Aliphatic-aromatic copolyesters, processes for their preparation and use

Abstract

The present application discloses an aliphatic-aromatic copolyester, a preparation method and application thereof. The aliphatic-aromatic copolyester comprises the following components: component A, comprising the following components: a1) 63-69 mol% of terephthalic acid or its derivative, or a mixture thereof, based on the total mole percentage content of a1) and a2); a2) 31-37 mol% of at least one C4-C 10 aliphatic dicarboxylic acid or its derivative, or a mixture thereof, based on the total mole percentage content of a1) and a2); and component B: at least 1,4-butanediol in an equimolar amount of component A; the melt mass flow rate of the aliphatic-aromatic copolyester is 120-175 g / 10 min, measured at 190 DEG C, 2.16 kg according to standard ISO1133-2-2011. The aliphatic-aromatic copolyester with ultra-high flow performance can improve the opening performance of the film bag product.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, specifically relating to an aliphatic-aromatic copolyester, its preparation method, and its application. Background Technology

[0002] In addition to its biodegradability, biodegradable polyesters obtained from dicarboxylic acids and diols also possess good extensibility and mechanical properties, exhibiting similar performance to low-density polyethylene (LDPE) and linear low-density polyethylene (LLDPE). Therefore, they are widely used in bag products such as shopping bags, garbage bags, and express delivery bags.

[0003] To maintain sufficient biodegradability, commercially available biodegradable polyesters typically have an aromatic dicarboxylic acid content of less than 49% in the polyester chain. This is because above this threshold, the biodegradability percentage of such polyesters decreases significantly. While biodegradable polyesters with an aromatic dicarboxylic acid content of less than 49 mol% as the base resin exhibit good biodegradability, lower aromatic dicarboxylic acid content in the polyester leads to greater molecular chain flexibility, slower crystallization rate, and slower cooling of the film material during blown film processing. This results in greater adhesion between films, causing difficulties in opening the resulting bags (such as shopping bags, garbage bags, and fruit and vegetable bags) for a short period after production (e.g., ≤24 hours).

[0004] To improve the opening performance of film bags, opening agents are often added to the polyester composition. Commonly used opening agents include organic opening agents such as oleamide and erucamide, and inorganic opening agents such as silica. Organic opening agents such as oleamide and erucamide are small molecules with poor compatibility with biodegradable polyesters. After the polyester composition is prepared into a film material, they migrate rapidly within the film material, but have poor thermal stability, are prone to precipitation, and may affect printability. While silica, as an inorganic opening agent, migrates and precipitates less than oleamide and erucamide, a larger amount is required to achieve good opening performance. Excessive addition can lead to decreased film transparency and reduced mechanical properties.

[0005] Therefore, developing a material with low exudation and good opening properties to solve the problem of poor opening performance of film bag products prepared from polyester compositions is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] The present invention aims to solve at least one of the aforementioned technical problems existing in the prior art.

[0007] Therefore, one of the objectives of this invention is to provide an aliphatic-aromatic copolyester with ultra-high flow properties, which enables film and bag products prepared from polyester compositions including the aliphatic-aromatic copolyester to have good opening performance.

[0008] The second objective of this invention is to provide a method for preparing this aliphatic-aromatic copolyester.

[0009] A third objective of this invention is to provide a polyester composition containing the aforementioned aliphatic-aromatic copolyester.

[0010] The fourth objective of this invention is to provide the aforementioned aliphatic-aromatic copolyester as an opening agent for films / bags.

[0011] The fifth objective of this invention is to provide a film / bag comprising the aforementioned aliphatic-aromatic copolyester or polyester composition.

[0012] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0013] A first aspect of the present invention provides an aliphatic-aromatic copolyester, the aliphatic-aromatic copolyester comprising the following components:

[0014] Component A includes the following components:

[0015] a1) Based on the total molar percentage of a1) and a2), 63-69 mol% of terephthalic acid or its derivatives or mixtures thereof;

[0016] a2) Based on the total molar percentage content of a1) and a2), at least one C4-C at 31-37 mol% 10 Aliphatic dicarboxylic acids or their derivatives, or mixtures thereof;

[0017] Component B: 1,4-Butanediol in at least an equimolar amount with component A;

[0018] The aliphatic-aromatic copolyester, according to standard ISO 1133-2-2011, has a melt flow rate (MFR) of 120~175 g / 10 min measured at 190°C and 2.16 kg.

[0019] According to the aliphatic-aromatic copolyester provided by the present invention, by controlling the molar content of aromatic dicarboxylic acid and the melt mass flow rate in the aliphatic-aromatic copolyester within a specific range, the polyester composition including the aliphatic-aromatic copolyester can have the advantages of low precipitation and good opening performance. This enables the film bag products made from the polyester composition containing the aliphatic-aromatic copolyester to have good opening performance and also take into account good processing performance.

[0020] Specifically: 1. For aliphatic-aromatic copolyesters, the higher the content of aromatic dicarboxylic acids, the more difficult the degradation, and the weaker the molecular chain flexibility, the faster the crystallization rate. By controlling the molar content of aromatic dicarboxylic acids in the aliphatic-aromatic copolyester within a specific range (63~69 mol%), the crystallinity of the material can be effectively controlled, improving the material's processing performance without excessively sacrificing its degradation performance. 2. The higher the melt flow rate of the aliphatic-aromatic copolyester, the better its flow properties and the easier it is to disperse in the polyester composition. However, when the flow rate is too high, the aliphatic-aromatic copolyester is prone to entanglement on the cutter during production, making it impossible to achieve stable slicing. By controlling the melt flow rate of the aliphatic-aromatic copolyester within a specific range (120~175 g / 10 min), the aliphatic-aromatic copolyester can possess good flow properties, processing performance, and degradability.

[0021] According to some embodiments of the present invention, the molar content of the aromatic dicarboxylic acid, 63-69 mol%, can be any value or a range between any two of the following: 63 mol%, 63.2 mol%, 63.3 mol%, 63.4 mol%, 63.6 mol%, 63.8 mol%, 64 mol%, 64.2 mol%, 64.4 mol%, 64.6 mol%, 64.8 mol%, 65 mol%, 65.2 mol%, 65.4 mol%, 65.6 mol%, 65.8 mol%, 66 mol%, 66.2 mol%, 66.4 mol%, 66.6 mol%, 66.8 mol%, 67 mol%, 67.2 mol%, 67.4 mol%, 67.6 mol%, 67.8 mol%, 68 mol%, 68.2 mol%, 68.4 mol%, 68.5 mol%, 68.6 mol%, 68.8 mol%, and 69 mol%. For example, in some specific embodiments, the molar content of the aromatic dicarboxylic acid is preferably 64.0-68.0 mol%.

[0022] The aliphatic-aromatic copolyester according to the present invention is composed of repeating units derived from component A and component B. The total molar percentage of components a1) and a2) in component A is 100 mol%.

[0023] According to some embodiments of component a1) of the present invention, the derivative of terephthalic acid may be a di-C1-C6 alkyl ester of terephthalic acid, exemplarily such as dimethyl ester, diethyl ester, di-n-propyl ester, diisopropyl ester, di-n-butyl ester, diisobutyl ester, di-tert-butyl ester, di-n-pentyl ester, diisopentyl ester, or di-n-hexyl ester. The derivative of terephthalic acid may be used alone or in a mixture of two or more. In some specific embodiments, component a1) is selected from terephthalic acid or a derivative thereof forming an ester, such as dimethyl terephthalate.

[0024] According to some embodiments of component a2 of the present invention, the C4-C 10 Aliphatic dicarboxylic acid derivatives can be C4-C 10 Di-C1-C6 alkyl esters of aliphatic dicarboxylic acids, exemplary examples such as dimethyl ester, diethyl ester, di-n-propyl ester, diisopropyl ester, di-n-butyl ester, diisobutyl ester, di-tert-butyl ester, di-n-pentyl ester, diisopentyl ester, or di-n-hexyl ester. The C4-C... 10 Aliphatic dicarboxylic acid derivatives can be used alone or in mixtures of two or more.

[0025] According to some embodiments of the present invention, component a2) comprises at least one selected from succinic acid or a derivative thereof, adipic acid or a derivative thereof, azelaic acid or a derivative thereof, sebacic acid or a derivative thereof. In some specific embodiments, component a2) is selected from adipic acid or a derivative thereof, and optionally, one or more compounds of adipic acid derivatives such as di-C1-C6 alkyl esters of adipic acid.

