CN111944285A

CN111944285A - Polylactic acid composition, toughened transparent material and preparation method thereof

Info

Publication number: CN111944285A
Application number: CN202010787256.7A
Authority: CN
Inventors: 贾雷; 余波; 钱玉英
Original assignee: Guangzhou Huaxinke Intelligent Manufacturing Technology Co Ltd
Current assignee: Guangzhou Huaxinke Intelligent Manufacturing Technology Co Ltd
Priority date: 2020-08-07
Filing date: 2020-08-07
Publication date: 2020-11-17

Abstract

The invention relates to a polylactic acid composition, which comprises the following components in percentage by mass: 75 to 95 percent of polylactic resin; 1.5 to 15 percent of toughening agent; 0.1 to 6 percent of other auxiliary agents; wherein the toughening agent is prepared from (2-3) by mass: 5 and polyether polyol, wherein the refractive index of the epoxy oil is 1.471-1.478. The invention also relates to a toughened transparent material formed by the polylactic acid composition. The invention further relates to a preparation method of the toughened transparent material.

Description

Polylactic acid composition, toughened transparent material and preparation method thereof

Technical Field

The invention relates to the technical field of polylactic acid materials, in particular to a polylactic acid composition, a toughened transparent material and a preparation method thereof.

Background

With the economic development, the demand and consumption of plastic products are remarkably increased, and the plastic industry is rapidly developed. While plastic consumption is rapidly increasing, waste nuisance is also a global concern. The generation of large quantities of waste plastics not only increases the economic burden on the aspect of disposal cost, but also causes environmental pollution, and in addition, the petroleum-based plastic industry in China is still in the predicament of raw material shortage, and one of the effective ways for solving the problems is to develop biological materials.

The biomaterial generally includes a bio-based material and a biodegradable material, wherein a polymer that can be converted into a small molecule (water, carbon dioxide, and other substances) in nature by a microorganism or the like in a natural environment is defined as a biodegradable material. The problems of increasingly severe energy shortage, environmental protection and the like are faced, and with the gradual implementation of plastic forbidden commands, degradable materials become more important. Polylactic acid (PLA) is a biodegradable material derived from renewable resources such as corn, wheat, etc., and is excellent in strength and rigidity, and has begun to be industrialized on a large scale in the late 90 s. At present, the capacity of the world's largest polylactic acid producer, Nature works company in America, reaches 15 ten thousand tons/year in 2009; in recent years, China also builds a plurality of ten-thousand-ton PLA production lines. The polylactic acid product is actively developed, popularized and applied, and has very important significance for the market consumption of China and the development of automobiles, packaging, foods and environmental protection industries. The production and development of polylactic acid products are always hot spots of research in various countries around the world. Other degradable materials include PBAT resin which is a copolymer of butylene adipate and butylene terephthalate, PBS polyester resin (e.g., polybutylene succinate), and PHA resin which is a polymer synthesized by transgenic plants. Because of the advantages of high strength, good processing performance and the like of the polylactic acid, the polylactic acid accounts for the highest proportion in the use of the synthesized degradable material. However, polylactic acid has fatal defects of high brittleness, poor toughness and the like, and the application of the polylactic acid is limited.

At present, the toughening mode of polylactic acid is generally as follows: adding inorganic filler, fiber and the like for toughening; blending and modifying the elastomer; toughening and modifying by a plasticizing method; copolymerization toughening modification and the like. However, the light transmittance of the material is seriously reduced while toughening, so that the transparency of the polylactic acid is maintained as much as possible while the toughness of the polylactic acid is improved.

The prior art also reports research on transparent toughened polylactic acid, for example, chinese patent CN103467941A discloses a transparent high-toughness polylactic acid film prepared from methyl MQ resin and polylactic acid. Patent CN105837850A discloses a method for realizing high toughness and high transparency of polylactic acid by utilizing nano-pores obtained by phase separation. However, the polylactic acid prepared by the prior art is still low in transparency, relatively complex in process and not suitable for large-scale production.

Disclosure of Invention

Therefore, the polylactic acid composition with high transparency and high toughness, which is prepared by a simple process, the toughened transparent material and the preparation method thereof are needed to be provided.

The invention provides a polylactic acid composition, which comprises the following components in percentage by mass: 75 to 95 percent of polylactic resin; 6 to 20 percent of toughening agent; 0.1 to 6 percent of other additives; the toughening agent is epoxy oil and polyether polyol in a mass ratio of (2-3): 5, and the refractive index of the epoxy oil is 1.471-1.478.

In one embodiment, the polylactic acid resin is a levorotatory polylactic acid resin and/or a dextrorotatory polylactic acid resin.

In one embodiment, the levorotatory polylactic acid resin has an optical purity of 5-20%, a molecular weight of 150-200 kg/mol, and a molecular weight distribution of 1.2-1.6.

