Aliphatic-aromatic polyester compositions, polyester fibers, and methods for preparing and using same

Abstract

The present invention discloses an aliphatic-aromatic polyester composition, polyester fiber, and its preparation and use. The aliphatic-aromatic polyester composition of the present invention comprises: i) an aliphatic-aromatic polyester based on an aliphatic dicarboxylic acid, an aromatic dicarboxylic acid, and an aliphatic dihydroxy compound; and ii) a titanium element content of 55 to 88 ppm, based on the weight of the aliphatic-aromatic polyester composition. The aliphatic-aromatic polyester composition has an acid value of 0.84 mg KOH / g or less according to standard DIN EN 12634-1998. The aliphatic-aromatic polyester composition of the present invention not only has a low yellowness index and good colorability, but also effectively improves hydrolysis resistance, making it suitable for wide use in the field of polyester fibers.

Description

[Technical Field]

[0001] The present invention relates to the technical field of polyester compositions, and more particularly to aliphatic-aromatic polyester compositions, polyester fibers, and methods for preparing and using the same. [Background technology]

[0002] With the rapid development of polymeric materials, their importance is becoming increasingly evident. However, it has also been discovered that most synthetic polymeric materials are difficult to decompose in nature, causing "white pollution." As textile materials are essential to human production and life, their waste is also attracting considerable attention. In particular, traditional man-made chemical fibers such as PET and PBT fibers are difficult to decompose and have become a new source of pollution. Textile products made from biodegradable materials can be decomposed into carbon dioxide and water by the action of microorganisms, are harmless to the environment, and are the best alternative to traditional chemical fiber materials.

[0003] Coloring is usually required during the processing of polyester materials into fibers, and to facilitate coloring, polyester materials typically require a low yellowness index. Aliphatic-aromatic polyesters obtained from aliphatic dicarboxylic acids such as adipic acid, aromatic dicarboxylic acids such as terephthalic acid, and aliphatic dihydroxy compounds such as 1,4-butanediol are known in the prior art. Commonly used catalysts for synthesizing aliphatic-aromatic polyesters include tin compounds, antimony compounds, cobalt compounds, lead compounds, zinc compounds, aluminum compounds, and titanium compounds, with titanium compounds being the most preferred. Titanium compounds, such as tetrabutyl titanate and tetraisopropyl titanate, have an advantage over other compounds in that they leave low residual toxicity in the final product or downstream products. This characteristic is particularly important for biodegradable polyesters, since products containing these compounds are quickly released into the environment after disposal. However, when adipic acid and titanium compounds are used as catalysts, the resulting aliphatic-aromatic polyesters generally exhibit a yellow to red color, making it difficult to meet the color requirements of textile products.

[0004] Prior art discloses a method for preparing aliphatic-aromatic polyesters by adding 0.03 to 0.04 weight percent of a phosphorus compound to the polymerization process (between step II and step III) to improve the color of the resulting aliphatic-aromatic polyester, resulting in a whiteness index of at least 25. The phosphorus compound acts as a passivator for the titanium catalyst, weakening its activity to some extent and increasing the acid value (1.1 to 1.4 mg KOH / g) of the resulting aliphatic-aromatic polyester, resulting in a decrease in its hydrolysis resistance. Therefore, there is a need to develop biodegradable polyesters that combine a lower yellowness index with better hydrolysis resistance. Summary of the Invention [Problem to be solved by the invention]

[0005] The object of the present invention is to overcome the drawbacks and shortcomings of existing biodegradable polyesters, which are that they are unable to combine a low yellowness index (YI) with excellent hydrolysis resistance, and to provide an aliphatic-aromatic polyester composition that not only has a low yellowness index (YI) value but also has excellent hydrolysis resistance.

[0006] Another object of the present invention is to provide a method for preparing an aliphatic-aromatic polyester composition.

[0007] It is yet another object of the present invention to provide polyester fibers, the polyester fibers having as a base resin the aliphatic-aromatic polyester composition according to the present invention.

[0008] A further object of the present invention is to provide a method for preparing polyester fibers.

[0009] A further object of the present invention is to provide the use of polyester fibers in masks and clothing. [Means for solving the problem]

[0010] The above object of the present invention is achieved by the following technical solutions. 1. An aliphatic-aromatic polyester composition comprising: The composition comprises, as components: i) aliphatic-aromatic polyesters based on aliphatic and aromatic dicarboxylic acids and aliphatic dihydroxy compounds, said aliphatic-aromatic polyesters having as components: A) Dicarboxylic acid component: the total molar percentage of components a1) and a2) is 100%; a1) 46.2 to 49.5 mol% of aromatic dicarboxylic acid or its ester derivative, or a mixture thereof, based on the total molar amount of a1) and a2); a2) 50.5 to 53.8 mol % of adipic acid or its ester derivatives, or mixtures thereof, based on the total molar amount of a1) and a2), and B) a dihydroxy compound component: b1) a C2-C6 aliphatic alkanediol or a mixture thereof in at least an equimolar amount with component A; b2) 0 to 3 wt% of a compound containing at least three functional groups, based on the total weight of components A and b1 an aliphatic-aromatic polyester comprising ii) titanium element in a content of 55 to 88 ppm based on the weight of the aliphatic-aromatic polyester composition; Including, The aliphatic-aromatic polyester composition is characterized by an acid number of less than or equal to 0.84 mg KOH / g according to standard DIN EN 12634-1998.

[0011] The aliphatic-aromatic polyester composition has a Yellowness Index YI value of 23 or less, measured according to standard ASTM E313-73.

[0012] The aliphatic-aromatic polyester composition is boiled in water at 60°C for 48 hours, and the viscosity number retention rate η of the aliphatic-aromatic polyester composition after boiling is 65% or more, which indicates excellent hydrolysis resistance; The viscosity number retention rate is calculated by the following formula: η=η1 / η0 (where, η1 represents the viscosity number of the aliphatic-aromatic polyester composition after boiling in water at 60°C for 48 hours; η represents the viscosity number of the aliphatic-aromatic polyester composition before boiling. Follow.

[0013] Specifically, the hydrolysis resistance of the aliphatic-aromatic polyester composition is evaluated as follows. 1) The aliphatic-aromatic polyester composition sample was dehumidified and dried at 80°C for 4 hours, and its initial viscosity number η before boiling was tested according to standard GB / T 17931-1999; 2) The aliphatic-aromatic polyester composition sample was placed in a water bath at 60°C and boiled for 48 hours. 3) After 48 hours, the aliphatic-aromatic polyester composition sample is taken out and transferred to a desiccator and stored at ambient temperature for 24 hours to achieve internal equilibrium conditions for the sample; 4) After equilibration, the sample is dried under dehumidification at 80°C for 4 hours, and its viscosity number η1 after boiling for 48 hours is tested according to standard GB / T 17931-1999.

[0014] When adipic acid is used as a raw material and a titanium compound is used as a catalyst, the resulting aliphatic-aromatic polyester generally exhibits a yellow to red color. If the titanium content in the aliphatic-aromatic polyester composition is too high, the color of the aliphatic-aromatic polyester composition will be affected, resulting in a high Yellowness Index (YI) value. Furthermore, if the titanium content is too high, the hydrolysis resistance of the aliphatic-aromatic polyester composition will be weakened. Furthermore, if the amount of titanium added during the synthesis of the aliphatic-aromatic polyester exceeds a certain range, the increased amount of titanium will intensify the thermal decomposition reaction (reverse reaction) of the aliphatic-aromatic polyester, causing yellowing of the product. If the titanium content is too low, the residence time of the polymerization reaction will be too long, which is unfavorable for reducing the acid value of the aliphatic-aromatic polyester, and a low-acid-value aliphatic-aromatic polyester composition will not be obtained. If the acid value is too high, the hydrolysis resistance of the aliphatic-aromatic polyester composition will be further weakened. In addition, a high acid value further aggravates the thermal decomposition reaction during the polymerization of the aliphatic-aromatic polyester, causing the product to turn yellow.

[0015] The titanium element in the present invention may be derived from a titanium compound such as tetrabutyl titanate or tetraisopropyl titanate, or may be derived from other titanium-containing compounds added during the polymerization process.

[0016] In a specific embodiment, the A) dicarboxylic acid component preferably comprises as a component: a1) 47.3 to 48.8 mol% of an aromatic dicarboxylic acid or its ester derivative, or a mixture thereof, based on the total molar amount of a1) and a2), a2) 51.2 to 52.7 mol% of adipic acid or its ester derivative, or a mixture thereof, based on the total molar amount of a1) and a2), Including, The total molar percentage of components a1) and a2) is taken as 100%.

