Transparent high-strength and high-toughness polylactic acid material as well as preparation method and application thereof

Abstract

The invention relates to the technical field of green and environment-friendly new materials, in particular to a transparent high-strength and high-toughness polylactic acid material and a preparation method thereof. The polylactic acid material provided by the invention comprises the following raw materials in parts by weight: 96.0-99.6 parts of polylactic acid; 0.3 to 3.0 parts of a silane coupling agent; 0.1 to 1.0 part of bio-based organic acid; wherein the biological organic acid comprises citric acid monohydrate and / or tartaric acid monohydrate. The invention also provides a preparation method of the transparent high-strength high-toughness polylactic acid material. The transparent high-toughness polylactic acid not only has high toughness, but also keeps the advantage of high transparency. The transparent high-strength and high-toughness polylactic acid material can be widely applied to the fields of transparent blister cup covers, transparent blister meal boxes, transparent blister trays, transparent injection molding cups, transparent injection molding bowls and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of green and environmentally friendly new materials, and in particular to a transparent high-strength and high-toughness polylactic acid material, a preparation method and application thereof. Background Art

[0002] As people's awareness of environmental protection gradually increases, bio-based degradable new materials have received more and more attention from academia and the business community. Among them, polylactic acid (PLA) comes from renewable biomass resources and is completely biodegradable, which meets the dual development needs of green economy and sustainable economy. However, PLA is brittle, which greatly limits its application areas.

[0003] At present, the methods for improving the toughness of polylactic acid mainly include toughening agents and plasticizers. However, the toughening effect of toughening agents is often poor, and some toughening agents are even non-degradable, which will sacrifice the biodegradability of polylactic acid. In addition, the addition of toughening agents will cause the modulus of polylactic acid to be significantly reduced and lose transparency. The addition of plasticizers often leads to a significant reduction in the modulus of polylactic acid, and plasticizers have the problem of easy precipitation. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides a transparent high-strength and high-toughness polylactic acid material, a preparation method and an application thereof.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] The first aspect of the present invention relates to a polylactic acid material, comprising the following raw materials in parts by weight:

[0007] Polylactic acid 96.0-99.6 parts;

[0008] Silane coupling agent 0.3-3.0 parts;

[0009] 0.1-1.0 parts of bio-based organic acid;

[0010] Wherein, the biological organic acid includes citric acid monohydrate and / or tartaric acid monohydrate.

[0011] Optionally, the biological organic acid is 0.3 parts by weight of tartaric acid monohydrate.

[0012] Optionally, the silane coupling agent is one or more combinations of epoxy silane coupling agents, amino silane coupling agents and isocyanate silane coupling agents.

[0013] Optionally, the silane coupling agent is 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldiethoxysilane, N -(2-aminoethyl)-3-aminoisobutylmethyldimethoxysilane, 3-(diethylenetriamino)propyltrimethoxysilane, 3-glycidyloxypropyltrimethoxysilane, 3-glycidyloxypropyltriethoxysilane, 3-glycidyloxypropylmethyldimethoxysilane, 3-glycidyloxypropylmethyldiethoxysilane, 3-isocyanatopropyltriethoxysilane, 3-isocyanatopropyltrimethoxysilane or one or more combinations thereof.

[0014] Optionally, the weight portion of the polylactic acid is 98.7 parts.

[0015] Optionally, the silane coupling agent is 3-aminopropyltrimethoxysilane, and the weight portion is 3 parts.

[0016] The second aspect of the present invention relates to a method for preparing a polylactic acid material, comprising the following steps: uniformly mixing polylactic acid, a silane coupling agent and a bio-based organic acid according to the raw material ratio of the above-mentioned polylactic acid material to obtain a mixture; adding the mixture to an extruder, and obtaining the polylactic acid material through melting, extrusion, drawing, air cooling and pelletizing.

[0017] Optionally, the extruder is a twin-screw extruder, the screw aspect ratio of the extruder is 48:1 to 56:1, the extrusion temperature is 180° C. to 220° C., and the extrusion speed is 200 to 400 rpm.

[0018] The third aspect of the present invention relates to the use of the above-mentioned polylactic acid material in the preparation of packaging or tableware.

