Thermoplastic resin composition and use of plastic film

Abstract

To provide a strengthened polybutylene adipate terephthalate (PBAT) / polylactic acid (PLA) thermoplastic resin composition exhibiting excellent physical characteristics, a method for preparing the thermoplastic resin composition, and use of a plastic film.SOLUTION: A thermoplastic resin composition contains polybutylene adipate terephthalate, polylactic acid, and additives. The additives are selected from the group consisting of one or more of phenolic antioxidants and a combination of phenolic antioxidants and styrene maleic anhydride copolymers. The styrene maleic anhydride copolymer has a weight average molecular weight of less than 10,000. An amount of phenolic antioxidant is greater than or equal to 1 ppm and less than 3,000 ppm.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present disclosure relates to polymeric materials, and more specifically to thermoplastic resin compositions, methods for preparing the thermoplastic resin compositions, and uses of plastic films. [Background technology]

[0002] Polylactic acid (PLA) is now a well-established biodegradable resin and is considered a suitable alternative to petroleum-based resins such as polyethylene. Despite its high tensile strength, polylactic acid is not an ideal substitute for polyethylene in the production of plastic wraps, packaging films, and agricultural films due to its insufficient low tear resistance, slow crystallization rate, low crystallinity, and low heat deflection temperature. These characteristics make it difficult for polylactic acid to meet the technical requirements of polyethylene films. Polybutylene adipate terephthalate (PBAT) has favorable flexibility, good film formability, and high thermal stability, making it ideal for film production. However, its low strength and modulus, as well as its high cost, have prevented its widespread adoption. To address these limitations and enhance its properties, polybutylene adipate terephthalate is blended with polylactic acid to prepare PBAT / PLA composites (Patent Document 1).

[0003] Incorporating polylactic acid into polybutylene adipate terephthalate has the potential to enhance the tensile properties of PBAT / PLA composites. However, this enhancement can come at the cost of reduced tensile strength and tear resistance. As a result, addressing the challenge of simultaneously maintaining tensile strength in the transverse direction (TD) and tear resistance in the machine direction (MD) of the film is a significant problem that requires a solution.

[0004] Therefore, there is a need in the market for reinforced PBAT / PLA thermoplastic compositions that exhibit superior physical characteristics. Prior Art Disclosures / References Patent Literature

[0005] [Patent Document 1] People's Republic of China Patent No. CN104744898A Summary of the Invention

[0006] According to one embodiment of the present disclosure, a thermoplastic resin composition is provided. The thermoplastic resin composition includes polybutylene adipate terephthalate, polylactic acid, and an additive. The additive is one selected from the group consisting of a phenolic antioxidant and a combination of a phenolic antioxidant and a styrene-maleic anhydride (SMA) copolymer. The styrene-maleic anhydride copolymer has a weight average molecular weight (Mw) less than 10,000. The amount of the phenolic antioxidant is greater than or equal to 1 ppm and less than 3,000 ppm.

[0007] According to another embodiment of the present disclosure, a method for preparing a thermoplastic resin composition is provided. The method includes feeding polybutylene adipate terephthalate, polylactic acid, and an additive to a molding apparatus to produce a thermoplastic resin composition, where the additive is one selected from the group consisting of a phenolic antioxidant and a combination of a phenolic antioxidant and a styrene-maleic anhydride copolymer. The styrene-maleic anhydride copolymer has a weight average molecular weight less than 10,000. The amount of the phenolic antioxidant in the thermoplastic resin composition is greater than or equal to 1 ppm and less than 3,000 ppm.

[0008] According to yet another embodiment of the present disclosure, there is provided a use of a plastic film, which is produced from a thermoplastic resin composition and has applications in various forms such as plastic bags, shopping bags and agricultural films.

[0009] The present disclosure provides a thermoplastic resin composition comprising polybutylene adipate terephthalate, polylactic acid and additives. It also outlines a method for preparing the thermoplastic resin composition and the use of a plastic film produced from the thermoplastic resin composition. The thermoplastic resin composition and plastic film according to the present disclosure exhibit improved tensile strength, tear resistance, crystallinity, and thermal stability as a result of their components.

[0010] These and other embodiments of the present disclosure will be better understood with respect to the following detailed description of non-limiting embodiments. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The present disclosure provides a thermoplastic resin composition comprising polybutylene adipate terephthalate, polylactic acid, and an additive, the additive being one selected from the group consisting of a phenolic antioxidant and a combination of a phenolic antioxidant and a styrene maleic anhydride copolymer.

[0012] The components of the thermoplastic resin composition are described in detail below.

[0013] <Polybutylene adipate terephthalate>

[0014] Polybutylene adipate terephthalate (PBAT) is a copolymer composed of 1,4 butylene adipate (BA) and butylene terephthalate (BT), which combines the characteristics of poly(1,4 butylene adipate) (PBA) and polybutylene terephthalate (PBT). Polybutylene adipate terephthalate has favorable mechanical properties and excellent biodegradability. It is a completely biodegradable material with wide applications in agriculture, packaging and medical fields.