[0017] In a specific embodiment, the aromatic dicarboxylic acid in a1) above may be an aromatic dicarboxylic acid having 8 to 20 carbon atoms, preferably 8 to 12 carbon atoms, such as terephthalic acid, isophthalic acid, 2,6-naphthoic acid, and 1,5-naphthoic acid, as well as ester derivatives formed therefrom, particularly di-C1 to C6 alkyl esters such as dimethyl, diethyl, di-n-propyl, diisopropyl, di-n-butyl, diisobutyl, di-tert-butyl, di-n-pentyl, diisopentyl, or di-n-hexyl esters. Acid anhydrides of these dicarboxylic acids a1 are also suitable derivatives for forming esters.

[0018] The aromatic dicarboxylic acid or ester derivative a1 formed therefrom may be used alone or in a mixture of two or more. Particularly preferably, terephthalic acid or an ester derivative formed therefrom, such as dimethyl terephthalate, is used.

[0019] In a specific embodiment, a2) above is a derivative of adipic acid or its ester, or a mixture thereof. Derivatives of the esters include, in particular, di-C1-C6 alkyl esters, such as dimethyl, diethyl, di-n-propyl, diisopropyl, di-n-butyl, diisobutyl, di-tert-butyl, di-n-pentyl, diisopentyl or di-n-hexyl esters. Acid anhydrides of the dicarboxylic acids mentioned above can also be used.

[0020] In the present invention, the dicarboxylic acid or the ester derivative formed therefrom may be used alone or in the form of a mixture of two or more kinds.

[0021] The dihydroxy compound component b1 is typically selected from branched or linear aliphatic alkanediols having 2 to 6 carbon atoms. Examples of suitable aliphatic alkanediols include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 2,4-dimethyl-2-ethyl-1,3-hexanediol, 2,2-dimethyl-1,3-propanediol, and 2-ethyl-2-butyl-1,3-propanediol, especially ethylene glycol, 1,3-propanediol, and 1,4-butanediol. Particularly preferred is 1,4-butanediol, especially in combination with component a2), adipic acid. Mixtures of different aliphatic alkanediols can also be used.

[0022] Component b2) preferably comprises a compound having at least three functional groups. Particularly preferred compounds have 3 to 6 hydroxyl groups. Examples include tartaric acid, citric acid, malic acid, trimethylolpropane, trimethylolethane, pentaerythritol, polyether triols, glycerol, 1,3,5-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic acid anhydride, 1,2,4,5-prenitic acid, and pyromellitic dianhydride. Preferred are polyols, such as trimethylolpropane, pentaerythritol, and glycerol, with glycerol being particularly preferred.

[0023] The amount of component b2) used is more preferably 0.02 to 1 wt %, and particularly preferably 0.08 to 0.60 wt %, based on the total weight of components A) and b1).

[0024] The aliphatic polyester composition according to the present invention may further comprise a component C) used as a chain extender, said component C) being They are selected from c1) isocyanates, c2) peroxides, c3) epoxides, c4) oxazolines, oxazines, caprolactams and / or carbodiimides.

[0025] As the isocyanate in component c1) of the present invention, an aromatic diisocyanate or an aliphatic diisocyanate may be used. For example, the aromatic diisocyanate may be toluene 2,4-diisocyanate, toluene 2,6-diisocyanate, diphenylmethane 2,2'-diisocyanate, diphenylmethane 2,4'-diisocyanate, diphenylmethane 4,4'-diisocyanate, naphthalene 1,5-diisocyanate, or xylene diisocyanate.

[0026] Particularly preferably here, diphenylmethane 2,2'-, 2,4'- or 4,4'-diisocyanate is used as component c1).

[0027] Also usable isocyanates include tris(4-isocyanatophenyl)methane, which has three rings. The polynuclear aromatic diisocyanates can be formed, for example, in the process of producing diisocyanates having one or two rings.

[0028] In 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-1,6-diisocyanate, isophorone diisocyanate, or methylenebis(4-isocyanatocyclohexane).

[0029] A particularly preferred aliphatic diisocyanate is hexamethylene-1,6-diisocyanate.

[0030] The amount of component c1) used may be 0.05 to 2 wt %, particularly preferably 0.1 to 1.5 wt %, based on the total weight of the aliphatic-aromatic polyester composition.

[0031] The peroxide of the present invention (component c2) may be a mixture of one or more of the following compounds: Benzoyl peroxide, 1,1-di(tert-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1-di(tert-butylperoxy)methylcyclododecane, butyl 4,4-di(butylperoxy)pentanoate, dicumyl peroxide, tert-butyl perbenzoate, dibutyl peroxide, α,α-di(tert-butylperoxy)diisopropylbenzene, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, 2,5-bis(tert-butylperoxy)-2,5-dimethyl-3-hexyne, and t-butylperoxycumene.

[0032] The amount of component c2) used may be 0.1 to 2 wt %, particularly preferably 0.2 to 1 wt %, based on the total weight of the aliphatic-aromatic polyester composition.

[0033] The epoxides (component c3) of the present invention may be one or more of diglycidyl ethers, 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, diglycol diglycidyl ether, polyethylene glycol diglycidyl ether, propanediol diglycidyl ether, dipropylene glycol diglycidyl ether, polypropanediol diglycidyl ether and polybutanediol diglycidyl ether, epoxy-containing copolymers based on styrene, acrylates and / or methacrylates.

[0034] The amount of component c3) used may be 0.1 to 2 wt %, preferably 0.2 to 1 wt %, based on the total weight of the aliphatic-aromatic polyester composition.

[0035] Component c4) of the present invention may also be dioxazolines and dioxazines in which the bridging moiety is a single bond (CH2)z-alkylene (where z=2, 3 or 4), such as methylene, ethane-1,2-diyl, propane-1,3-diyl, propane-1,2-diyl or phenylene.

[0036] The dioxazoline in component c4) 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.

[0037] 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.

[0038] 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.

[0039] The amount of component c4) used may be 0.1 to 2 wt %, preferably 0.2 to 1 wt %, based on the total weight of the aliphatic-aromatic polyester composition.

[0040] In the aliphatic-aromatic polyester composition, component i), particularly preferably the aliphatic-aromatic polyester, may comprise, as the aromatic dicarboxylic acid (component a1), terephthalic acid or a derivative of its ester, or a mixture thereof; as the aliphatic dicarboxylic acid (component a2), adipic acid or a derivative of its ester, or a mixture thereof; as the dihydroxy compound component (component b1), 1,4-butanediol; as the component b2), glycerol, pentaerythritol, or trimethylolpropane; and as the component c1), hexamethylene-1,6-diisocyanate.

[0041] In a specific embodiment, the content of the titanium element is preferably 63 to 81 ppm based on the weight of the aliphatic-aromatic polyester composition.

[0042] Preferably, the aliphatic-aromatic polyester composition has an acid number of less than or equal to 0.78 mg KOH / g according to standard DIN EN 12634-1998.

[0043] Preferably, the aliphatic-aromatic polyester composition has a Yellowness Index YI value of 19 or less according to standard ASTM E313-73.

[0044] Preferably, when the aliphatic-aromatic polyester composition is boiled in water at 60° C. for 48 hours, the viscosity number retention η of the aliphatic-aromatic polyester composition after boiling is 72% or more.

[0045] Preferably, the melt index of the aliphatic-aromatic polyester composition measured according to standard ISO 1133-2-2011 at 190°C and 2.16 kg is 1.0 to 22.0 g / 10 min, more preferably 2.0 to 10.0 g / 10 min.

[0046] The aliphatic-aromatic polyester composition of the present invention is also biodegradable.

[0047] In the present invention, a substance or mixture of substances is characterized as "biodegradable" if it exhibits a biodegradation rate as defined in DIN EN 13432 of at least 90%.

[0048] Biodegradation typically results in the breakdown of polyesters or polyester blends within a reasonable time. Degradation can occur through enzymes, hydrolysis, oxidation pathways, and / or exposure to electromagnetic radiation such as ultraviolet light; the most common cause is exposure to microorganisms such as bacteria, yeast, fungi, and algae. Biodegradability can be quantified by mixing polyesters into compost and storing them for a certain period of time. For example, according to DIN EN 13432, during the composting process, CO2-free air is passed through the mature compost, and the compost is subjected to a specific temperature regime. Here, biodegradability is defined as the percentage of biodegradability, expressed as the ratio between the net amount of CO2 released from the sample (after subtracting the amount of CO2 released from the compost without the sample) and the maximum amount of CO2 the sample can release (calculated based on the sample's carbon content).