[0026] According to some embodiments of the present invention, the melt mass flow rate of the aliphatic-aromatic copolyester, which is 120~175 g / 10 min, can be 120 g / 10 min, 121 g / 10 min, 123 g / 10 min, 125 g / 10 min, 127 g / 10 min, 130 g / 10 min, 132 g / 10 min, 135 g / 10 min, 137 g / 10 min, 140 g / 10 min, 142 g / 10 min, 145 g / 10 min, etc. The melt flow rate of the aliphatic-aromatic copolyester is any value or a range between any two of the following: 10 min, 147 g / 10 min, 148 g / 10 min, 150 g / 10 min, 152 g / 10 min, 155 g / 10 min, 156 g / 10 min, 157 g / 10 min, 160 g / 10 min, 162 g / 10 min, 165 g / 10 min, 167 g / 10 min, 170 g / 10 min, 172 g / 10 min, and 175 g / 10 min. For example, in some specific embodiments, the melt flow rate of the aliphatic-aromatic copolyester is preferably 135 to 160 g / 10 min.

[0027] According to some embodiments of the present invention, the aliphatic-aromatic copolyester further comprises 0.05 to 0.45 wt% of a branching agent, based on a mass of 100 wt% of the aliphatic-aromatic copolyester.

[0028] In polymer compounds, the degree of branching has a significant impact on the physical properties of polymers, such as melting point, tensile properties, cell size, and crystallinity, which largely depend on the linearity of the molecules. Highly branched polymers possess a highly branched spherical three-dimensional structure with no entanglement between molecules, resulting in significantly improved solubility. Compared to linear molecules of the same molecular weight, they exhibit lower solution viscosity and melt viscosity, leading to better processability. Furthermore, the numerous terminal groups on the molecular periphery can be modified to achieve desired properties, making them widely applicable in many fields, especially those where traditional linear molecules are difficult to utilize. Therefore, the addition of branching agents can further improve the physical and chemical properties of aliphatic-aromatic copolyesters. Within a certain content range, the higher the branching agent content in the aliphatic-aromatic copolyester, the higher the degree of branching, the more compact the molecular structure, and the faster the crystallization rate. However, when the branching agent content exceeds the upper limit of a specific range, the steric hindrance of the aliphatic-aromatic copolyester increases, weakening the molecular chain mobility and, to some extent, also reducing the polyester's crystallization ability.

[0029] Furthermore, the branching structure is also related to the type and amount of branching agent added. Therefore, by controlling the mass percentage of the branching agent to 0.05~0.45wt%, such a specific amount can yield a branched modified aliphatic-aromatic copolyester with good performance.

[0030] According to some embodiments of the present invention, the mass percentage content of the branching agent may be any value or a range between any two of the following: 0.05wt%, 0.055wt%, 0.06wt%, 0.065wt%, 0.07wt%, 0.075wt%, 0.08wt%, 0.085wt%, 0.09wt%, 0.095wt%, 0.1wt%, 0.12wt%, 0.14wt%, 0.16wt%, 0.17wt%, 0.18wt%, 0.2wt%, 0.22wt%, 0.25wt%, 0.28wt%, 0.3wt%, 0.32wt%, 0.35wt%, 0.38wt%, 0.4wt%, 0.42wt%, and 0.45wt%. For example, in some specific embodiments, the mass percentage content of the branching agent is preferably 0.12 to 0.17wt%.

[0031] According to some embodiments of the present invention, the branching agent has a functionality ≥3, for example, it can be 3, 4, 5, 6, etc. In some specific embodiments, the functionality of the branching agent is 3 to 6.

[0032] According to some embodiments of the present invention, the branching agent contains at least one of hydroxyl, carboxyl, and anhydride groups in its molecular structure; the functionality ≥3 refers to the total functionality of hydroxyl, carboxyl, and anhydride groups in the molecular structure being ≥3. In some specific embodiments, the branching agent is selected from compounds containing 3 to 6 hydroxyl groups.

[0033] According to some embodiments of the present invention, the branching agent includes at least one selected from tartaric acid, citric acid, malic acid, trimethylolpropane, trimethylolethane, pentaerythritol, polyether triol, glycerol, 1,3,5-benzotriic acid, 1,2,4-benzotriic acid, 1,2,4-benzotriic anhydride, 1,2,4,5-benzotetraic acid, and benzopyrenic acid dianhydride. In some specific embodiments, the branching agent includes at least one selected from trimethylolpropane, pentaerythritol, and glycerol. In some embodiments, glycerol is selected as the branching agent.

[0034] According to some embodiments of the present invention, the aliphatic-aromatic copolyester further includes a chain extender.

[0035] According to some embodiments of the present invention, the functionality of the chain extender is ≥2, for example, it can be 2, 3, 4, 5, etc.

[0036] According to some embodiments of the present invention, the chain extender includes at least one selected from isocyanate compounds, isocyanurate compounds, peroxides, epoxides, oxazoline compounds, oxazine compounds, caprolactam, and carbodiimide.

[0037] In some specific embodiments, the isocyanate compound may be an aromatic diisocyanate and / or an aliphatic diisocyanate; wherein the aromatic diisocyanate may be selected from at least one of toluene-2,4-diisocyanate, toluene-2,6-diisocyanate, 2,2'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, and xylene diisocyanate. The aliphatic diisocyanate may be any straight-chain or branched alkylene diisocyanate or cycloalkylene diisocyanate containing 2 to 20 carbon atoms, particularly preferably 3 to 12 carbon atoms, such as at least one selected from hexamethylene diisocyanate, isophorone diisocyanate, and 1,1'-methylenebis(isocyanate-based)cyclohexane. In some embodiments, the aliphatic diisocyanate is selected from hexamethylene diisocyanate.

[0038] According to some embodiments of the present invention, the molar ratio of component A to component B is 1:(1.2~2.4), wherein the value of (1.2~2.4) can be any value among 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.1, 2.2, 2.3, and 2.4, or a range between any two. For example, in some specific embodiments, the molar ratio of component A to component B is 1:(1.4~1.8).

[0039] According to some embodiments of the present invention, the melt enthalpy of the aliphatic-aromatic copolyester is 20~36 J / g. For example, it can be 20 J / g, 20.5 J / g, 20.7 J / g, 21 J / g, 21.5 J / g, 22 J / g, 22.5 J / g, 23 J / g, 23.5 J / g, 23.8 J / g, 24 J / g, 24.5 J / g, 25 J / g, 25.5 J / g, 25.7 J / g, 26 J / g, 26.5 J / g, 27 J / g, 27.5 J / g, 27.8 J / g, 28 J / g, etc. The enthalpy of melt is any value or a range between any two of the following: 3 J / g, 28.5 J / g, 29 J / g, 29.5 J / g, 30 J / g, 30.5 J / g, 31 J / g, 31.2 J / g, 31.5 J / g, 32 J / g, 32.5 J / g, 32.8 J / g, 33 J / g, 33.5 J / g, 34 J / g, 34.5 J / g, 35 J / g, 35.2 J / g, 35.5 J / g, and 36 J / g. For example, in some specific embodiments, the enthalpy of melt of the aliphatic-aromatic copolyester is preferably 23~36 J / g.

[0040] According to the aliphatic-aromatic copolyester of the present invention, the melt enthalpy can be tested by differential scanning calorimetry (DSC).

[0041] A second aspect of the present invention provides a method for preparing an aliphatic-aromatic copolyester according to the first aspect of the present invention, comprising the following steps:

[0042] (1) Mix component A and component B with an optional branching agent and react to obtain an esterified product;

[0043] (2) The esterified product is subjected to a pre-condensation reaction to obtain a pre-condensation product;

[0044] (3) The prepolymerization product is subjected to a polycondensation reaction to obtain the aliphatic-aromatic copolyester.

[0045] According to some embodiments of the present invention, in the method for preparing the aliphatic-aromatic copolyester, the reaction temperature of step (1) is 180~240℃, such as any value or a range between 180℃, 185℃, 190℃, 195℃, 200℃, 205℃, 210℃, 215℃, 220℃, 225℃, 230℃, 235℃, and 240℃. For example, in some specific embodiments, the reaction temperature of step (1) is 220~235℃.

