Heat-resistant, highly crystalline PLA / PBS alloy materials and their preparation methods

Abstract

This application discloses a heat-resistant, highly crystalline PLA / PBS alloy material and its preparation method. In this technical solution, the distribution of the nucleating agent and the addition of a compatibilizer are controlled to increase nucleation sites and lower the nucleation barrier, thereby inducing rapid PLA crystallization. Simultaneously, the addition of the compatibilizer reduces the interfacial tension between PLA and PBS, improving their compatibility; furthermore, it links flexible PBS chains to PLA segments, enhancing molecular chain mobility and thus improving the crystallinity and heat resistance of the PLA matrix. Based on this, this solution has advantages such as simple preparation process, high product quality, short preparation cycle, and high production efficiency, and has broad application prospects and economic benefits.

Description

Technical Field

[0001] This application relates to the technical field of biodegradable materials, and in particular to heat-resistant, highly crystalline PLA / PBS alloy materials and their preparation methods. Background Technology

[0002] Polylactic acid (PLA) is a biodegradable polyester material. It is produced by polymerizing lactic acid from industrial starch fermentation, using resources such as cassava as raw materials. Waste PLA products ultimately degrade into water and carbon dioxide, thus exhibiting biodegradability and recyclability. Furthermore, PLA possesses high mechanical strength and excellent biocompatibility. PLA has excellent processing properties and can be processed using techniques such as extrusion molding, injection molding, and blown film molding. However, PLA products produced using traditional processing methods exhibit slow crystallization rates and low crystallinity during molding. The poor heat resistance of PLA severely limits its application range at higher temperatures, such as for disposable heat-resistant products, utensils, and other food packaging containers.

[0003] Currently, the heat resistance modification of PLA mainly involves improving PLA crystallinity; blending PLA with other rigid materials such as heat-resistant materials or fibers; and altering the molecular chain structure and orientation structure of PLA. Among these methods, increasing the crystallinity of PLA is one of the most common ways to improve its heat resistance, typically achieved by adding nucleating agents or annealing. However, annealing is energy-intensive and prolongs the production cycle, resulting in persistently high production costs. For example, patent CN106883569 developed a PLA-modified polyester that can crystallize outside the membrane and effectively reduce the warpage of PLA during annealing, while significantly improving PLA heat resistance. However, this PLA-modified polyester has only 30-50% toughness and poor mechanical properties, severely affecting the performance of the finished product.

[0004] PBS, as an important aliphatic biodegradable material, possesses high crystallinity and heat resistance, but its low molecular weight leads to low mechanical strength and processing difficulties. Therefore, PBS is often added to PLA to enhance PLA's heat resistance and improve its flexibility, resulting in blends with excellent tensile strength and elongation at break. However, the interfacial bonding between PBS and the PLA matrix is ​​weak, and PLA and PBS are thermodynamically incompatible. Therefore, compatibilizers are often added to improve the compatibility between PLA and PBS. For example, patent CN 113185821A improves the compatibility between PLA and PBS using a compatibilizer, thereby improving the thermal stability of the PLA blend and increasing the crystallinity of the composite material to approximately 30%. However, it uses PBS as the matrix, and due to the high crystallinity, the composite material has low strength and poor toughness.

[0005] Existing technologies often fail to address both low crystallinity and heat resistance in preparing high-heat-resistant polylactic acid composites. Summary of the Invention

[0006] In view of this, this application provides a heat-resistant, highly crystalline PLA / PBS alloy material and its preparation method, which can significantly improve the low crystallinity and heat resistance.

[0007] It is widely recognized that the high heat-resistant polylactic acid composite materials prepared in related technologies often cannot simultaneously address the issues of low crystallinity and heat resistance.

[0008] To address this problem, the inventors selected specific compatibilizers to ensure excellent compatibility among the components of the PLA / PBS system of the present invention. At the same time, they added a specific proportion of nucleating agents to improve the crystallinity of the PLA / PBS alloy material, thereby obtaining a PLA / PBS alloy material with high heat resistance, excellent mechanical properties, and good toughness.

[0009] Based on this, the present invention was created.