[0049] Other methods for determining biodegradability are described in ASTM D5338 and ASTM D6400.

[0050] The present invention specifically relates to The method comprises the steps of: mixing component A and component B, with or without the addition of a titanium catalyst, to form a paste; and then: Step i): subjecting the paste to esterification or transesterification with all or part of a titanium catalyst in a phenol / o-dichlorobenzene solution with a weight ratio of 1:1 according to GB / T 17931-1999 standard until the viscosity number of the esterification or transesterification product reaches 12-21 ml / g as measured in a constant temperature water bath at 25±0.05°C; Step ii): subjecting the esterification or transesterification product obtained in step i) to a preliminary polycondensation reaction until the viscosity number of the prepolymer is 36-52 ml / g, as measured in a phenol / o-dichlorobenzene solution with a weight ratio of 1:1 according to GB / T 17931-1999 standard in a constant temperature water bath at 25±0.05°C; Step iii): Carry out polycondensation of the prepolymer obtained in step ii) until the viscosity number of the final polymerization product is 145-203 ml / g, as measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C according to GB / T 17931-1999 standard; Step iv): The final polymerization product of step iii) is sliced, and the resulting polyester particles are further contacted with an aqueous tetrahydrofuran solution to obtain the aliphatic-aromatic polyester composition, thereby protecting the method for preparing the aliphatic-aromatic polyester composition.

[0051] Here, the following should be explained:

[0052] In the preparation method of the aliphatic-aromatic polyester composition of the present invention, the specific procedure for measuring the viscosity number according to GB / T 17931-1999 is as follows:

[0053] The viscosity number of the product is measured in a solution of phenol / o-dichlorobenzene in a weight ratio of 1:1 in a constant temperature water bath at 25±0.05° C. according to GB / T 17931-1999.

[0054] Preferably, in step i), the dicarboxylic acid component of component A and the dihydroxy compound component of component B are mixed in a preliminary step. Typically, the materials mixed are:

[0055] 1.0 mol equivalent of a mixture of an aliphatic dicarboxylic acid and an aromatic dicarboxylic acid or their esters (component A), 1.2 to 2.4 mol equivalents, preferably 1.3 to 1.8 mol equivalents, of a C2-C6 aliphatic alkanediol (component b1), and preferably 0 to 3 wt %, more preferably 0.02 to 1 wt %, and particularly preferably 0.08 to 0.60 wt %, of a compound b2 containing at least three functional groups, based on the total weight of components A) and b1).

[0056] The catalyst may be a tin compound, an antimony compound, a cobalt compound, a lead compound, a zinc compound, an aluminum compound or a titanium compound, more preferably a zinc compound, an aluminum compound or a titanium compound, most preferably a titanium compound.

[0057] Furthermore, in the preparation method of the present invention, the amount of titanium catalyst used in step iii) is 0.001-1 wt%, preferably 0.03-0.2 wt%, of the mass of the final polymerization product. Preferably, the amount of catalyst added in step i) is 50-80% of the total amount of catalyst used. By controlling the amount of catalyst added, the subsequent processing can be more stable.

[0058] The titanium catalyst may be tetrabutyl titanate or tetraisopropyl titanate because the residual amounts left in the product or downstream products are less toxic than other compounds, a property that is particularly important since the biodegradable polyester is released directly into the environment in the form of compost bags or mulch film.

[0059] In step i), the esterification reaction temperature may be 180 to 260°C, preferably 220 to 250°C, and the reaction pressure may be 40 to 120 KPa, preferably 60 to 90 KPa.

[0060] Step i) may be carried out in a mixing device, for example a vertical stirred reactor, with a retention time of 2 to 6 hours, preferably 3 to 5 hours.

[0061] In step ii), the liquid obtained by the esterification reaction in step i) is added to a reactor for a pre-condensation reaction together with the remaining catalyst, and the reaction temperature is set to 235 to 260°C, preferably 240 to 250°C, and the pressure is set to 600 to 3000 Pa, preferably 800 to 2100 Pa. The typical retention time is 2 to 6 hours, preferably 3 to 4 hours.

[0062] Steps i), ii) and iii) may be carried out in the presence of the same titanium catalyst.

[0063] In step iii), for example, if necessary, other titanium-containing compounds may be added to the reaction system. Usable other titanium-containing compounds include one or a mixture of titanium tetrachloride, ferrous titanate, and barium metatitanate. The amount of the titanium-containing compound added may be 0 to 0.06 wt%, preferably 0.001 to 0.04 wt%, based on the amount of the final polymerization product obtained in step iii).

[0064] The polycondensation process of step iii) is carried out in a reactor such as a rotating disk reactor or a cage reactor, and the reaction temperature of the polycondensation is preferably 235-260°C, preferably 240-250°C, the pressure is 50-600 Pa, preferably 100-300 Pa, and the typical holding time is preferably 2-6 h, preferably 3-5 h.

[0065] Preferably, after step iii) and before step iv), the final polymerization product is subjected to the chain extension reaction of step iii-1) with a chain extender.

[0066] The specific procedure for the chain extension reaction is as follows.

[0067] Step iii-1): After step iii) is completed, the final polymerization product obtained in step iii) is added to a twin-screw extruder or a static mixer, and 0.05 to 2 wt%, particularly preferably 0.1 to 1.5 wt%, of a chain extender is added based on the mass of the final polymerization product. The reaction is carried out at 195 to 225°C for 5 to 12 minutes to obtain a chain-extended product having a viscosity of 163 to 232 mL / g as measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C in accordance with GB / T 17931-1999.

[0068] In specific embodiments, the chain extender is one or more of an isocyanate, a peroxide, an epoxide, and an oxazoline, an oxazine, a caprolactam, and / or a carbodiimide.

[0069] The chain extender may be, for example, one or more of toluene 2,4-diisocyanate, toluene 2,6-diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, and isophorone diisocyanate.

[0070] More preferably, the chain extender is hexamethylene-1,6-diisocyanate, and the amount used is 0.1 to 1.5 wt % of the weight of the chain-extended product.

[0071] Step iv) may be performed to further improve the yellowness index and hydrolysis resistance of the aliphatic-aromatic polyester composition. In step iv), the weight content of tetrahydrofuran in the tetrahydrofuran aqueous solution is 10 to 65 wt%, preferably 25 to 45 wt%. If the tetrahydrofuran content in the tetrahydrofuran aqueous solution is high, the amount of tetrahydrofuran remaining in the polyester particles will also be high. If the tetrahydrofuran content in the tetrahydrofuran aqueous solution is low, the elution effect will not be effectively achieved, and the yellowness index and hydrolysis resistance of the polyester composition will not be significantly improved.

[0072] More preferably, in step iv), the contact treatment temperature is 20 to 65°C, and more preferably 35 to 55°C.

[0073] More preferably, in step iv), the contact treatment time is 2 to 20 hours, more preferably 5 to 16 hours, and even more preferably 8 to 12 hours.

[0074] Preferably, in step iv), the mass ratio of the polyester particles to the aqueous tetrahydrofuran solution is 1:1 to 1:10.

[0075] More preferably, in step iv), the mass ratio of the polyester particles to the aqueous tetrahydrofuran solution is 1:2 to 1:5.

[0076] The temperature and time of the contact treatment of the polyester particles with the aqueous tetrahydrofuran solution, as well as the mass ratio of the polyester particles to the aqueous tetrahydrofuran solution, affect the final leaching effect and thus the yellowness index and hydrolysis resistance of the prepared aliphatic-aromatic polyester composition.

[0077] If the contact temperature is too high, the tetrahydrofuran will volatilize quickly, resulting in a large loss, and if the contact temperature is too low, the elution effect will not be effectively achieved, and the yellowness and hydrolysis resistance of the polyester composition will not be significantly improved.

[0078] If the contact time is too long, the content of tetrahydrofuran remaining in the polyester composition will be too high, and if the contact time is too short, the elution effect will not be effectively achieved, and the yellowness index and hydrolysis resistance of the polyester composition will not be significantly improved.

[0079] If the mass ratio of the tetrahydrofuran aqueous solution to the polyester particles is too high, the elution effect can be effectively improved, but the consumption of solvent increases, a lot of waste liquid is generated, and the economic benefit is low. In addition, the content of tetrahydrofuran remaining in the polyester composition is too high. If the mass ratio of the tetrahydrofuran aqueous solution to the polyester particles is too low, the polyester particles cannot be uniformly dispersed in the solution, the elution effect is uneven and poor, and the yellowness index and hydrolysis resistance of the polyester composition are not significantly improved.