[0015] The polybutylene adipate terephthalate described in this disclosure can be synthesized by conventional methods commonly adopted in the art.For example, polybutylene adipate terephthalate can be obtained through a reaction involving the following components: component (a1) and component (a2). (a1) 35 mol% (mole percentage) to 95 mol%, preferably 45 mol% to 80 mol% of hexanedioic acid or its ester derivatives (especially C1-C6 dialkyl esters such as dimethyl adipate, diethyl adipate, dipropyl adipate, dibutyl adipate, dipentyl adipate, dihexyl adipate, or mixtures thereof, preferably hexanedioic acid, dimethyl adipate, and mixtures thereof), and 5 mol% to 65 mol%, preferably 20 mol% to 55 mol% of benzene-1,4-dicarboxylic acid or its ester derivatives (especially C1-C6 dialkyl esters such as dimethyl terephthalate, diethyl terephthalate, dipropyl terephthalate, dibutyl terephthalate, dipentyl terephthalate, dihexyl terephthalate, or mixtures thereof, preferably benzene-1,4-dicarboxylic acid, dimethyl terephthalate, and mixtures thereof); the sum of all the molar percentages in (a1) is equal to 100%. (a2) C2-C6 alkanediols and C5-C 10 A dihydroxy compound selected from cycloalkanediols. The molar ratio of component (a1) to component (a2) is 0.4:1 to 1.5:1, preferably 0.6:1 to 1.1:1.

[0016] The dihydroxy compound (a2) may be selected from the group consisting of C2-C6 alkanediols and C5-C6 alkanediols such as ethane-1,2-diol, propane-1,2-diol, propane-1,3-diol, 1,2-butanediol, 1,4-butanediol, 1,5-pentanediol, or 1,6-hexanediol, in particular ethane-1,2-diol, propane-1,3-diol, 1,4-butanediol, cyclopentanediol, 1,4-cyclohexanediol, 1,2-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, and mixtures thereof, more preferably 1,4-butanediol. 10cycloalkanediols, the amount of component (a2) being 95 mol% to 100 mol% based on the amount of component (a1). In addition to components (a1) and (a2), 0 mol% to 5 mol%, preferably 0.05 mol% to 4 mol% of at least one compound D (based on the amount of component (a1)) having at least three groups capable of forming esters can be used in the synthesis of polybutylene adipate terephthalate. Preferably, compound D has 3 to 10 functional groups capable of forming ester bonds. More preferably, compound D has 3 to 6 functional groups capable of forming ester bonds, in particular 3 to 6 hydroxyl and / or carboxyl groups. For example, tartaric acid, citric acid, malic acid, trimethylolpropane, trimethylolethane, pentaerythritol, polyether triols, glycerin, 1,3,5-trimellitic acid, 1,2,4-trimellitic anhydride, 1,2,4,5-benzenetetracarboxylic dianhydride and hydroxyisophthalic acid.

[0017] The amount of butylene terephthalate units (T%) in polybutylene adipate terephthalate is in the range of 35wt%-65wt% (weight percent). If T% is less than 35wt%, the resulting product is too soft for practical use. Conversely, if it is more than 65wt%, the product is too hard for practical application. The viscosity number is 30g / ml-350g / ml, preferably 50g / ml-300g / ml (50:50 w / w orthodichlorobenzene / hydroxybenzene, measured at 25℃, the concentration of PBAT is 0.5wt%). The melting point is in the range of 50℃-170℃, preferably 60℃-160℃.

[0018] Preferably, the polybutylene adipate terephthalate includes polybutylene adipate terephthalate Ecoflex, polybutylene adipate terephthalate FLEX-262, polybutylene adipate terephthalate EBAG-262, polybutylene adipate terephthalate Ecoworld. More preferably, the polybutylene adipate terephthalate is polybutylene adipate terephthalate Ecoworld. In the present disclosure, polybutylene adipate terephthalate Ecoflex is preferably manufactured by BASF SE; polybutylene adipate terephthalate FLEX-262 and polybutylene adipate terephthalate EBAG-262 are preferably manufactured by GUANGDONG KINGFA SCI.& TECH. CO., LTD.; polybutylene adipate terephthalate Ecoworld is preferably manufactured by JinHui ZhaoLong High Technology Co., Ltd.

[0019] In one embodiment, the temperature corresponding to 10% mass loss (TGA-10%) of the polybutylene adipate terephthalate used in this disclosure in thermogravimetric analysis is lower than 400°C, preferably lower than 390°C, more preferably lower than 380°C.

[0020] In addition, the weight average molecular weight of the polybutylene adipate terephthalate according to the present disclosure is generally 10,000 to 400,000, preferably 50,000 to 400,000, more preferably 80,000 to 300,000. The weight average molecular weight of the polybutylene adipate terephthalate is obtained by gel permeation chromatography (GPC) using oxolane as a solvent, a refractive index detector (RI) as a detector, and polystyrene of known molecular weight as a standard.

[0021] <Polylactic acid>

[0022] Polylactic acid can be divided into two types: one is obtained by condensation of lactic acid alone as a monomer; the other is obtained by condensation of a combination of lactic acid as a monomer and another hydroxycarboxylic acid component.

[0023] In the present disclosure, the lactic acid component may consist of either or both enantiomers of lactic acid. In order to enhance the flexibility, rigidity, heat resistance, and productivity of polylactic acid during molding, it is recommended to utilize lactic acid with high optical purity containing one of the enantiomers as the main component. The term "main component" as used herein refers to a component that is greater than or equal to 80 mol% in the lactic acid component.

[0024] In view of the above, when the condensation reaction involves only lactic acid components, the lactic acid components preferably consist of 95.0 mol % or more of either the L form (levorotatory; L-lactic acid) or the D form (dextrorotatory; D-lactic acid), with 98 mol % or more being preferred.

[0025] In view of the above, in the case of a condensation reaction between a lactic acid component and a hydroxycarboxylic acid component, the lactic acid component preferably consists of either the L- or D-form (i.e., the more abundant amount of one of the isomers) in the lactic acid component in an amount of 95.0 mol % or more, with 98 mol % or more being preferred.

[0026] In addition, the polylactic acid referred to above can be obtained from the enrichment of only D-lactic acid, only L-lactic acid, a combination of D-lactic acid and L-lactic acid, or a mixture of polylactic acid composed primarily of L-lactic acid and composed primarily of D-lactic acid in any ratio.

