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 and application thereof, and belongs to the technical field of degradable materials. The biodegradable aliphatic polyester composition comprises a biodegradable aliphatic polyester and a cyclic ester compound. The biodegradable aliphatic polyester comprises: component A, a dicarboxylic acid compound; and component B, at least 1,4-butanediol with the same molar amount as component A. The cyclic ester compound comprises compounds shown in formula (I) and formula (II). The content of the cyclic ester compound is 0.6-1.1 wt.% based on the total weight of the biodegradable aliphatic polyester composition, and the mass ratio of the compounds shown in formula (I) and formula (II) is 2-6:1. By controlling the polymerization monomers of the biodegradable aliphatic polyester composition and reasonably regulating the proportion of the compounds shown in formula (I) and formula (II), the application greatly reduces the precipitation of the cyclic ester compound and effectively improves the heat sealing strength.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of degradable materials, and particularly relates to a biodegradable aliphatic polyester composition, a preparation method and application thereof. BACKGROUND

[0002] Polybutylene succinate-adipate (PBSA) is prepared by esterification and polycondensation reaction of succinic acid, adipic acid and 1,4-butanediol three monomers, and the molar ratio of succinic acid and adipic acid in the molecular structure of the product will significantly affect the product performance. When the content of succinic acid is high, the product performance is biased towards polybutylene succinate (PBS), which has a high melting point, crystallinity and heat resistance, but it is difficult to meet the requirements of home composting; when the content of adipic acid is high, the product performance is biased towards polybutylene adipate (PBA), which has good home composting effect, but has a low melting point and poor heat resistance, and is difficult to meet the practical requirements. Commercial PBSA products generally consider various performances by using molecular structure design method according to the terminal application requirements.

[0003] PBSA has good processing performance and can be processed on ordinary molding equipment by extrusion, injection molding, blow molding, spinning, suction molding, lamination, foaming and the like. The product is widely used, and the main application fields include: packaging field, such as preservative film and express bag; daily necessities field, such as disposable tableware; agricultural field, such as biodegradable mulch film. For the packaging field and daily necessities field, the materials are directly in contact with the human body, so the food contact performance of the materials is particularly important.

[0004] The EU food contact regulation EU 10-2011 requires that the total migration of food contact materials during the food contact test is less than or equal to 10 mg / dm 2 During the synthesis of biodegradable polyester, monomer diacid and diol are prone to esterification to generate cyclic ester or polyester oligomer and other small molecular compounds. The cyclic ester or polyester oligomer is prone to migrate and precipitate during use. In addition, the residues of monomers, the transfer of impurities in monomers, the degradation of polyester and other factors will further affect the food contact performance of the polyester material.

[0005] In addition, when aliphatic polyester is used as a base resin to prepare degradable express bags, the production workshop layout is limited, and the production efficiency is also considered. Under normal circumstances, the manufacturer will first produce packaging film for preparing express bags, and then concentrate on printing and bag making after the film material accumulates to a certain amount. The film material stored for a period of time is prone to have low heat sealing strength during the bag making heat sealing process, resulting in quality problems such as "blown edge" of the express bag.

[0006] Japanese patent JP2002003606 discloses a method of cleaning aliphatic polyester with one or more solvents selected from aliphatic ketones, cyclic aliphatic ethers, aliphatic monoesters, in order to reduce the oligomers contained in the aliphatic polyester resin. The method is complicated and the organic solvents used remain in the resin, which is difficult to remove, and the organic solvents used further affect the food contact properties of the material.

[0007] Therefore, it is necessary to develop a biodegradable aliphatic polyester material with small cyclic ester migration amount and high heat sealing strength. SUMMARY

[0008] The present application aims to overcome the defects of high migration amount and low heat sealing strength of the biodegradable aliphatic polyester in the prior art, and to provide a biodegradable aliphatic polyester composition with small total migration amount and high heat sealing strength.

[0009] Another object of the present application is to provide a preparation method of the biodegradable aliphatic polyester composition.

[0010] Another object of the present application is to provide an application of the biodegradable aliphatic polyester composition.

[0011] To achieve the above objects, the present application adopts the following technical solutions:

[0012] A biodegradable aliphatic polyester composition comprises:

[0013] Component i), a biodegradable aliphatic polyester, wherein the biodegradable aliphatic polyester comprises:

[0014] Component A, a dicarboxylic acid compound, comprising:

[0015] a1, 68-82 mol% of succinic acid,

[0016] a2, 18-32 mol% of adipic acid;

[0017] Component B, at least 1,4-butanediol in an equimolar amount of component A;

[0018] Component ii), a cyclic ester compound represented by formula (I) and formula (II),

[0019]

[0020] wherein n and m in formula (I) and formula (II) are positive integers in 1-8;

[0021] The content of the cyclic ester compound is 0.6-1.1 wt.% based on the total weight of the biodegradable aliphatic polyester composition, and the mass ratio η of the compounds represented by formula (I) and formula (II) is 2-6:1.

[0022] The content of the cyclic ester compound in the biodegradable aliphatic polyester composition according to the present application can be measured by the following method:

[0023] Weigh 25 g of the biodegradable aliphatic polyester composition, and add it into a Soxhlet extractor to extract with ethanol as the solvent. The temperature of the condensate water is controlled to ensure that the temperature of the ethanol solution in the Soxhlet extractor is 45-55°C. After continuous extraction for 48 hours, the extract is dried. 50 ml of ethanol is added to the dried residue, stirred, and then filtered. The filter cake is washed with ethanol until there is no 1,4-butanediol in the washing liquid (whether there is 1,4-butanediol in the washing liquid is determined by gas chromatography). The filter cake is dried to constant weight, and the mass of the obtained filter cake is the weight of the cyclic ester compound in 25 g of the biodegradable aliphatic polyester composition.

[0024] The mass ratio of the compounds represented by formula (I) and formula (II) in the cyclic ester compound can be measured by the following method:

[0025] 20 mg of the above dried filter cake is dissolved in deuterated chloroform, and then a Bruker AV 500 nuclear magnetic resonance spectrometer is used to measure the 1 H-NMR, the chloroform solvent peak is calibrated at about 7.26 ppm.

[0026] According to the literature, the chemical shifts of the four hydrogen atoms of the two CH2 units of succinic acid adjacent to the carbonyl group in the compound represented by formula (I) appear at about 2.63 ppm; the chemical shifts of the four hydrogen atoms of the two CH2 units of adipic acid adjacent to the carbonyl group in the compound represented by formula (II) appear at about 2.33 ppm. Thus, the molar ratio of the repeating units of the compound represented by formula (I) and the compound represented by formula (II) in the biodegradable aliphatic polyester mixture can be represented by the integral areas (I SA and I AA ) of the two peaks at 2.63 ppm and 2.33 ppm:

[0027] Relative to the total molar amount of the repeating units of the compounds represented by formula (I) and formula (II),

[0028] The molar content m I of the repeating units of the compound represented by formula (I) is: SA = I SA / (I AA + I AA ) x 100%,

[0029] The molar content m II of the repeating units of the compound represented by formula (II) is: AA = I SA / (I AA + I AA ) x 100%.

