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

Abstract

The application discloses a biodegradable polyester composition and a preparation method and application thereof, and belongs to the technical field of polymer materials; the biodegradable polyester composition provided by the application comprises the following components in mass parts: 8-42 parts of polylactic acid, 42-72 parts of degradable copolyester, 1-32 parts of calcium carbonate, 0.01-5 parts of a purple light absorber, 0.1-1 part of a hindered phenol antioxidant and 0.1-1 part of a phosphate antioxidant; the molar content of dextro-D monomers of the polylactic acid is 1.3-10%; the melt index of the degradable copolyester under the condition of 190 DEG C / 2.16 kg is 18-42 g / 10 min, and the ratio of the weight average molecular weight to the number average molecular weight (PDI) is 1.7-2.8; and the purple light absorber comprises a metal oxide and a benzotriazole compound; the biodegradable polyester composition provided by the application has good heat-oxygen aging resistance, and meanwhile, excellent clarity can be achieved during purple light marking.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, and particularly relates to a biodegradable polyester composition, its preparation method and application. Background Technology

[0002] Biodegradable materials are of great significance for environmental protection, resource conservation, sustainable development, and human health because they can be broken down by microorganisms in the natural environment and ultimately transformed into harmless substances such as water, carbon dioxide, and biomass. Furthermore, with increasing public awareness of environmental protection and supportive policies in various countries, the application areas of biodegradable plastics are expanding, including but not limited to food service, agriculture, medical applications, packaging, textiles, and 3D printing.

[0003] Laser marking technology boasts advantages such as low cost, high marking efficiency, and good processing quality, making it widely used in plastic marking across various industries. It provides permanent markings for products, offering not only aesthetic appeal but also anti-counterfeiting and brand identification functions. However, due to the inherent characteristics of biodegradable materials like polylactic acid (PLA), they struggle to effectively absorb 355nm ultraviolet light, resulting in marking difficulties and unclear markings. Furthermore, as biodegradable materials, PLA exhibits poor resistance to heat and oxygen aging, making it more susceptible to performance degradation under the high-energy field of laser marking. These issues, to some extent, limit the application of biodegradable materials in ultraviolet marking. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a biodegradable polyester composition with excellent heat and oxygen aging resistance and clear application in ultraviolet marking, as well as its preparation method and application.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a biodegradable polyester composition, wherein the biodegradable polyester composition comprises the following components in parts by weight:

[0006] 8-42 parts polylactic acid, 42-72 parts biodegradable copolyester, 1-32 parts calcium carbonate, 0.01-5 parts ultraviolet light absorber, 0.1-1 part hindered phenolic antioxidant, 0.1-1 part phosphate ester antioxidant;

[0007] The polylactic acid contains 1.3-10% dextrorotatory D monomer molar content.

[0008] The biodegradable copolyester has a melt index of 18 g / 10 min to 42 g / 10 min at 190 °C / 2.16 kg, and a weight-average molecular weight (PDI) ratio of 1.7 to 2.8.

[0009] The ultraviolet light absorber includes metal oxides and benzotriazole compounds.

[0010] The present invention provides a biodegradable polyester composition that, by selecting appropriate mass fractions of components, achieves synergistic effects between the components, effectively improving the heat and oxygen aging resistance of the prepared product, while also achieving excellent clarity during ultraviolet marking.

[0011] Specifically, in the first aspect, the present invention selects polylactic acid with a specific range of dextrorotatory D monomer molar content and biodegradable copolyester with a specific melt index range and a weight-average molecular weight to number-average molecular weight ratio range as the resin matrix. The two have excellent compatibility. Moreover, the specific range of dextrorotatory D monomer molar content of polylactic acid not only affects the molecular structure and crystallization properties of polylactic acid itself, but also affects the interaction with the biodegradable copolyester. Similarly, the weight-average molecular weight to number-average molecular weight ratio (PDI) of the biodegradable copolyester reflects the molecular chain distribution of the biodegradable copolyester to a certain extent. Combined with the specific melt index range, it can effectively improve the compatibility with polylactic acid, and jointly improve the heat and oxygen aging resistance and UV marking clarity of the product.