[0046] According to some embodiments of the present invention, in the method for preparing the aliphatic-aromatic copolyester, the reaction pressure in step (1) is 40~120 kPa, such as any value or a range between 40 kPa, 45 kPa, 50 kPa, 55 kPa, 60 kPa, 65 kPa, 70 kPa, 75 kPa, 80 kPa, 85 kPa, 90 kPa, 95 kPa, 100 kPa, 105 kPa, 110 kPa, 115 kPa, and 120 kPa. For example, in some specific embodiments, the reaction pressure in step (1) is 60~90 kPa.

[0047] According to some embodiments of the present invention, in the preparation method of the aliphatic-aromatic copolyester, the reaction time of step (1) is 3 to 5 hours, such as any value of 3 hours, 3.5 hours, 4 hours, 4.5 hours, 5 hours or any range between two of them.

[0048] According to some embodiments of the present invention, step (1) of the preparation method of the aliphatic-aromatic copolyester includes:

[0049] S1: Mix components a1), a2), and B with an optional branching agent and react to obtain the esterified product;

[0050] Or S2: React component a1) with component B to obtain the first esterified product; react component a2) with component B and optional branching agent to obtain the second esterified product; mix the first esterified product and the second esterified product, and then proceed to step (2).

[0051] According to some embodiments of the present invention, when step (1) of the preparation method of the aliphatic-aromatic copolyester is S1, the reaction temperature is 180~240℃, which can be selected from any value or a range between any two of 180℃, 185℃, 190℃, 195℃, 200℃, 205℃, 210℃, 215℃, 220℃, 225℃, 230℃, 235℃, and 240℃. For example, in some specific embodiments, the reaction temperature of step S1 is 220~235℃.

[0052] According to some embodiments of the present invention, when step (1) of the preparation method of the aliphatic-aromatic copolyester is S1, the reaction pressure is 40~120 kPa, which can be selected from any value or a range between 40 kPa, 45 kPa, 50 kPa, 55 kPa, 60 kPa, 65 kPa, 70 kPa, 75 kPa, 80 kPa, 85 kPa, 90 kPa, 95 kPa, 100 kPa, 105 kPa, 110 kPa, 115 kPa, and 120 kPa. For example, in some specific embodiments, the reaction pressure of step S1 is 60~90 kPa.

[0053] According to some embodiments of the present invention, when step (1) of the preparation method of the aliphatic-aromatic copolyester is S1, the reaction time is 3~5h, which can be selected from any value of 3h, 3.5h, 4h, 4.5h, 5h or any range between two.

[0054] According to some embodiments of the present invention, when step (1) of the preparation method of the aliphatic-aromatic copolyester is S2, the reaction temperature of component a1) with component B is 230~240℃, which can be selected from any value of 230℃, 232℃, 235℃, 237℃, 240℃ or any range between two.

[0055] According to some embodiments of the present invention, when step (1) of the preparation method of the aliphatic-aromatic copolyester is S2, the pressure at which component a1) reacts with component B is 58~120 kPa, which can be selected from any value or a range between any two of 58 kPa, 60 kPa, 65 kPa, 70 kPa, 75 kPa, 80 kPa, 85 kPa, 90 kPa, 95 kPa, 100 kPa, 105 kPa, 110 kPa, 115 kPa, and 120 kPa.

[0056] According to some embodiments of the present invention, when step (1) of the preparation method of the aliphatic-aromatic copolyester is S2, the reaction time of component a1) with component B is 3~5h, which can be selected from any value of 3h, 3.5h, 4h, 4.5h, 5h or any range between two.

[0057] According to some embodiments of the present invention, when step (1) of the preparation method of the aliphatic-aromatic copolyester is S2, the reaction temperature of component a2) with component B is 190~210℃, which can be selected from any value of 190℃, 195℃, 200℃, 205℃, 210℃ or any range between two.

[0058] According to some embodiments of the present invention, when step (1) of the preparation method of the aliphatic-aromatic copolyester is S2, the pressure at which component a2) reacts with component B is 80~120 kPa, which can be selected from any value or any range between 80 kPa, 85 kPa, 90 kPa, 95 kPa, 100 kPa, 105 kPa, 110 kPa, 115 kPa, and 120 kPa.

[0059] According to some embodiments of the present invention, when step (1) of the preparation method of the aliphatic-aromatic copolyester is S2, the reaction time of component a2) with component B is 3~5h, which can be selected from any value of 3h, 3.5h, 4h, 4.5h, 5h or any range between two.

[0060] According to some embodiments of the present invention, when step (1) of the preparation method of the aliphatic-aromatic copolyester is S2, the molar ratio of component a1) to component B is 1:(1.6~2.4), wherein the value of (1.6~2.4) can be any value among 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4 or any range between two.

[0061] According to some embodiments of the present invention, when step (1) of the preparation method of the aliphatic-aromatic copolyester is S2, the molar ratio of component a2) to component B is 1:(1.2~1.4), wherein the value of (1.2~1.4) can be any value of 1.2, 1.3, 1.4 or any range between two of them.

[0062] According to some embodiments of the present invention, step (1) of the preparation method of the aliphatic-aromatic copolyester can be carried out in a mixing device, such as in a vertical reactor with stirring.

[0063] According to some embodiments of the present invention, in the preparation method of the aliphatic-aromatic copolyester, the pre-condensation reaction temperature of step (2) is 230~250℃, such as any value of 230℃, 235℃, 240℃, 245℃, 250℃ or any range between two.

[0064] According to some embodiments of the present invention, in the preparation method of the aliphatic-aromatic copolyester, the pre-condensation reaction pressure in step (2) is 600~3000 Pa, such as any value or a range between any two of 600 Pa, 700 Pa, 800 Pa, 900 Pa, 1000 Pa, 1100 Pa, 1200 Pa, 1400 Pa, 1600 Pa, 1800 Pa, 2000 Pa, 2200 Pa, 2400 Pa, 2600 Pa, 2800 Pa, and 3000 Pa.

[0065] According to some embodiments of the present invention, in the preparation method of the aliphatic-aromatic copolyester, the pre-condensation reaction time of step (2) is 2 to 4 hours, such as any value of 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours or any range between two.

[0066] According to some embodiments of the present invention, in the preparation method of the aliphatic-aromatic copolyester, the polycondensation reaction temperature in step (3) is 240~260℃, such as any value of 240℃, 245℃, 250℃, 255℃, 260℃ or any range between two.

[0067] According to some embodiments of the present invention, in the preparation method of the aliphatic-aromatic copolyester, the polycondensation reaction pressure in step (3) is 50~200 Pa, such as any value of 50 Pa, 60 Pa, 80 Pa, 100 Pa, 150 Pa, 200 Pa or any range between two.

[0068] According to some embodiments of the present invention, in the preparation method of the aliphatic-aromatic copolyester, the polycondensation reaction time in step (3) is 1 to 4 hours, such as any value of 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours or any range between two of them.

[0069] According to some embodiments of the present invention, step (3) of the preparation method of the aliphatic-aromatic copolyester is to carry out a polycondensation reaction in a rotating reactor or a cage reactor.

[0070] According to some embodiments of the present invention, when the aliphatic-aromatic copolyester further includes a chain extender, the following preparation steps are also included: after the polycondensation reaction in step (3) is completed, the obtained polycondensation product is mixed with the chain extender to carry out a chain extension reaction.

[0071] According to some embodiments of the present invention, the temperature of the chain extension reaction is 190~210°C, for example, any value of 190°C, 195°C, 200°C, 205°C, 210°C or a range between any two.

[0072] According to some embodiments of the present invention, the chain extension reaction time is 3 to 15 min, for example, it can be any value or a range between any two of 3 min, 4 min, 5 min, 6 min, 7 min, 8 min, 9 min, 10 min, 11 min, 12 min, 13 min, 14 min, and 15 min.

[0073] According to some embodiments of the invention, the chain extension reaction is carried out in a twin-screw extruder or a static mixer.

[0074] According to the present invention, without the addition of a chain extender, the product obtained by polycondensation is an aliphatic-aromatic copolyester; with the addition of a chain extender, the product obtained by the chain extension reaction is an aliphatic-aromatic copolyester. In some specific embodiments of the present invention, by adding a chain extender to carry out the chain extension reaction, the acid value of the aliphatic-aromatic copolyester can be better controlled.