[0030] The mass ratio η of the compounds represented by formula (I) and formula (II) in the biodegradable aliphatic polyester mixture can be calculated in combination with the molar mass of the repeating units of the compounds represented by formula (I) and formula (II), and the specific calculation method is as follows:

[0031] η = (m I × 172.2) / (m II × 200.2) × 100%.

[0032] The molar mass of the repeating units of the compound represented by formula (I) is 172.2 g / mol,

[0033] The molar mass of the repeating units of the compound represented by formula (II) is 200.2 g / mol.

[0034] The PH value of succinic acid is about 2.7, and the PH value of adipic acid is between 4.4 and 5.4. For esterification reaction, under the same reaction conditions, the lower the PH value of the system, the more conducive to the esterification reaction, so in the synthesis of PBSA, succinic acid is more prone to esterification reaction than adipic acid, and accordingly, the cyclic ester represented by formula (I) is more prone to form. In terms of molecular structure, under the condition that the number of repeating units is the same, the molecular weight of the cyclic ester represented by formula (I) is smaller than that of the cyclic ester represented by formula (II), and it is more prone to migrate and precipitate. In terms of product properties, the cyclic ester represented by formula (I) is an oil, while the cyclic ester represented by formula (II) is a crystal, and the precipitation of oil on the surface of the film is more prone to cause the failure of the heat sealing adhesion performance of the film.

[0035] The present application greatly reduces the precipitation of cyclic ester by regulating the mass ratio of the compounds represented by formula (I) and formula (II), effectively solving the problem of low heat sealing strength after storage of the film material.

[0036] Preferably, in the component A, based on the total molar amount of the component A, it comprises:

[0037] a1, 72-78 mol% of succinic acid,

[0038] a2, 22-28 mol% of adipic acid.

[0039] Preferably, the mass ratio of the compounds represented by formula (I) and formula (II) is 3.2-4.8:1.

[0040] Preferably, the biodegradable aliphatic polyester composition can further comprise a crosslinking agent having at least three functional groups. The weight content of the crosslinking agent having at least three functional groups is 0-3 wt.%, preferably 0.01-2 wt.%, more preferably 0.05-1 wt.%, and particularly preferably 0.3-0.4 wt.%, based on the total weight of the biodegradable aliphatic polyester composition.

[0041] The crosslinking agent having at least three functional groups is particularly preferably a compound having 3-6 hydroxyl groups, and optionally, the crosslinking agent is at least one of tartaric acid, citric acid, malic acid, trimethylolpropane, trimethylolethane, pentaerythritol, polyether triol, glycerol, 1,3,5-benzene tricarboxylic acid, 1,2,4-benzene tricarboxylic acid, 1,2,4-benzene tricarboxylic anhydride, 1,2,4,5-benzene tetracarboxylic acid, pyromellitic dianhydride. Preferably, the polyols such as trimethylolpropane, pentaerythritol and glycerol, and particularly preferably glycerol.

[0042] Preferably, the biodegradable aliphatic polyester composition can further comprise a chain extender (component C).

[0043] Preferably, the chain extender comprises one or several of the following components:

[0044] c1, isocyanate,

[0045] c2, peroxide,

[0046] c3, epoxide,

[0047] c4, oxazoline, oxazine, caprolactam and / or carbodiimide.

[0048] Preferably, the biodegradable aliphatic polyester composition has a total migration amount of less than or equal to 10 mg / dm 2 , preferably less than or equal to 7 mg / dm 2 , according to the OM6 test condition of the EU 10-2011 standard with 10% ethanol as the simulation liquid.

[0049] The present application also protects a preparation method of the above-mentioned biodegradable aliphatic polyester composition, comprising the following steps:

[0050] S1-i. Mixing component a1 with part of component B, adding a basic compound to adjust the pH value of the system to 3.2-5.8, and mixing with or without a catalyst to obtain slurry A, and performing esterification or transesterification reaction on slurry A until the viscosity number of the esterification product is 5-15 ml / g, as determined according to DIN 53728-3-1985, to obtain a first esterification product;

[0051] S1 -ii. Mixing component a2 with the remaining component B, adding a basic compound to adjust the pH of the system to 5.2 to 5.8, adding or not adding a catalyst and mixing to obtain a slurry B, which is subjected to an esterification or transesterification reaction until the esterification product has a viscosity number of 7 to 16 ml / g, measured according to DIN 53728-3-1985, to obtain a second esterification product;

[0052] S2. Mixing the first esterification product and the second esterification product obtained in steps S1 -i and S1 -ii to obtain a mixture of esterification products, which is prepolymerized until the prepolymer thereof has a viscosity number of 24 to 55 ml / g, measured according to DIN 53728-3-1985;

[0053] S3. Poiymerizing the prepolymer obtained in step S2 until the poiymerized product thereof has a viscosity number of 143 to 226 ml / g, measured according to DIN 53728-3-1985, to obtain the biodegradable aliphatic polyester composition.

[0054] Steps S1 -i and S1 -ii can be carried out simultaneously or in reverse order, without any sequence.

[0055] Preferably, in step S1 -i, the ratio of component a1 to component B in slurry A is 1.0 mole equivalent of component a1 : 1.0 to 1.8 mole equivalents, preferably 1.05 to 1.60 mole equivalents, particularly preferably 1.15 to 1.50 mole equivalents, of component B.

[0056] Preferably, in step S1 -ii, the ratio of component a2 to component B in slurry B is 1.0 mole equivalent of component a2 : 1.1 to 2.2 mole equivalents, preferably 1.2 to 1.8 mole equivalents, particularly preferably 1.3 to 1.6 mole equivalents, of component B.

[0057] Preferably, in step S1, 0 to 3 wt.%, preferably 0.01 to 2 wt.%, more preferably 0.05 to 1 wt.%, particularly preferably 0.3 to 0.4 wt.%, of a crosslinking agent having at least three functional groups, based on the total weight of the biodegradable aliphatic polyester composition, can also be included.

[0058] Preferably, in step S1, the entire amount or a part of the catalyst is metered in. The catalysts used generally include zinc, aluminum, and in particular titanium compounds. Titanium catalysts such as tetrabutyl titanate or tetraisooctyl titanate have the further advantage that the residual amount of catalyst remaining in the product or downstream products is less toxic. This is particularly important in biodegradable polyesters, which, for example, directly enter the environment in the form of compost bags or mulch films. The catalyst is preferably a titanium catalyst.

[0059] Preferably, the titanium catalyst is added in an amount of 40 to 180 ppm (as Ti element content) based on the total weight of the biodegradable aliphatic polyester composition.

[0060] Preferably, in step S1-i, during the preparation of the first esterification product, the esterification or transesterification reaction is carried out at a temperature of 150 to 210 °C, preferably 150 to 200 °C, and at a pressure of 0.7 to 1.1 bar, preferably 0.85 to 1.0 bar. Step S1 can be carried out in one mixing device and typically takes 3 to 5 hours. An esterification product having a viscosity number of 5 to 15 ml / g, determined according to DIN 53728-3-1985, can be produced.