[0019] Beneficial effects of the present invention:

[0020] 1. The present invention uses bio-based organic acid to cooperate with silane coupling agent to improve the toughness of polylactic acid. Among them, bio-based organic acid plays a dual role in this system. On the one hand, at high temperature, bio-based organic acid can release crystal water, which helps to promote the hydrolysis of silane coupling agent, thereby promoting in-situ polycondensation between silane coupling agents and forming nano-silica particles; on the other hand, because bio-based organic acid has weak acidity and can release crystal water, this can properly promote polylactic acid acidolysis to form a certain content of terminal carboxyl and terminal hydroxyl groups. In addition, under high temperature and high shear, polylactic acid can undergo terminal grafting reaction with the functional group (isocyanate group, amino group or epoxy group) of the silane coupling agent through the terminal carboxyl group and or terminal hydroxyl group. Finally, in the polylactic acid matrix, a uniformly dispersed silica-polylactic acid core-shell coordination nanostructure is formed, thereby giving polylactic acid excellent toughness without sacrificing the high modulus and high transparency of polylactic acid.

[0021] 2. The preparation method of the transparent high-strength and high-toughness polylactic acid 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

[0022] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] The specific information of the raw materials used in the following examples and comparative examples is as follows:

[0024] Polylactic acid PLA (NatureWorks, 4032D, USA; Total-Corbion, L175, Thailand; Pulisi, PT101, Fengyuan, FY801);

[0025] Silane coupling agent (Jiangxi Chenguang, 3-aminopropyltrimethoxysilane, 3-glycidyloxypropyltrimethoxysilane, 3-isocyanatopropyltrimethoxysilane)

[0026] Bio-based organic acids (Weifang Yingxuan, citric acid monohydrate, Hangzhou Lin'an Jinlong, tartaric acid monohydrate);

[0027] 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.

[0028] 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.

[0029] Example 1

[0030] 9.96 kg of polylactic acid, 0.03 kg of 3-aminopropyltrimethoxysilane and 0.01 kg of citric acid monohydrate were mixed evenly, and then the mixture was added to a twin-screw extruder for melt extrusion, stranding, air cooling and granulation to obtain a polylactic acid material. The aspect ratio of the twin-screw extruder was 48, and the screw temperature was 220°C.

[0031] Example 2

[0032] 9.87 kg of polylactic acid, 0.1 kg of 3-glycidyloxypropyltrimethoxysilane and 0.03 kg of tartaric acid monohydrate were mixed evenly, and then the mixture was added to a twin-screw extruder for melt extrusion, stranding, air cooling and granulation to obtain a polylactic acid material. The aspect ratio of the twin-screw extruder was 52, and the screw temperature was 210°C.

[0033] Example 3

[0034] 9.74 kg of polylactic acid, 0.2 kg of 3-isocyanatopropyltrimethoxysilane, 0.03 kg of citric acid monohydrate, and 0.03 kg of tartaric acid monohydrate were mixed evenly, and then the mixture was added to a twin-screw extruder for melt extrusion, stranding, air cooling, and granulation to obtain a polylactic acid material. The twin-screw extruder had an aspect ratio of 56 and a screw temperature of 200°C.

[0035] Example 4

[0036] 9.60 kg of polylactic acid, 0.1 kg of 3-aminopropyltrimethoxysilane, 0.2 kg of 3-isocyanatopropyltrimethoxysilane, 0.05 kg of citric acid monohydrate, and 0.05 kg of tartaric acid monohydrate were mixed evenly, and then the mixture was added to a twin-screw extruder for melt extrusion, stranding, air cooling, and granulation to obtain a polylactic acid material. The aspect ratio of the twin-screw extruder was 56, and the screw temperature was 180°C.

[0037] Comparative Example 1

[0038] Comparative Example 1 is pure polylactic acid resin.

[0039] Comparative Example 2

[0040] 9.90 kg of polylactic acid and 0.10 kg of 3-aminopropyltrimethoxysilane were mixed evenly, and then the mixture was added to a twin-screw extruder for melt extrusion, stranding, air cooling, and granulation to obtain a polylactic acid material. The twin-screw extruder had an aspect ratio of 52 and a screw temperature of 210°C.