[0012] Secondly, this invention selects calcium carbonate as a filler. As an inorganic nucleating agent, it can provide heterogeneous nucleation sites in polylactic acid and biodegradable copolyester matrices, promote the crystallization rate of polylactic acid and biodegradable copolyester, increase their crystallinity, and improve their heat oxidation resistance. In addition, the introduction of calcium carbonate also enhances the radiation absorption capacity of the biodegradable polyester composition for lasers, ultimately improving the ultraviolet marking effect of the product.

[0013] Thirdly, the violet light absorber provided by this invention includes metal oxides and benzotriazole compounds, which can synergistically enhance the absorption capacity of violet light, thereby effectively realizing violet light marking and improving the clarity of violet light marking.

[0014] Fourthly, this invention selects hindered phenolic antioxidants and phosphate ester antioxidants in synergy. Under the high-energy field of subsequent laser marking, these antioxidants can effectively decompose the peroxides generated during the marking process and capture free radicals in the polylactic acid and biodegradable polyester system, preventing the continued progress of the oxidation chain reaction, significantly reducing the oxidative degradation of the material, and mitigating the problem of decreased material stability caused by the marking process; thus improving the product's resistance to heat and oxygen aging.

[0015] For example, the polylactic acid can be any point value or any two-point range between 8 and 42 parts, such as 10-40 parts, or 8, 10, 12, 15, 18, 20, 22, 25, 28, 30, 32, 35, 38, 40, 42, etc.; the biodegradable copolyester can be any point value or any two-point range between 42 and 72 parts, such as 45-70 parts, or 42, 45, etc. The quantities are 48, 50, 52, 55, 58, 60, 62, 65, 68, 70, and 72 parts, etc.; the calcium carbonate can be any point value or any two-point range value between 1 and 32 parts, for example, it can be 3-30 parts, or it can be 1 part, 3 parts, 5 parts, 8 parts, 10 parts, 12 parts, 15 parts, 18 parts, 20 parts, 22 parts, 25 parts, 28 parts, 30 parts, and 32 parts, etc.; the ultraviolet light absorber can be any value between 0.01 and 5 parts. The value can be a single point or any two-point range, for example, 0.03-4.8 parts, or 0.01 parts, 0.03 parts, 0.05 parts, 0.1 parts, 0.2 parts, 0.5 parts, 0.8 parts, 1 part, 1.2 parts, 1.5 parts, 1.8 parts, 2 parts, 2.2 parts, 2.5 parts, 2.8 parts, 3 parts, 3.2 parts, 3.5 parts, 3.8 parts, 4 parts, etc.; the hindered phenolic antioxidant can be any single point or any two-point range between 0.1 and 1 part, for example, The dosage is 0.2-0.9 parts, or it can be 0.1 parts, 0.2 parts, 0.3 parts, 0.4 parts, 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts, 1 part, etc.; the phosphate ester antioxidant can be any point value or any two-point range value between 0.1-1 parts, for example, it can be 0.2-0.9 parts, or it can be 0.1 parts, 0.2 parts, 0.3 parts, 0.4 parts, 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts, 1 part, etc.

[0016] Preferably, in the biodegradable polyester composition, the mass percentage of the biodegradable copolyester is ≥34%.

[0017] More preferably, the biodegradable polyester composition contains 37-82% by mass of the biodegradable copolyester.

[0018] It should be noted that the molar content of the dextrorotatory D monomer of polylactic acid was obtained by gas chromatography. Specifically, the gas chromatography test was conducted using an Agilent 8860 gas chromatograph with a CP7502 column, an FID detector temperature of 200°C, a hydrogen flow rate of 45 mL / min, an air flow rate of 450 mL / min, and a split ratio of 5:1.

[0019] For example, the molar content of the dextrorotatory D monomer of polylactic acid can be any point value or any two points between 1.3% and 10%, such as 1.3%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, etc.

[0020] It should be noted that the melt index of the biodegradable copolyester was obtained by a melt indexer, and the weight-average and number-average molecular weights were obtained by GPC testing. The melt index was obtained according to ISO 1133-1:2022, and the test conditions were 190℃ / 2.16kg.

[0021] For example, the melt index of the biodegradable copolyester at 190℃ / 2.16kg can be any point value or any two-point range between 18-42g / 10min, such as 20-40g / 10min, or 18g / 10min, 20g / 10min, 25g / 10min, 30g / 10min, 35g / 10min, 40g / 10min, 42g / 10min, etc.; the weight-average molecular weight to number-average molecular weight ratio (PDI) of the biodegradable copolyester can be any point value or any two-point range between 1.7-2.8, such as 1.8-2.5, or 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, etc.