[0075] According to some embodiments of the present invention, steps (1), (2), and (3), as well as the optional chain extension reaction step, of the preparation method of the aliphatic-aromatic copolyester can each be carried out independently in the presence of a catalyst. The catalysts used in each step can be the same or different. The catalyst can be an external catalyst or a catalyst present in the system. For example, in step (1), 50-80 wt% of the total mass of the catalyst is added; in step (2), the remaining catalyst is added; and the catalysts required for step (3) and the optional chain extension reaction are catalysts present in the system. By controlling the amount of catalyst added, the subsequent processing can be made more stable. In some specific embodiments of the present invention, the total mass of the catalyst is 0.001 to 1 wt% of the mass of the final polymerization product, for example, it can be any value or a range between any two of 0.001 wt%, 0.002 wt%, 0.005 wt%, 0.008 wt%, 0.01 wt%, 0.02 wt%, 0.03 wt%, 0.05 wt%, 0.08 wt%, 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, and 1 wt%. In some examples, the total mass of the catalyst is 0.03 to 0.2 wt% of the mass of the final polymerization product.

[0076] According to some embodiments of the present invention, the catalyst comprises at least one selected from tin compounds, antimony compounds, cobalt compounds, lead compounds, zinc compounds, aluminum compounds, and titanium compounds. According to some specific embodiments of the present invention, the catalyst comprises at least one selected from zinc compounds, aluminum compounds, and titanium compounds. In some examples, the catalyst is selected from titanium compounds, such as tetrabutyl titanate or tetraisopropyl titanate, which have lower residual amounts and lower toxicity in the product or downstream products compared to other compounds.

[0077] The melt flow rate of aliphatic-aromatic copolyesters is directly related to their molecular weight, which is mainly affected by reaction conditions such as reaction time, temperature, pressure, catalyst dosage, and alkyd-acid ratio. By controlling these reaction conditions, polymers with different melt flow rates can be obtained.

[0078] A third aspect of the present invention provides a polyester composition comprising the following components in parts by weight: 45 to 75 parts of a first polyester, 0 to 10 parts of polylactic acid, 2 to 8 parts of a second polyester and 10 to 40 parts of filler; the second polyester comprising the aliphatic-aromatic copolyester described in the first aspect of the present invention.

[0079] According to some embodiments of the present invention, the first polyester comprises the following components:

[0080] Acid components:

[0081] i-1) Based on the total molar percentage of i-1) and i-2), 40-55 mol% of aromatic dicarboxylic acids or their esters, or mixtures thereof;

[0082] i-2) Based on the total molar percentage of i-1) and i-2), 45-60 mol% of aliphatic dicarboxylic acids or their esters, or mixtures thereof;

[0083] Dihydroxy compound components:

[0084] i-3) At least in equimolar amounts with the acid component a C2-C6 aliphatic alkanediol, or a mixture thereof.

[0085] According to some embodiments of the present invention, the molar content of component i-1) of 40-55 mol% can be any value or a range between any two of 40 mol%, 41 mol%, 42 mol%, 43 mol%, 44 mol%, 45 mol%, 45.5 mol%, 46 mol%, 46.5 mol%, 47 mol%, 47.3 mol%, 47.5 mol%, 47.8 mol%, 48 mol%, 48.3 mol%, 48.5 mol%, 49 mol%, 49.5 mol%, 50 mol%, 51 mol%, 52 mol%, 53 mol%, 54 mol%, and 55 mol%.

[0086] According to some embodiments of the present invention, the molar content of component i-2) of 45-60 mol% can be any value or a range between any two of 45 mol%, 46 mol%, 47 mol%, 48 mol%, 49 mol%, 50 mol%, 50.5 mol%, 51 mol%, 51.5 mol%, 52 mol%, 52.5 mol%, 53 mol%, 53.5 mol%, 54 mol%, 54.5 mol%, 55 mol%, 56 mol%, 57 mol%, 58 mol%, 59 mol%, and 60 mol%.

[0087] The first polyester according to the present invention is composed of repeating units comprising an acid component and a dihydroxy compound component. The total molar percentage of components i-1) and i-2) in the acid component is 100 mol%.

[0088] According to some embodiments of the present invention, in component i-3), the C2-C6 aliphatic alkyldiol may be selected from at least one of C2 aliphatic alkyldiol, C3 aliphatic alkyldiol, C4 aliphatic alkyldiol, C5 aliphatic alkyldiol, and C6 aliphatic alkyldiol.

[0089] According to some embodiments of the present invention, the first polyester is a biodegradable polyester, including at least one of polybutylene terephthalate, polybutylene adipate, polybutylene sebacate, polypropylene adipate, and polypropylene sebacate.

[0090] According to some embodiments of the present invention, the melt mass flow rate of the first polyester, measured according to standard ISO 1133-2-2011 at 190°C and 2.16 kg, is 2~10. g / 10min, for example, can be any value or a range between any two of the following: 2g / 10min, 2.2g / 10min, 2.4g / 10min, 2.6g / 10min, 2.8g / 10min, 3g / 10min, 3.2g / 10min, 3.4g / 10min, 3.6g / 10min, 3.7g / 10min, 3.8g / 10min, 4g / 10min, 4.2g / 10min, 4.4g / 10min, 4.6g / 10min, 4.8g / 10min, 5g / 10min, 6g / 10min, 7g / 10min, 8g / 10min, 9g / 10min, and 10g / 10min.

[0091] According to some embodiments of the present invention, the weight parts of the first polyester may be any value or a range between any two of 45 parts, 48 ​​parts, 50 parts, 52 parts, 54 parts, 55 parts, 56 parts, 58 parts, 60 parts, 62 parts, 64 parts, 66 parts, 68 parts, 69 parts, 70 parts, 72 parts, and 75 parts.

[0092] According to some embodiments of the present invention, the polylactic acid may be in any one of the following weight parts: 0 parts, 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, and 10 parts, or a range between any two. For example, in some specific embodiments, the polylactic acid is in the range of 3 to 10 parts by weight.

[0093] According to some specific embodiments of the present invention, the polylactic acid is not zero parts by weight.

[0094] According to some embodiments of the present invention, the polylactic acid is based on the standard ISO. According to 1133-2-2011, the melt mass flow rate measured at 190℃ and 2.16 kg is 2~25 g / 10 min, for example, it can be any value or a range between any two of the following: 2 g / 10 min, 3 g / 10 min, 4 g / 10 min, 5 g / 10 min, 6 g / 10 min, 7 g / 10 min, 8 g / 10 min, 9 g / 10 min, 10 g / 10 min, 11 g / 10 min, 12 g / 10 min, 13 g / 10 min, 14 g / 10 min, 15 g / 10 min, 16 g / 10 min, 17 g / 10 min, 18 g / 10 min, 19 g / 10 min, 20 g / 10 min, 21 g / 10 min, 22 g / 10 min, 23 g / 10 min, 24 g / 10 min, and 25 g / 10 min. For example, in some specific embodiments, the melt mass flow rate of polylactic acid is 2~6 g / 10 min.

[0095] According to some embodiments of the present invention, the polylactic acid includes at least one of poly-L-lactic acid (PLLA), poly-D-lactic acid (PDLA), and PLLA / PDLA copolymer. According to some specific embodiments of the present invention, the polylactic acid may be selected from at least one of FY804 and FY802 from Anhui Fengyuan Futailai Polylactic Acid Co., Ltd., and PLA 4032D, PLA4060D, PLA4044D, and PLA3001D from NatureWorks.

[0096] According to some embodiments of the present invention, the weight parts of the second polyester may be any value of 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, or 8 parts, or any range between two.

[0097] According to some embodiments of the present invention, the weight parts of the filler may be any value or a range between any two of 10 parts, 12 parts, 14 parts, 16 parts, 18 parts, 20 parts, 22 parts, 24 parts, 26 parts, 28 parts, 30 parts, 32 parts, 34 parts, 36 parts, 38 parts, and 40 parts.

[0098] According to some embodiments of the present invention, the filler includes one or a combination of organic fillers, inorganic fillers, or other similar materials.

[0099] According to some embodiments of the present invention, the organic filler includes at least one of starch, cellulose, straw, wood flour, and bamboo flour.

[0100] According to some embodiments of the present invention, the inorganic filler includes at least one selected from calcium carbonate, barium sulfate, talc, graphite, gypsum, carbon black, chalk, calcium oxide, calcium chloride, iron oxide, dolomite, kaolin, silicon dioxide, titanium dioxide, silicates, mica, and montmorillonite. In some specific embodiments, the inorganic filler includes calcium carbonate and talc.