[0061] Preferably, in step S1-ii, during the preparation of the second esterification product, the esterification or transesterification reaction is carried out at a temperature of 185 to 225 °C, preferably 190 to 215 °C, and at a pressure of 0.8 to 1.1 bar, preferably 0.9 to 1.0 bar. Step S1 can be carried out in one mixing device and typically takes 2 to 4 hours. An esterification product having a viscosity number of 7 to 16 ml / g, determined according to DIN 53728-3-1985, can be produced.

[0062] The excess diol component is typically removed by distillation and returned to the loop, e.g. after distillative purification.

[0063] In step S1, the pH of the system is adjusted by adding a basic compound, which leads to a partial neutralization of succinic acid and adipic acid and effectively reduces the esterification rate of succinic acid and adipic acid with 1,4-butanediol, thereby effectively reducing the content of the cyclic esterification products according to formula (I) and (II). In step S1-i, the pH of the system is preferably adjusted to 4.2 to 5.4.

[0064] Preferably, the basic compound is a carbonate and / or a hydroxide.

[0065] Optionally, the carbonate is at least one of sodium carbonate, sodium bicarbonate, potassium carbonate, and potassium bicarbonate. Preferably, the carbonate is sodium carbonate.

[0066] Optionally, the hydroxide is sodium hydroxide and / or potassium hydroxide. Preferably, the hydroxide is sodium hydroxide.

[0067] Preferably, in step S2, the mixture of esterification products, together with the remaining catalyst, is fed to a reactor suitable for the precondensation reaction, and the precondensation reaction is carried out at a temperature of 225 to 260 °C, preferably 235 to 248 °C, at a pressure of 0.2 to 0.7 bar, preferably 0.32 to 0.55 bar, and for a reaction time of 75 to 180 minutes, to produce a prepolymer having an intrinsic viscosity of 24 to 55 ml / g, as determined according to DIN 53728-3-1985. In a preferred embodiment, the intrinsic viscosity of the prepolymer is controlled to be in the range of 32 to 46 ml / g.

[0068] Preferably, in step S3, a catalyst deactivator is mixed with the prepolymer, if appropriate. Useful deactivators are, in particular, phosphorus compounds: either organic phosphites such as phosphorous acid, or phosphoric acid. It is noted that the deactivator can be added if a highly active titanium catalyst is used. The deactivator can be added in an amount of 0.001 to 0.1 wt.%, preferably 0.01 to 0.05 wt.%, based on the amount of polymer after step S3. The Ti / P ratio (mol / mol) is preferably set to 1.1 to 1.5:1, particularly preferably 1.1 to 1.3:1.

[0069] If appropriate, a color stabilizer for the condensation process is mixed with the prepolymer in step S3. Useful color stabilizers are, in particular, phosphorus compounds. Examples are phosphoric acid, phosphorous acid, triphenyl phosphite, triphenyl phosphate, sodium hypophosphite and sodium phosphite. The phosphorus compounds can also be used in mixtures. The use of color stabilizers generally leads to a reduction in the condensation rate. Triphenyl phosphate is a particularly suitable color stabilizer, as it has no adverse effect on the condensation rate.

[0070] The color stabilizer can be added in an amount of 0.001 to 1.5 wt.%, preferably 0.01 to 1.0 wt.%, based on the total weight of the biodegradable aliphatic polyester composition. 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.

[0071] If appropriate, an activator for the condensation process is mixed with the prepolymer in step S3. Useful activators are, in particular, phosphorus compounds. Examples are disodium hydrogen phosphate, calcium hypophosphite, calcium phosphite, calcium phosphate, sodium hypophosphite, sodium phosphite, triphenyl phosphite, triphenyl phosphate, trimethyl phosphate, triethyl phosphate, tripropyl phosphate, tributyl phosphate. The phosphorus compounds can also be used in mixtures. Particularly suitable activators are disodium hydrogen phosphate and sodium phosphite.

[0072] The activator is preferably added in an amount of 0.001 to 1.5 wt.%, based on the total weight of the biodegradable aliphatic polyester composition, preferably in an amount of 0.01 to 1.0 wt.%. The Ti / P ratio (mol / mol) is preferably set to 1.0 to 1.5:1, particularly preferably to 1.1 to 1.3:1.

[0073] The combination of a color stabilizer with an activator is of particular interest, one example being triphenyl phosphate / dibasic sodium phosphate.

[0074] The polycondensation process described in step S3 takes place in a finisher. It has proven particularly suitable to use a reactor such as a rotating disc reactor or a cage reactor, the reaction temperature being set typically to 235 to 260°C, preferably to 240 to 255°C, and the pressure being set typically to 0.2 to 5 mbar, preferably to 0.5 to 3 mbar. A typical reaction time is a reaction time of 45 to 110 minutes, preferably of 60 to 90 minutes, and a polycondensation product having a viscosity number of 143 to 226 ml / g, determined according to DIN 53728-3-1985, is produced.

[0075] If necessary, step S4, chain extension reaction, can also be carried out. The polycondensation product described in step S3 is added to an extruder, or to a continuous kneader (List reactor), or to a static mixer, together with a chain extender (component C). The static mixer can use SMR, SMX or SMXL components, or combinations 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. The chain extension reaction according to the application is preferably carried out in an extruder, and after chain extension, the chain extension product obtained finally has a viscosity number of 167 to 242 ml / g, determined according to DIN 53728-3-1985.

[0076] Preferably, the chain extender (component C) comprises one or several of the following components:

[0077] c1, isocyanate,

[0078] c2, peroxide,

[0079] c3, epoxide,

[0080] c4, oxazoline, oxazine, caprolactam and / or carbodiimide.

[0081] The isocyanate used in the present application can be an aromatic diisocyanate or an aliphatic diisocyanate, 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.

[0082] Among them, it is particularly preferred to use diphenylmethane 2,2'-diisocyanate, 2,4'-diisocyanate or 4,4'-diisocyanate.

[0083] The isocyanate that can also be used includes tri(4-isocyanatophenyl)methane with three rings. This polynuclear aromatic diisocyanate can be formed, for example, in the process of producing diisocyanates with one or two rings.

[0084] For the present application, the aliphatic diisocyanate can be any straight-chain or branched alkylene diisocyanate or cycloalkylene diisocyanate containing 2 to 20 carbon atoms, preferably 3 to 12 carbon atoms, for example, hexamethylene diisocyanate, pentamethylene diisocyanate, isophorone diisocyanate and the diisocyanate of methylene bis(4-isocyanatocyclohexane). Particularly preferred is hexamethylene diisocyanate.

[0085] The amount of isocyanate used can be 0.05 to 2% by weight, particularly preferably 0.1 to 1.5% by weight, based on the total weight of the biodegradable aliphatic polyester composition.

[0086] The peroxide of the present application can be one or a mixture of several of the following compounds:

[0087] Benzoyl peroxide, 1,1-di(tert-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1-di(tert-butylperoxy)methylcyclo-dodecane, n-butyl 4,4-di(tert-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-butyl cumyl peroxide.