[0022] It should be noted that the weight-average molecular weight and number-average molecular weight of the biodegradable copolyester were obtained by gel permeation chromatography. After obtaining the results, the polydispersity index of the biodegradable copolyester was calculated according to the definition of polydispersity index: the ratio of weight-average molecular weight to number-average molecular weight PDI = weight-average molecular weight / number-average molecular weight.

[0023] As a preferred embodiment of the biodegradable polyester composition of the present invention, the biodegradable polyester composition comprises the following components in parts by weight:

[0024] 25-30 parts polylactic acid, 55-60 parts biodegradable copolyester, 10-20 parts calcium carbonate, 2-4 parts ultraviolet light absorber, 0.5-0.7 parts hindered phenolic antioxidant, and 0.3-0.4 parts phosphate ester antioxidant.

[0025] The present invention has found that when the mass fraction of the biodegradable polyester composition is further selected within the above range, the resulting product has higher clarity in UV marking and better resistance to heat and oxygen aging.

[0026] As a preferred embodiment of the biodegradable polyester composition of the present invention, the polylactic acid has a melt index of 18-42 g / 10 min at 190°C / 2.16 kg.

[0027] It should be noted that the melt index of the polylactic acid was obtained by testing according to the standard ISO 1133-1:2022, and the test conditions were 190℃ / 2.16kg.

[0028] For example, the melt index of the polylactic acid at 190℃ / 2.16kg can be any point value or any two-point range between 18-42g / 10min, such as 20-40g / 10min, or 20g / 10min, 22g / 10min, 24g / 10min, 26g / 10min, 28g / 10min, 30g / 10min, 32g / 10min, 34g / 10min, 36g / 10min, 38g / 10min, 40g / 10min, etc.

[0029] This invention has found that the melt index of polylactic acid (PLA) affects the fluidity of the system, as well as its compatibility with biodegradable copolyesters and the dispersibility of calcium carbonate, UV absorbers, hindered phenolic antioxidants, and phosphate ester antioxidants in the resin matrix. When the melt index of PLA at 190℃ / 2.16kg is further selected to be 18-42g / 10min, the overall performance of the obtained product is better.

[0030] As a preferred embodiment of the biodegradable polyester composition of the present invention, the polylactic acid has a dextrorotatory D monomer molar content of 1.7-5%.

[0031] This invention has found that the molar content of the dextrorotatory D monomer in polylactic acid (PLA) affects the molecular structure and crystallization properties of PLA, thus affecting not only its interaction with other components but also the heat and oxygen aging resistance of the product. When the molar content of the dextrorotatory D monomer in PLA is further selected to be 1.7-5%, the resulting product not only has better heat and oxygen aging resistance but also higher clarity in UV marking.

[0032] As a preferred embodiment of the biodegradable polyester composition of the present invention, the biodegradable copolyester includes at least one of polybutylene adipate terephthalate, polybutylene sebacate terephthalate, polybutylene azelaate terephthalate, polybutylene terephthalate succinate, and polybutylene succinate.

[0033] In a preferred embodiment of the biodegradable polyester composition of the present invention, the calcium carbonate has a Dv50 particle size of 1-6 μm.

[0034] It should be noted that the Dv50 particle size of the calcium carbonate was obtained by laser particle size analyzer. The specific testing method is determined according to GB / T 19077.1-2008 "Particle Size Analysis by Laser Diffraction".

[0035] For example, the Dv50 particle size of the calcium carbonate can be any point value or any two-point range value between 1 and 6 μm, such as 1.4-5.5 μm, or 1 μm, 1.4 μm, 2.0 μm, 2.5 μm, 3.0 μm, 5.5 μm, 6.0 μm, etc.

[0036] Preferably, the Dv50 particle size of the calcium carbonate is 2.5-4 μm.

[0037] This invention has found that the Dv50 particle size of calcium carbonate affects its heterogeneous nucleation effect on resins such as PLA. When the Dv50 particle size of calcium carbonate is further selected to be 2.5-4μm, the resulting product has better heat and oxygen aging resistance and higher clarity of ultraviolet marking.

[0038] In a preferred embodiment of the biodegradable polyester composition of the present invention, the mass ratio of the metal oxide to the benzotriazole compound in the ultraviolet absorber is (1-5):1.