[0101] According to some embodiments of the present invention, the particle size D50 of the filler is 0.1~12μm, for example, it can be any value or a range between 0.1μm, 0.5μm, 0.8μm, 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm.

[0102] According to some embodiments of the present invention, when the filler comprises calcium carbonate and talc, the mass ratio of calcium carbonate to talc is (1~6):1; wherein the value of (1~6) can be any value or a range between any two of 1, 1.2, 1.4, 1.6, 1.8, 2, 2.2, 2.4, 2.6, 2.8, 3, 3.2, 3.4, 3.6, 3.8, 4, 4.2, 4.4, 4.6, 4.8, 5, 5.2, 5.4, 5.6, 5.8, 6. For example, in some specific embodiments, the mass ratio of calcium carbonate to talc is (1.4~5):1.

[0103] According to some embodiments of the present invention, the filler comprises 3 to 12 parts by weight of talc and 12 to 26 parts by weight of calcium carbonate. In some specific embodiments, the filler comprises 4 to 10 parts by weight of talc and 14 to 24 parts by weight of calcium carbonate.

[0104] According to some embodiments of the present invention, the polyester composition further includes the following components in parts by weight: 0.01 to 1 part of a copolymer containing epoxy groups.

[0105] According to some embodiments of the present invention, the epoxy-containing copolymer includes at least one of a copolymer of styrene and acrylate, a copolymer of styrene and methacrylate, and a copolymer of styrene, acrylate and methacrylate.

[0106] According to some embodiments of the present invention, the copolymer containing epoxy groups can be any value or a range between 0.01 parts, 0.02 parts, 0.04 parts, 0.06 parts, 0.08 parts, 0.1 parts, 0.2 parts, 0.4 parts, 0.6 parts, 0.8 parts, and 1 part by weight.

[0107] According to some embodiments of the present invention, the polyester composition further includes at least one additive selected from antioxidants and compatibilizers.

[0108] According to some embodiments of the present invention, the polyester composition further comprises 0.01 to 3 wt% of additives, based on a mass of 100 wt%. The amount of the additives may be, for example, any value or a range between 0.01 wt%, 0.05 wt%, 0.1 wt%, 0.2 wt%, 0.5 wt%, 0.8 wt%, 1 wt%, 1.5 wt%, 2 wt%, and 3 wt%.

[0109] Antioxidants are additives used to prevent oxidation during storage and to prevent the deterioration of the physical properties of polyester products (such as film bag products). Any commonly used antioxidant may be used, as long as it does not impair the effectiveness of the present invention.

[0110] According to some embodiments of the present invention, the antioxidant includes at least one of hindered phenolic antioxidants, phosphite antioxidants, and thioester antioxidants. For example, hindered phenolic antioxidants may be selected from pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], N,N' β-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hydrazine, β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate stearyl ester, N,N’ - At least one of hexamethylene bis(3,5-di-tert-butyl-4-hydroxyphenylpropionamide) and 4,4'-methylene bis(2,6-di-tert-butylphenol); phosphite antioxidants may be selected from at least one of tris(2,4-di-tert-butylphenyl) phosphite, bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite, bis(2,6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphite, and distearate pentaerythritol diphosphite; thioester antioxidants may be selected from at least one of distearate thiodipropionate, dilaurate thiodipropionate, and pentaerythritol dodecyl thiopropyl ester.

[0111] According to some embodiments of the present invention, the polyester composition further comprises 0.01 to 2 wt% of an antioxidant, based on a mass of 100 wt%. The amount of the antioxidant may be, for example, any value or a range between 0.01 wt%, 0.05 wt%, 0.1 wt%, 0.2 wt%, 0.5 wt%, 0.8 wt%, 1 wt%, 1.5 wt%, and 2 wt%.

[0112] Compatibilizers are additives used to impart compatibility to multiphase polyester compositions by removing the first polyester, second polyester, polylactic acid, and / or fillers. Any commonly used compatibilizer may be used, as long as it does not impair the effects of the invention.

[0113] According to some embodiments of the present invention, the compatibilizer includes at least one selected from polyvinyl acetate, polypropylene carbonate, glycidyl methacrylate, ethylene-vinyl alcohol copolymer, polyvinyl alcohol, ethylene-vinyl acetate copolymer, and maleic anhydride graft compatibilizer.

[0114] According to some embodiments of the present invention, the polyester composition further comprises 0.01 to 3 wt% of a compatibilizer, based on a mass of 100 wt%. The amount of the compatibilizer may be, for example, any value or a range between 0.01 wt%, 0.05 wt%, 0.1 wt%, 0.2 wt%, 0.5 wt%, 0.8 wt%, 1 wt%, 1.5 wt%, 2 wt%, and 3 wt%. By adding a compatibilizer within the above-mentioned range, the physical properties of polyester articles (such as film bag products) can be enhanced by improving the compatibility between the components of the polyester composition used, and the desired effects of the present invention can be more readily achieved.

[0115] According to some embodiments of the present invention, the preparation method of the polyester composition includes, but is not limited to, obtaining it via reactive extrusion in an extruder. The extruder may be a single-screw extruder, a twin-screw extruder, or a multi-screw extruder. In some specific embodiments, the extrusion temperature is 140~220°C, for example, any value or a range between 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, and 220°C; the screw speed is 200~500 rpm, for example, any value or a range between 200 rpm, 300 rpm, 400 rpm, and 500 rpm.

[0116] The polyester composition comprising the second polyester mentioned in the present invention is biodegradable, and the articles prepared therefrom are also biodegradable.

[0117] In this invention, a substance or mixture of substances is considered "biodegradable" if it exhibits a biodegradability of at least 90%, as defined in DIN EN 13432.

[0118] According to DIN EN 13432, during composting, CO2-free air is introduced into the maturing compost, and the compost is subjected to a specific temperature process. Here, 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 compost without the sample) to the maximum amount of CO2 that the sample can release (calculated from the carbon content in the sample). After only a few days of composting, biodegradable polyesters and biodegradable polyester mixtures typically show obvious signs of degradation, such as fungal growth, lysis, and perforation.

[0119] Other methods for determining biodegradability are described, for example, in ASTM D5338 and ASTM D6400.

[0120] A fourth aspect of the present invention provides an opening agent for a film / bag, comprising the aliphatic-aromatic copolyester described in the first aspect of the present invention.

[0121] The aliphatic-aromatic copolyester provided by this invention can be used as an opening agent for films / bags, which can improve the opening performance of films / bags, while also having good processing performance.

[0122] According to some embodiments of the present invention, the opening agent of the film / bag is a biodegradable film / bag opening agent.

[0123] A fifth aspect of the present invention provides a film / bag comprising the following components: the aliphatic-aromatic copolyester described in the first aspect of the present invention, or the polyester composition described in the third aspect of the present invention.

[0124] The film / bag provided by the present invention is formed from an aliphatic-aromatic copolyester (second polyester) as described above, or a polyester composition including the aforementioned second polyester, wherein the second polyester can act as an opening agent to improve the opening performance of the film / bag, while also having good processing performance.

[0125] According to some embodiments of the present invention, the film is obtained by blown film processing from a polyester composition including the one described in the third aspect of the present invention. In some specific embodiments, the optional blown film processing parameters are as follows: the screw length-to-diameter ratio of the extruder is (30~32):1; the blown film processing temperature is 115~150℃; the blow-up ratio is 3.5~4.0; and the blown film thickness is 12±2μm.

[0126] According to some embodiments of the present invention, the bag is obtained by the aforementioned film heat sealing.

[0127] According to some embodiments of the present invention, the bag has an opening rating ≥2.5 when the film thickness is 12±2μm. For example, it can be any value among 2.5, 3.0, 3.5, 4.0, and 4.5, or a range between any two. In some specific embodiments, the bag has an opening rating ≥3.5. In some examples, the bag has an opening rating ≥4.0. The higher the opening rating number, the better the bag's opening performance. The opening rating of the bag is tested by storing the bag in an environment with a temperature of 25±5℃ and a humidity of 55±5%, and the specific evaluation criteria are as follows:

[0128] Opening level 1.0: After 24 hours of storage, the bag cannot be opened after being rubbed by hand more than 40 times, and the bag is severely deformed after being torn open;

[0129] Opening grade 1.5: After 24 hours of storage, the bag cannot be opened after being rubbed by hand more than 40 times, and the bag does not deform after being torn.