[0088] The amount of peroxide used can be 0.05 to 2% by weight, particularly preferably 0.2 to 1% by weight, based on the total weight of the biodegradable aliphatic polyester composition.

[0089] The epoxide of the present application can 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 polytetramethylene glycol diglycidyl ether, a copolymer containing an epoxy group based on styrene, acrylate and / or methacrylate.

[0090] The amount of the epoxide can be 0.05 to 2% by weight, preferably 0.2 to 1% by weight, based on the total weight of the biodegradable aliphatic polyester composition.

[0091] The dioxazoline of the present application can preferably be 2,2'-bis(2-oxazoline), bis(2-oxazolinyl)methane, 1,2-bis(2-oxazolinyl)ethane, 1,3-bis(2-oxazolinyl)propane, or 1,4-bis(2-oxazolinyl)butane, particularly 1,4-bis(2-oxazolinyl)benzene, 1,2-bis(2-oxazolinyl)benzene, or 1,3-bis(2-oxazolinyl)benzene.

[0092] The dioxazine can preferably be 2,2'-bis(2-dioxazine), bis(2-dioxazinyl)methane, 1,2-bis(2-dioxazinyl)ethane, 1,3-bis(2-dioxazinyl)propane, or 1,4-bis(2-dioxazinyl)butane, particularly 1,4-bis(2-dioxazinyl)benzene, 1,2-bis(2-dioxazinyl)benzene, or 1,3-bis(2-dioxazinyl)benzene.

[0093] The carbodiimide can 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.

[0094] The amount of the oxazoline, the oxazine, the caprolactam, and / or the carbodiimide can be 0.05 to 2% by weight, preferably 0.2 to 1% by weight, based on the total weight of the biodegradable aliphatic polyester composition.

[0095] The chain extension reaction is carried out at a reaction temperature of 170 to 240°C, preferably 180 to 220°C, under superatmospheric or atmospheric pressure, depending on the system used. A residence time of 2 to 15 minutes, preferably 4 to 10 minutes, is used.

[0096] The present application also protects the use of the above-mentioned biodegradable aliphatic polyester composition for the preparation of a preservative film.

[0097] The present application also protects a biodegradable mixture comprising the following components in weight percent:

[0098] i) 5 to 95 wt.% of the biodegradable aliphatic polyester composition, based on the total weight of components i) and ii),

[0099] ii) 5 to 95 wt.% of at least one or more components selected from the group consisting of aliphatic-aromatic copolyesters, aliphatic polyesters, starch, cellulose, polyhydroxyalkanoates, polyglycolic acid and polylactic acid, based on the total weight of components i) and ii),

[0100] iii) 0 to 35 wt.% of talc, based on the total weight of components i) to iv),

[0101] iv) 0 to 20 wt.% of calcium carbonate, based on the total weight of components i) to iv).

[0102] The present application also protects the use of the above-mentioned biodegradable mixture for the preparation of a heat-sealable film.

[0103] In particular, the heat-sealable film can be an express delivery bag.

[0104] The express delivery bag prepared from the biodegradable polyester mixture according to the present application has a heat-seal strength of greater than or equal to 10 N / 15 mm, measured according to the standard QB / T 2358-1998, after being stored for 10 days at 25 ± 5°C and 50% ± 10% humidity, effectively solving the problem of poor heat-seal strength and easy "blown edge" after storage of the film material.

[0105] The biodegradable aliphatic polyester composition and the biodegradable mixture mentioned in the present application are both biodegradable.

[0106] For the purposes of the present application, a substance or mixture of substances is considered to be "biodegradable" if it exhibits a degree of biodegradation of at least 90%, as defined in DIN EN 13432.

[0107] According to DIN EN 13432, during the composting process, CO2-free air is passed through the composting heap and the compost is subjected to a specific temperature process. Here, the biodegradability is defined as the percentage degree of biodegradation expressed as the ratio of the net amount of CO2 released by the sample (minus the amount of CO2 released by the compost without sample) to the maximum amount of CO2 that can be released by the sample (calculated from the carbon content in the sample). Biodegradable polyesters and biodegradable polyester mixtures usually show clear signs of degradation, such as fungal growth, cracking and perforation, only after a few days of composting.

[0108] Other methods for determining biodegradability are described, for example, in ASTM D5338 and ASTM D6400.

[0109] Compared to the prior art, the present application has the following advantages:

[0110] The present application develops a biodegradable aliphatic polyester composition, by optimizing the composition of the biodegradable aliphatic polyester composition, and reasonably controlling the total amount and ratio of the cyclic ester compounds represented by formula (I) and formula (II) in the biodegradable aliphatic polyester composition, the heat sealing strength of the film material is effectively improved, and the total migration amount of the film material is reduced. DETAILED DESCRIPTION

[0111] For the purpose of better illustrating the object, technical scheme and advantages of the present application, the present application will be further described in combination with specific examples, but the examples do not limit the present application in any form.

[0112] The raw materials in the examples and comparative examples can be obtained by market purchase;

[0113] The evaluation method of the total migration amount of the biodegradable aliphatic polyester composition in the present application is as follows:

[0114] The evaluation method of the total migration amount of the biodegradable aliphatic polyester composition refers to the EU food contact standard EU10-2011, and according to the OM6 test condition, 10% ethanol is selected as the simulation material, the biodegradable aliphatic polyester composition is made into a sample with a thickness of 50±5μm, the total migration amount test is carried out, 10% ethanol is selected as the simulation material for food contact test, and the total migration amount of the biodegradable aliphatic polyester composition is obtained, and each sample is tested in parallel with double samples, and the average value is taken.

[0115] The evaluation method of the heat sealing strength of the express packaging film in the present application is as follows:

[0116] The heat sealing strength of the film material is tested according to the QB / T2358-1998 standard, the film material thickness is 25±2μm, and the film material width is 15mm.

[0117] The reagents, methods, and equipment employed in the present application are those conventional in the art unless otherwise indicated.

[0118] Example 1

[0119] Example 1 provides a biodegradable aliphatic polyester composition, which is prepared as follows:

[0120] S1-i. 195 kg of succinic acid, 210 kg of 1,4-butanediol and 1.2 kg of glycerol are mixed, a 1,4-butanediol solution containing sodium hydroxide is added, and the pH value of the system is adjusted to 5.4 to obtain slurry A. The slurry A is transferred to a reactor with stirring. The reaction mixture is esterified at a temperature of 150°C and a pressure of 1.0 bar for 3 hours. The viscosity number of the first esterification product obtained is 5 ml / g.

[0121] S1-ii. 68 kg of adipic acid, 65 kg of 1,4-butanediol and 0.21 kg of tetrabutyl titanate are physically mixed, a 1,4-butanediol solution containing sodium hydroxide is added, and the pH value of the system is adjusted to 5.6 to obtain slurry B. The slurry B is transferred to a reactor with stirring. The reaction mixture is esterified at a temperature of 215°C and a pressure of 0.9 bar for 4 hours. The viscosity number of the second esterification product obtained is 16 ml / g.

