A tough and balanced fully biodegradable material and its preparation method

Abstract

The present invention discloses a tough and balanced fully biodegradable material and a preparation method thereof. The composite material is made from the following raw materials in parts by weight: 50 - 85 parts of polylactic acid, 10 - 30 parts of polybutylene succinate, 5 - 20 parts of poly(butylene adipate-co-terephthalate), 1 - 2 parts of compatibilizer A, and 0.5 - 1 part of compatibilizer B. The compatibilizer A is a graft copolymer of a lactic acid oligomer and a polybutylene succinate oligomer; the compatibilizer B is a graft copolymer of a poly(butylene adipate-co-terephthalate) oligomer and a polybutylene succinate oligomer. In the present invention, the combined use of two compatibilizers can not only improve the interfacial compatibility between different components, but also promote the in-situ formation of a PBS-coated PBAT structure, avoiding a significant reduction in the strength / modulus of the PLA matrix caused by PBAT, and ultimately obtaining a tough and balanced fully biodegradable material.

Description

Technical Field

[0001] The present invention relates to the technical field of biodegradable composite materials, and particularly relates to a tough and balanced fully biodegradable material and a preparation method thereof. Background Art

[0002] In recent years, the "white pollution" and "micro-nano plastics" brought by traditional polymer materials have become increasingly serious, which will seriously damage the earth's ecological system and affect the health and safety of humans. In addition, since traditional polymer materials are derived from non-renewable petrochemical resources, it not only exacerbates the shortage of petrochemical resources, but also does not have sustainable development. With the gradual enhancement of people's awareness of environmental protection, bio-based degradable new materials have received more and more attention from the academic and industrial circles. Among them, polylactic acid (PLA) is derived from renewable biomass such as corn starch, sucrose, cassava starch, and straw, and can be completely biodegradable into water and carbon dioxide, fully meeting the development needs of the green and sustainable economy. At present, PLA has achieved large-scale industrial application. However, PLA is brittle, with an elongation at break of only 3-5% and a notched impact strength of only 3 kJ / m 2 , which severely limits its application fields.

[0003] In order to maintain the complete biodegradability of PLA, biodegradable materials such as polybutylene succinate (PBS) and / or poly(butylene adipate-co-terephthalate) (PBAT) are often used to toughen and modify PLA. However, PLA, PBS, and PBAT show thermodynamic incompatibility, resulting in a low toughening efficiency of PBS and PBAT for PLA. In addition, using PBAT alone as a toughening agent will also cause a significant decrease in the strength / modulus of PLA.

[0004] At present, the methods to improve the compatibility of the PLA / PBS / PBAT system mainly include adding chain extenders, maleic anhydride-grafted polylactic acid, and glycidyl methacrylate-grafted polylactic acid, etc. However, the improvement effects of the above-mentioned additives are low, and it is difficult to obtain a tough and balanced fully biodegradable material. Summary of the Invention

[0005] In view of this, the present invention provides a tough and balanced fully biodegradable material and a preparation method thereof to solve the problems raised in the above background art. By using a biodegradable oligomer copolymer prepared by a continuous extrusion technique as a compatibilizer, the interfacial compatibility between components is greatly improved.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A tough and balanced fully biodegradable material is prepared from the following components by weight:

[0008]

[0009] The compatibilizer A is a graft copolymer of a lactic acid oligomer and a butylene succinate oligomer;

[0010] The compatibilizer B is a graft copolymer of a butylene terephthalate - adipate oligomer and a butylene succinate oligomer.

[0011] The polylactic acid, polybutylene succinate, and polybutylene terephthalate - adipate in the present invention are all commercially available general products.

[0012] The molecular weights of the lactic acid oligomer, butylene terephthalate - adipate oligomer, and butylene succinate oligomer are 9000 - 20000 g / mol.

[0013] In a further embodiment, the compatibilizer A is prepared from the following components in parts by weight:

[0014] Butylene succinate oligomer 40 - 60 parts;

[0015] Lactic acid oligomer 40 - 60 parts;

[0016] Chain extender 0.5 - 1.5 parts.

[0017] In a further embodiment, the compatibilizer B is prepared from the following components in parts by weight:

[0018] Butylene succinate oligomer 40 - 60 parts;

[0019] Butylene terephthalate - adipate oligomer 40 - 60 parts;

[0020] Chain extender 0.5 - 1.5 parts.