[0080] The aliphatic-aromatic polyester composition of the present invention also contains small amounts of tetrahydrofuran, mainly derived from three sources: tetrahydrofuran produced by decomposition of 1,4-butanediol during the polyester synthesis process; tetrahydrofuran produced by "biting" polyester end groups due to thermal decomposition during the polymerization process; and residual tetrahydrofuran aqueous solution from the contact treatment step (iv). In the present invention, residual tetrahydrofuran in polyester particles is undesirable. In principle, the lower the content of residual tetrahydrofuran in polyester particles, the better.

[0081] The reduction of the tetrahydrofuran content can be achieved by controlling the reaction temperature, reaction pressure, etc. in steps i), ii), and iii), or by optimizing the contact treatment conditions in step iv), such as the concentration of the tetrahydrofuran aqueous solution, the contact treatment temperature, time, and solid-liquid ratio in the contact treatment. If the reaction temperature in steps i), ii), and iii) is too low, the polymerization time will be too long, making it difficult to obtain a low-acid polyester. If the reaction pressure is too low, the equipment requirements will be high, requiring a large capital investment. The contact treatment conditions in step iv) must also take into account the effect on leaching and the improvement of the color and hydrolysis resistance of the polyester product.

[0082] The aliphatic-aromatic polyester composition prepared by the preparation method of the present invention comprises, as components: i) aliphatic-aromatic polyesters based on aliphatic and aromatic dicarboxylic acids and aliphatic dihydroxy compounds, said aliphatic-aromatic polyesters comprising at least as components: A) Dicarboxylic acid component: the total molar percentage of components a1) and a2) is 100%; a1) 46.2 to 49.5 mol% of aromatic dicarboxylic acid or its ester derivative, or a mixture thereof, based on the total molar amount of a1) and a2); a2) 50.5 to 53.8 mol% of aliphatic dicarboxylic acids or derivatives of their esters, or mixtures thereof, based on the total molar amount of a1) and a2), and B) a dihydroxy compound component: b1) a C2-C6 aliphatic alkanediol or a mixture thereof, in at least an equimolar amount with component A; b2) 0 to 3 wt% of a compound containing at least three functional groups, based on the total weight of components A and b1 an aliphatic-aromatic polyester comprising ii) titanium element in a content of 55 to 88 ppm based on the weight of the aliphatic-aromatic polyester composition; iii) tetrahydrofuran in an amount of 40 to 170 ppm based on the weight of the aliphatic-aromatic polyester composition; The aliphatic-aromatic polyester composition has an acid number of less than or equal to 0.84 mg KOH / g according to DIN EN 12634-1998.

[0083] Preferably, the content of the tetrahydrofuran is 86 to 136 ppm based on the weight of the aliphatic-aromatic polyester composition.

[0084] The aliphatic-aromatic polyester composition produced by the production method of the present invention has an odor rating of 4.5 or less according to the FLTM BO131-03 standard.

[0085] The present invention specifically further provides for the use of said aliphatic-aromatic polyester compositions in the preparation of polyester fibers.

[0086] The polyester composition of the present invention has a low yellowness index and excellent hydrolysis resistance. The polyester composition of the present invention is also suitable for producing biodegradable polymer blends containing, as a base resin, one or more components selected from the following:

[0087] Aliphatic polyesters, polycaprolactone, starch (thermoplastic or non-thermoplastic), cellulose, polyhydroxyalkanoates, and polylactic acid.

[0088] The biodegradable polymer mixture can be used to prepare polyester fibers.

[0089] Specifically, the present invention comprises the following components: i) 5 to 15 wt % of the aliphatic-aromatic polyester composition described above, based on the total weight of components i) to iv); ii) 35 to 70 wt % of an aliphatic polyester based on the total weight of components i) to iv); iii) 10 to 40 wt % of one or more components selected from starch, wood flour, cellulose, polyhydroxyalkanoate, polyglycolic acid, and polylactic acid, based on the total weight of components i) to iv); iv) 10 to 35 wt % of one or more components selected from talc, calcium carbonate, barium sulfate, montmorillonite, and kaolin, based on the total weight of components i) to iv); Further protecting the polyester fibers.

[0090] The present invention further provides for the use of said polyester fibers in particular in masks and clothing. [Effects of the Invention]

[0091] The present invention has the following advantageous effects compared to the prior art.

[0092] The aliphatic-aromatic polyester composition of the present invention contains titanium element in an amount of 55 to 88 ppm based on the mass of the aliphatic-aromatic polyester composition, and the acid value of the aliphatic-aromatic polyester composition is 0.84 mg KOH / g or less according to standard DIN EN 12634-1998. By comprehensively adjusting the titanium element content and acid value, the aliphatic-aromatic polyester composition not only has a low yellowness index and excellent colorability, but also effectively improves hydrolysis resistance, making it widely usable in the field of polyester fibers.

[0093] Furthermore, the content of tetrahydrofuran in the aliphatic-aromatic polyester composition of the present invention is 20-170 ppm, and its odor grade is 4.5 or less according to the FLTM BO131-03 standard. DETAILED DESCRIPTION OF THE INVENTION

[0094] The present invention will be further described below with reference to specific embodiments, but the examples do not limit the present invention in any way. The raw materials and reagents used in the examples of the present invention are commonly purchased raw materials and reagents unless otherwise specified.

[0095] The information on the raw materials used in the examples and comparative examples of the present invention is as follows: 1,4-Butanediol was purchased from MARKORCHEM (Xinjiang) Co., Ltd. Terephthalic acid was purchased from INEOS (Zhuhai) Co., Ltd. Adipic acid was purchased from Chongqing Huafeng Chemical Group Co., Ltd. Sebacic acid was purchased from Hengshui Jinghua Chemical Co., Ltd. Glycerol was purchased from Aladdin. Tetrabutyl titanate was purchased from JianYi Chemical Import & Export Co., Ltd. Titanium tetrachloride was purchased from Aladdin. Hexamethylene diisocyanate was purchased from Aladdin. The performance test method of the present invention is specifically explained as follows.

[0096] Testing the molar content of aromatic dicarboxylic acids (a1) and adipic acid (a2) in aliphatic-aromatic polyesters: 20 mg of an aliphatic-aromatic polyester composition sample was dissolved in 0.6 mL of deuterated chloroform and measured at room temperature using a Bruker AV500 nuclear magnetic resonance spectrometer. 1 H NMR was measured and the chloroform solvent peak was calibrated to approximately 7.26 ppm. Literature: Chen, X.; Chen, W.; Zhu, G.; Huang, F.; Zhang, J., Synthesis, 1 H-NMR characterization and biodegradation behavior of aliphatic-aromatic random copolyester. J. Appl. Polym. Sci. 2007, 104(4): 2643-2649. It was found that in the case of aromatic dicarboxylic acids such as terephthalic acid, the four hydrogen atoms on the benzene ring of the repeating unit appear at around 8.10 ppm, and in the case of aliphatic dicarboxylic acids such as adipic acid, the four hydrogen atoms of the two CH2 units adjacent to the carbonyl of the repeating unit appear at around 2.33 ppm. Therefore, the molar content of the diacid component is determined by the integrated area (I) of the two peaks at 8.10 ppm and 2.33 ppm. T and I A ) can be expressed as Molar content of aromatic dicarboxylic acid in aliphatic-aromatic polyester = I T / (I T +I A )×100% Molar content of adipic acid in aliphatic-aromatic polyester = I A / (I T +I A )×100%

[0097] Viscosity number test: According to GB / T 17931-1999, the viscosity number was measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C, and the sample concentration was 5mg / ml.

[0098] Acid number: The acid number AN (mg KOH / g) of the samples was determined according to DIN EN 12634 of October 1998. The solvent mixture used contained 1 part by volume of dimethyl sulfoxide, 8 parts by volume of isopropanol, and 7 parts by volume of toluene, and the volume of the solvent mixture was 150 ml. In accordance with the DIN EN 12634-1998 standard, the sample was pre-titrated to determine the appropriate sample mass and ensure that the volume of titrant consumed was 2-3 ml. The sample was added to the solvent mixture and heated to 70-85°C to completely dissolve the sample and form a clear solution. The solution temperature was maintained between 65-75°C during titration to avoid sample precipitation. Tetrabutylammonium hydroxide was used as the titrant, if appropriate; tetramethylammonium hydroxide, which is highly toxic, should be avoided. To prevent the solvent mixture from absorbing CO2 from the air and affecting the volume of titrant consumed by the blank solvent, the blank solvent should be pretreated using the same process as the sample test. For example, the blank solvent was heated for the same time and temperature, and then titrated.