[0122] S2. The first esterification product and the second esterification product obtained in steps S1-i and S1-ii are mixed, and the mixture is transferred to a vertical reactor with stirring. 0.16 kg of tetrabutyl titanate is added. The reaction mixture is pre-polymerized at a temperature of 248°C and a reactor pressure of 0.32 bar for 120 minutes. The viscosity number of the pre-polymer obtained is 46 ml / g.

[0123] S3. The pre-polymer obtained in step S2 is transferred to a horizontal reactor with stirring. The reaction mixture is polycondensed at a temperature of 245°C and a pressure of 1.3 mbar for 90 minutes. The viscosity number of the biodegradable aliphatic polyester composition obtained is 188 ml / g.

[0124] The total content and mass ratio η of the compounds represented by formula (I) and formula (II) in the biodegradable aliphatic polyester composition are shown in Table 1.

[0125] Example 2

[0126] Example 2 provides a biodegradable aliphatic polyester composition, which is prepared as follows:

[0127] S1-i. 195 kg of succinic acid, 215 kg of 1,4-butanediol and 1.5 kg of glycerol were mixed, a 1,4-butanediol solution containing sodium carbonate was added, and the pH value of the system was adjusted to 4.2 to obtain slurry A. The slurry A was transferred to a reactor with stirring. The reaction mixture was esterified at a temperature of 210 °C and a pressure of 0.70 bar for 3 hours. The viscosity number of the obtained first esterification product was 15 ml / g;

[0128] S1-ii. 94 kg of adipic acid, 93 kg of 1,4-butanediol and 0.23 kg of tetrabutyl titanate were physically mixed, a 1,4-butanediol solution containing sodium carbonate was added, and the pH value of the system was adjusted to 5.5 to obtain slurry B. The slurry B was transferred to a reactor with stirring. The reaction mixture was esterified at a temperature of 225 °C and a pressure of 0.8 bar for 3 hours. The viscosity number of the obtained second esterification product was 14 ml / g;

[0129] S2. The first esterification product and the second esterification product obtained in steps S1-i and S1-ii were mixed, and the mixture was transferred to a vertical reactor with stirring. 0.19 kg of tetrabutyl titanate was added. The reaction mixture was pre-polycondensation reacted at 250 °C and a reactor pressure of 0.25 bar for 180 minutes. The viscosity number of the obtained pre-polymer was 55 ml / g;

[0130] S3. The pre-polymer obtained in step S2 was transferred to a horizontal reactor with stirring, and was polycondensation reacted at 240 °C and a pressure of 2.0 mbar for 100 minutes. The viscosity number of the obtained biodegradable aliphatic polyester composition was 187 ml / g.

[0131] The total content and mass ratio η of the compounds represented by formula (I) and formula (II) in the biodegradable aliphatic polyester composition are shown in Table 1.

[0132] Example 3

[0133] Example 3 provides a biodegradable aliphatic polyester composition, which is prepared by the following method:

[0134] S1-i. 195 kg of succinic acid, 215 kg of 1,4-butanediol and 1.5 kg of glycerol were mixed, a 1,4-butanediol solution containing sodium carbonate was added, and the pH value of the system was adjusted to 4.2 to obtain slurry A. The slurry A was transferred to a reactor with stirring. The reaction mixture was esterified at a temperature of 210 °C and a pressure of 0.70 bar for 3 hours. The viscosity number of the obtained first esterification product was 15 ml / g;

[0135] S1-ii. 76 kg of adipic acid, 70 kg of 1,4-butanediol and 0.24 kg of tetrabutyl titanate were physically mixed, a 1,4-butanediol solution containing sodium hydroxide was added, the pH value of the system was adjusted to 5.8 to obtain slurry B, and slurry B was transferred to a reactor with stirring. The reaction mixture was esterified at a temperature of 190 °C and a pressure of 1.0 bar for 3 hours, and the viscosity number of the obtained second esterification product was 7 ml / g;

[0136] S2. The first esterification product and the second esterification product obtained in steps S1-i and S1-ii were mixed, and the mixture was transferred to a stirred vertical reactor. 0.16 kg of tetrabutyl titanate was added, and the reaction mixture was pre-polycondensation reacted at 245 °C and a reactor pressure of 0.30 bar for 140 minutes. The viscosity number of the obtained pre-polymer was 34 ml / g;

[0137] S3. The pre-polymer obtained in step S2 was transferred to a stirred horizontal reactor and polycondensation reacted at 244 °C and a pressure of 1.4 mbar for 90 minutes. The viscosity number of the obtained biodegradable aliphatic polyester composition was 173 ml / g.

[0138] The total content and mass ratio η of the compounds represented by formula (I) and formula (II) in the biodegradable aliphatic polyester composition are shown in Table 1.

[0139] Example 4

[0140] Example 4 provides a biodegradable aliphatic polyester composition, which is prepared as follows:

[0141] S1-i. 195 kg of succinic acid, 210 kg of 1,4-butanediol and 1.3 kg of glycerol were mixed, a 1,4-butanediol solution containing sodium hydroxide was added, and the pH value of the system was adjusted to 4.6 to obtain slurry A. Slurry A was transferred to a reactor with stirring. The reaction mixture was esterified at a temperature of 170 °C and a pressure of 0.85 bar for 3 hours, and the viscosity number of the obtained first esterification product was 10 ml / g;

[0142] S1-ii. 53 kg of adipic acid, 52 kg of 1,4-butanediol and 0.22 kg of tetrabutyl titanate were physically mixed, a 1,4-butanediol solution containing sodium hydroxide was added, the pH value of the system was adjusted to 5.4 to obtain slurry B, and slurry B was transferred to a reactor with stirring. The reaction mixture was esterified at a temperature of 200 °C and a pressure of 1.0 bar for 4 hours, and the viscosity number of the obtained second esterification product was 12 ml / g;

[0143] S2. The first esterification product and the second esterification product obtained in steps S1-i and S1-ii are mixed, and the mixture is transferred to a vertical reactor with a stirrer. 0.15 kg of tetrabutyl titanate is added, and the reaction mixture is prepolymerized at 242 °C and 0.28 bar in the reactor for 135 minutes. The viscosity of the resulting prepolymer is 35 ml / g.

[0144] S3. The prepolymer obtained in step S2 is transferred to a horizontal reactor with a stirrer and subjected to polycondensation reaction at 245°C and 1.5 mbar for 90 minutes. The resulting biodegradable aliphatic polyester composition has a viscosity of 175 ml / g.

[0145] The total content and mass ratio η of the compounds represented by formula (I) and formula (II) in the biodegradable aliphatic polyester composition are shown in Table 1.

[0146] Example 5

[0147] Example 5 provides a biodegradable aliphatic polyester composition, prepared by the following method:

[0148] S1-i. 195 kg succinic acid, 215 kg 1,4-butanediol and 1.3 kg glycerol were mixed, and a 1,4-butanediol solution containing sodium hydroxide was added to adjust the pH of the system to 3.2 to obtain slurry A. Slurry A was transferred to a stirred reactor, and the reaction mixture was esterified at 190 °C and 0.7 bar for 3 hours. The viscosity of the first ester obtained was 9 ml / g.