[0130] Opening level 2.0: After 24 hours of storage, the bag can be opened after rubbing it 30-40 times by hand;

[0131] Opening level 2.5: After 24 hours of storage, the bag can be opened after rubbing it 20-29 times by hand.

[0132] Opening level 3.0: After 24 hours of storage, the bag can be opened after rubbing it 10-19 times by hand;

[0133] Opening level 3.5: After 24 hours of storage, the bag can be opened after rubbing it 5-9 times by hand;

[0134] Opening rating 4.0: After 24 hours of storage, the bag can be opened after being rubbed by hand less than 5 times;

[0135] Opening level 4.5: After 8 hours of storage, the bag can be opened after being rubbed by hand less than 5 times.

[0136] According to some embodiments of the present invention, the film includes a packaging film.

[0137] According to some embodiments of the present invention, the bag includes a packaging bag.

[0138] According to some embodiments of the present invention, the bag includes a shopping bag, a garbage bag, a courier bag, a medical bag, or a fruit and vegetable bag.

[0139] It should be noted that the numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0140] Compared with the prior art, the beneficial effects of the present invention are:

[0141] The aliphatic-aromatic copolyester provided by this invention, by controlling the molar content of aromatic dicarboxylic acids and the melt mass flow rate within a specific range, enables the film bag products prepared from the biodegradable polyester composition including the aliphatic-aromatic copolyester to have good opening performance and good processing performance. Detailed Implementation

[0142] The present invention will be further described in detail below through specific embodiments. Those skilled in the art should understand that the embodiments are merely illustrative of the invention and should not be considered as specific limitations thereof.

[0143] Unless otherwise specified, the raw materials, reagents, or apparatus used in the following examples and comparative examples are all available from conventional commercial sources and can be used directly without further processing, or can be obtained by existing technical methods. Unless otherwise specified, the test or experimental methods are conventional methods in the art.

[0144] Unless otherwise specified, the term "about" in this invention actually means that the error is allowed to be within ±2%, for example, about 100 is actually 100 ± 2% × 100.

[0145] The materials used in the specific embodiments of this invention are as follows:

[0146] 1,4-Butanediol was purchased from Meike Chemical Co., Ltd.

[0147] Terephthalic acid was purchased from Zhuhai INEOS Chemical Co., Ltd.

[0148] Adipic acid was purchased from Chongqing Huafeng Chemical Group Co., Ltd.

[0149] Sebacic acid was purchased from Hengshui Jinghua Chemical Co., Ltd.

[0150] Glycerin, purchased from Aladdin;

[0151] Tetrabutyl titanate was purchased from Jianyi Chemical Import & Export Co., Ltd.

[0152] Calcium carbonate, purchased from OMYA, with a particle size D50 of approximately 2.2 μm;

[0153] Talc powder, purchased from Guangxi Longsheng Huamei Talc Development Co., Ltd., with a particle size D50 of approximately 3.1μm;

[0154] Polylactic acid, purchased from Anhui Fengyuan Futailai Polylactic Acid Co., Ltd., brand name FY804.

[0155] The first polyester is PBAT (polybutylene terephthalate), a product with the grade KB100 NC901 provided by Kingfa Biomaterials Co., Ltd. The product has a molar content of terephthalic acid of 47.8±0.5mol%, a melt flow rate of 3.7±0.3g / 10min (according to ISO 1133-2-2011, 190℃, 2.16kg), and a melting point of 117±3℃.

[0156] In a specific embodiment of the present invention, the molar content of aromatic diacids and the molar content of aliphatic diacids in the aliphatic-aromatic copolyester are tested using the following methods:

[0157] 20 mg of aliphatic-aromatic copolyester sample was dissolved in 0.6 mL of deuterated chloroform, and then 1H NMR was measured at room temperature using a Bruker AV500 nuclear magnetic resonance spectrometer. The chloroform solvent peak was calibrated to around 7.26 ppm.

[0158] According to the reference "1H-NMR characterization, and biodegradation behavior of aliphatic–aromatic random copolyester" (Chen, X.; Chen, W.; Zhu, G.; Huang, F.; Zhang, J., Synthesis, J. Appl. Polym. Sci. 2007, 104(4): 2643-2649), aromatic dicarboxylic acids, such as terephthalic acid, have four hydrogen atoms on the benzene ring in the repeating unit appearing around 8.10 ppm; aliphatic dicarboxylic acids, such as adipic acid, have four hydrogen atoms in the two CH2 units adjacent to the carbonyl group in the repeating unit appearing around 2.33 ppm. Thus, the molar content of the dicarboxylic acid component can be determined by the integral area (I0.10) of the peaks at 8.10 ppm and 2.33 ppm. T and I A )express:

[0159] The molar content of aromatic dicarboxylic acids in aliphatic-aromatic copolyesters = I T / (I T +I A )×100%;

[0160] The molar content of aliphatic dicarboxylic acids in aliphatic-aromatic copolyesters = I A / (I T +I A )×100%.

[0161] In a specific embodiment of the present invention, the melting point and enthalpy of the aliphatic-aromatic copolyester are tested by DSC. The specific method includes: taking 5-10 mg of sample, placing it in a crucible, and testing it using a NETZSCH DSC device. The test procedure is as follows: initial temperature: 20℃, heating to 220℃ at a heating rate of 10 K / min, holding at 220℃ for 5 minutes, cooling to 20℃ at a cooling rate of 10 K / min, holding at 20℃ for 3 minutes, heating to 220℃ at a heating rate of 10 K / min, holding at 220℃ for 2 minutes, cooling to 50℃ at a cooling rate of 20 K / min. The entire test process is carried out under nitrogen protection.

[0162] Example 1

[0163] This embodiment provides an aliphatic-aromatic copolyester, the preparation method of which includes:

[0164] (1) Add 4700g terephthalic acid, 2400g adipic acid, 5500g 1,4-butanediol, 12g glycerol and 4.3g tetrabutyl titanate to a 20L reactor. Esterify at 200℃ for 2 hours under a pressure of 110kPa. Then raise the temperature to 235℃ and continue esterifying at a pressure of 85kPa for 1.5 hours.

[0165] (2) After the esterification in step (1), 3.2g of tetrabutyl titanate was added to the reactor, the temperature was raised to 238℃, and the reaction was carried out at a pressure of 2100Pa for 2h. Most of the excess 1,4-butanediol was removed by distillation to obtain the prepolymer.

[0166] (3) After the prepolymerization in step (2), the temperature is raised to 245°C and polycondensed at 165Pa for 2 hours. The excess 1,4-butanediol and other byproducts are removed by distillation and granulation and drying to obtain aliphatic-aromatic copolyester.

[0167] Example 2

[0168] This embodiment provides an aliphatic-aromatic copolyester, the preparation method of which includes:

[0169] (1) Add 5900g terephthalic acid, 2400g adipic acid, 6100g 1,4-butanediol, 15g glycerol and 5.2g tetrabutyl titanate to a 20L reactor. Esterify at 200℃ for 2.5 hours under 110kPa pressure. Then raise the temperature to 230℃ and continue esterification at 90kPa pressure for 2 hours.

[0170] (2) After the esterification in step (1), 4.0 g of tetrabutyl titanate was added to the reactor, the temperature was raised to 240 °C, and the reaction was carried out at a pressure of 1800 Pa for 2 h. Most of the excess 1,4-butanediol was removed by distillation to obtain the prepolymer.

[0171] (3) After the prepolymerization in step (2), the temperature is raised to 243°C and polycondensed at 145Pa for 2 hours. The excess 1,4-butanediol and other byproducts are removed by distillation and granulation and drying to obtain aliphatic-aromatic copolyester.

[0172] Example 3

[0173] This embodiment provides an aliphatic-aromatic copolyester, the preparation method of which includes:

[0174] (1) Add 5100g terephthalic acid, 2370g adipic acid, 6000g 1,4-butanediol, 13g glycerol and 3.5g tetrabutyl titanate to a 20L reactor. Esterify at 180℃ for 2 hours under 100kPa pressure. Then, raise the temperature to 240℃ under 90kPa pressure and continue esterifying for 1 hour.