[0021] In a further embodiment, the lactic acid oligomer is L - lactic acid (L - lactide) or D - lactic acid (D - lactide), and its molecular weight is 9000 - 15000 g / mol;

[0022] The molecular weights of the butylene terephthalate - adipate oligomer and the butylene succinate oligomer are 5000 - 8000 g / mol.

[0023] In a further embodiment, the chain extender is trimethylolpropane - tris(2 - methyl - 1 - aziridinepropionate).

[0024] Another object of the present invention is to provide a method for preparing the above - mentioned tough and balanced fully biodegradable material, comprising the following steps:

[0025] S1. Prepare compatibilizer A:

[0026] The lactic acid oligomer, butylene succinate oligomer and chain extender are uniformly mixed and then added into a twin-screw extruder. After melting, extrusion and pelletizing, compatibilizer A is obtained;

[0027] S2. Preparation of compatibilizer B:

[0028] The butylene terephthalate-adipate oligomer, butylene succinate oligomer and chain extender are uniformly mixed and then added into a twin-screw extruder. After melting, extrusion and pelletizing, compatibilizer B is obtained;

[0029] S3. Preparation of fully biodegradable material:

[0030] Polylactic acid, polybutylene succinate, polybutylene terephthalate-adipate, compatibilizer A and compatibilizer B are uniformly mixed to obtain a mixture; the mixture is added into a twin-screw extruder. After melting, extrusion, strand drawing, air cooling and pelletizing, a strong and tough balanced fully biodegradable material is obtained.

[0031] In a further aspect, the ratio of the length to the diameter of the screw of the twin-screw extruder described in step S1 or S2 is 52:1 to 56:1, and the screw temperature is 100°C to 150°C.

[0032] In a further aspect, the ratio of the length to the diameter of the screw of the twin-screw extruder described in step S3 is 36:1 to 48:1, and the screw temperature is 180°C to 210°C.

[0033] The present application adopts a reactive extrusion technology to continuously prepare graft copolymers of lactic acid oligomers and butylene succinate oligomers, and graft copolymers of butylene terephthalate-adipate oligomers and butylene succinate oligomers as compatibilizers; then through a continuous extrusion technology, a strong and tough balanced fully biodegradable material is prepared.

[0034] Compared with the prior art, the beneficial effects of the present invention are:

[0035] The present invention uses a degradable oligomer copolymer as the interfacial compatibility, which can effectively improve the interfacial compatibility of PLA / PBS / PBAT. Among them, compatibilizer A improves the interfacial compatibility between PLA and PBS, and compatibilizer B improves the interfacial compatibility between PBS and PBAT, thereby greatly improving the toughening efficiency of PBS / PBAT.

[0036] The present invention can promote the formation of a core-shell structure with PBS coating PBAT by compounding two compatibilizers, which can effectively avoid the hidden danger of the reduction of the strength / modulus of PLA caused by PBAT, and further effectively maintain the advantages of high strength / high modulus of PLA. Finally, PBS / PBAT is compounded to toughen PLA to obtain a strong and tough balanced biodegradable material.

[0037] The preparation method of the strong and tough balanced fully biodegradable material in the present invention is a continuous extrusion technology, which has the advantages of simple operation, high production efficiency and low production cost, and is very suitable for large-scale industrial production. DETAILED DESCRIPTION

[0038] For ease of understanding of the present invention, the present invention will be described more fully below in conjunction with specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thoroughly understood.

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0040] The specific information of the raw materials used in the following examples and comparative examples is as follows:

[0041] Polylactic acid PLA (Natureworks, 4032D, USA; Total-Corbion, L175, Thailand; Fengyuan FY802), PBAT (Tunhe, Lanshan, Xinjiang, TH801T), PBS (Tunhe, Lanshan, Xinjiang, TH801T);

[0042] D-lactic acid oligomer (Pulisi, molecular weight 9000g / mol), terephthalic acid-butylene adipate oligomer (Tunhe, Lanshan, Xinjiang, molecular weight 5000g / mol), butylene succinate oligomer (Xuelang, Anhui, molecular weight 7000g / mol);

[0043] Chain extender: trimethylolpropane tris[3-(2-methylaziridine-1-yl) propionate], Aladdin, purity 99%;

[0044] Interface compatibilizer: BASF ADR4468

[0045] All the above materials are commercially available conventional products.