[0039] For example, in the ultraviolet absorber, the mass ratio of metal oxide to benzotriazole compound can be any point value or any two points between (1-5):1, such as 1:1, 2:1, 3:1, 4:1, 5:1, etc.

[0040] This invention has found that the mass ratio of metal oxides to benzotriazole compounds affects their absorption of violet light. When the mass ratio of the two is further selected within the above range, the violet marking clarity of the obtained product is higher.

[0041] In a preferred embodiment of the biodegradable polyester composition of the present invention, the metal oxide includes at least one of antimony oxide, tin oxide, zinc oxide, and titanium oxide.

[0042] As a preferred embodiment of the biodegradable polyester composition of the present invention, the benzotriazole compound includes at least one of 2-(2'-hydroxy-3',5'-bis(a,a-dimethylbenzyl)phenyl)benzotriazole and 2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole.

[0043] As a preferred embodiment of the biodegradable polyester composition of the present invention, the hindered phenolic antioxidant includes at least one of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (RIANOX 1010), octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (RIANOX 1076), and N,N'-hexamethylenebis(3,5-di-tert-butyl-4-hydroxyphenylpropionamide) (RIANOX 1098).

[0044] As a preferred embodiment of the biodegradable polyester composition of the present invention, the phosphate ester antioxidant includes at least one of tris(2,4-di-tert-butylphenyl) phosphite (RIANOX 168), pentaerythritol diphosphate bis(2,6-di-tert-butyl-4-methylphenyl) bis(2,6-di-tert-butyl-4-methylphenyl) phosphate (PEP-36), and pentaerythritol distearate diphosphate (AP-618).

[0045] In a second aspect, the present invention provides a method for preparing the biodegradable polyester composition, the method comprising the following steps: mixing the components uniformly and then melt-extruding to obtain the biodegradable polyester composition.

[0046] In a preferred embodiment of the preparation method described in this invention, the temperature of the melt extrusion is 150-240°C, and the screw speed of the melt extrusion is 300-500 rpm.

[0047] In a third aspect, the present invention provides the use of the biodegradable polyester composition in the preparation of heat-resistant, oxygen-aging-resistant violet lithography products.

[0048] Examples of such products include biodegradable name tags, nucleic acid test reagent casings, and e-cigarette casings.

[0049] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0050] The biodegradable polyester composition provided by this invention, through the selection of appropriate mass proportions of components, exhibits synergistic effects, effectively improving the heat and oxygen aging resistance of the prepared product while achieving excellent clarity during ultraviolet marking. Furthermore, the preparation method of the biodegradable polyester composition provided by this invention is simple to operate and beneficial for practical production applications. Attached Figure Description

[0051] Figure 1 A schematic diagram of the results of Level 1 marking by Ziguang;

[0052] Figure 2 A schematic diagram of the results of Level 2 marking by Ziguang;

[0053] Figure 3 A schematic diagram of the results of Level 3 marking by Ziguang;

[0054] Figure 4 A schematic diagram of the results of Level 4 marking for Ziguang (a Chinese optical marking company).

[0055] Figure 5 A schematic diagram of the results of Ziguang marking at level 5. Detailed Implementation

[0056] To better illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0057] Unless otherwise specified, the reagents, methods and equipment used in this invention are all conventional reagents, methods and equipment in the field.

[0058] Polylactic acid 1: PLA FY202, with a dextrorotatory D monomer molar content of 1.79% and a melt index of 30 g / 10 min, manufactured by Anhui Fengyuan Biotechnology Co., Ltd.

[0059] Polylactic acid 2: 5% molar content of dextrorotatory D monomer, melt index of 30 g / 10 min, self-made;

[0060] Polylactic acid 3: PLA 3251D, with a dextrorotatory D monomer molar content of 1.35% and a melt index of 30 g / 10 min, manufactured by Anhui Fengyuan Biotechnology Co., Ltd.