[0175] (2) After the esterification in step (1), 3.0 g of tetrabutyl titanate was added to the reactor, the temperature was raised to 243 °C, and the reaction was carried out at a pressure of 1850 Pa for 2.5 h. Most of the excess 1,4-butanediol was removed by distillation to obtain the prepolymer.

[0176] (3) After the prepolymerization in step (2), the temperature is raised to 245°C and polycondensed at 150 Pa for 1.5 h. The excess 1,4-butanediol and other byproducts are removed by distillation and granulation and drying to obtain aliphatic-aromatic copolyester.

[0177] Example 4

[0178] This embodiment provides an aliphatic-aromatic copolyester, the preparation method of which includes:

[0179] (1) Add 5100g terephthalic acid, 2370g adipic acid, 6200g 1,4-butanediol, 13g glycerol and 5.5g tetrabutyl titanate to a 20L reactor. Esterify at 190℃ for 3 hours under 85kPa pressure. Then, raise the temperature to 240℃ under 85kPa pressure and continue esterification for 1.5 hours.

[0180] (2) After the esterification in step (1), 4.0 g of tetrabutyl titanate was added to the reactor, the temperature was raised to 243 °C, and the reaction was carried out at a pressure of 1700 Pa for 3 h. Most of the excess 1,4-butanediol was removed by distillation to obtain the prepolymer.

[0181] (3) After the prepolymerization in step (2), the temperature is raised to 247°C and polycondensed at 130 Pa for 1.5 h. The excess 1,4-butanediol and other byproducts are removed by distillation and granulation and drying to obtain aliphatic-aromatic copolyester.

[0182] Example 5

[0183] This embodiment provides an aliphatic-aromatic copolyester, the preparation method of which includes:

[0184] (1) Add 5100g terephthalic acid, 2370g adipic acid, 5800g 1,4-butanediol, 13g glycerol and 3.0g tetrabutyl titanate to a 20L reactor. Esterify at 180°C for 2 hours under 100kPa pressure. Then, raise the temperature to 235°C under 90kPa pressure and continue esterifying for 1 hour.

[0185] (2) After the esterification in step (1), 2.6g of tetrabutyl titanate was added to the reactor, the temperature was raised to 240℃, and the reaction was carried out at a pressure of 1700Pa for 2h. Most of the excess 1,4-butanediol was removed by distillation to obtain the prepolymer.

[0186] (3) After the prepolymerization in step (2), the temperature is raised to 245°C and polycondensed at 120Pa for 1 hour. The excess 1,4-butanediol and other byproducts are removed by distillation and granulation and drying to obtain aliphatic-aromatic copolyester.

[0187] Example 6

[0188] This embodiment provides an aliphatic-aromatic copolyester, the preparation method of which includes:

[0189] (1) Add 5300g terephthalic acid, 3500g sebacic acid, 6100g 1,4-butanediol, 17g glycerol and 5.2g tetrabutyl titanate to a 20L reactor. Esterify at 200℃ for 2.5 hours under 95kPa pressure. Then, raise the temperature to 235℃ under 60kPa pressure and continue esterifying for 1.5 hours.

[0190] (2) After the esterification of step (1), 3.8g of tetrabutyl titanate was added to the reactor, the temperature was raised to 240℃, and the reaction was carried out at a pressure of 1600Pa for 3h. Most of the excess 1,4-butanediol was removed by distillation to obtain the prepolymer.

[0191] (3) After the prepolymerization in step (2), the temperature is raised to 245°C and polycondensed at 130 Pa for 2 hours. The excess 1,4-butanediol and other byproducts are removed by distillation and granulation and drying to obtain aliphatic-aromatic copolyester.

[0192] Example 7

[0193] This embodiment provides an aliphatic-aromatic copolyester, the preparation method of which includes:

[0194] (1) Add 5300g terephthalic acid, 3500g sebacic acid, 6100g 1,4-butanediol, 6.5g glycerol and 5.2g tetrabutyl titanate to a 20L reactor. Esterify at 200℃ for 3 hours under 110kPa pressure. Then, raise the temperature to 235℃ under 100kPa pressure and continue esterification for 1.5 hours.

[0195] (2) After the esterification in step (1), 3.8g of tetrabutyl titanate was added to the reactor, the temperature was raised to 240℃, and the reaction was carried out at a pressure of 1800Pa for 3h. Most of the excess 1,4-butanediol was removed by distillation to obtain the prepolymer.

[0196] (3) After the prepolymerization in step (2), the temperature is raised to 247°C and polycondensed at 140Pa for 2.5 hours. The excess 1,4-butanediol and other byproducts are removed by distillation and granulation and drying to obtain aliphatic-aromatic copolyester.

[0197] Example 8

[0198] This embodiment provides an aliphatic-aromatic copolyester, the preparation method of which includes:

[0199] (1) Add 4700g terephthalic acid, 2400g adipic acid, 5500g 1,4-butanediol, 3.0g glycerol and 5.2g tetrabutyl titanate to a 20L reactor. Esterify at 190℃ for 2 hours under 100kPa pressure. Then, esterify at 235℃ for 1 hour under 90kPa pressure.

[0200] (2) After the esterification in step (1), 3.0 g of tetrabutyl titanate was added to the reactor, the temperature was raised to 242℃, and the reaction was carried out at a pressure of 2000 Pa for 2.0 h. Most of the excess 1,4-butanediol was removed by distillation to obtain the prepolymer.

[0201] (3) After the prepolymerization in step (2), the temperature is raised to 246°C and polycondensed at 145 Pa for 1 hour. The excess 1,4-butanediol and other byproducts are removed by distillation and granulation and drying to obtain aliphatic-aromatic copolyester.

[0202] Comparative Example 1

[0203] This comparative example provides an aliphatic-aromatic copolyester, the preparation method of which includes:

[0204] (1) Add 4120g terephthalic acid, 3000g adipic acid, 5600g 1,4-butanediol, 14g glycerol and 4.0g tetrabutyl titanate to a 20L reactor. Esterify at 210℃ for 2 hours under a pressure of 110kPa. Then, esterify at 230℃ under a pressure of 90kPa for another hour.

[0205] (2) After the esterification in step (1), 3.0 g of tetrabutyl titanate was added to the reactor, the temperature was raised to 242 °C, and the reaction was carried out at a pressure of 1700 Pa for 2.5 h. Most of the excess 1,4-butanediol was removed by distillation to obtain the prepolymer.

[0206] (3) After the prepolymerization in step (2), the temperature is raised to 245°C and polycondensed at 130 Pa for 2.5 h. The excess 1,4-butanediol and other byproducts are removed by distillation and granulation and drying to obtain aliphatic-aromatic copolyester.

[0207] Comparative Example 2

[0208] This comparative example provides an aliphatic-aromatic copolyester, the preparation method of which includes:

[0209] (1) 6200g terephthalic acid, 2000g adipic acid, 6000g 1,4-butanediol, 16g glycerol and 4.0g tetrabutyl titanate were added to a 20L reactor. After esterification at 210℃ for 2 hours under a pressure of 110kPa, the temperature was raised to 235℃ under a pressure of 90kPa and esterification was continued for 2 hours.

[0210] (2) After the esterification of step (1), 3.0 g of tetrabutyl titanate was added to the reactor, the temperature was raised to 242 °C, and the reaction was carried out at a pressure of 1600 Pa for 3 h. Most of the excess 1,4-butanediol was removed by distillation to obtain the prepolymer.

[0211] (3) After the prepolymerization in step (2), the temperature is raised to 245°C and polycondensed at 130Pa for 3 hours. The excess 1,4-butanediol and other byproducts are removed by distillation and granulation and drying to obtain aliphatic-aromatic copolyester.

[0212] Comparative Example 3

[0213] This comparative example provides an aliphatic-aromatic copolyester, the preparation method of which includes:

[0214] (1) Add 5100g terephthalic acid, 2370g adipic acid, 6200g 1,4-butanediol, 55g glycerol and 5.0g tetrabutyl titanate to a 20L reactor. Esterify at 190℃ for 2 hours under 110kPa pressure. Then, raise the temperature to 240℃ under 90kPa pressure and continue esterification for 3 hours.

[0215] (2) After the esterification in step (1), 4.0 g of tetrabutyl titanate was added to the reactor, the temperature was raised to 243 °C, and the reaction was carried out at a pressure of 1600 Pa for 3 h. Most of the excess 1,4-butanediol was removed by distillation to obtain the prepolymer.