[0046] It is to be understood that the above raw materials and reagents are only examples of some specific embodiments of the present invention, so that the technical solution of the present invention is clearer, and it does not mean that the present invention can only use the above reagents, and the specific scope in the claims shall prevail. In addition, the "parts" described in the examples and comparative examples, unless otherwise specified, refer to parts by weight.

[0047] Any range described in the present invention includes the end value and any numerical value between the end values ​​and any sub-range formed by the end value or any numerical value between the end values.

[0048] The preparation methods of compatibilizers A and B in the following examples are as follows respectively:

[0049] Mix 5 kg of D-lactic acid oligomer, 5 kg of butylene succinate oligomer, and 0.1 kg of trimethylolpropane tris[3-(2-methylaziridin-1-yl)propionate] evenly, and then add the above mixture to a twin-screw extruder for melt extrusion, strand drawing, air cooling, and pelletizing to obtain compatibilizer A. The aspect ratio of the above twin-screw extruder is 56, and the screw temperature is 150 °C.

[0050] Mix 5 kg of butylene succinate oligomer, 5 kg of butylene terephthalate / adipate oligomer, and 0.1 kg of trimethylolpropane tris[3-(2-methylaziridin-1-yl)propionate] evenly, and then add the above mixture to a twin-screw extruder for melt extrusion, strand drawing, air cooling, and pelletizing to obtain compatibilizer B. The aspect ratio of the above twin-screw extruder is 56, and the screw temperature is 130 °C.

[0051] Example 1

[0052] First, mix 8.5 kg of PLA, 1 kg of PBS, 0.5 kg of PBAT, 0.1 kg of compatibilizer A, and 0.05 kg of compatibilizer B evenly, and then add the above mixture to a twin-screw extruder for melt extrusion, strand drawing, air cooling, and pelletizing to obtain a fully biodegradable material. The aspect ratio of the above twin-screw extruder is 44, and the screw temperature is 190 °C.

[0053] Example 2

[0054] First, mix 7 kg of PLA, 2 kg of PBS, 1 kg of PBAT, 0.15 kg of compatibilizer A, and 0.075 kg of compatibilizer B evenly, and then add the above mixture to a twin-screw extruder for melt extrusion, strand drawing, air cooling, and pelletizing to obtain a fully biodegradable material. The aspect ratio of the above twin-screw extruder is 44, and the screw temperature is 185 °C.

[0055] Example 3

[0056] First, mix 5 kg of PLA, 3 kg of PBS, 2 kg of PBAT, 0.2 kg of compatibilizer A, and 0.1 kg of compatibilizer B evenly, and then add the above mixture to a twin-screw extruder for melt extrusion, strand drawing, air cooling, and pelletizing to obtain a fully biodegradable material. The aspect ratio of the above twin-screw extruder is 44, and the screw temperature is 180 °C.

[0057] Comparative Example 1

[0058] Comparative Example 1 is pure PLA, PBAT, and PBS resins respectively.

[0059] Comparative Example 2

[0060] First, 5 kg of PLA, 3 kg of PBS, and 2 kg of PBAT were mixed evenly, and then the above mixture was added to a twin-screw extruder for melt extrusion, strand drawing, air cooling, and pelletizing to obtain a fully biodegradable material. The aspect ratio of the above twin-screw extruder was 44, and the screw temperature was 180 °C.

[0061] Comparative Example 3

[0062] First, 5 kg of PLA, 3 kg of PBS, 2 kg of PBAT, and 0.03 kg of ADR4468 were mixed evenly, and then the above mixture was added to a twin-screw extruder for melt extrusion, strand drawing, air cooling, and pelletizing to obtain a fully biodegradable material. The aspect ratio of the above twin-screw extruder was 44, and the screw temperature was 190 °C.

[0063] The samples of Examples 1-3 and Comparative Examples 1-3 were respectively injection molded into standard specimens. After being placed for 24 hours, tensile property tests (GB / T1040-92), flexural property tests (GB / T9341-2008), and Izod impact property tests (GB / 1843-1996) were carried out. The results are shown in Table 2. Before injection molding, all samples were dried sufficiently.