[0099] Yellowness Index (YI) Test Method: The yellowness index of aliphatic-aromatic polyester composition particles was measured using a Minolta CM-5 spectrophotometer according to ASTM E313-73. The particles had a particle size of 1.2 to 5.4 g / 100 particles. The average value was determined from three parallel tests. A glass cuvette (Minolta) was filled with the particulate material to be analyzed (fill height at least 3 cm). The particulate material was compressed using pressure from the measurement head of the Minolta instrument.

[0100] Hydrolysis resistance rating: The hydrolysis resistance of the aliphatic-aromatic polyester composition was evaluated as follows. 1) The aliphatic-aromatic polyester composition sample was dehumidified and dried at 80°C for 4 hours, and the initial viscosity η before boiling was tested according to the standard GB / T 17931-1999; 2) The aliphatic-aromatic polyester composition sample was placed in a water bath at 60°C and boiled for 48 hours. 3) After 48 hours, the aliphatic-aromatic polyester composition sample is taken out and transferred to a desiccator and stored at ambient temperature for 24 hours to achieve internal equilibrium conditions for the sample; 4) After reaching equilibrium, the sample is dehumidified and dried at 80°C for 4 hours, and its viscosity number η1 after boiling for 48 hours is tested according to standard GB / T 17931-1999. The viscosity number retention of the aliphatic-aromatic polyester composition after boiling in water is calculated by the following formula: η=η1 / η0 (Here, η1 represents the viscosity number of the aliphatic-aromatic polyester composition after boiling in water at 60°C for 48 hours, and η0 represents the viscosity number of the aliphatic-aromatic polyester composition before boiling.) Follow. The greater the viscosity number retention η of the aliphatic-aromatic polyester composition after boiling, the stronger the hydrolysis resistance of the sample. The smaller the viscosity number retention η, the weaker the hydrolysis resistance of the sample.

[0101] Titanium element content: The titanium element content in the aliphatic-aromatic polyester composition was measured by the following procedure using ICP-OES analysis, with reference to US EPA Method 3052:1996. Approximately 0.1 g of the aliphatic-aromatic polyester composition was weighed and pulverized, and 5 ml of nitric acid was added to completely immerse the aliphatic-aromatic polyester composition. 1.0 ml of hydrogen peroxide was then added dropwise over 2 minutes. The mixture was sealed in a microwave digestion tank and decomposed at 210°C for 3 hours. After cooling to room temperature, the mixture was filtered through a 0.45 μm filter membrane, diluted to 50 ml with distilled water, and tested by ICP-OES.

[0102] Tetrahydrofuran (THF) content test method: Approximately 1.2 g of sample was weighed, the headspace temperature was 105° C., and the headspace time was 2 hours. The test was performed using an Agilent 7697A-7890A instrument. Tables 1 and 2 show the test parameters and test methods for the Agilent 7697A-7890A.

[0103] [Table 1]

[0104] [Table 2]

[0105] GC temperature ramp procedure: Initial temperature: 50°C, holding time: 3 minutes; heating to 200°C, heating rate: 12°C / min, holding time: 4 minutes. [Example]

[0106] Comparative Examples 1 to 7 Comparative Example 1 Step i): 452 kg of terephthalic acid, 437 kg of adipic acid, 690 kg of 1,4-butanediol, 2.30 kg of glycerol, and 0.560 kg of tetrabutyl titanate were physically mixed in an esterification reactor at room temperature, and then the mixture was esterified at 235°C and 90 kPa pressure for 4-5 hours to obtain an esterified product. The viscosity number of the esterified product was measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C in accordance with GB / T 17931-1999, and was found to be 23 ml / g. Step ii): The esterified product was placed in a vertically stirred, thoroughly mixed reactor. 0.400 kg of tetrabutyl titanate was added to the reactor and heated to 242°C. The reaction was carried out at a pressure of 1800 Pa for 2-3 hours. Most of the excess 1,4-butanediol was removed by distillation to obtain a prepolymer. The viscosity of the prepolymer was measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C in accordance with GB / T 17931-1999, and found to be 65 ml / g. Step iii): The reaction mixture was transferred to a final polymerization reactor and polycondensed at 248°C and 115 Pa for 2-3 hours. Excess 1,4-butanediol and other by-products were removed by distillation. The resulting mixture was then granulated and dried to obtain the final polymerization product. The viscosity number of the final polymerization product was measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C according to GB / T 17931-1999, and was found to be 181 ml / g. Step iv): The polyester particles were placed in a reactor and contacted with the tetrahydrofuran aqueous solution at a mass ratio of 1:5. The mass concentration of the tetrahydrofuran aqueous solution was 45%, the contact temperature was 35°C, and the contact time was 8 hours. A drying step may be further provided after the contact treatment step, and the drying may be carried out in a blower drying tower. According to the test method of the present invention, the biodegradable composition obtained by drying in step iv) was tested for viscosity number, acid value, melt index, titanium element content, THF content, and yellowness index, and also evaluated for hydrolysis resistance and odor. Specific data are shown in Table 1.

[0107] Comparative Example 2 Step i): 452 kg of terephthalic acid, 437 kg of adipic acid, 690 kg of 1,4-butanediol, 2.30 kg of glycerol, and 0.235 kg of tetrabutyl titanate were physically mixed in an esterification reactor at room temperature, and then the mixture was esterified at 240°C and 85 kPa pressure for 5-6 hours to obtain an esterified product. The viscosity number of the esterified product was measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C in accordance with GB / T 17931-1999, and was found to be 8 ml / g. Step ii): The esterified product was placed in a vertically stirred, thoroughly mixed reactor. 0.125 kg of tetrabutyl titanate was added to the reactor and heated to 245°C. The reaction was carried out at a pressure of 1600 Pa for 3-4 hours. Most of the excess 1,4-butanediol was removed by distillation to obtain a prepolymer. The viscosity of the prepolymer was measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C in accordance with GB / T 17931-1999, and found to be 28 ml / g. Step iii): The reaction mixture was transferred to a final polymerization reactor and polycondensed at 252°C and 145 Pa for 4-5 hours. Excess 1,4-butanediol and other by-products were removed by distillation. The resulting mixture was then granulated and dried to obtain the final polymerization product. The viscosity number of the final polymerization product was measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C according to GB / T 17931-1999, and was found to be 169 ml / g. Step iv): The polyester particles were placed in a reactor and contacted with the tetrahydrofuran aqueous solution at a mass ratio of 1:5. The mass concentration of the tetrahydrofuran aqueous solution was 45%, the contact temperature was 35°C, and the contact time was 8 hours. A drying step may be further provided after the contact treatment step, and the drying may be carried out in a blower drying tower. According to the test method of the present invention, the biodegradable polyester composition obtained by drying in step iv) was tested for viscosity number, acid value, melt index, titanium element content, THF content, and yellowness index, and also evaluated for hydrolysis resistance and odor. Specific data are shown in Table 1.

[0108] Comparative Example 3 Step i): 452 kg of terephthalic acid, 437 kg of adipic acid, 690 kg of 1,4-butanediol, 2.30 kg of glycerol, and 0.350 kg of tetrabutyl titanate were physically mixed in an esterification reactor at room temperature, and then the mixture was esterified at 238°C and 90 kPa pressure for 4-5 hours to obtain an esterified product. The viscosity number of the esterified product was measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C in accordance with GB / T 17931-1999, and was found to be 17 ml / g. Step ii): The esterified product was placed in a vertically stirred, thoroughly mixed reactor. 0.220 kg of tetrabutyl titanate was added to the reactor and heated to 245°C. The reaction was carried out at a pressure of 2100 Pa for 3-4 hours. Most of the excess 1,4-butanediol was removed by distillation to obtain a prepolymer. The viscosity of the prepolymer was measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C in accordance with GB / T 17931-1999, and found to be 48 ml / g. Step iii): The reaction mixture was transferred to a final polymerization reactor and polycondensed at 251°C and 100 Pa for 3-4 hours. Excess 1,4-butanediol and other by-products were removed by distillation. The resulting mixture was then granulated and dried to obtain the final polymerization product. The viscosity number of the final polymerization product was measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C according to GB / T 17931-1999, and was found to be 180 ml / g. According to the test method of the present invention, the biodegradable polyester composition obtained by drying in step iii) was tested for viscosity number, acid value, melt index, titanium element content, THF content, and also evaluated for hydrolysis resistance and odor. Specific data are shown in Table 1.