[0027] In addition, apart from lactic acid, the hydroxycarboxylic acid component may consist of other hydroxycarboxylic acid compounds such as glycolic acid, hydroxybutyric acid, hydroxyvalerenic acid, hydroxyvaleric acid, hydroxycaproic acid and hydroxyheptanoic acid. These hydroxycarboxylic acid compounds may be utilized individually or in combination with two or more of the listed compounds. Preferably, the hydroxycarboxylic acid component is glycolic acid or hydroxycaproic acid.

[0028] In addition, in the present disclosure, the lactic acid component may be composed of a dimer of lactic acid, and the hydroxycarboxylic acid component may include a dimer of a hydroxycarboxylic acid compound. For example, the dimer of lactic acid may be a cyclic dimer of lactic acid, i.e., lactide. For example, the dimer of a hydroxycarboxylic acid compound may be a cyclic dimer of glycolic acid, i.e., glycolide. Lactide includes a cyclic dimer of L-lactic acid (L-lactide), a cyclic dimer of D-lactic acid (D-lactide), meso-lactide obtained by cyclic dimerization of D-lactic acid and L-lactic acid, and DL-lactide, which is a racemate of D-lactide and L-lactide. Any kind of lactide may be used in the present disclosure. In view of the flexibility and rigidity of polylactic acid and the efficiency of polylactic acid resin in the molding process, it is recommended to use D-lactide and L-lactide. It will be appreciated that the lactic acid dimer may be incorporated either in the concentrate of just the lactic acid component or in the concentrate of the lactic acid component and the hydroxycarboxylic acid component.

[0029] Condensation reactions involving only the lactic acid component, or the lactic acid component and the hydroxycarboxylic acid component, can be carried out using established methods without specific limitation.

[0030] The weight average molecular weight range of polylactic acid in the present disclosure is typically within the range of 10,000 to 400,000, preferably 50,000 to 400,000, and more preferably 80,000 to 300,000. The reason for selecting this weight average molecular weight range is that when the weight average molecular weight of polylactic acid is below the above range, the mechanical properties of the molded resin product are reduced; when the weight average molecular weight of polylactic acid is above the above range, it may result in reduced fluidity during the molding process. Furthermore, the weight average molecular weight of polylactic acid is determined using gel permeation chromatography (GPC) using oxolane as a solvent, a differential refractive index detector (RI) for detection, and polystyrene with an established molecular weight as a reference standard.

[0031] In one embodiment, the temperature at which the polylactic acid in this study experiences a 10% mass loss during thermogravimetric analysis (TGA-10%) is below 360°C, preferably below 355°C, and more preferably below 345°C.

[0032] Preferably, the polylactic acid includes one or more of polylactic acid LX175, polylactic acid L130, polylactic acid LX530, polylactic acid 4032D, polylactic acid 3001D, polylactic acid FY801, polylactic acid FY802, polylactic acid FY601, and polylactic acid REVODE 110. More preferably, the polylactic acid is polylactic acid LX175. In the present disclosure, polylactic acid LX175, polylactic acid L130 and polylactic acid LX530 are preferably manufactured by TotalEnergies Corbion Ltd. (Thailand); polylactic acid 4032D, polylactic acid 3001D and polylactic acid 2003D are preferably manufactured by NatureWorks LLC (USA); polylactic acid FY801, polylactic acid FY802 and polylactic acid FY601 are preferably manufactured by Anhui BBCA Biochemical Co., Ltd.; polylactic acid REVODE110 is preferably manufactured by Zhejiang Hisun Biomaterials Co., Ltd.

[0033] <Additives>

[0034] The additive may be a phenolic antioxidant. Alternatively, the additive may be a combination of a phenolic antioxidant and a styrene maleic anhydride copolymer.

[0035] Phenolic antioxidants are primary antioxidants. Phenolic antioxidants refer to antioxidants that have a phenolic hydroxyl group in their molecule, such as antioxidants that have an alkyl group and an -OH group (phenolic hydroxyl group) that occupy adjacent positions. Phenolic antioxidants can be antioxidants in which steric effects are observed in the molecule, where the phenol ring in the molecule is substituted with one or more alkyl groups, such as methyl, ethyl, isopropyl, and tert-butyl. Phenolic antioxidants are not particularly limited. In one embodiment, the phenolic antioxidant is selected from the group consisting of pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, octadecyl-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 3,5-bis(1,1-dimethylethyl)-4-hydroxyphenylpropionate stearyl ester, triethylene glycol bis[3-(3-tert-butyl-5-methyl-4-hydroxyphenyl)propionate], tetrakis[methylene-3-(3,5-bis-tert-butyl-4-hydroxyphenyl)propionate]methane, 2-tert-butyl-6-(3-tert-butyl-2-hydroxy-6-methylbenzyl)-4-methylphenyl acrylate, and 2,2′-methyl In one embodiment, the phenolic antioxidant may be at least one selected from the group consisting of pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, octadecyl-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], triethylene glycol bis(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate, and octyl-3,5-di-tert-butyl-4-hydroxyhydrocinnamate. The above phenolic antioxidants may be used alone or more than one of the above phenolic antioxidants may be used in combination.

[0036] Examples of commercially available phenolic antioxidants include Irganox® 1010, Irganox® 1076, Irganox® 1098, Irganox® 1425WL, Irganox® 3114, Irganox® 245, and Irganox® 1135. The above phenolic antioxidants may be used alone or more than one of the above phenolic antioxidants may be used in combination.