[0010] In a first aspect, this application provides a heat-resistant, highly crystalline PLA / PBS alloy material, the raw materials of which, by weight, comprise the following components:

[0011]

[0012] Suitable but not limiting, the nucleating agent is one or any combination of amide nucleating agents, hydrazide nucleating agents, and inorganic nucleating agents.

[0013] Suitable but not limiting, the nucleating agent is one or any combination of OXA, TMC, EBH, TMBH, nano silica, montmorillonite, talc, and diatomaceous earth.

[0014] Suitable but not limiting, the compatibilizer is one or any combination of compounds containing polyepoxy groups, prepolymers containing polyepoxy groups, polyisocyanate compounds, polyisocyanate prepolymers, and compounds containing polyanhydride groups.

[0015] Suitable, but not limiting, the compatibilizer is one or any combination of triglycidyl isocyanurate (TGIC), methyl methacrylate, and glycidyl methacrylate.

[0016] Suitable but not limiting, the heat stabilizer is one or any combination of polyethylene wax, zinc stearate, calcium stearate, magnesium stearate, maleates, oleamide, and erucamide.

[0017] Suitable but not limiting, the antioxidant is one or any combination of tea polyphenols (TP), tocopherols, flavonoids, butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), tert-butylhydroquinone (TBHQ), phosphite antioxidants, and thioester antioxidants.

[0018] Secondly, this application provides a method for preparing the heat-resistant, highly crystalline PLA / PBS alloy material as described above, comprising the following steps:

[0019] S1. Preheat PLA to fully melt it, then add nucleating agent, compatibilizer and antioxidant in sequence, and fully melt and blend.

[0020] S2. Based on step S1, add PBS and melt-mix to obtain the PLA / PBS alloy material.

[0021] Suitable but not limiting, in step S1: the preheating temperature is 160-200℃, and the melt blending time is 2-5 minutes.

[0022] Suitable but not limiting, in step S2, the melting temperature is 160-200°C and the melt blending time is 3-10 min.

[0023] Compared with related technologies, this application has the following advantages:

[0024] The heat-resistant, highly crystalline PLA / PBS alloy material provided in this application is made from ordinary commercial PLA and PBS. By selecting specific compatibilizers, the compatibility between the components of the PLA / PBS system of this invention is excellent. At the same time, a specific proportion of nucleating agents is added to improve the crystallinity of the PLA / PBS alloy material, thereby obtaining a PLA / PBS alloy material with high heat resistance. In addition, the material has excellent mechanical properties and good toughness, and has great application potential in packaging, daily life and other fields. Detailed Implementation

[0025] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the embodiments of this application. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0026] In the description of this application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, features defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0027] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0028] The following disclosure provides many different embodiments or examples for implementing different structures of this application. To simplify the disclosure, specific examples of components and arrangements are described below. Of course, these are merely examples and are not intended to limit the scope of this application. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, various specific examples of processes and materials are provided in this application, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0029] Example 1:

[0030] PLA and PBS were dried in a forced-air drying oven at 60°C for 24 hours. After drying, 90 parts of PLA, 10 parts of PBS, 0.8 parts of methyl methacrylate, 0.5 parts of composite nucleating agent (nano silica / TMC-306 (1:1)), 0.1 parts of zinc stearate, and 0.1 parts of tea polyphenols were weighed according to the following mass ratio.

[0031] The weighed PLA was preheated to 200℃ to fully melt it, and then a composite nucleating agent (nano silica / TMC-306 (1:1)) and tea polyphenols were added sequentially and melt-blended for 3 min. Then PBS, methyl methacrylate, and tea polyphenols were added and melt-blended at 200℃ for 7 min to obtain the PLA / PBS alloy material.

[0032] The final heat-resistant, highly crystalline PLA / PBS alloy material had an HDT of 71.4℃ and a PLA crystallinity of 32.7%.

[0033] Example 2:

[0034] PLA and PBS were dried in a forced-air drying oven at 60°C for 24 hours. After drying, 80 parts of PLA, 20 parts of PBS, 1.5 parts of composite nucleating agent (nano silica / TMC-306 (1:2)), 1 part of triglycidyl isocyanate (TGIC), 1 part of calcium stearate, and 1 part of butylated hydroxyanisole (BHA) were weighed according to the following mass ratio.