[0061] Polylactic acid 4: D-monomer molar content is 9%, melt index is 30g / 10min, self-made;

[0062] Polylactic acid 5: 5% molar content of dextrorotatory D monomer, melt index of 20 g / 10 min, self-made;

[0063] Polylactic acid 6: 5% molar content of dextrorotatory D monomer, melt index of 40 g / 10 min, self-made;

[0064] Polylactic acid 7: PLA L105, with a dextrorotatory D monomer molar content of 0.42% and a melt index of 30 g / 10 min, Total Klein;

[0065] Polylactic acid 8: D-monomer molar content is 14%, melt index is 30g / 10min, self-made;

[0066] Biodegradable copolyester 1:PBS, melt index 30g / 10min, PDI 2.0, self-made;

[0067] Biodegradable copolyester 2: PBAT, melt index 20 g / 10 min, PDI 2.0, self-made;

[0068] Biodegradable copolyester 3:PBST, melt index 40g / 10min, PDI 2.0, self-made;

[0069] Biodegradable copolyester 4:PBS, melt index 30g / 10min, PDI 1.8, self-made;

[0070] Biodegradable copolyester 5:PBS, melt index 30g / 10min, PDI 2.5, self-made;

[0071] Biodegradable copolyester 6:PBS, melt index 4 g / 10 min, PDI 2.0, self-made;

[0072] Biodegradable copolyester 7:PBS, melt index 50g / 10min, PDI 2.0, self-made;

[0073] Biodegradable copolyester 8:PBS, melt index 30g / 10min, PDI 1.4, self-made;

[0074] Biodegradable copolyester 9:PBS, melt index 30g / 10min, PDI 3.0, self-made;

[0075] Calcium carbonate 1: Filmlink 525, Dv50 particle size 2.5μm, Engelware;

[0076] Calcium carbonate 2: Filmlink 400C, Dv50 particle size 1.4μm, Engelware;

[0077] Calcium carbonate 3: omyacarb 5T-JI, Dv50 particle size 5.5μm, omyacarb;

[0078] Kaolin: Chinafill BSK-H, Dv50 particle size 2.0μm, Quarzwerke;

[0079] Benzotriazole compound 1: UV-234, 2-(2'-hydroxy-3',5'-dicumylphenyl)benzotriazole, commercially available;

[0080] Benzotriazole compound 2: UV-326, 2'-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole, commercially available;

[0081] UV-531: 2-Hydroxy-4-n-octyloxybenzophenone, commercially available;

[0082] Hindered phenolic antioxidant 1: RIANOX 1010, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid], commercially available;

[0083] Hindered phenolic antioxidant 2: RIANOX 1076, β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate n-octadecyl alcohol ester, commercially available;

[0084] Phosphate ester antioxidant: RIANOX 168, tris(2,4-di-tert-butylphenyl) phosphite, commercially available;

[0085] Thioester antioxidant: RIANOX 412S, pentaerythritol tetra(3-lauryl thiopropionate), commercially available.

[0086] The preparation method of polylactic acid 2 includes the following steps:

[0087] 91 parts by weight of L,L-lactide (L content ≥ 99.5%, the same below) and 9 parts by weight of meso-lactide (D content approximately 50%, the same below) were mixed, and stannous octoate was added for ring-opening polymerization: the reaction was first carried out at a reaction temperature of 150℃ and a reaction pressure of 5000Pa for 2 hours, and then at a reaction temperature of 180℃ and a reaction pressure of 10000Pa for 4 hours (denoted as time t1); the mixture was then granulated underwater, crystallized, and dried to obtain polylactic acid 2;

[0088] The molar content of polylactic acid (PLA) dextrorotatory D monomer was changed by adjusting the amounts of L,L-lactide and meso-lactide; the melt index of PLA was changed by adjusting the reaction time; thus, PLA 4-6 and PLA 8 were prepared.

[0089] The preparation method of biodegradable copolyester 1 (PBS) includes the following steps:

[0090] 1,4-Butanediol, 1,4-Butanediol, and tetrabutyl titanate were added to a reaction vessel; the molar ratio of 1,4-butanediol to 1,4-butanediol was 1:1.2; the mass ratio of 1,4-butanediol to tetrabutyl titanate was 3000:1; the reaction temperature was 230℃, the reaction pressure was 200Pa, and the reaction time was 3.0h, to obtain biodegradable copolyester 1.

[0091] Based on biodegradable copolyester 1, the melt index, weight-average molecular weight, and number-average molecular weight ratio (PDI) of the biodegradable copolyester can be changed by adjusting the mass ratio of monomer to catalyst and the reaction time, thereby preparing biodegradable copolymers 4-9.

