Biodegradable polyester composition as well as preparation method and application thereof

Abstract

The invention discloses a biodegradable polyester composition as well as a preparation method and application thereof, and belongs to the technical field of high polymer materials. The biodegradable polyester composition provided by the invention is prepared from the following components in parts by mass: 8 to 42 parts of polylactic acid, 42 to 72 parts of degradable copolyester, 1 to 32 parts of calcium carbonate, 0.01 to 5 parts of purple light absorbent, 0.1 to 1 part of hindered phenol antioxidant and 0.1 to 1 part of phosphate ester antioxidant. The molar content of the right-handed D monomer of the polylactic acid is 1.3-10%; the melt index of the degradable copolyester at 190 DEG C / 2.16 kg is 18-42 g / 10 min, and the ratio PDI of the weight-average molecular weight to the number-average molecular weight is 1.7-2.8; the purple light absorbent comprises a metal oxide and a benzotriazole compound. The biodegradable polyester composition provided by the invention has good thermo-oxidative aging resistance, and can realize excellent definition during purple light marking.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer materials, and particularly relates to a biodegradable polyester composition, a preparation method thereof, and an application thereof. Background Art

[0002] Biodegradable materials are of great significance in environmental protection, resource conservation, sustainable development, and human health because they can be decomposed by microorganisms in the natural environment and ultimately converted into harmless substances such as water, carbon dioxide, and biomass. In addition, with the improvement of people's environmental protection awareness and the support of policies in various countries around the world, the application fields of biodegradable plastics have been further expanded, including but not limited to catering, agriculture, medical, packaging, fiber textile, 3D printing, etc.

[0003] Laser marking technology has the advantages of low cost, high marking efficiency, and good processing quality. It has a very wide application in the plastic marking field of all walks of life. It can provide permanent marks for products, and these marks are not only beautiful but also have the functions of anti-counterfeiting and brand recognition. However, due to the characteristics of biodegradable materials such as polylactic acid, it is difficult to effectively absorb the 355nm purple light, resulting in difficult marking and unclear marking of the material. Also, because polylactic acid and the like are themselves degradation materials, their heat resistance to oxidative aging is poor, and their own properties are more likely to deteriorate under the high-energy field during the laser marking process. The above problems have limited the application of biodegradable materials in the purple light marking field to a certain extent. Summary of the Invention

[0004] The purpose of the present invention is to overcome the deficiencies of the above-mentioned prior art and provide a biodegradable polyester composition with excellent heat resistance to oxidative aging and capable of being clearly applied to purple light marking, a preparation method thereof, and an application thereof.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is: a biodegradable polyester composition, and the biodegradable polyester composition includes the following components in parts by mass:

[0006] 8 - 42 parts of polylactic acid, 42 - 72 parts of degradable copolyester, 1 - 32 parts of calcium carbonate, 0.01 - 5 parts of purple light absorber, 0.1 - 1 part of hindered phenol antioxidant, 0.1 - 1 part of phosphate antioxidant;

[0007] The molar content of the right-handed D monomer of the polylactic acid is 1.3 - 10%;

[0008] The melt index of the degradable copolyester at 190°C / 2.16 kg is 18 g / 10 min - 42 g / 10 min, and the ratio PDI of the weight average molecular weight to the number average molecular weight is 1.7 - 2.8;

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

[0010] The biodegradable polyester composition provided by the present invention can effectively improve the heat and oxygen aging resistance of the prepared product and achieve excellent clarity during ultraviolet marking by selecting appropriate mass parts of components and the synergy among the components.

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

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

[0013] In the third aspect, the ultraviolet absorber provided by the present invention includes metal oxides and benzotriazole compounds. The two can cooperate with each other to jointly improve the absorption ability of ultraviolet light, thereby effectively realizing ultraviolet marking and improving the clarity of ultraviolet marking.

[0014] In the fourth aspect, the present invention selects a combination of a hindered phenol antioxidant and a phosphate antioxidant. Under the high-energy field of subsequent laser marking, it can effectively decompose the peroxides generated during the marking process and capture free radicals in the material in the polylactic acid and biodegradable polyester system, prevent the continuation of the oxidation chain reaction, significantly reduce the oxidative degradation of the material, and weaken the problem of the decrease in material stability caused by the marking process; improve the heat and oxygen aging resistance of the product.

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

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

[0017] More preferably, in the biodegradable polyester composition, the mass percentage of the biodegradable copolyester is 37 - 82%.