[0041] Comparative Example 3

[0042] 9.97 kg of polylactic acid and 0.03 kg of tartaric acid monohydrate were mixed evenly, and then the mixture was added to a twin-screw extruder for melt extrusion, stranding, air cooling, and granulation to obtain a polylactic acid material. The twin-screw extruder had an aspect ratio of 52 and a screw temperature of 210°C.

[0043] Examples 1 to 4 and Comparative Examples 1 to 3 were respectively injection molded into standard specimens and compression molded into discs with a diameter of 50 mm and a thickness of 1.0 mm. After standing for 24 hours, tensile performance test (GB / T1040-92), bending performance test (GB / T9341-2008), Izod notched impact performance test (GB / 1843-1996) and light transmittance test (GB / T 2410-2008) were performed. The results are shown in Table 1. Before injection molding, all samples were dried at 100° C. for 5 hours.

[0044] Table 1 Comparison of mechanical properties between the examples and the comparative examples

[0045]

[0046] Compared with Comparative Example 1 (pure PLA), Comparative Example 2 (only adding silane coupling agent) and Comparative Example 3 (only adding bio-based organic acid), the toughness of the polylactic acid materials prepared in Examples 1 to 4 of the present invention is greatly improved, which is manifested in that their elongation at break and notched impact strength are greatly improved. Compared with Comparative Example 1 (pure PLA), the polylactic acid materials prepared in Examples 1-4 of the present invention show the advantages of high strength and high transparency of the same level, which is manifested in that their strength, modulus and light transmittance remain basically unchanged. This is attributed to the polylactic acid material prepared by reactive extrusion technology in the present invention, which forms a unique uniformly dispersed silica-polylactic acid core-shell coordination nanostructure through in-situ reaction, thereby giving polylactic acid the characteristics of high toughness, while maintaining the advantages of high strength and high transparency of polylactic acid. The transparent high-strength and high-toughness polylactic acid material prepared by the present invention can be widely used in transparent blister cup covers, transparent blister lunch boxes, transparent blister trays, transparent injection molded cups, transparent injection molded bowls and other fields.

[0047] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0048] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. A polylactic acid material, characterized in that: It includes the following raw materials in parts by weight: Polylactic acid 96.0-99.6 parts; Silane coupling agent 0.3-3.0 parts; 0.1-1.0 parts of bio-based organic acid; Wherein, the biological organic acid includes citric acid monohydrate and / or tartaric acid monohydrate.

2. A polylactic acid material according to claim 1, characterized in that: The biological organic acid is 0.3 parts by weight of tartaric acid monohydrate.

3. A polylactic acid material according to claim 1, characterized in that: The silane coupling agent is one or more combinations of epoxy silane coupling agents, amino silane coupling agents and isocyanate silane coupling agents.

4. A polylactic acid material according to claim 3, characterized in that: The silane coupling agent is 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldiethoxysilane, N-( One or more combinations of 2-aminoethyl)-3-aminoisobutylmethyldimethoxysilane, 3-(diethylenetriamino)propyltrimethoxysilane, 3-glycidyloxypropyltrimethoxysilane, 3-glycidyloxypropyltriethoxysilane, 3-glycidyloxypropylmethyldimethoxysilane, 3-glycidyloxypropylmethyldiethoxysilane, 3-isocyanatopropyltriethoxysilane, and 3-isocyanatopropyltrimethoxysilane.

5. The polylactic acid material according to claim 1, characterized in that: The weight portion of the polylactic acid is 98.7 parts.

6. A polylactic acid material according to claim 1, characterized in that: The silane coupling agent is 3-aminopropyltrimethoxysilane, with a weight portion of 3 parts.

7. A method for preparing a polylactic acid material, characterized in that: The method comprises the following steps: uniformly mixing polylactic acid, a silane coupling agent and a bio-based organic acid according to the raw material ratio of the polylactic acid material according to any one of claims 1 to 6 to obtain a mixture; adding the mixture into an extruder, and obtaining the polylactic acid material through melting, extrusion, drawing, air cooling and pelletizing.

8. The preparation method according to claim 7, characterized in that: The extruder is a twin-screw extruder, the screw length-diameter ratio of the extruder is 48:1-56:1, the extrusion temperature is 180° C.-220° C., and the extrusion speed is 200-400 rpm.

9. Use of the polylactic acid material according to any one of claims 1 to 6 in the preparation of packaging or tableware.

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