[0037] The amount of the phenolic antioxidant is greater than or equal to 1 ppm and less than 3000 ppm, relative to the total amount of the thermoplastic resin composition. Alternatively, the amount of the phenolic antioxidant is greater than or equal to 400 ppm and less than or equal to 2800 ppm, relative to the total amount of the thermoplastic resin composition. Alternatively, the amount of the phenolic antioxidant is greater than or equal to 800 ppm and less than or equal to 2300 ppm, relative to the total amount of the thermoplastic resin composition.

[0038] Styrene maleic anhydride copolymers are copolymers of styrene monomers and maleic anhydride monomers. For example, the styrene maleic anhydride copolymers can be linear random copolymers, branched copolymers, linear block copolymers, or branched block copolymers. Styrene monomers can include styrene, α-methylstyrene, p-tert-butylstyrene, p-methylstyrene, o-methylstyrene, m-methylstyrene, 2,4-dimethylstyrene, ethylstyrene, α-methyl-p-methylstyrene, bromostyrene, and the like. The above styrene monomers can be used alone, or more than one of the above styrene monomers can be used in combination. In an embodiment, the styrene monomer can be selected from one or more of styrene and α-methylstyrene. The maleic anhydride monomers can include maleic anhydride, itaconic anhydride, citraconic anhydride, aconitic anhydride, and the like. The above maleic anhydride monomers may be used alone or more than one of the above maleic anhydride monomers may be used in combination.

[0039] The additive can be a combination of styrene-maleic anhydride copolymer and a phenolic antioxidant. Compared with using only a phenolic antioxidant as an additive, using a combination of styrene-maleic anhydride copolymer and a phenolic antioxidant as an additive can further improve the physical properties and significantly increase the tear resistance and tensile strength, especially the tensile strength in the width direction (transverse direction; TD) of the film and the tear resistance in the length direction (machine direction; MD) of the film. When using a combination of styrene-maleic anhydride copolymer and a phenolic antioxidant as an additive, the total amount of additive is 1 ppm to 5000 ppm, preferably 500 ppm to 4000 ppm, more preferably 1000 ppm to 3000 ppm based on the total amount of the thermoplastic resin composition; the amount of styrene-maleic anhydride copolymer is 1 ppm to 2000 ppm, preferably 100 ppm to 1500 ppm, more preferably 500 ppm to 1000 ppm based on the total amount of the thermoplastic resin composition. The selection of the phenolic antioxidant is described above. The amount of the phenolic antioxidant is greater than or equal to 1 ppm and less than 3000 ppm. The weight average molecular weight (Mw) of the styrene-maleic anhydride copolymer is less than 10000, preferably less than 8000, more preferably less than 6000; the weight average molecular weight (Mw) of the styrene-maleic anhydride copolymer is greater than 1000, preferably greater than 2000, more preferably greater than 3000. The amount of maleic anhydride monomer in the styrene-maleic anhydride copolymer is 20%-55%, preferably 20%-50%, more preferably 30%-45%.

[0040] In one embodiment of the present disclosure, the weight ratio of polybutylene adipate terephthalate to polylactic acid in the thermoplastic resin composition is in the range of 9.5:0.5 to 0.5:9.5, preferably in the ratio of 9.5:0.5 to 4:6, and more preferably in the ratio of 9:1 to 1:1. In one embodiment of the present disclosure, the thermoplastic resin composition is characterized by a polydispersity index (mass average molecular weight / number average molecular weight; Mw / Mn) in the range of 1.00 to 2.00, preferably in the ratio of 1.50 to 2.00, and more preferably in the ratio of 1.80 to 2.00.

[0041] In an embodiment of the present disclosure, the weight ratio of polybutylene adipate terephthalate to polylactic acid in the thermoplastic resin composition is in the range of 9.5:0.5 to 4:6, the additive is pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate or octadecyl-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] or a combination of pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate and styrene-maleic anhydride copolymer, or a combination of octadecyl-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and styrene-maleic anhydride copolymer, and the amount of phenolic antioxidant is greater than or equal to 1 ppm and less than 3000 ppm based on the total amount of the thermoplastic resin composition, and the amount of styrene-maleic anhydride copolymer is greater than or equal to 1 ppm and less than 3000 ppm based on the total amount of the thermoplastic resin composition. The weight average molecular weight of the carboxylic acid anhydride copolymer is lower than 10000, and the tensile strength in the width direction (transverse direction; TD) of the film formed by the thermoplastic resin composition is greater than 20 MPa; in one embodiment, the weight ratio of polybutylene adipate terephthalate to polylactic acid in the thermoplastic resin composition is in the range of 9.5:0.5 to 7:3, the tear resistance in the length direction (machine direction; MD) of the film is greater than 1650 MPa; in one embodiment, the weight ratio of polybutylene adipate terephthalate to polylactic acid in the thermoplastic resin composition is in the range of 6:4 to 4:6, the tear resistance in the length direction (machine direction; MD) of the film is greater than 110 MPa. Films have different physical property requirements in the length direction (MD) and the width direction (TD). For example, in film applications, the film must be able to be blown or stretched biaxially in the TD direction while exhibiting tensile strength in the MD direction.

[0042] In an embodiment of the present disclosure, the weight ratio of polybutylene adipate terephthalate to polylactic acid in the thermoplastic resin composition is in the range of 9.5:0.5 to 7:3, the additive is 400 ppm to 2800 ppm of pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate or 1800 ppm to 2300 ppm of octadecyl-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] relative to the total amount of the thermoplastic resin composition, the tear resistance in the machine direction (MD) of the film formed by the thermoplastic resin composition is greater than 1650 MPa, and the elongation in the machine direction (MD) of the film formed by the thermoplastic resin composition is greater than 600%. The present disclosure provides a film that exhibits high tensile strength in the MD direction and has excellent resistance to tearing.