[0149] S1-ii. 76 kg of adipic acid, 70 kg of 1,4-butanediol, and 0.21 kg of tetrabutyl titanate were physically mixed. A 1,4-butanediol solution containing sodium hydroxide was added to adjust the pH of the system to 5.2, yielding slurry B. Slurry B was transferred to a stirred reactor. The reaction mixture was esterified at 195 °C and 0.9 bar for 4 hours, resulting in a second ester with a viscosity of 10 ml / g.

[0150] S2. The first esterification product and the second esterification product obtained in steps S1-i and S1-ii are mixed, and the mixture is transferred to a vertical reactor with a stirrer. 0.13 kg of tetrabutyl titanate is added, and the reaction mixture is prepolymerized at 245 °C and 0.35 bar in the reactor for 75 minutes. The viscosity of the resulting prepolymer is 24 ml / g.

[0151] S3. The prepolymer obtained in step S2 is transferred to a horizontal reactor with a stirrer and subjected to polycondensation reaction at 248°C and 1.2 mbar for 110 minutes. The resulting biodegradable aliphatic polyester composition has a viscosity of 169 ml / g.

[0152] The total content of compounds represented by formula (I) and formula (II) and the mass ratio η in the biodegradable aliphatic polyester composition are shown in Table 1.

[0153] Example 6

[0154] Example 6 provides a biodegradable aliphatic polyester composition, and the preparation method is as follows:

[0155] S1-i. 195 kg of succinic acid, 215 kg of 1,4-butanediol and 1.3 kg of glycerol are mixed, a 1,4-butanediol solution containing sodium hydroxide is added, and the pH value of the system is adjusted to 4.5 to obtain slurry A. The slurry A is transferred to a stirred reactor. The reaction mixture is esterified at a temperature of 200°C and a pressure of 0.8 bar for 4 hours. The viscosity number of the obtained first esterification product is 11 ml / g;

[0156] S1-ii. 114 kg of adipic acid, 105 kg of 1,4-butanediol and 0.28 kg of tetrabutyl titanate are physically mixed, a 1,4-butanediol solution containing sodium hydroxide is added, and the pH value of the system is adjusted to 5.7 to obtain slurry B. The slurry B is transferred to a stirred reactor. The reaction mixture is esterified at a temperature of 180°C and a pressure of 0.9 bar for 3 hours. The viscosity number of the obtained second esterification product is 9 ml / g;

[0157] S2. The first esterification product and the second esterification product obtained in steps S1-i and S1-ii are mixed, and the mixture is transferred to a stirred vertical reactor. 0.17 kg of tetrabutyl titanate is added. The reaction mixture is pre-polycondensation reacted at 245°C and a reactor pressure of 0.55 bar for 110 minutes. The viscosity number of the obtained pre-polymer is 29 ml / g;

[0158] S3. The pre-polymer obtained in step S2 is transferred to a stirred horizontal reactor and polycondensation reacted at 245°C and a pressure of 1.8 mbar for 100 minutes. The viscosity number of the obtained biodegradable aliphatic polyester composition is 162 ml / g.

[0159] The total content of compounds represented by formula (I) and formula (II) and the mass ratio η in the biodegradable aliphatic polyester composition are shown in Table 1.

[0160] Example 7

[0161] Example 7 provides a biodegradable aliphatic polyester composition, and the preparation method is as follows:

[0162] S1-i. 195 kg of succinic acid, 215 kg of 1,4-butanediol and 1.3 kg of glycerol were mixed, a 1,4-butanediol solution containing sodium hydroxide was added, the pH value of the system was adjusted to 4.0 to obtain slurry A, and slurry A was transferred to a reactor with stirring. The reaction mixture was esterified at a temperature of 210 °C and a pressure of 0.85 bar for 4 hours, and the viscosity number of the obtained first esterification product was 14 ml / g;

[0163] S1-ii. 114 kg of adipic acid, 105 kg of 1,4-butanediol and 0.28 kg of tetrabutyl titanate were physically mixed, a 1,4-butanediol solution containing sodium hydroxide was added, the pH value of the system was adjusted to 5.5 to obtain slurry B, and slurry B was transferred to a reactor with stirring. The reaction mixture was esterified at a temperature of 190 °C and a pressure of 0.8 bar for 4 hours, and the viscosity number of the obtained second esterification product was 13 ml / g;

[0164] S2. The first esterification product and the second esterification product obtained in steps S1-i and S1-ii were mixed, and the mixture was transferred to a stirred vertical reactor. 0.19 kg of tetrabutyl titanate was added, and the reaction mixture was pre-polycondensation reacted at 248 °C and a reactor pressure of 0.40 bar for 110 minutes. The viscosity number of the obtained pre-polymer was 35 ml / g;

[0165] S3. The pre-polymer obtained in step S2 was transferred to a stirred horizontal reactor and polycondensation reacted at 245 °C and a pressure of 1.8 mbar for 95 minutes. The viscosity number of the obtained biodegradable aliphatic polyester composition was 176 ml / g.

[0166] The total content and mass ratio η of the compounds represented by formula (I) and formula (II) in the biodegradable aliphatic polyester composition are shown in Table 1.

[0167] Example 8

[0168] Example 8 provides a biodegradable aliphatic polyester composition, which is prepared as follows:

[0169] S1-i. 195 kg of succinic acid, 215 kg of 1,4-butanediol and 1.3 kg of glycerol were mixed, a 1,4-butanediol solution containing sodium hydroxide was added, the pH value of the system was adjusted to 5.7 to obtain slurry A, and slurry A was transferred to a reactor with stirring. The reaction mixture was esterified at a temperature of 160 °C and a pressure of 1.0 bar for 5 hours, and the viscosity number of the obtained first esterification product was 8 ml / g;

[0170] S1-ii. 53 kg of adipic acid, 52 kg of 1,4-butanediol and 0.26 kg of tetrabutyl titanate were physically mixed, a 1,4-butanediol solution containing sodium hydroxide was added, the pH value of the system was adjusted to 5.6 to obtain slurry B, and slurry B was transferred to a reactor with stirring. The reaction mixture was esterified at a temperature of 200 °C and a pressure of 0.9 bar for 4 hours, and the viscosity number of the obtained second esterification product was 10 ml / g;

[0171] S2. The first esterification product and the second esterification product obtained in steps S1-i and S1-ii were mixed, and the mixture was transferred to a stirred vertical reactor, 0.17 kg of tetrabutyl titanate was added, and the reaction mixture was pre-polycondensation reacted at 246 °C and a reactor pressure of 0.70 bar for 100 minutes, and the viscosity number of the obtained pre-polymer was 26 ml / g;

[0172] S3. The pre-polymer obtained in step S2 was transferred to a stirred horizontal reactor, and was polycondensation reacted at 248 °C and a pressure of 1.6 mbar for 90 minutes, and the viscosity number of the obtained biodegradable aliphatic polyester composition was 163 ml / g.