[0064] Table 2 Comparison of Mechanical Properties between Examples and Comparative Examples

[0065]

[0066] The fully biodegradable materials prepared in Examples 1-3 of the present invention have greatly improved toughness compared with pure PLA in Comparative Example 1, and significant improvements in tensile elongation and notched impact strength; while compared with pure PBS and pure PBAT in Comparative Example 1, the examples of the present invention have higher strength.

[0067] In addition, for the tough and strong balanced fully biodegradable materials prepared in the examples of the present invention, compared with Comparative Example 2 without a compatibilizer and Comparative Example 3 with the industry general ADR4468 as a compatibilizer, the performance of the fully biodegradable materials of the present invention is much higher than the mechanical properties of Comparative Examples 2-3. By comparing Example 3 and Comparative Example 2, it is found that due to the addition of compatibilizers A and B in the present application, the elongation at break and notched impact strength of the material are greatly improved.

[0068] Comparing Example 3 with Comparative Example 3, Example 3 has higher strength and toughness, which is attributed to the use of a compound compatibilizer system in the present invention. This system can not only improve the interfacial compatibility between different components but also promote the in-situ formation of a PBS-coated PBAT structure. Examples 1-2 exhibit extremely excellent comprehensive properties, and their properties perfectly match the physical properties of traditional PP and ABS, making them very suitable for application fields such as disposable straws, thermoformed products, and electrical appliance housings.

[0069] Although this specification is described in terms of embodiments, not every embodiment contains only one independent technical solution. This narrative style of the specification is merely for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0070] Therefore, the above description is only the preferred embodiment of the present application and is not used to limit the scope of implementation of the present application; that is, all equivalent transformations made according to the scope of the claims of the present application are within the protection scope of the claims of the present application.

Claims

1. A tough and balanced fully biodegradable material, characterized in that, it is prepared from the following components by weight: The compatibilizer A is a graft copolymer of a lactic acid oligomer and a butylene succinate oligomer; The compatibilizer B is a graft copolymer of a butylene terephthalate-adipate oligomer and a butylene succinate oligomer.

2. A tough and balanced fully biodegradable material according to claim 1, characterized in that, The compatibilizer A is prepared from the following components by weight: 40 - 60 parts of butylene succinate oligomer; 40 - 60 parts of lactic acid oligomer; 0.5 - 1.5 parts of chain extender.

3. A tough and balanced fully biodegradable material according to claim 1, characterized in that, The compatibilizer B is prepared from the following components by weight: 40 - 60 parts of butylene succinate oligomer; 40 - 60 parts of butylene terephthalate-adipate oligomer; 0.5 - 1.5 parts of chain extender.

4. A tough and balanced fully biodegradable material according to claim 1, characterized in that, The lactic acid oligomer is L-lactic acid or D-lactic acid, and its molecular weight is 9000 - 15000 g / mol; The molecular weights of the butylene terephthalate-adipate oligomer and the butylene succinate oligomer are 5000 - 8000 g / mol.

5. A tough and balanced fully biodegradable material according to claim 2 or 3, characterized in that, The chain extender is trimethylolpropane tris(2-methyl-1-aziridinepropionate).

6. A preparation method of a tough and balanced fully biodegradable material according to any one of claims 1 - 5, characterized in that, it includes the following steps: S1. Prepare the compatibilizer A: Mix the lactic acid oligomer, the butylene succinate oligomer and the chain extender evenly, then add them into a twin-screw extruder, and obtain the compatibilizer A after melting, extrusion and pelletizing; S2. Prepare the compatibilizer B: Mix the butylene terephthalate-adipate oligomer, the butylene succinate oligomer and the chain extender evenly, then add them into a twin-screw extruder, and obtain the compatibilizer B after melting, extrusion and pelletizing; S3. Prepare the fully biodegradable material: Mix polylactic acid, polybutylene succinate, polybutylene terephthalate-adipate, the compatibilizer A and the compatibilizer B evenly to obtain a mixture; add the mixture into a twin-screw extruder, and obtain a tough and balanced fully biodegradable material after melting, extrusion, strand drawing, air cooling and pelletizing.

7. The preparation method according to claim 6, characterized in that, In step S1 or S2, the length-diameter ratio of the screw of the twin-screw extruder is 52:1 - 56:1, and the screw temperature is 100°C - 150°C.

8. The preparation method according to claim 6, characterized in that, In step S3, the length-diameter ratio of the screw of the twin-screw extruder is 36:1 - 48:1, and the screw temperature is 180°C - 210°C.

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