[0043] In an embodiment of the present disclosure, the weight ratio of polybutylene adipate terephthalate to polylactic acid in the thermoplastic resin composition is in the range of 6:4 to 4:6, the additive is 1800 ppm to 2300 ppm of pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate or 400 ppm to 2800 ppm of octadecyl-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] relative to the total amount of the thermoplastic resin composition, the tear resistance in the machine direction (MD) of the film formed by the thermoplastic resin composition is greater than 110 MPa, and the elongation in the transverse direction (TD) of the film formed by the thermoplastic resin composition is greater than 26.5%. For example, in film applications, the film must also be capable of being blown or stretched biaxially in the TD while exhibiting tensile strength in the MD.

[0044] In an embodiment of the present disclosure, the weight ratio of polybutylene adipate terephthalate to polylactic acid in the thermoplastic resin composition is within the range of 9.5:0.5 to 7:3, the additive is pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate at 400 ppm to 2800 ppm relative to the total amount of the thermoplastic resin composition, and the tensile strength in the machine direction (MD) of the film formed by the thermoplastic resin composition is greater than 33 MPa. For example, in film applications, plastic bags need to have sufficient load-bearing capacity in the MD direction to prevent breakage.

[0045] In an embodiment of the present disclosure, the weight ratio of polybutylene adipate terephthalate to polylactic acid in the thermoplastic resin composition is within the range of 6:4 to 4:6, the additive is pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate or octadecyl-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] of 1800 ppm to 2300 ppm relative to the total amount of the thermoplastic resin composition, and the tensile strength in the machine direction (MD) of the film formed by the thermoplastic resin composition is greater than 33 MPa. For example, in film applications, plastic bags need to have sufficient load-bearing capacity in the MD direction to prevent breakage.

[0046] In an embodiment of the present disclosure, the weight ratio of polybutylene adipate terephthalate to polylactic acid in the thermoplastic resin composition is within the range of 9.5:0.5 to 7:3, the additives are 800 ppm to 1300 ppm of pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (or octadecyl-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]) and 100 ppm to 1500 ppm of styrene-maleic anhydride copolymer relative to the total amount of the thermoplastic resin composition, the weight average molecular weight of the styrene-maleic anhydride copolymer is lower than 10,000, the tensile strength in the transverse direction (TD) of the film formed by the thermoplastic resin composition is greater than 20 MPa, and the tear resistance in the longitudinal direction (MD) of the film formed by the thermoplastic resin composition is greater than 1650 MPa.

[0047] In an embodiment of the present disclosure, the weight ratio of polybutylene adipate terephthalate to polylactic acid in the thermoplastic resin composition is in the range of 9.5:0.5 to 7:3, the additive is pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate in an amount of 1800 ppm to 2300 ppm relative to the total amount of the thermoplastic resin composition, and the temperature corresponding to 10% mass loss (TGA-10%) of the thermogravimetric analysis of the thermoplastic resin composition can be greater than or equal to 358°C, and the temperature difference is greater than 1.6°C. Alternatively, in one embodiment where the weight ratio of polybutylene adipate terephthalate to polylactic acid in the thermoplastic resin composition is within the range of 6:4 to 4:6, the additive is pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate in an amount of 400 ppm to 2800 ppm relative to the total amount of the thermoplastic resin composition, and the temperature corresponding to 10% mass loss of the thermogravimetric analysis (TGA-10%) of the thermoplastic resin composition can be greater than or equal to 343°C, and the temperature difference is greater than 13°C.

[0048] In an embodiment of the present disclosure, the weight ratio of polybutylene adipate terephthalate to polylactic acid in the thermoplastic resin composition is in the range of 9.5:0.5 to 7:3, the additive is pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate or octadecyl-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] in an amount of 1800 ppm to 2300 ppm relative to the total amount of the thermoplastic resin composition, and the temperature corresponding to 10% mass loss of the thermogravimetric analysis (TGA-10%) of the thermoplastic resin composition can be higher than or equal to 358°C, and the temperature difference is greater than 1.6°C.

[0049] In an embodiment of the present disclosure, the weight ratio of polybutylene adipate terephthalate to polylactic acid in the thermoplastic resin composition is in the range of 6:4 to 4:6, the additive is pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate or octadecyl-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] in an amount of 1800 ppm to 2300 ppm relative to the total amount of the thermoplastic resin composition, and the temperature corresponding to 10% mass loss of the thermogravimetric analysis (TGA-10%) of the thermoplastic resin composition can be higher than or equal to 343°C, and the temperature difference is greater than 13°C.

[0050] In an embodiment of the present disclosure, the weight ratio of polybutylene adipate terephthalate to polylactic acid in the thermoplastic resin composition is in the range of 9.5:0.5 to 7:3, the additives are 800 ppm to 1300 ppm of pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate and 100 ppm to 1500 ppm of styrene-maleic anhydride copolymer relative to the total amount of the thermoplastic resin composition, the weight average molecular weight of the styrene-maleic anhydride copolymer is lower than 10000, and the temperature corresponding to 10% mass loss of the thermogravimetric analysis (TGA-10%) of the thermoplastic resin composition can be greater than or equal to 365°C, and the temperature difference is greater than 8°C.

[0051] In one embodiment, in addition to the polybutylene adipate terephthalate, polylactic acid, and additives above, the thermoplastic resin composition may also include other ingredients such as modifiers and colorants. In one embodiment, the thermoplastic resin composition consists of polybutylene adipate terephthalate, polylactic acid, and additives.