[0173] The total content and mass ratio η of the compounds represented by formula (I) and formula (II) in the biodegradable aliphatic polyester composition are shown in Table 1.

[0174] Example 9

[0175] Example 9 provides a biodegradable aliphatic polyester composition, and the preparation method is as follows:

[0176] S1-i. 195 kg of succinic acid, 215 kg of 1,4-butanediol and 1.5 kg of glycerol were mixed, a 1,4-butanediol solution containing sodium carbonate was added, the pH value of the system was adjusted to 4.2 to obtain slurry A, and slurry A was transferred to a reactor with stirring. The reaction mixture was esterified at a temperature of 210 °C and a pressure of 0.7 bar for 3 hours, and the viscosity number of the obtained first esterification product was 15 ml / g;

[0177] S1-ii. 53 kg of adipic acid, 52 kg of 1,4-butanediol and 0.26 kg of tetrabutyl titanate were physically mixed, a 1,4-butanediol solution containing sodium hydroxide was added, the pH value of the system was adjusted to 5.6 to obtain slurry B, and slurry B was transferred to a reactor with stirring. The reaction mixture was esterified at a temperature of 200 °C and a pressure of 0.9 bar for 4 hours, and the viscosity number of the obtained second esterification product was 10 ml / g;

[0178] S2. The first esterification product and the second esterification product obtained in steps S1-i and S1-ii were mixed and the mixture was transferred to a stirred vertical reactor. 0.10 kg of tetrabutyl titanate was added and the reaction mixture was pre-polycondensation reacted at 235 °C under a pressure of 0.60 bar in the reactor for 75 minutes. The viscosity of the obtained pre-polymer was 25 ml / g.

[0179] S3. The pre-polymer obtained in step S2 was transferred to a stirred horizontal reactor and polycondensation reacted at 242 °C under a pressure of 2.2 mbar for 85 minutes. The viscosity of the obtained final polycondensation product was 143 ml / g.

[0180] S4. The final polycondensation product in step S3 was passed through a static mixer and 1.0 kg of hexamethylene diisocyanate was added and blended at 210 °C for 7 minutes to obtain a biodegradable aliphatic polyester composition having a viscosity of 190 ml / g.

[0181] The total content of the compounds represented by formula (I) and formula (II) and the mass ratio η in the biodegradable aliphatic polyester composition are shown in Table 1.

[0182] Comparative Example 1

[0183] Comparative Example 1 provides a biodegradable aliphatic polyester composition, which was prepared as follows:

[0184] S1-i. 195 kg of succinic acid, 210 kg of 1,4-butanediol and 1.2 kg of glycerol were mixed to obtain slurry A, which was transferred to a stirred reactor. The reaction mixture was esterification reacted at a temperature of 190 °C and a pressure of 1.1 bar for 3 hours. The viscosity of the obtained first esterification product was 10 ml / g.

[0185] S1-ii. 53 kg of adipic acid, 52 kg of 1,4-butanediol and 0.20 kg of tetrabutyl titanate were physically mixed to obtain slurry B, which was transferred to a stirred reactor. The reaction mixture was esterification reacted at a temperature of 210 °C and a pressure of 1.0 bar for 3 hours. The viscosity of the obtained second esterification product was 12 ml / g.

[0186] S2. The first esterification product and the second esterification product obtained in steps S1-i and S1-ii were mixed and the mixture was transferred to a stirred vertical reactor. 0.14 kg of tetrabutyl titanate was added and the reaction mixture was pre-polycondensation reacted at 245 °C under a pressure of 0.28 bar in the reactor for 110 minutes. The viscosity of the obtained pre-polymer was 41 ml / g.

[0187] S3. The prepolymer obtained in step S2 is transferred to a horizontal reactor with stirring and is subjected to polycondensation at 248°C and a pressure of 1.5 mbar for 90 minutes, the resulting biodegradable aliphatic polyester composition having a viscosity of 186 ml / g.

[0188] The total content of the compounds represented by formula (I) and formula (II) and the mass ratio η in the biodegradable aliphatic polyester composition are shown in Table 1.

[0189] Comparative Example 2

[0190] Comparative Example 2 provides a biodegradable aliphatic polyester composition, which is prepared as follows:

[0191] S1-i. 195 kg of succinic acid, 225 kg of 1,4-butanediol and 1.2 kg of glycerol are mixed, a 1,4-butanediol solution containing sodium hydroxide is added to adjust the pH of the system to 4.4, to obtain slurry A, slurry A is transferred to a reactor with stirring, and the reaction mixture is esterified at a temperature of 200°C and a pressure of 0.8 bar for 6 hours, the first esterification product obtained has a viscosity of 17 ml / g;

[0192] S1-ii. 53 kg of adipic acid, 52 kg of 1,4-butanediol and 0.24 kg of tetrabutyl titanate are physically mixed to obtain slurry B, slurry B is transferred to a reactor with stirring. The reaction mixture is esterified at a temperature of 220°C and a pressure of 0.70 bar for 5 hours, the second esterification product obtained has a viscosity of 19 ml / g;

[0193] S2. The first esterification product and the second esterification product obtained in steps S1-i and S1-ii are mixed, the mixture is transferred to a vertical reactor with stirring, 0.18 kg of tetrabutyl titanate is added, and the reaction mixture is subjected to pre-polycondensation at 245°C and a pressure of 0.2 bar in the reactor for 150 minutes, the prepolymer obtained has a viscosity of 59 ml / g;

[0194] S3. The prepolymer obtained in step S2 is transferred to a horizontal reactor with stirring and is subjected to polycondensation at 243°C and a pressure of 2.0 mbar for 80 minutes, the resulting biodegradable aliphatic polyester has a viscosity of 192 ml / g.

[0195] The total content of the compounds represented by formula (I) and formula (II) and the mass ratio η in the biodegradable aliphatic polyester composition are shown in Table 1.

[0196] Comparative Example 3

[0197] Comparative Example 3 provides a biodegradable aliphatic polyester composition, which is prepared as follows:

[0198] S1-i. 195 kg of succinic acid, 225 kg of 1,4-butanediol and 1.2 kg of glycerol were mixed, a 1,4-butanediol solution containing sodium hydroxide was added to adjust the pH of the succinic acid to 5.1 to obtain slurry A, and the slurry A was transferred to a reactor with stirring. The reaction mixture was esterified at a temperature of 160°C and a pressure of 0.9 bar for 5 hours, and the viscosity number of the obtained first esterification product was 9 ml / g;

[0199] S1-ii. 33 kg of adipic acid, 28 kg of 1,4-butanediol and 0.23 kg of tetrabutyl titanate were physically mixed to obtain slurry B, and the slurry B was transferred to a reactor with stirring. The reaction mixture was esterified at a temperature of 205°C and a pressure of 1.0 bar for 3 hours, and the viscosity number of the obtained second esterification product was 11 ml / g;

[0200] S2. The first esterification product and the second esterification product obtained in steps S1-i and S1-ii were mixed, and the mixture was transferred to a vertical reactor with stirring. 0.13 kg of tetrabutyl titanate was added, and the reaction mixture was pre-polycondensed at 252°C and a reactor pressure of 0.50 bar for 110 minutes, and the viscosity number of the obtained pre-polymer was 28 ml / g;

[0201] S3. The pre-polymer obtained in step S2 was transferred to a horizontal reactor with stirring, and was polycondensed at 251°C and a pressure of 1.3 mbar for 75 minutes, and the viscosity number of the obtained biodegradable aliphatic polyester composition was 163 ml / g.

