resistance rating, static friction coefficient (COF), and haze tests. The test results are shown in Tables 6 and 7.

[0262] The TVOC content can be directly tested using the biodegradable aliphatic polyester composition pellets.

[0263] For precipitation resistance grade, static friction coefficient test and haze test, the thickness of the film is 15±2μm.

[0264] Table 6 Test results of the embodiment

[0265]

[0266]

[0267] Table 7 Test results of comparative examples

[0268]

[0269] The test results in Table 6 show that the biodegradable aliphatic polyester compositions prepared in various examples of this application have a cyclic ester content of ≤1100 ppm and a TVOC content of ≤157 ppm. Films prepared from these biodegradable aliphatic polyester compositions have a precipitation resistance rating of no higher than 4, a COF of ≥6.2, and a haze of ≤18%. Specifically, the TVOC content ranges from 42 to 157 ppm, the static friction coefficient remains within a range of 6.2 to 13.9, and the haze remains within a range of 10.3 to 18.0. The biodegradable aliphatic polyester compositions of the present invention exhibit excellent precipitation resistance, high adhesion, and low haze.

[0270] According to the test results of the comparative examples, it can be seen from Comparative Examples 1 to 3 that when neither the contact treatment nor the solid-phase polycondensation step is performed, the cyclic ester content of the obtained biodegradable aliphatic polyester composition is too high, resulting in poor precipitation resistance, low adhesion ability, and high haze.

[0271] Comparative Examples 4 to 8 show that reasonable control of the polymerization monomer ratio of the biodegradable aliphatic polyester composition, control of the intrinsic viscosity of the product in each step of the preparation process, and adoption of appropriate contact treatment conditions and solid-phase polycondensation conditions will all affect the cyclic ester content of the biodegradable aliphatic polyester composition, thereby affecting the material's precipitation resistance, adhesion ability, and haze.

[0272] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A biodegradable aliphatic polyester composition, characterized in that Includes the following components: i) a biodegradable aliphatic polyester, wherein the biodegradable aliphatic polyester comprises: Component A, the dicarboxylic acid compound, based on the total molar amount of component A, comprises: a1, 65 to 95 mol% of a derivative of succinic acid or its ester, or a mixture thereof, a2, 5 to 35 mol% of adipic acid or its ester derivatives, or mixtures thereof; Component B, 1,4-butanediol in an amount at least equimolar to that of component A; ii) Cyclic esters, including compounds represented by formula (I) and formula (II): Based on the total weight of the biodegradable aliphatic polyester composition, the total content of the cyclic esters of the structures represented by formula (I) and formula (II) is 538-1100 ppm; The TVOC content of the biodegradable aliphatic polyester composition is not higher than 157 ppm.

2. The biodegradable aliphatic polyester composition according to claim 1, characterized in that: The component A, based on the total molar amount of component A, comprises: a1, 72 to 82 mol% of a derivative of succinic acid or its ester, or a mixture thereof, a2, 18 to 28 mol% of adipic acid or its ester derivative, or a mixture thereof.

3. The biodegradable aliphatic polyester composition according to claim 1, characterized in that: Based on the total weight of the biodegradable aliphatic polyester composition, the total content of the cyclic esters of the structures represented by formula (I) and formula (II) is 538-850 ppm.

4. The biodegradable aliphatic polyester composition according to claim 1, characterized in that: The biodegradable aliphatic polyester composition further includes a chain extender. Based on the total weight of the biodegradable aliphatic polyester composition, the content of the chain extender is 0.05 to 2.0 wt.%.

5. The biodegradable aliphatic polyester composition according to claim 4, wherein the chain extender comprises one or more of the following components: c1, isocyanate, c2, peroxide, c3, epoxide, c4, oxazoline, oxazine, caprolactam and / or carbodiimide.

6. The biodegradable aliphatic polyester composition according to claim 1, characterized in that: The biodegradable aliphatic polyester composition further includes a cross-linking agent having at least three functional groups. The content of the cross-linking agent is 0 to 3 wt. % based on the total weight of the biodegradable aliphatic polyester composition.