[0052] The present disclosure provides a method for preparing a thermoplastic resin composition. The method includes feeding the polybutylene adipate terephthalate, the polylactic acid, and the additives to a molding apparatus to mix the polybutylene adipate terephthalate, the polylactic acid, and the additives to produce a solid thermoplastic resin composition. The molding apparatus may include a dryer and / or a blender and / or a mixer and / or an extruder and / or an injection molding machine and / or a plastic pelletizer and / or a film former, etc. The thermoplastic resin composition includes the above components in the above content ranges. The relative proportions and / or contents of the polybutylene adipate terephthalate, the polylactic acid, and the additives may not change substantially before and after passing through the molding apparatus.

[0053] The thermoplastic resin composition according to the present disclosure may be used in degradable plastic products. In some embodiments, the thermoplastic resin composition according to the present disclosure may be used to form a plastic film. The plastic film may be produced from the above thermoplastic resin composition. For example, the plastic film may be produced from the above thermoplastic resin composition through a blow molding process. For example, the thermoplastic resin composition may be softened, the softened thermoplastic resin composition may be extruded and expanded at a certain pressure and speed into a hollow shape of a certain size, and then the material is cooled and / or stretched to form a plastic film. The tensile strength and elongation are determined according to the ISO 527 standard, and the tear resistance is determined according to the ISO 6838 standard. The plastic film according to the present disclosure may be used in any one of plastic bags, shopping bags, and agricultural films. The thermoplastic resin composition according to the present disclosure may be used in molding processes such as injection molding, compression molding, extrusion molding, stretch blow molding, vacuum forming, and blow molding to form a plastic product.

[0054] The present disclosure will be described with reference to the following examples and comparative examples below. However, the present disclosure is not limited to the components, contents and proportions disclosed in the following examples.

[0055] <Preparation of Thermoplastic Resin Composition>

[0056] The monomers and additives used in the following examples and comparative examples are as follows. Polybutylene adipate terephthalate (PBAT): C1200 from BASF, Mn: 55,719, Mw: 125703, TGA-10%: 374.0. Polylactic acid: 2003D from Natureworks, Mn: 117,210, Mw: 213,023, TGA-10%: 340.3. Additives: (1) Phenolic antioxidants Pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate: Irganox® 1010 Octadecyl-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]: Irganox® 1076 (2) Non-phenolic antioxidants Tris(2,4-di-tert-butylphenyl)phosphite: Irganox® 168 2-{1-[2-hydroxy-3,5-bis(2-methylbut-2-yl)phenyl]ethyl}-4,6-bis(2-methylbut-2-yl)benzeneacrylate: GS (3) Styrene-maleic anhydride copolymer XIRAN1000P, weight average molecular weight: 3385, maleic anhydride monomer content: 42% XIRAN4000, weight average molecular weight: 10536, maleic anhydride monomer content: 24%

[0057] Based on the components, contents, and ratios detailed in Tables 1, 2, 3, and 4, polybutylene adipate terephthalate, polylactic acid, and additives are subjected to a molding process to produce thermoplastic resin compositions for Examples 1-10 and Comparative Examples 1-24.

[0058] <Preparation of plastic form>

[0059] The plastic film is produced using a thermoplastic resin composition via blow molding technique, with a film thickness of 25 μm.

[0060] <Evaluation of Thermoplastic Resin Composition>

[0061] The number average molecular weight and weight average molecular weight are determined using gel permeation chromatography (GPC) using oxolane as a solvent, a refractive index detector (RI) for detection, and polystyrene with known molecular weight as a standard. The columns used are Agilent Part No. PL1110-6520 / PLgel 5 μm 100 Å 300x7.5mm, Part No. PL1110-6525 / PLgel 5 μm 500 Å 300x7.5mm, Part No. PL1110-6530 / PLgel 5 μm 1000 Å 300x7.5mm and Part No. PL1110-6540 / PLgel 5 10000 Å 300x7.5mm. The crystallization temperature (Tc) of the thermoplastic resin composition in both the examples and comparative examples was analyzed using a differential scanning calorimeter (DSC) Q2000 from TA Instruments. Thermogravimetric analysis (TGA) was performed using a Q5000 analyzer from TA Instruments. The temperature at which the sample experiences a 10% mass loss due to heating in a nitrogen environment is recorded, which is designated in this disclosure as TGA-10%. The crystallinity (Xc) is calculated according to the following formula 1. In formula 1, ΔHm is the melting enthalpy (J / g), ΔHcc is the cold crystallization enthalpy (J / g), and ΔHm of polybutylene adipate terephthalate is 0 is 114 J / g, and the △Hm of polylactic acid 0 is 93.6 J / g, and ψi represents the ratio of the weight of polybutylene adipate terephthalate or polylactic acid to the combined weight of polybutylene adipate terephthalate and polylactic acid. The evaluation results are shown in Tables 1 to 7 below. (Formula 1)

number

[0062] <Evaluation of plastic films>

[0063] The thickness of the film is 25 μm. Tensile strength and elongation are determined according to the ISO 527 standard. Tear resistance is determined according to the following ISO 6838 standard. The tensile properties of the plastic films produced from the thermoplastic resin compositions outlined in Examples 1 to 10 and Comparative Examples 1 to 14 are evaluated. The evaluation results are shown in Tables 1 and 2 below. [Table 1] [Table 1] [Table 2] [Table 2]

[0064] The improved physical properties of the thermoplastic resin composition are evident from Tables 1 and 2, where the thermoplastic resin composition includes PBAT, PLA, and additives, and the additives consist of either a phenolic antioxidant alone or a combination of a phenolic antioxidant and a styrene-maleic anhydride copolymer, the styrene-maleic anhydride copolymer having a weight average molecular weight lower than 10,000. The amount of the phenolic antioxidant is greater than or equal to 1 ppm, but less than 3,000 ppm, relative to the total amount of the thermoplastic resin composition. The data show that the tensile strength is significantly improved, especially in the transverse direction (TD) of the film, where all tensile strengths are greater than or equal to 20 MPa. The data show that the tear resistance in the machine direction (MD) of the film is greater than 1,650 MPa when the weight ratio of PBAT to PLA is 9.5:0.5 to 7:3. The data show that the tear resistance in the machine direction (MD) of the film is greater than 110 MPa when the weight ratio of PBAT to PLA is 6:4 to 4:6. Due to the difference in applications, the physical property requirements in the machine direction (MD) and transverse direction (TD) of the film are different. For example, in film applications, the film needs to be stretchable in the MD direction, while it also needs to be blown or stretchable in both TD directions; the tear resistance requirement in the TD direction is not as high as in the MD direction.