[0216] (3) After the prepolymerization in step (2), the temperature is raised to 245°C and polycondensed at 120Pa for 4 hours. The excess 1,4-butanediol and other byproducts are removed by distillation, and the product is granulated and dried to obtain an aliphatic-aromatic copolyester.

[0217] Comparative Example 4

[0218] This comparative example provides an aliphatic-aromatic copolyester, the preparation method of which includes:

[0219] (1) Add 4000g terephthalic acid, 3000g adipic acid, 6000g 1,4-butanediol, 21g glycerol and 4.0g tetrabutyl titanate to a 20L reactor. Esterify at 200℃ for 3 hours under a pressure of 110kPa. Then, esterify at 236℃ under a pressure of 45kPa for another 2 hours.

[0220] (2) After the esterification in step (1), 3.0 g of tetrabutyl titanate was added to the reactor, the temperature was raised to 243 °C, and the reaction was carried out at a pressure of 1500 Pa for 3 h. Most of the excess 1,4-butanediol was removed by distillation to obtain the prepolymer.

[0221] (3) After the prepolymerization in step (2), the temperature is raised to 245°C and polycondensed at 130 Pa for 5 hours. The excess 1,4-butanediol and other byproducts are removed by distillation and granulation and drying to obtain aliphatic-aromatic copolyester.

[0222] The relevant parameters of the aliphatic-aromatic copolyesters provided in Examples 1-8 and Comparative Examples 1-4 of this invention are shown in Table 1.

[0223] Table 1

[0224]

[0225] Application Examples 1-12, Comparative Application Examples 1-5

[0226] Application Examples 1-12 and Comparative Application Examples 1-5 respectively provide polyester compositions, the formulations of which are shown in Table 2 by weight. Specifically, in the polyester compositions provided in Application Examples 1-8 and Comparative Application Examples 1-4, the aliphatic-aromatic copolyesters are the aliphatic-aromatic copolyesters provided in Examples 1-8 and Comparative Examples 1-4, respectively; in the polyester compositions provided in Application Examples 9-12, the aliphatic-aromatic copolyesters are all the aliphatic-aromatic copolyesters provided in Example 3.

[0227] Table 2

[0228]

[0229] Performance testing

[0230] The polyester compositions described in Application Examples 1-12 and Comparative Application Examples 1-5 were blown into films under the following conditions: a screw length-to-diameter ratio of (30-32):1, a spiral flow channel die head, a double- or multi-port air ring, a blown film processing temperature setting of 115-150°C, a blow-up ratio of 3.5-4.0, and a blown film thickness of 12±2 μm. The resulting film was then heat-sealed into bags.

[0231] The prepared bag samples were stored in an environment with a temperature of 25±5℃ and a humidity of 55±5% to test the opening grade of the bags. The test method for the opening grade of the bags is shown in Table 3.

[0232] Table 3

[0233]

[0234] The results of the bag opening level are shown in Table 4.

[0235] Table 4

[0236]

[0237] As shown in Table 4, the opening grade of the bags in Application Examples 1 to 12 is ≥2.5, and the opening grade range is 2.5 to 4.5. In contrast, the opening grade of the bags in Application Examples 1 to 5 is 2.0 or below, and their opening performance is worse than that of Application Examples 1 to 12.

[0238] Therefore, the aliphatic-aromatic copolyester provided by this invention, by controlling the molar content of aromatic dicarboxylic acids and the melt flow rate within a specific range, results in film bag products prepared from polyester compositions comprising the aliphatic-aromatic copolyester exhibiting low food contact migration, good opening performance, and excellent processing properties. This aliphatic-aromatic copolyester can be used as an opening agent for film bag products. Furthermore, polyester compositions comprising this aliphatic-aromatic copolyester can be widely used in bag products such as shopping bags, garbage bags, express delivery bags, medical bags, or fruit and vegetable bags.

[0239] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. An aliphatic-aromatic copolyester, characterized in that, The aliphatic-aromatic copolyester comprises the following components: Component A includes the following components: a1) Based on the total molar percentage of a1) and a2), 63-69 mol% of terephthalic acid or its derivatives or mixtures thereof; a2) Based on the total molar percentage content of a1) and a2), at least one C4-C at 31-37 mol% 10 Aliphatic dicarboxylic acids or their derivatives, or mixtures thereof; Component B: 1,4-Butanediol in at least an equimolar amount with component A; The terephthalic acid derivative is a di-C1-C6 alkyl ester of terephthalic acid; the C4-C 10 Aliphatic dicarboxylic acid derivatives are C4-C 10 Di-C1-C6 alkyl esters of aliphatic dicarboxylic acids; Based on 100 wt% of the aliphatic-aromatic copolyester, the aliphatic-aromatic copolyester further comprises 0.05 to 0.45 wt% of a branching agent; the branching agent includes at least one selected from tartaric acid, citric acid, malic acid, trimethylolpropane, trimethylolethane, pentaerythritol, polyether triol, glycerol, 1,3,5-benzotriic acid, 1,2,4-benzotriic acid, 1,2,4-benzotriic anhydride, 1,2,4,5-benzotetraic acid, and benzopyrenic acid dianhydride. The aliphatic-aromatic copolyester, according to standard ISO 1133-2-2011, has a melt mass flow rate of 120~175g / 10min measured at 190℃ and 2.16kg. The melt enthalpy of the aliphatic-aromatic copolyester is 20~36 J / g.

2. The aliphatic-aromatic copolyester according to claim 1, characterized in that, The C4-C 10 The aliphatic dicarboxylic acid or its derivatives are at least one of succinic acid or its derivatives, adipic acid or its derivatives, azelaic acid or its derivatives, sebacic acid or its derivatives.

3. A method for preparing an aliphatic-aromatic copolyester according to any one of claims 1 to 2, characterized in that, Includes the following steps: (1) Mix component A and component B with a branching agent and react to obtain an esterified product; (2) The esterified product is subjected to a pre-condensation reaction to obtain a pre-condensation product; (3) The prepolymerization product is subjected to a polycondensation reaction to obtain the aliphatic-aromatic copolyester.

4. The preparation method according to claim 3, characterized in that, The preparation method includes at least one of the following reaction conditions: 1) The reaction temperature in step (1) is 180~240℃; 2) The reaction pressure in step (1) is 40~120 kPa; 3) The reaction time for step (1) is 3-5 hours; 4) The pre-condensation reaction temperature in step (2) is 230~250℃; 5) The pre-condensation reaction pressure in step (2) is 600~3000 Pa; 6) The pre-condensation reaction time in step (2) is 2-4 hours; 7) The polycondensation reaction temperature in step (3) is 240~260℃; 8) The polycondensation reaction pressure in step (3) is 50~200 Pa; 9) The polycondensation reaction time in step (3) is 1~4h.

5. A polyester composition, characterized in that, It comprises the following components in parts by weight: 45-75 parts of a first polyester, 0-10 parts of polylactic acid, 2-8 parts of a second polyester and 10-40 parts of filler; the second polyester comprises the aliphatic-aromatic copolyester as described in any one of claims 1 to 2.

6. The polyester composition according to claim 5, characterized in that, The first polyester comprises the following components: Acid components: i-1) Based on the total molar percentage of i-1) and i-2), 40-55 mol% of aromatic dicarboxylic acids or their esters, or mixtures thereof; i-2) Based on the total molar percentage of i-1) and i-2), 45-60 mol% of aliphatic dicarboxylic acids or their esters, or mixtures thereof; Dihydroxy compound components: i-3) At least in equimolar amounts with the acid component a C2-C6 aliphatic alkanediol, or a mixture thereof.

7. The polyester composition according to claim 6, characterized in that, The filler includes one or a combination of organic fillers, inorganic fillers, or other types of fillers. The organic filler includes at least one of starch, cellulose, straw, wood flour, and bamboo flour; the inorganic filler includes at least one of calcium carbonate, barium sulfate, talc, graphite, gypsum, carbon black, chalk, calcium oxide, calcium chloride, iron oxide, dolomite, kaolin, silicon dioxide, titanium dioxide, silicate, mica, and montmorillonite.

8. An opening agent for a film or bag, characterized in that, Includes the aliphatic-aromatic copolyester as described in any one of claims 1 to 2.

9. A film or bag, characterized in that, It comprises the following components: the aliphatic-aromatic copolyester according to any one of claims 1 to 2, or the polyester composition according to any one of claims 5 to 7.

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