7. The biodegradable aliphatic polyester composition according to claim 6, characterized in that: The cross-linking agent having at least three functional groups is selected from at least one of trimethylolpropane, pentaerythritol and glycerol.

8. The method for preparing the biodegradable aliphatic polyester composition according to any one of claims 1 to 7, characterized in that: The steps include: S1. Component a1 is mixed with a portion of component B, with or without the addition of a catalyst to obtain slurry A, and slurry A is subjected to an esterification or transesterification reaction until the intrinsic viscosity of the esterified product is 0.05 to 0.12 dL / g as measured in accordance with GB / T 17931-1999; S2. Component a2 is mixed with the remaining component B, with or without the addition of a catalyst to obtain a slurry B, and the slurry B is subjected to an esterification or transesterification reaction until the intrinsic viscosity of the esterified product is 0.05 to 0.14 dL / g as measured in accordance with GB / T 17931-1999; S3. The esterification products obtained in steps S1 and S2 are mixed to obtain a mixture of esterification products, and the mixture is pre-condensed until the intrinsic viscosity of the prepolymer product is 0.30 to 0.55 dL / g as measured according to GB / T 17931-1999; S4. The prepolymer obtained in step S3 is polycondensed until the intrinsic viscosity of the polycondensation product is 1.18 to 1.85 dL / g as measured in accordance with GB / T 17931-1999; S5. The polycondensation product obtained in step S4 is sliced ​​to obtain polyester particles, which are contacted with an organic solvent or an aqueous solution thereof; S6. The product after the contact treatment in step S5 is dried and subjected to solid phase polycondensation to obtain the biodegradable aliphatic polyester composition; In step S5, the temperature of the contact treatment is 35-50° C., the time of the contact treatment is 5-20 hours, and the mass ratio of the polyester particles to the organic solvent or its aqueous solution is 1:(1-10); In step S6, the solid phase polycondensation temperature is 65 to 95° C., and the solid phase polycondensation pressure is 0.3 to 6 mbar.

9. The preparation method according to claim 8, characterized in that: After step S4 and before step S5, step S4' may be further performed; the operation of step S4' is: mixing the polycondensation product obtained in step S4 with a chain extender to perform a chain extension reaction, wherein the chain extension product obtained by the chain extension reaction has an intrinsic viscosity of 1.30 to 1.92 dL / g as measured according to GB / T 17931-1999.

10. The preparation method according to claim 8, characterized in that: At least one of the following (1) to (3): (1) In step S3, the intrinsic viscosity of the prepolymer product measured according to GB / T 17931-1999 is 0.35 to 0.48 dL / g; (2) In step S5, the mass concentration of the organic solvent aqueous solution is 35-90 wt%; (3) In step S6, the solid phase polycondensation time is 8 to 16 hours.

11. A biodegradable mixture, characterized in that The composition comprises the following components in weight percentage: I) 5 to 95 wt.% of the biodegradable aliphatic polyester composition according to any one of claims 1 to 7, based on the total weight of components I) and II), II) 5 to 95 wt.% of at least one or more components selected from aliphatic-aromatic copolyesters, aliphatic polyesters, starch, cellulose, polyhydroxyalkanoates, polyglycolic acid and polylactic acid, based on the total weight of components I) and II), III) 0 to 35 wt.% of talc, based on the total weight of components I) to IV), IV) 0 to 20 wt.% of calcium carbonate, based on the total weight of components I) to IV).

12. Use of the biodegradable aliphatic polyester composition according to any one of claims 1 to 7 in the preparation of food packaging films and food packaging bags.

13. The use according to claim 12, characterized in that The thickness of the food packaging film is 8 μm to 50 μm ， and include at least one of the following (1) to (3): (1) The food packaging film has a precipitation resistance rating of no higher than 4; (2) The static friction coefficient of the food packaging film is ≥6.2; (3) The haze of the food packaging film is ≤18%.

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