[0065] In addition, the data show that tear resistance is significantly improved when a combination of a phenolic antioxidant and a styrene maleic anhydride copolymer is utilized as an additive compared to using only a phenolic antioxidant.

[0066] As shown in Tables 1 and 2, when the weight ratio of polybutylene adipate terephthalate to polylactic acid in the thermoplastic resin composition is within the range of 9.5:0.5 to 7:3, and the additive is 400 ppm to 2800 ppm of pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate or 1800 ppm to 2300 ppm of octadecyl-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] relative to the total amount of the thermoplastic resin composition, the tear resistance in the machine direction (MD) of the resulting film is greater than 1650 MPa, and the elongation in the machine direction (MD) is greater than 600%. The film provided by the present disclosure exhibits high tensile strength in the MD direction and has high resistance to tearing, which is important for uses such as packaging films or plastic bags.

[0067] In one embodiment of the present disclosure, when the weight ratio of polybutylene adipate terephthalate to polylactic acid in the thermoplastic resin composition is in the range of 6:4 to 4:6, and the additive is 1800 ppm to 2300 ppm of pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate or 400 ppm to 2800 ppm of octadecyl-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] relative to the total amount of the thermoplastic resin composition, the tear resistance in the machine direction (MD) of the resulting film is greater than 110 MPa, and the elongation in the transverse direction (TD) is greater than 26.5%. For example, in film applications, the film needs to be stretchable in the MD direction, while it also needs to be blown or stretchable in both TD directions.

[0068] In one embodiment of the present disclosure, when the weight ratio of polybutylene adipate terephthalate to polylactic acid in the thermoplastic resin composition is within the range of 9.5:0.5 to 7:3, and the additive is pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate at 400 ppm to 2800 ppm relative to the total amount of the thermoplastic resin composition, the tensile strength of the resulting film in the machine direction (MD) is greater than 33 MPa. For example, in film applications, plastic bags need to have sufficient load-bearing capacity in the MD direction to prevent breakage.

[0069] In one embodiment of the present disclosure, the weight ratio of polybutylene adipate terephthalate to polylactic acid in the thermoplastic resin composition is in the range of 6:4 to 4:6, the additive is pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate or octadecyl-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] of 1800 ppm to 2300 ppm relative to the total amount of the thermoplastic resin composition, and the tensile strength of the resulting film in the machine direction (MD) is greater than 33 MPa. For example, in film applications, plastic bags need to have sufficient load-bearing capacity in the MD direction to prevent breakage.

[0070] In one embodiment of the present disclosure, when the weight ratio of polybutylene adipate terephthalate to polylactic acid in the thermoplastic resin composition is within the range of 9.5:0.5 to 7:3, the additive is 800 ppm to 1300 ppm of pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (or octadecyl-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]) and 100 ppm to 1500 ppm of styrene maleic anhydride copolymer relative to the total amount of the thermoplastic resin composition, the weight average molecular weight of the styrene maleic anhydride copolymer is less than 10000, the tensile strength of the resulting film in the transverse direction (TD) is greater than 20 MPa, and the tear resistance of the resulting film in the longitudinal direction (MD) is greater than 1650 MPa.

[0071] As shown in Table 1, the thermoplastic resin compositions of Examples 9 and 10 incorporate a phenolic antioxidant and a styrene-maleic anhydride copolymer as additives. The tear resistance and tensile strength in the machine direction (MD) or transverse direction (TD) of the plastic films produced by these compositions are significantly improved compared to those of Examples 1 and 3, in which only a phenolic antioxidant is utilized as an additive. For example, in Examples 9 and 10, the tear resistance in the machine direction (MD) is greater than 1800 MPa, the tear resistance in the transverse direction (TD) is greater than 580 MPa, and the tensile strength in the transverse direction (TD) is greater than 22 MPa.

[0072] As shown in Table 2, the thermoplastic resin compositions of Comparative Examples 11 and 12 incorporate only styrene-maleic anhydride copolymer as an additive without using a phenolic antioxidant. As a result, the tear resistance in the machine direction (MD) of the plastic film is less than 1650 MPa, significantly lower than the tear resistance found in Examples 1 or 9. In the thermoplastic resin compositions of Comparative Examples 13 and 14, the additive consists of styrene-maleic anhydride copolymer and a phenolic antioxidant. However, since the weight average molecular weight of the styrene-maleic anhydride copolymer is greater than 10,000, it is impossible to simultaneously meet the requirements of tear resistance in the machine direction (MD) greater than 1650 MPa and tensile strength in the transverse direction (TD) greater than 20 MPa. [Table 3] [Table 3]

[0073] When the additive is a phenolic antioxidant and the amount of the phenolic antioxidant is greater than or equal to 1 ppm but less than 3000 ppm, enhanced physical properties result, as shown in Table 3. For example, a polydispersity index (Q) below 2.0 indicates excellent miscibility and the achievement of balanced physical properties in the resin.