[0035] The weighed PLA was preheated to 180°C to fully melt it, and then a composite nucleating agent (nano silica / TMC-306 (1:2) and butylated hydroxyanisole (BHA)) were added sequentially and melt-blended for 2 min. Then PBS, triglycidyl isocyanate (TGIC), and calcium stearate were added and melt-blended at 200°C for 8 min to obtain the PLA / PBS alloy material.

[0036] The final heat-resistant, highly crystalline PLA / PBS alloy material had an HDT of 85℃ and a PLA crystallinity of 43.4%.

[0037] Example 3:

[0038] PLA and PBS were dried in a forced-air drying oven at 60°C for 24 hours. After drying, 40 parts of PLA, 40 parts of PBS, 4 parts of composite nucleating agent (nano silica / TMC-306 (1:4)), 4 parts of diphenylmethane diisocyanate (MDI), 2 parts of oleamide, and 2 parts of tert-butylhydroquinone were weighed according to the following mass ratio.

[0039] The weighed PLA was preheated to 190°C to fully melt it, and then a composite nucleating agent (nano silica / TMC-306 (1:4)) and oleamide were added sequentially, and the mixture was melt-blended for 5 min. Then PBS, diphenylmethane diisocyanate (MDI) and oleamide were added, and the mixture was melt-blended at 190°C for 5 min to obtain the PLA / PBS alloy material.

[0040] The final heat-resistant, highly crystalline PLA / PBS alloy material had an HDT of 96℃ and a PLA crystallinity of 50.2%.

[0041] Comparative Example 1

[0042] The only difference from Example 1 is that the compatibilizer is maleic anhydride, and the amount added is 5 parts.

[0043] The resulting HDT was 56℃, and the PLA crystallinity was 3.49%.

[0044] Comparative Example 2

[0045] The only difference from Example 1 is that the nucleating agent is triphenyl phosphite (TPP), and the amount added is 0.05 parts.

[0046] The resulting HDT was 59℃, and the PLA crystallinity was 8.07%.

[0047] The above description is merely a preferred embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application.

Claims

1. A heat-resistant, highly crystalline PLA / PBS alloy material, characterized by, According to the weight parts, the raw materials comprise the following components: PLA 60-90 parts; PBS 10-40 parts; Nucleating agent 0.1-5 parts; Compatibility agent 0.1-5 parts; Thermal stabilizer 0.1-2 parts; Antioxidant 0.1-2 parts; The nucleating agent is mixed by nano-silica and TMC-306 with a mass ratio of 1:1, 1:2 or 1:4; The compatibility agent is one or any of methyl methacrylate, isocyanuric acid triglycidyl ester, and diphenyl methane diisocyanate; The thermal stabilizer is one or any of polyethylene wax, zinc stearate, calcium stearate, magnesium stearate, maleate, oleic acid amide, and erucic acid amide; The preparation method of the heat-resistant and high-crystalline PLA / PBS alloy material comprises the following steps: S1. Preheat the PLA to fully melt, then add the nucleating agent and antioxidant in sequence, and fully melt and blend; S2. On the basis of step S1, add PBS, compatibility agent, and thermal stabilizer, melt and mix to obtain the PLA / PBS alloy material.

2. The heat-resistant, high-crystalline PLA / PBS alloy material according to claim 1, characterized in that, The antioxidant is one or any of tea polyphenol (TP), tocopherol, flavonoids, butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), tertiary butyl hydroquinone (TBHQ), phosphite antioxidant, and thioester antioxidant.

3. The heat resistant, high crystalline PLA / PBS alloy material according to claim 1, characterized in that, In step S1, the preheating temperature is 160-200℃, and the melt blending time is 2-5 min.

4. The heat resistant, high crystalline PLA / PBS alloy material according to claim 1, characterized in that, In step S2, the melting temperature is 160-200℃, and the melt blending time is 3-10 min.

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