[0092] The preparation method of biodegradable copolyester 2 (PBAT) includes the following steps:

[0093] Adipic acid, terephthalic acid, 1,4-butanediol, and tetrabutyl titanate were added to a reaction vessel; the molar ratio of adipic acid, terephthalic acid, and 1,4-butanediol was 1:1:2.8; the mass ratio of 1,4-butanediol to tetrabutyl titanate was 3000:1; the reaction temperature was 250℃, the reaction pressure was 200Pa, and the reaction time was 3.0h, yielding biodegradable copolyester 2.

[0094] The preparation method of biodegradable copolyester 3 (PBST) includes the following steps:

[0095] 1,4-Butanediol, terephthalic acid, 1,4-butanediol, and tetrabutyl titanate were added to a reaction vessel; the molar ratio of adipic acid, terephthalic acid, and 1,4-butanediol was 1:1:2.8; the mass ratio of 1,4-butanediol to tetrabutyl titanate was 3000:1; the reaction temperature was 240℃, the reaction pressure was 200Pa, and the reaction time was 3.0h, yielding biodegradable copolyester 3.

[0096] Examples and Comparative Examples

[0097] The present invention provides a biodegradable polyester composition in the embodiments and comparative examples, wherein the components (parts by mass) of the biodegradable polyester composition are shown in Tables 1-3;

[0098] Table 1

[0099]

[0100] Table 2

[0101]

[0102]

[0103] Table 3

[0104]

[0105]

[0106] The method for preparing the biodegradable polyester composition provided in Example 1 includes the following steps:

[0107] The components are mixed evenly and then added to a twin-screw extruder for melt extrusion to obtain a biodegradable polyester composition. In the melt extrusion, the temperature of the solid conveying zone is 130-160℃, the temperature of the melting zone is 160-210℃, and the temperature of the melt conveying zone is 210-220℃. The length-to-diameter ratio of the twin-screw extruder is 75:1, and the rotation speed is 300-500 rpm.

[0108] The preparation methods of the biodegradable polyester compositions provided in Examples 2-18 and Comparative Examples 1-11 are consistent with those in Example 1.

[0109] Example of effect

[0110] The effects of this invention on the performance of the biodegradable polyester compositions provided in Examples 1-18 and Comparative Examples 1-11 include the following aspects:

[0111] 1. Purple Marking: Observed using a two-dimensional measuring instrument, the marking is scored based on the clarity and color contrast, with level 5 being the highest and level 1 the lowest. Specifically:

[0112] Level 1: Some labeled content lacks significant color contrast;

[0113] Level 2: Complete marking content, no obvious color contrast;

[0114] Level 3: Complete labeling content, slight color contrast;

[0115] Level 4: Clear and complete marking content, with relatively obvious color contrast;

[0116] Level 5: Clear and complete marking content, with obvious color contrast;

[0117] Among them, the ultraviolet laser marking machine is UV-3X, manufactured by Shenzhen Dapeng Laser Technology Co., Ltd.; typical marking process: processing current 1A, processing frequency 20KHZ, processing speed 1000 mm / s;

[0118] The preparation process of the purple light lithography film is as follows: the biodegradable polyester composition prepared in the examples and comparative examples is dried at 80°C for 4 hours and then injection molded at 180°C-200°C to obtain the film.

[0119] 2. Weather resistance: The marked products were subjected to accelerated thermo-oxidative aging at 100℃. The cracking phenomenon on the product surface was observed and the time of cracking was recorded as the powdering cracking time. The instrument used was a gas-exchange precision aging tester, Jufu Instruments, IAT-216.

[0120] The results are shown in Table 4.

[0121] Table 4

[0122]

[0123]

[0124] As can be seen from Table 4, when the technical solution provided by the present invention is adopted, the obtained product has good comprehensive performance. Specifically, the obtained product has a purple violet marking level of 4 or above and a powdering and cracking time of 108 hours or more.

[0125] As can be seen from Examples 1-3 and Comparative Example 1, the mass fraction of the components affects the overall performance of the product. When the mass fraction of polylactic acid and biodegradable copolyester in Comparative Example 1 is not within the range given in this invention, the violet graffiti level of the obtained product decreases, and the heat and oxygen aging resistance also shows a certain downward trend.