[0109] Comparative Example 4 In Comparative Example 4, steps i) to iii) were the same as those in Comparative Example 3. Step iv): The polyester particles were placed in a reactor and contacted with the tetrahydrofuran aqueous solution at a mass ratio of 1:15, with the mass concentration of the tetrahydrofuran aqueous solution being 5%, the contact temperature being 20°C, and the contact time being 24 hours. A drying step may be further provided after the contact treatment step, and the drying may be carried out in a blower drying tower. According to the test method of the present invention, the biodegradable polyester composition obtained by drying in step iv) was tested for viscosity number, acid value, melt index, titanium element content, THF content, and yellowness index, and also evaluated for hydrolysis resistance and odor. Specific data are shown in Table 1.

[0110] Comparative Example 5 Comparative Example 5: Steps i) to iii) were the same as those in Comparative Example 3. Step iv): The polyester particles were placed in a reactor and contacted with the tetrahydrofuran aqueous solution at a mass ratio of 1:0.5. The mass concentration of the tetrahydrofuran aqueous solution was 75%, the contact temperature was 40°C, and the contact time was 3 hours. A drying step may be further provided after the contact treatment step, and the drying may be carried out in a blower drying tower. According to the test method of the present invention, the biodegradable polyester composition obtained by drying in step iv) was tested for viscosity number, acid value, melt index, titanium element content, THF content, and yellowness index, and also evaluated for hydrolysis resistance and odor. Specific data are shown in Table 1.

[0111] Comparative Example 6 Step i): 420 kg of terephthalic acid, 437 kg of adipic acid, 690 kg of 1,4-butanediol, 2.30 kg of glycerol, and 0.385 kg of tetrabutyl titanate were physically mixed in an esterification reactor at room temperature, and then the mixture was esterified at 238°C and 90 kPa pressure for 4-5 hours to obtain an esterified product. The viscosity number of the esterified product was measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C in accordance with GB / T 17931-1999, and was found to be 11 ml / g. Step ii): The esterified product was placed in a vertically stirred, thoroughly mixed reactor. 0.200 kg of tetrabutyl titanate was added to the reactor and heated to 245°C. The reaction was carried out at a pressure of 2100 Pa for 3-4 hours. Most of the excess 1,4-butanediol was removed by distillation to obtain a prepolymer. The viscosity of the prepolymer was measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C in accordance with GB / T 17931-1999, and found to be 33 ml / g. Step iii): The reaction mixture was transferred to a final polymerization reactor and polycondensed at 251°C and 100 Pa for 3-4 hours. Excess 1,4-butanediol and other by-products were removed by distillation. The resulting mixture was then granulated and dried to obtain the final polymerization product. The viscosity number of the final polymerization product was measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C according to GB / T 17931-1999, and was found to be 173 ml / g. Step iv): The polyester particles were placed in a reactor and contacted with the tetrahydrofuran aqueous solution at a mass ratio of 1:5. The mass concentration of the tetrahydrofuran aqueous solution was 45%, the contact temperature was 35°C, and the contact time was 8 hours. A drying step may be further provided after the contact treatment step, and the drying may be carried out in a blower drying tower. According to the test method of the present invention, the biodegradable composition obtained by drying in step iv) was tested for viscosity number, acid value, melt index, titanium element content, THF content, and yellowness index, and also evaluated for hydrolysis resistance. Specific data are shown in Table 1.

[0112] Comparative Example 7 Step i): 585 kg of terephthalic acid, 437 kg of adipic acid, 760 kg of 1,4-butanediol, 2.60 kg of glycerol, and 0.520 kg of tetrabutyl titanate were physically mixed in an esterification reactor at room temperature, and then the mixture was esterified at 238°C and 90 kPa pressure for 4-5 hours to obtain an esterified product. The viscosity number of the esterified product was measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C in accordance with GB / T 17931-1999, and was found to be 24 ml / g. Step ii): The esterified product was placed in a vertically stirred, thoroughly mixed reactor. 0.225 kg of tetrabutyl titanate was added to the reactor and heated to 245°C. The reaction was carried out at a pressure of 2100 Pa for 3-4 hours. Most of the excess 1,4-butanediol was removed by distillation to obtain a prepolymer. The viscosity of the prepolymer was measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C in accordance with GB / T 17931-1999, and found to be 55 ml / g. Step iii): The reaction mixture was transferred to a final polymerization reactor and polycondensed at 251°C and 100 Pa for 3-4 hours. Excess 1,4-butanediol and other by-products were removed by distillation. The resulting mixture was then granulated and dried to obtain the final polymerization product. The viscosity number of the final polymerization product was measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C according to GB / T 17931-1999, and was found to be 188 ml / g. Step iv): The polyester particles were placed in a reactor and contacted with the tetrahydrofuran aqueous solution at a mass ratio of 1:5. The mass concentration of the tetrahydrofuran aqueous solution was 45%, the contact temperature was 35°C, and the contact time was 8 hours. A drying step may be further provided after the contact treatment step, and the drying may be carried out in a blower drying tower. According to the test method of the present invention, the biodegradable composition obtained by drying in step iv) was tested for viscosity number, acid value, melt index, titanium element content, THF content, and yellowness index, and also evaluated for hydrolysis resistance. Specific data are shown in Table 1.

[0113] [Table 3]

[0114] Example 1 Step i): 452 kg of terephthalic acid, 437 kg of adipic acid, 690 kg of 1,4-butanediol, 2.30 kg of glycerol, and 0.400 kg of tetrabutyl titanate were physically mixed in an esterification reactor at room temperature, and then the mixture was esterified at 240°C and 100 kPa pressure for 4-5 hours to obtain an esterified product. The viscosity number of the esterified product was measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C in accordance with GB / T 17931-1999, and was found to be 18 ml / g. Step ii): The esterified product was placed in a vertically stirred, thoroughly mixed reactor. 0.200 kg of tetrabutyl titanate was added to the reactor and heated to 247°C. The reaction was carried out at a pressure of 1900 Pa for 3-4 hours. Most of the excess 1,4-butanediol was removed by distillation to obtain a prepolymer. The viscosity of the prepolymer was measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C in accordance with GB / T 17931-1999, and found to be 50 ml / g. Step iii): 0.050 kg of titanium tetrachloride was added, and the reaction mixture was transferred to a final polymerization reactor and polycondensed at 250°C and 120 Pa for 3-4 hours. Excess 1,4-butanediol and other by-products were removed by distillation, and the resulting mixture was granulated and dried to obtain the final polymerization product. The viscosity number of the final polymerization product was measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C in accordance with GB / T 17931-1999, and was found to be 181 ml / g. Step iv): The polyester particles were placed in a reactor and contacted with the tetrahydrofuran aqueous solution at a mass ratio of 1:2. The mass concentration of the tetrahydrofuran aqueous solution was 25%, the contact temperature was 55°C, and the contact time was 12 hours. A drying step may be further provided after the contact treatment step, and the drying may be carried out in a blower drying tower. According to the test method of the present invention, the biodegradable polyester composition obtained by drying in step iv) was tested for viscosity number, acid value, melt index, titanium element content, THF content, and yellowness index, and also evaluated for hydrolysis resistance and odor. Specific data are shown in Table 2.

[0115] Examples 2 to 7 Example 2-7: Steps i) to iii) were the same as those in Comparative Example 3, and in step iv), the biodegradable polyester composition was subjected to a contact treatment step under the process conditions shown in Table 2.

[0116] [Table 4]

[0117] Example 8 Step i): 425 kg of terephthalic acid, 437 kg of adipic acid, 690 kg of 1,4-butanediol, 2.30 kg of glycerol, and 0.310 kg of tetrabutyl titanate were physically mixed in an esterification reactor at room temperature, and then the mixture was esterified at 233°C and 70 kPa pressure for 3-4 hours to obtain an esterified product. The viscosity number of the esterified product was measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C in accordance with GB / T 17931-1999, and was found to be 12 ml / g. Step ii): The esterified product was placed in a vertically stirred, thoroughly mixed reactor. 0.240 kg of tetrabutyl titanate was added to the reactor and heated to 243°C. The reaction was carried out at a pressure of 1200 Pa for 3-4 hours. Most of the excess 1,4-butanediol was removed by distillation to obtain a prepolymer. The viscosity of the prepolymer was measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C in accordance with GB / T 17931-1999, and found to be 36 ml / g. Step iii): The reaction mixture was transferred to a final polymerization reactor and polycondensed at 252°C and 110 Pa for 3-4 hours. Excess 1,4-butanediol and other by-products were removed by distillation. The resulting mixture was then granulated and dried to obtain the final polymerization product. The viscosity number of the final polymerization product was measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C according to GB / T 17931-1999, and was found to be 177 ml / g. Step iv): The polyester particles were placed in a reactor and contacted with the tetrahydrofuran aqueous solution at a mass ratio of 1:3. The mass concentration of the tetrahydrofuran aqueous solution was 65%, the contact temperature was 30°C, and the contact time was 2 hours. A drying step may be further provided after the contact treatment step, and the drying may be carried out in a blower drying tower. According to the test method of the present invention, the biodegradable polyester composition obtained by drying in step iv) was tested for viscosity number, acid value, melt index, titanium content, THF content, and yellowness index, and also evaluated for hydrolysis resistance and odor. Specific data are shown in Table 3.