[0018] It should be noted that the molar content of the right-handed D monomer of the polylactic acid is obtained by gas chromatography test; specifically, in the gas chromatography test, the instrument used is Agilent 8860 gas chromatograph, the chromatographic column is CP7502, the temperature of the FID detector is 200 °C, the hydrogen flow rate is 45 mL / min, the air flow rate is 450 mL / min, and the split ratio is 5:1.

[0019] Exemplarily, the molar content of the right-handed D monomer of the polylactic acid can be any point value or any two-point range value 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 is obtained by testing with a melt index instrument, and the weight average and number average molecular weights are obtained by GPC testing. The melt index is obtained by referring to ISO 1133-1:2022, and the test conditions are 190°C / 2.16 kg.

[0021] Exemplarily, the melt index of the biodegradable copolyester at 190°C / 2.16 kg can be any point value or any two-point range value between 18 and 42 g / 10 min, such as 20 - 40 g / 10 min, or can be 18 g / 10 min, 20 g / 10 min, 25 g / 10 min, 30 g / 10 min, 35 g / 10 min, 40 g / 10 min, 42 g / 10 min, etc.; the ratio PDI of the weight average molecular weight and the number average molecular weight of the biodegradable copolyester can be any point value or any two-point range value between 1.7 and 2.8, such as 1.8 - 2.5, or can be 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 the number average molecular weight of the biodegradable copolyester are obtained by gel permeation chromatography testing; after the testing, according to the definition of the polydispersity coefficient: the ratio PDI of the weight average molecular weight and the number average molecular weight = weight average molecular weight / number average molecular weight, the polydispersity coefficient of the biodegradable copolyester is calculated.

[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 mass:

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

[0025] The present invention has found through research that when the parts by mass of the biodegradable polyester composition are further selected within the above range, the clarity of the ultraviolet marking of the obtained product is higher, and the heat and oxygen aging resistance of the product is better.

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

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

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

[0029] The research of the present invention finds that the melt index of polylactic acid will affect the fluidity of the system, and also affect its compatibility with the biodegradable copolyester and the dispersibility of calcium carbonate, ultraviolet absorber, hindered phenol antioxidant and phosphate antioxidant in the resin matrix. When further selecting the melt index of polylactic acid at 190 °C / 2.16 kg to be 18 - 42 g / 10 min, the comprehensive performance of the obtained product is better.

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

[0031] The research of the present invention finds that the molar content of the right-handed D monomer of polylactic acid will affect the molecular structure and crystallization properties of polylactic acid, thereby not only affecting its interaction with other components, but also affecting the heat-resistant oxygen aging property of the product. When further selecting the molar content of the right-handed D monomer of polylactic acid to be 1.7 - 5%, the obtained product not only has better heat-resistant oxygen aging property, but also has higher clarity of ultraviolet 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 terephthalate sebacate, polybutylene terephthalate azelate, polybutylene terephthalate succinate, and polybutylene succinate.

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

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

[0035] Exemplarily, the Dv50 particle size of the calcium carbonate can be any point value or any two-point range value between 1 and 6 μm. For example, it can be 1.4 - 5.5 μm, or it can be 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] The research of the present invention finds that the Dv50 particle size of calcium carbonate will affect its heterogeneous nucleation effect on resins such as PLA. When the Dv50 particle size of calcium carbonate is further selected to be 2.5 - 4 μm, the heat-resistant oxidative aging property of the obtained product is better and the clarity of UV marking is higher.

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

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

[0040] The research of the present invention finds that the mass ratio of the metal oxide to the benzotriazole compound will affect its absorption effect on ultraviolet light. When the mass ratio of the two is further selected within the above range, the clarity of UV marking of the obtained product is higher.

[0041] As 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 phenol antioxidant includes at least one of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (RIANOX 1010), n-octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (RIANOX 1076), and N,N'-hexamethylenebis(3,5-di-tert-butyl-4-hydroxyhydrocinnamide) (RIANOX 1098).

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

[0045] In a second aspect of the present invention, there is provided a method for preparing the biodegradable polyester composition, the preparation method comprising the following steps: mixing the components evenly and then melt-extruding to obtain the biodegradable polyester composition.

[0046] As a preferred embodiment of the preparation method of the present 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 of the present invention, there is provided an application of the biodegradable polyester composition in the preparation of heat-resistant oxygen-aging purple laser marking products.

[0048] Exemplarily, the products include biodegradable work cards, nucleic acid test reagent shells, e-cigarette shells, etc.