[0074] As shown in Table 3, the use of non-phenolic antioxidants as additives in thermoplastic resin compositions results in a decrease in number average molecular weight (Mn), an increase in polydispersity index (Q), and a decrease in crystallization temperature (Tc) of the resin when the amount of additive is greater than or equal to 1 ppm, and even when the amount is less than 3000 ppm. As a result, the poor miscibility and crystallization behavior of the resin prevent the achievement of balanced physical properties. [Table 4] [Table 4] [Table 5] [Table 5] [Table 6] [Table 6] [Table 7] [Table 7]

[0075] The data shown in Table 4 indicates that the use of PBAT and phenolic antioxidant alone, or PLA and phenolic antioxidant alone, cannot effectively enhance the thermal stability (TGA-10%). The data even indicates that the use of PBAT alone with Irganox® 1076 reduces the thermal stability. In addition, the use of PLA without PBAT may result in issues such as low tear resistance, slow crystallization rate, reduced crystallinity, and lower heat deflection temperature, making it difficult to meet the technical market demand for the film. Conversely, the use of PBAT without PLA has issues such as lower strength and modulus. The data shown in Tables 4 to 7 indicate that the combination of PBAT, PLA, and phenolic antioxidant, or the combination of PBAT, PLA, phenolic antioxidant, and styrene maleic anhydride copolymer can effectively enhance the thermal stability (TGA-10%).

[0076] The data shown in Tables 4 to 7 show that when the weight ratio of polybutylene adipate terephthalate to polylactic acid in the thermoplastic resin composition is within the range of 9.5:0.5 to 7:3, and the additive is either pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate or octadecyl-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] at 1800 ppm to 2300 ppm relative to the total amount of the thermoplastic resin composition, the result is that the temperature corresponding to 10% mass loss (TGA-10%) is greater than or equal to 358 in thermogravimetric analysis, and the temperature difference is greater than 1.6°C.

[0077] The data shown in Tables 4 to 7 show that when the weight ratio of polybutylene adipate terephthalate to polylactic acid in the thermoplastic resin composition is within the range of 6:4 to 4:6, and the additive is either pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate or octadecyl-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] at 400 ppm to 2800 ppm relative to the total amount of the thermoplastic resin composition, the result is that the temperature corresponding to 10% mass loss (TGA-10%) is greater than or equal to 343 in thermogravimetric analysis, and the temperature difference is greater than 13°C.

[0078] The data shown in Tables 4 to 7 show that when the weight ratio of polybutylene adipate terephthalate to polylactic acid in the thermoplastic resin composition is in the range of 9.5:0.5 to 7:3, the additives are 800 ppm to 1300 ppm of pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate and 100 ppm to 1500 ppm of styrene maleic anhydride copolymer relative to the total amount of the thermoplastic resin composition, and the weight average molecular weight of the styrene maleic anhydride copolymer is lower than 10000, and as a result, the temperature corresponding to 10% mass loss (TGA-10%) is greater than or equal to 365°C in thermogravimetric analysis, and the temperature difference is greater than 8°C.

[0079] The present disclosure provides a thermoplastic resin composition comprising polybutylene adipate terephthalate, polylactic acid and additives. It also outlines a method for preparing the thermoplastic resin composition and the use of the plastic film produced therefrom. By incorporating either a phenolic antioxidant or a combination of a phenolic antioxidant and a styrene-maleic anhydride copolymer as an additive (the weight average molecular weight (Mw) of the styrene-maleic anhydride copolymer is less than 10,000, and the amount of the phenolic antioxidant is greater than or equal to 1 ppm and less than 3,000 ppm), the thermoplastic resin composition according to the present disclosure exhibits balanced physical properties, such as excellent heat resistance, excellent tensile strength, and good crystallinity.

[0080] While the present disclosure has been described by way of example and in terms of exemplary embodiments, it is to be understood that the disclosure is not limited thereto, but is intended to cover various modifications and similar arrangements and procedures, and the scope of the appended claims should therefore be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements and procedures.

Claims

1. Polybutylene adipate terephthalate (PBAT); Polylactic acid; and an additive which is one selected from the group consisting of a phenolic antioxidant and a combination of a phenolic antioxidant and a styrene maleic anhydride copolymer; Equipped with wherein the weight ratio of the polybutylene adipate terephthalate to the polylactic acid is within a range of 9.5:0.5 to 0.5:9.5; wherein the styrene-maleic anhydride copolymer has a weight average molecular weight (Mw) less than 10,000, the amount of maleic anhydride monomer in the styrene-maleic anhydride copolymer is 20% to 55%, and the amount of the phenolic antioxidant is greater than or equal to 1 ppm and less than 3,000 ppm; Thermoplastic resin composition.

2. The thermoplastic resin composition according to claim 1, wherein the phenolic antioxidant is at least one selected from the group consisting of pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, octadecyl-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], triethylene glycol bis(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate, and octyl-3,5-di-tert-butyl-4-hydroxyhydrocinnamate.

3. When the weight ratio of the polybutylene adipate terephthalate to the polylactic acid is in the range of 9.5:0.5 to 7:3, the amount of pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate is greater than or equal to 1800 ppm and less than or equal to 2300 ppm; or When the weight ratio of the polybutylene adipate terephthalate to the polylactic acid is in the range of 6:4 to 4:6, the amount of pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate is greater than or equal to 400 ppm and less than or equal to 2800 ppm; The thermoplastic resin composition according to claim 1.

4. 4. Use of a plastic film in any one of a plastic bag, a shopping bag, and an agricultural film, said plastic film being produced from the thermoplastic resin composition according to any one of claims 1 to 3.

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