[0202] The total content of the compounds represented by formula (I) and formula (II) in the biodegradable aliphatic polyester composition and the mass ratio η are shown in Table 1.

[0203] The biodegradable aliphatic polyester compositions prepared in the above examples and comparative examples were subjected to food contact performance evaluation, and the total migration amount was detected, and the results are shown in Table 1.

[0204] Table 1

[0205]

[0206] According to the test results in Table 1, it can be seen that the biodegradable aliphatic polyester compositions prepared in each example of the present application were prepared into a film with a thickness of 25±2 μm, and subjected to food contact test according to OM6 condition with 10% ethanol as a simulation liquid, and the sample total migration amount was ≤10 mg / dm 2 .

[0207] The weight ratio η of the compound represented by formula (I) and the compound represented by formula (II) in the biodegradable aliphatic polyester compositions in Comparative Examples 1 to 3 was > 6:1, and the sample total migration amount of the prepared biodegradable aliphatic polyester compositions was also too large.

[0208] Application Examples

[0209] Application Examples 1-3 each provide a biodegradable mixture, the component contents being shown in Table 2, and the preparation method is as follows:

[0210] According to Table 2, the components are mixed and then added to a twin-screw extruder (L / D = 48; diameter 40 mm) to perform melt mixing and extrusion granulation. The extrusion temperature is 140-200°C, the screw rotation speed is 300 rpm, and the vacuum is -0.50 to -0.65 kg / cm 2 , to obtain a biodegradable mixture.

[0211] Table 2 Component contents (wt.%) of Application Examples 1-3

[0212]

[0213]

[0214] The biodegradable mixtures of Application Examples 1-3 are subjected to food contact testing and heat seal strength testing, and the results are shown in Table 3.

[0215] Table 3

[0216] Application Example 1 Application Example 2 Application Example 3 Total migration (mg / dm 2 )]]> 14.8 4.6 5.7 Heat seal strength (N / 15mm) 7 22 18

[0217] It can be seen that the biodegradable mixtures prepared using the biodegradable aliphatic polyester composition of the present application not only have very low total migration amounts, but also have high heat seal strength and excellent heat seal performance.

[0218] Finally, it should be noted that the above examples are merely used to illustrate the technical solutions of the present application and not to limit the protection scope of the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present application.

Claims

1. A biodegradable aliphatic polyester composition, characterized in that, include: Component i), a biodegradable aliphatic polyester, wherein the biodegradable aliphatic polyester comprises: Component A, a dicarboxylic acid compound, comprises, based on the total molar amount of component A: a1, 68~82 mol% succinic acid, a2, 18~32 mol% adipic acid; Component B, with at least an equimolar amount of 1,4-butanediol as component A; Component ii), the cyclic esters shown in formulas (I) and (II), 、 ； Formula (I) Formula (II) In equations (I) and (II), n and m are both positive integers from 1 to 8; The content of cyclic esters is 0.6 to 1.1 wt.% based on the total weight of the biodegradable aliphatic polyester composition, and the mass ratio η of the compounds shown in formula (I) and formula (II) is 2 to 6:

1.

2. The biodegradable aliphatic polyester composition according to claim 1, characterized in that, In component A, based on the total molar amount of component A, it includes: a1, 72~78 mol% succinic acid, a2, 22~28 mol% adipic acid.

3. The biodegradable aliphatic polyester composition according to claim 1, characterized in that, It must include at least one of the following (1) to (2): (1) The mass ratio of the compounds shown in formula (I) and formula (II) is (3.2~4.8):1; (2) The biodegradable aliphatic polyester composition, according to EU 10-2011 standard, under OM6 test conditions with 10% ethanol as the simulated solution, has a total migration amount of less than or equal to 10 mg / dm³. 2 .

4. The biodegradable aliphatic polyester composition according to claim 1, characterized in that, The biodegradable aliphatic polyester composition may further include component C, a chain extender: The chain extender comprises one or more of the following components: c1, isocyanate c2, peroxide c3, epoxide c4, oxazoline, oxazine, caprolactam and / or carbodiimide.

5. A method for preparing the biodegradable aliphatic polyester composition according to any one of claims 1 to 4, characterized in that, Includes the following steps: S1-i. Mix component a1 with a portion of component B, add an alkaline compound to adjust the pH of the system to 3.2~5.8, mix with or without a catalyst to obtain slurry A, slurry A undergoes esterification reaction until the viscosity of the esterification product, as determined according to DIN53728-3-1985, is 5~15 ml / g, to obtain the first esterification product; S1-ii. Mix component a2 with the remaining component B, add an alkaline compound to adjust the pH of the system to 5.2~5.8, mix with or without a catalyst to obtain slurry B, slurry B undergoes esterification reaction until the viscosity of the esterification product, as determined according to DIN53728-3-1985, is 7~16 ml / g, to obtain the second esterification product; S2. The first esterification product and the second esterification product obtained in steps S1-i and S1-ii are mixed to obtain a mixture of esterification products. The mixture is prepolymerized until the viscosity of its prepolymer, as determined according to DIN 53728-3-1985, is 24~55 ml / g. S3. The prepolymer obtained in step S2 is polycondensed until the viscosity of the polycondensation product, as determined according to DIN 53728-3-1985, is 143~226 ml / g, which is the biodegradable aliphatic polyester composition.

6. The preparation method according to claim 5, characterized in that, It must include at least one of the following (1) to (2): (1) The alkaline compound is a carbonate and / or hydroxide; (2) In step S2, the viscosity of the prepolymer product, as determined according to DIN 53728-3-1985, is 32~46 ml / g.

7. The preparation method according to claim 5, characterized in that, It also includes step S4, in which the polycondensation product described in step S3 is mixed with the chain extender to carry out a chain growth reaction; the viscosity of the chain-grown product obtained after the chain growth reaction is 167~242 ml / g as determined by DIN 53728-3-1985.

8. Use of the biodegradable aliphatic polyester composition according to any one of claims 1 to 4 in food preservation film.

9. A biodegradable mixture, characterized in that, Includes the following components by weight percentage: i) Based on the total weight of components i) and ii), 5 to 95 wt.% of the biodegradable aliphatic polyester composition according to any one of claims 1 to 4, ii) Based on the total weight of components i) and 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. iii) Based on the total weight of components i) to iv), 0–35 wt.% talc. iv) 0 to 20 wt.% of calcium carbonate based on the total weight of components i) to iv).

10. The use of the biodegradable mixture of claim 9 in the preparation of a heat-sealing film.

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