[0126] As can be seen from Examples 1, 7-10 and Comparative Examples 2-3, the parameters of polylactic acid also affect the overall performance of the product. When the D molar content of polylactic acid in Comparative Example 2 is too low, the purple graffito level of the obtained product decreases significantly. When the D molar content of polylactic acid in Comparative Example 3 is too high, the purple graffito level of the obtained product decreases significantly, and the powdering cracking time also shows a certain downward trend.

[0127] As can be seen from Examples 1, 11-14, and Comparative Examples 4-7, the parameters of the biodegradable copolyester affect the performance of the product. When the melt index of the biodegradable copolyester in Comparative Example 4 is too low, the violet etch grade of the obtained product decreases significantly. When the melt index of the biodegradable copolyester in Comparative Example 5 is too high, the violet etch grade of the obtained product also decreases, and the heat and oxygen aging resistance also shows a certain downward trend. When the m of the biodegradable copolyester in Comparative Example 6 is too low, the violet etch grade of the obtained product decreases significantly. When the m of the biodegradable copolyester in Comparative Example 7 is too high, both the violet etch grade and the heat and oxygen aging resistance of the obtained product show a certain downward trend.

[0128] As can be seen from Example 1 and Comparative Example 8, when kaolin is used instead of calcium carbonate, the UV marking performance of the obtained product decreases; as can be seen from Example 1 and Comparative Examples 9-10, when the UV absorber of this invention is not used, the UV marking performance of the obtained product decreases significantly; as can be seen from Example 1 and Comparative Example 11, when phosphate ester antioxidants are not used, the obtained product not only has reduced heat and oxygen aging resistance, but also a certain downward trend in UV marking performance.

[0129] Finally, it should be noted that the above embodiments are used to illustrate the technical solutions of the present invention and not to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A biodegradable polyester composition, characterized in that, The biodegradable polyester composition comprises the following components in parts by weight: 8-42 parts polylactic acid, 42-72 parts biodegradable polyester, 1-32 parts calcium carbonate, 0.01-5 parts ultraviolet light absorber, 0.1-1 part hindered phenolic antioxidant, 0.1-1 part phosphate ester antioxidant; The polylactic acid contains 1.3-10% dextrorotatory D monomer molar content. The biodegradable polyester has a melt index of 18-42 g / 10 min at 190℃ / 2.16 kg and a weight-average molecular weight (PDI) ratio of 1.7-2.

8. The ultraviolet light absorber includes metal oxides and benzotriazole compounds; The biodegradable polyester is at least one of polybutylene adipate terephthalate, polybutylene sebacic acid terephthalate, polybutylene azelaic acid terephthalate, polybutylene terephthalate succinate, and polybutylene succinate.

2. The biodegradable polyester composition according to claim 1, characterized in that, The biodegradable polyester composition comprises the following components in parts by weight: 25-30 parts polylactic acid, 55-60 parts biodegradable polyester, 10-20 parts calcium carbonate, 2-4 parts ultraviolet light absorber, 0.5-0.7 parts hindered phenolic antioxidant, and 0.3-0.4 parts phosphate ester antioxidant.

3. The biodegradable polyester composition according to claim 1, characterized in that, The polylactic acid has a melt index of 18-42 g / 10 min at 190℃ / 2.16 kg.

4. The biodegradable polyester composition according to claim 1, characterized in that, The polylactic acid contains 1.7-5% molar content of dextrorotatory D monomer.

5. The biodegradable polyester composition according to claim 1, characterized in that, The Dv50 particle size of the calcium carbonate is 1-6 μm.

6. The biodegradable polyester composition according to claim 1, characterized in that, In the ultraviolet light absorber, the mass ratio of metal oxide to benzotriazole compound is (1-5):

1.

7. The biodegradable polyester composition according to claim 1, characterized in that, The metal oxide includes at least one of antimony oxide, tin oxide, zinc oxide, and titanium oxide; And / or, the benzotriazole compounds include at least one of 2-(2'-hydroxy-3',5'-bis(a,a-dimethylbenzyl)phenyl)benzotriazole and 2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole.

8. The method for preparing the biodegradable polyester composition according to any one of claims 1-7, characterized in that, The preparation method includes the following steps: mixing the components evenly and then melt-extruding to obtain a biodegradable polyester composition.

9. The use of the biodegradable polyester composition according to any one of claims 1-7 in the preparation of heat-resistant, oxygen-aging violet-etched products.

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