[0118] Example 9 Step i): 570 kg of dimethyl terephthalate, 437 kg of adipic acid, 730 kg of 1,4-butanediol, 2.60 kg of glycerol, and 0.340 kg of tetrabutyl titanate were physically mixed in an esterification reactor at room temperature, and then the mixture was esterified at 240°C and 65 kPa pressure for 3-4 hours to obtain an esterified product. The viscosity number of the esterified product was measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C in accordance with GB / T 17931-1999, and was found to be 21 ml / g. Step ii): The esterified product was placed in a vertically stirred, thoroughly mixed reactor. 0.250 kg of tetrabutyl titanate was added to the reactor and heated to 245°C. The reaction was carried out at 900 Pa for 3-4 hours. Most of the excess 1,4-butanediol was removed by distillation to obtain a prepolymer. The viscosity of the prepolymer was measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C in accordance with GB / T 17931-1999, and found to be 52 ml / g. Step iii): The reaction mixture was transferred to a final polymerization reactor and polycondensed at 250°C and 118 Pa for 4-5 hours. Excess 1,4-butanediol and other by-products were removed by distillation. The resulting mixture was then granulated and dried to obtain the final polymerization product. The viscosity number of the final polymerization product was measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C according to GB / T 17931-1999, and was found to be 186 ml / g. Step iv): The polyester particles were placed in a reactor and contacted with the tetrahydrofuran aqueous solution at a mass ratio of 1:8. The mass concentration of the tetrahydrofuran aqueous solution was 40%, the contact temperature was 65°C, and the contact time was 5 hours. A drying step may be further provided after the contact treatment step, and the drying may be carried out in a blower drying tower. According to the test method of the present invention, the biodegradable polyester composition obtained by drying in step iv) was tested for viscosity number, acid value, melt index, titanium content, THF content, and yellowness index, and also evaluated for hydrolysis resistance and odor. Specific data are shown in Table 3.

[0119] Example 10 Step i): 445 kg of terephthalic acid, 437 kg of adipic acid, 690 kg of 1,4-butanediol, 2.30 kg of glycerol, and 0.285 kg of tetrabutyl titanate were physically mixed in an esterification reactor at room temperature, and then the mixture was esterified at 240°C and 75 kPa pressure for 4-5 hours to obtain an esterified product. The viscosity number of the esterified product was measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C in accordance with GB / T 17931-1999, and was found to be 14 ml / g. Step ii): The esterified product was placed in a vertically stirred, thoroughly mixed reactor. 0.185 kg of tetrabutyl titanate was added to the reactor and heated to 250°C. The reaction was carried out at a pressure of 1400 Pa for 3-4 hours. Most of the excess 1,4-butanediol was removed by distillation to obtain a prepolymer. The viscosity of the prepolymer was measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C in accordance with GB / T 17931-1999, and found to be 39 ml / g. Step iii): The reaction mixture was transferred to a final polymerization reactor and polycondensed at 250°C and 130 Pa for 3-4 hours. Excess 1,4-butanediol and other by-products were removed by distillation. The resulting mixture was then granulated and dried to obtain the final polymerization product. The viscosity number of the final polymerization product was measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C according to GB / T 17931-1999, and was found to be 179 ml / g. Step iv): The polyester particles were placed in a reactor and contacted with the tetrahydrofuran aqueous solution at a mass ratio of 1:5. The mass concentration of the tetrahydrofuran aqueous solution was 45%, the contact temperature was 35°C, and the contact time was 8 hours. A drying step may be further provided after the contact treatment step, and the drying may be carried out in a blower drying tower. According to the test method of the present invention, the biodegradable polyester composition obtained by drying in step iv) was tested for viscosity number, acid value, melt index, titanium content, THF content, and yellowness index, and its hydrolysis resistance was also evaluated. Specific data are shown in Table 3.

[0120] Example 11 Step i): 475 kg of terephthalic acid, 437 kg of adipic acid, 690 kg of 1,4-butanediol, 2.40 kg of glycerol, and 0.460 kg of tetrabutyl titanate were physically mixed in an esterification reactor at room temperature, and then the mixture was esterified at 230°C and 60 kPa pressure for 3-4 hours to obtain an esterified product. The viscosity number of the esterified product was measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C in accordance with GB / T 17931-1999, and was found to be 13 ml / g. Step ii): The esterified product was placed in a vertically stirred, completely mixed reactor. 0.234 kg of tetrabutyl titanate was added to the reactor and heated to 240°C. The reaction was carried out at a pressure of 630 Pa for 2-3 hours. Most of the excess 1,4-butanediol was removed by distillation to obtain a prepolymer. The viscosity of the prepolymer was measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C in accordance with GB / T 17931-1999, and found to be 37 ml / g. Step iii): 0.042 kg of titanium tetrachloride was added, and the reaction mixture was transferred to a final polymerization reactor and polycondensed at 248°C and 110 Pa for 2-3 hours. Excess 1,4-butanediol and other by-products were removed by distillation to obtain the final polymerization product. The viscosity number of the final polymerization product was measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C according to GB / T 17931-1999, and was 147 ml / g. Step iii-1): The final polymerization product of Step iii) was placed in a static mixer, and 1.1 kg of hexamethylene diisocyanate was added. The mixture was blended and reacted at 200°C for 6 minutes, then granulated and dried to obtain a chain-extended product. The viscosity number of the chain-extended product was measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C in accordance with GB / T 17931-1999, and was found to be 192 ml / g. Step iv): The polyester particles were placed in a reactor and contacted with the tetrahydrofuran aqueous solution at a mass ratio of 1:2. The mass concentration of the tetrahydrofuran aqueous solution was 25%, the contact temperature was 55°C, and the contact time was 12 hours. A drying step may be further provided after the contact treatment step, and the drying may be carried out in a blower drying tower. According to the test method of the present invention, the biodegradable polyester composition obtained by drying in step iv) was tested for viscosity number, acid value, melt index, titanium content, THF content, and yellowness index, and its hydrolysis resistance was also evaluated. Specific data are shown in Table 3.

[0121] Example 12 Step i-1): 437 kg of adipic acid, 350 kg of 1,4-butanediol, and 2.60 kg of glycerol were physically mixed in esterification reactor A at room temperature, and then the mixture was esterified at 192°C and 110 kPa pressure for 2-3 hours to obtain esterification product P-1. The viscosity number of the esterification product was measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C in accordance with GB / T 17931-1999, and was found to be 7 ml / g. Step i-2): 452 kg of terephthalic acid, 480 kg of 1,4-butanediol, and 0.440 kg of tetrabutyl titanate were physically mixed in esterification reactor B at room temperature, and then the mixture was esterified at 240°C and 85 kPa pressure for 3-4 hours to obtain esterification product P-2. The viscosity number of the esterification product was measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C in accordance with GB / T 17931-1999, and was found to be 16 ml / g. Step ii): The esterification product P-1 from step i-1) was preheated to 230°C and placed in a vertically stirred reactor with complete mixing along with the esterification product P-2 from step i-2). 0.100 kg of tetrabutyl titanate was added to the reactor, heated to 243°C, and reacted at a pressure of 2200 Pa for 3-4 hours. Most of the excess 1,4-butanediol was removed by distillation to obtain a prepolymer. The viscosity number of the prepolymer was measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C in accordance with GB / T 17931-1999, and was found to be 43 ml / g. Step iii): The reaction mixture was transferred to a final polymerization reactor and polycondensed at a temperature of 248°C and a pressure of 110 Pa for 2-3 hours. Excess 1,4-butanediol and other by-products were removed by distillation. The viscosity number of the final polymerization product was measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C according to GB / T 17931-1999 standard, and was 145 ml / g. Step iii-1): The final polymerization product of step iii) was placed in a static mixer, and 1.1 kg of hexamethylene diisocyanate was added. The mixture was blended and reacted at 220°C for 7 minutes. The mixture was then granulated in an underwater granulator and dried to obtain a chain-extended product. The viscosity number of the chain-extended product was measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C in accordance with GB / T 17931-1999, and the result was 195 ml / g. According to the test method of the present invention, the biodegradable polyester composition obtained in step iii-1) was tested for viscosity number, acid value, melt index, titanium content, THF content, and yellowness index, and also evaluated for hydrolysis resistance and odor. Specific data are shown in Table 3.