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

[0050] A biodegradable polyester composition provided by the present invention can effectively improve the heat-resistant oxygen aging property of the prepared product and achieve excellent clarity during purple laser marking by selecting appropriate mass parts of components and the synergy between the components. Moreover, the preparation method of the biodegradable polyester composition provided by the present invention is simple in operation and is conducive to practical production applications. Description of the Drawings

[0051] Figure 1 It is a schematic diagram of the 1st-level marking result of purple laser marking;

[0052] Figure 2 It is a schematic diagram of the 2nd-level marking result of purple laser marking;

[0053] Figure 3 It is a schematic diagram of the 3rd-level marking result of purple laser marking;

[0054] Figure 4 It is a schematic diagram of the 4th-level marking result of purple laser marking;

[0055] Figure 5 It is a schematic diagram of the 5th-level marking result of purple laser marking. Detailed Embodiments

[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] The reagents, methods and equipment used in the present invention are all conventional reagents, methods and equipment in the art, unless otherwise specified.

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

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

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

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

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

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

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

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

[0066] Degradable copolyester 1: PBS, with a melt index of 30 g / 10 min and a PDI of 2.0, self-made;

[0067] Degradable copolyester 2: PBAT, with a melt index of 20 g / 10 min and a PDI of 2.0, self-made;

[0068] Degradable copolyester 3: PBST, with a melt index of 40 g / 10 min and a PDI of 2.0, self-made;

[0069] Degradable copolyester 4: PBS, with a melt index of 30 g / 10 min and a PDI of 1.8, self-made;

[0070] Degradable copolyester 5: PBS, with a melt index of 30 g / 10 min and a PDI of 2.5, self-made;

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

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

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

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

[0075] Calcium carbonate 1: filmlink 525, Dv50 particle size of 2.5 μm, Imerys;

[0076] Calcium carbonate 2: filmlink 400C, Dv50 particle size of 1.4 μm, Imerys;

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

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

[0079] Benzotriazole compound 1: UV-234, 2-(2'-hydroxy-3’,5'-di-tert-butylphenyl) 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 phenol antioxidant 1: RIANOX 1010, pentaerythritol tetrakis [β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate], commercially available;

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

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

[0085] Thioester antioxidants: RIANOX 412S, pentaerythritol tetra(3-laurylthiopropionate), commercially available.

[0086] Among them, the preparation method of polylactic acid 2 includes the following steps:

[0087] Mix 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 is about 50%, the same below), add stannous octoate, and carry out ring-opening polymerization: first react at a reaction temperature of 150 °C and a reaction pressure of 5000 Pa for 2 hours, and then react at a reaction temperature of 180 °C and a reaction pressure of 10000 Pa for 4 hours (denoted as time t1); underwater pelletize, crystallize, and dry to obtain polylactic acid 2;

[0088] By adjusting the dosages of L,L-lactide and meso-lactide, the change in the molar content of the right-handed D monomer of polylactic acid can be achieved; by adjusting the reaction time, the change in the melt index of polylactic acid can be achieved; thus, the preparation of polylactic acids 4-6 and polylactic acid 8 is realized.

[0089] Among them, the preparation method of degradable copolyester 1 (PBS) includes the following steps:

[0090] Put 1,4-butanedioic acid, 1,4-butanediol and tetrabutyl titanate into the reaction kettle; the molar ratio of 1,4-butanedioic acid to 1,4-butanediol is 1:1.2; the mass ratio of 1,4-butanedioic acid to tetrabutyl titanate is 3000:1; the reaction temperature is 230 °C, the reaction pressure is 200 Pa, and the reaction time is 3.0 h to obtain degradable copolyester 1;

[0091] On the basis of degradable copolyester 1, by adjusting the mass ratio of the monomer to the catalyst and the reaction time, etc., the change in the melt index, the ratio of the weight-average molecular weight to the number-average molecular weight PDI of the degradable copolyester can be achieved, and thus degradable copolymers 4-9 are prepared.

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

[0093] Put adipic acid, terephthalic acid, 1,4-butanediol and tetrabutyl titanate into the reaction kettle; the molar ratio of adipic acid, terephthalic acid to 1,4-butanediol is 1:1:2.8; the mass ratio of 1,4-butanediol to tetrabutyl titanate is 3000:1; the reaction temperature is 250 °C, the reaction pressure is 200 Pa, and the reaction time is 3.0 h to obtain degradable copolyester 2.

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

[0095] 1,4-butanediol, terephthalic acid, 1,4-butanediol and tetrabutyl titanate were put into a reaction kettle; the molar ratio of adipic acid, terephthalic acid and 1,4-butanediol was 1:1:2.8; the mass ratio of 1,4-butanediol and tetrabutyl titanate was 3000:1; the reaction temperature was 240°C, the reaction pressure was 200 Pa, and the reaction time was 3.0 h, to obtain a degradable copolyester 3.