[0122] [Table 5]

[0123] It is clear from the data in Tables 1, 2, and 3 that when the titanium content of an aliphatic-aromatic polyester composition is 55 to 88 ppm, preferably 63 to 81 ppm, and the acid value is 0.84 mg KOH / g or less, preferably 0.78 mg KOH / g or less, the aliphatic-aromatic polyester composition has a high viscosity number retention rate η after boiling in water at 60°C for 48 hours, and the yellowness index YI value of the biodegradable polyester composition is 23 or less, preferably 19 or less.

[0124] It is clear that the above examples of the present invention are merely examples for clearly explaining the present invention and do not limit the embodiments of the present invention. Those skilled in the art can make other different changes or modifications based on the above description. It is not necessary and cannot be possible to list all embodiments comprehensively here. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention should be included within the scope of the claims of the present invention.

Claims

1. 1. An aliphatic-aromatic polyester composition comprising: The composition comprises, as components: i) Aliphatic-aromatic polyesters based on aliphatic and aromatic dicarboxylic acids and aliphatic dihydroxy compounds, said aliphatic-aromatic polyesters comprising as components: A) a1) 46.2 to 49.5 mol %, based on the total molar amount of a1) and a2), of a derivative of an aromatic dicarboxylic acid or an ester thereof, or a mixture thereof; a2) 50.5 to 53.8 mol % of adipic acid or its ester derivatives, or mixtures thereof, based on the total molar amount of a1) and a2). wherein the total mole percentage of components a1) and a2) is 100%; and B) b1) C in an amount at least equimolar to that of component A ２ ~C ６ aliphatic alkanediols, or mixtures thereof; b2) 0 to 3 wt %, based on the total weight of components A and b1, of a compound containing at least three functional groups Dihydroxy compound components including an aliphatic-aromatic polyester comprising: ii) elemental titanium in an amount of 55 to 88 ppm based on the weight of the aliphatic-aromatic polyester composition; Including, 1. An aliphatic-aromatic polyester composition, characterized in that the aliphatic-aromatic polyester composition has an acid number of less than or equal to 0.84 mg KOH / g according to standard DIN EN 12634-1998.

2. 2. The aliphatic-aromatic polyester composition of claim 1, characterized in that the aliphatic-aromatic polyester composition has a Yellowness Index YI value of less than or equal to 23, measured according to standard ASTM E313-73.

3. when the aliphatic-aromatic polyester composition is boiled in water at 60°C for 48 hours, the viscosity number retention rate η of the aliphatic-aromatic polyester composition after boiling is 65% or more; Here, the viscosity number retention rate η is calculated by the following formula: the=the １ / or ０ (In the formula, η １ represents the viscosity number of the aliphatic-aromatic polyester composition after boiling in water at 60°C for 48 hours, η ０ represents the viscosity number of the aliphatic-aromatic polyester composition before boiling.

2. The aliphatic-aromatic polyester composition of claim 1, wherein the polyester is a polyester of which the temperature is 100° C. or less.

4. The dicarboxylic acid component A) includes the following components: a1) 47.3 to 48.8 mol % based on the total molar amount of a1) and a2) of a derivative of an aromatic dicarboxylic acid or an ester thereof, or a mixture thereof; a2) 51.2 to 52.7 mol %, based on the total molar amount of a1) and a2), of a derivative of adipic acid or its ester, or a mixture thereof; 2. The aliphatic-aromatic polyester composition of claim 1, comprising:

5. 2. The aliphatic-aromatic polyester composition according to claim 1, wherein the content of the titanium element is 63 to 81 ppm based on the weight of the aliphatic-aromatic polyester composition.

6. 2. The aliphatic-aromatic polyester composition according to claim 1, characterized in that the aliphatic-aromatic polyester composition has an acid number of less than or equal to 0.78 mg KOH / g according to standard DIN EN 12634-1998.

7. 3. The aliphatic-aromatic polyester composition according to claim 2, characterized in that the aliphatic-aromatic polyester composition has a Yellowness Index YI value of 19 or less, measured according to standard ASTM E313-73.

8. The aliphatic-aromatic polyester composition according to claim 3, characterized in that when the aliphatic-aromatic polyester composition is boiled in water at 60°C for 48 hours, the viscosity number retention rate η of the aliphatic-aromatic polyester composition after boiling is 72% or more.

9. The aliphatic-aromatic polyester composition according to claim 1, further comprising, as component iii), tetrahydrofuran in an amount of 40 to 170 ppm based on the weight of the aliphatic-aromatic polyester composition.

10. 10. The aliphatic-aromatic polyester composition according to claim 9, wherein the content of tetrahydrofuran in the aliphatic-aromatic polyester composition is 86 to 136 ppm based on the weight of the aliphatic-aromatic polyester composition.

11. Aliphatic-aromatic polyester composition according to claim 9 or 10, characterized in that it has an odor rating of 4.5 or less according to the FLTM BO131-03 standard.

12. A method for preparing the aliphatic-aromatic polyester composition of any one of claims 1 to 11, comprising the steps of: The method includes the steps of mixing the components A and B, with or without the addition of a titanium catalyst, to form a paste, and then performing the following operations: Step i): subjecting the paste to esterification or transesterification with all or part of a titanium catalyst in a phenol / o-dichlorobenzene solution in a weight ratio of 1:1 according to GB / T 17931-1999 until the viscosity number of the esterification or transesterification product is 12-21 ml / g, as measured in a constant temperature water bath at 25±0.05°C; Step ii): subjecting the esterification or transesterification product obtained in step i) to a preliminary polycondensation reaction until the viscosity number of the prepolymer measured in a phenol / o-dichlorobenzene solution in a weight ratio of 1:1 in accordance with GB / T 17931-1999 in a constant temperature water bath at 25±0.05°C is 36-52 ml / g; Step iii): carrying out a polycondensation reaction of the prepolymer obtained in step ii) until the viscosity number of the final polymerization product is 145-203 ml / g, as measured in a phenol / o-dichlorobenzene solution in a weight ratio of 1:1 according to GB / T 17931-1999 standard in a constant temperature water bath at 25±0.05°C, to obtain polyester particles; Step iv): The polyester particles obtained in step iii) are contacted with an aqueous tetrahydrofuran solution to obtain the aliphatic-aromatic polyester composition. A preparation method characterized by:

13. 13. The process according to claim 12, characterized in that after step iii) and before step iv), a step iii-1) is carried out in which the final polymerization product is chain-extended with a chain extender until the viscosity number of the chain-extended product, measured according to GB / T 17931-1999, is 163-232 mL / g.

14. 14. The process according to claim 13, characterized in that the chain extender is selected from one or more of: isocyanates; peroxides; epoxides; and oxazolines, oxazines, caprolactams and / or carbodiimides.

15. The preparation method according to claim 14, characterized in that the chain extender is hexamethylene-1,6-diisocyanate, and the amount used is 0.1-1.5 wt% of the weight of the chain extended product.

16. The preparation method according to claim 12, characterized in that in step iv), the weight content of tetrahydrofuran in the aqueous tetrahydrofuran solution is 10-65 wt%.

17. The preparation method according to claim 12, characterized in that the temperature of the contact treatment in step iv) is 20 to 65°C.

18. The preparation method according to claim 12, characterized in that the time of the contact treatment in step iv) is 2 to 20 h.

19. The preparation method according to claim 12, characterized in that in step iv), the mass ratio of polyester particles to tetrahydrofuran aqueous solution is 1:1 to 1:

10.

20. Use of the aliphatic-aromatic polyester composition according to any one of claims 1 to 11 in the preparation of polyester fibres.

21. A polyester fiber, As ingredients, i) 5 to 15 wt %, based on the total weight of components i) to iv), of the aliphatic-aromatic polyester composition of any one of claims 1 to 11; ii) 35 to 70 wt %, based on the total weight of components i) to iv), of an aliphatic polyester; iii) 10 to 40 wt %, based on the total weight of components i) to iv), of one or more components selected from starch, wood flour, cellulose, polyhydroxyalkanoates, polyglycolic acid, and polylactic acid; iv) 10 to 35 wt %, based on the total weight of components i) to iv), of one or more components selected from talc, calcium carbonate, barium sulfate, montmorillonite, and kaolin; A polyester fiber comprising:

22. Use of the polyester fiber according to claim 21 in masks and clothing.

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