[0096] Examples and Comparative Examples

[0097] The embodiments and comparative examples of the present invention provide a biodegradable polyester composition, and the components (parts by weight) 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 comprises 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; wherein during the melt extrusion, the temperature of the solid conveying zone is 130-160°C, the temperature of the melting zone is 160-210°C, and the temperature of the melt conveying zone is 210-220°C; the length-diameter ratio of the twin-screw extruder is 75:1, and the rotation speed is 300-500rpm;

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

[0109] Effect example

[0110] The performance of the biodegradable polyester composition provided in Examples 1-18 and Comparative Examples 1-11 of the present invention includes the following aspects:

[0111] 1. Purple mark: observed by a two-dimensional measuring instrument, the mark clarity and color contrast are comprehensively scored, with 5 being the highest level and 1 being the lowest level. Specifically:

[0112] Level 1: Part of the marking content, no obvious color contrast;

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

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

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

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

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

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

[0119] 2. Weather resistance: The marked products are subjected to accelerated thermal oxygen aging at 100 °C, and the cracking phenomenon on the product surface is observed, etc. The time of cracking is recorded, which is recorded as the powdering and cracking time. The instrument used is a ventilated precision aging test machine, Jufu Instrument, IAT-216;

[0120] The obtained 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 products have good comprehensive performance. Specifically, the purple light engraving level of the obtained products is above level 4, and the powdering and cracking time is above 108 h;

[0125] As can be seen from Examples 1-3 and Comparative Example 1, the mass parts of the components will affect the comprehensive performance of the products. When the mass parts of polylactic acid and biodegradable copolyester in Comparative Example 1 are not within the range given by the present invention, the purple light engraving level of the obtained products decreases, and the heat and oxygen aging resistance also shows a certain downward trend;

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

[0127] It can be seen from Example 1, Examples 11-14 and Comparative Examples 4-7 that 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 purple laser marking level of the obtained product decreases significantly; when the melt index of the biodegradable copolyester in Comparative Example 5 is too high, the purple laser marking level of the obtained product also decreases, and the heat resistance to oxygen aging also shows a certain downward trend; when m of the biodegradable copolyester in Comparative Example 6 is too low, the purple laser marking level of the obtained product decreases significantly; when m of the biodegradable copolyester in Comparative Example 7 is too high, the purple laser marking level and the heat resistance to oxygen aging of the obtained product both show a certain downward trend.

[0128] It can be seen from Example 1 and Comparative Example 8 that when kaolin is used instead of calcium carbonate, the purple laser marking performance of the obtained product decreases; it can be seen from Example 1 and Comparative Examples 9-10 that when the purple light absorber used is not the one in the present invention, the purple laser marking performance of the obtained product decreases significantly; it can be seen from Example 1 and Comparative Example 11 that when the phosphate antioxidant is not used, the heat resistance to oxygen aging of the obtained product decreases, and the purple laser marking performance also shows a certain downward trend.

[0129] Finally, it should be noted that the above examples are used to illustrate the technical solutions of the present invention rather than to limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced 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 of polylactic acid, 42-72 parts of degradable copolyester, 1-32 parts of calcium carbonate, 0.01-5 parts of ultraviolet light absorber, 0.1-1 parts of hindered phenol antioxidant, 0.1-1 parts of phosphate antioxidant; The molar content of the dextrorotatory D monomer of the polylactic acid is 1.3-10%; The melt index of the degradable copolyester at 190°C / 2.16kg is 18-42g / 10min, and the ratio of weight average molecular weight to number average molecular weight PDI is 1.7-2.8; The violet light absorber includes metal oxides and benzotriazole compounds.

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 of polylactic acid, 55-60 parts of degradable copolyester, 10-20 parts of calcium carbonate, 2-4 parts of ultraviolet light absorber, 0.5-0.7 parts of hindered phenol antioxidant, 0.3-0.4 parts of phosphate antioxidant.

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

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

5. The biodegradable polyester composition according to claim 1, characterized in that: The degradable copolyester includes at least one of polybutylene adipate terephthalate, polybutylene sebacate terephthalate, polybutylene azelaate terephthalate, polybutylene succinate terephthalate and polybutylene succinate.

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

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

1.

8. 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 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.

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

10. Use of the biodegradable polyester composition according to any one of claims 1 to 8 in the preparation of a heat-oxidative aging-resistant purple engraving product.

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