In one embodiment, the optical purity of the poly-D-lactic acid resin is 95-100%, the molecular weight is 30-50 kg/mol, and the molecular weight distribution is 1.3-1.7.

In one embodiment, the polylactic acid resin is a combination of the levorotatory polylactic acid resin and the dextrorotatory polylactic acid resin, and the mass ratio of the levorotatory polylactic acid resin to the dextrorotatory polylactic acid resin is 1 (0.1-1).

In one embodiment, the epoxy-based oil comprises one or more of epoxidized soybean oil, epoxidized linseed oil, epoxidized sunflower oil, epoxy-modified silicone oil.

In one embodiment, the polyether polyol comprises one or more of polyethylene glycol, polypropylene glycol, polybutylene glycol, polytetrahydrofuran glycol, and tetrahydrofuran-propylene oxide co-glycol.

In one embodiment, the polyether polyol is polyethylene glycol, the molecular weight of the polyethylene glycol is 200-6000, and the hydroxyl value is 18-650 mgKOH/g.

In one embodiment, the other auxiliary agent comprises a cross-linking agent, the cross-linking agent comprises one or more of organic peroxide and multifunctional anhydride type or epoxy type organic small molecules or oligomers, and the mass percentage of the cross-linking agent is 0.1-3%.

In one embodiment, the other auxiliary agents further comprise an antioxidant, and the antioxidant accounts for 0.1-1% by mass.

The invention also provides a toughened transparent material formed by the polylactic acid composition.

In one embodiment, the toughened transparent material comprises a wire, film, or sheet-form shaped body.

The invention further provides a preparation method of the toughened transparent material, which comprises the following steps:

melting and mixing polylactic resin, polyether polyol, epoxy oil or polylactic resin, polyether polyol, epoxy oil and other auxiliaries to obtain a toughened transparent material prefabricated body; and

and extruding and granulating or extruding and molding the obtained toughened transparent material preform.

In one embodiment, the temperature of the melt-mixing step is 140 ℃ to 240 ℃.

The polylactic acid composition provided by the invention adopts epoxy oil with the refractive index of 1.471-1.478 and polyether polyol as a toughening agent together to toughen and modify polylactic acid resin. The epoxy oil and the polyether polyol with the refractive index of 1.471-1.478 have the effect of synergistically softening the polylactic acid chain segment, so that the generation of large spherulites in the polylactic acid forming process is reduced or not generated, grains are refined, the crystallinity is reduced, the transparency of the polylactic acid is improved, and the toughening effect can be achieved. The polylactic acid composition provided by the invention can effectively improve the toughness of polylactic acid, the elongation at break can reach more than 200%, and the transparency of the toughened polylactic acid is kept more than 80%.

Detailed Description

In order that the invention may be more fully understood, reference will now be made to the following description. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

Other than as shown in the operating examples, or where otherwise indicated, all numbers expressing quantities of ingredients, reaction conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term "about". Unless indicated to the contrary, the numerical parameters set forth in the specification and attached claims are approximations that can be suitably varied by those skilled in the art in seeking to obtain the desired properties utilizing the teachings disclosed herein. The use of numerical ranges by endpoints includes all numbers within that range and any range within that range, for example, 1 to 6 includes 1, 2, 3, 4, 5, 6, and the like.

The "refractive index" as used herein refers to the refractive index of a material at 25 ℃.

The embodiment of the invention provides a polylactic acid composition, which comprises the following components in percentage by mass: 75 to 95 percent of polylactic resin; 6 to 20 percent of toughening agent; 0.1 to 6 percent of other auxiliary agents; wherein the toughening agent is prepared from (2-3) by mass: 5 and polyether polyol, wherein the refractive index of the epoxy oil is 1.471-1.478.

The reason why the polylactic acid material can exhibit transparency is that: in an amorphous state where polylactic acid molecules exist randomly without crystallizing, light can transmit without being hindered by crystals. When the crystallinity becomes high, light is reflected, and thus transparency is lowered. The inventor finds that the polylactic acid has the advantages of short distance between two ester groups, small flexibility, high molecular chain rigidity and poor material toughness, and is easy to generate large spherulites, cause birefringence and reduce light transmittance. According to the polylactic acid composition provided by the embodiment of the invention, epoxy oil with a refractive index of 1.471-1.478 and polyether polyol are jointly used as a toughening agent to toughen and modify polylactic acid resin. The epoxy oil with the refractive index of 1.471-1.478 and the polyether polyol have the effect of synergistically softening a polylactic acid chain segment, can increase the distance between ester groups in a polylactic acid molecular chain and improve the activity of the chain segment, thereby reducing or not generating the generation of large spherulites in the polylactic acid forming process, refining grains, reducing the crystallinity, improving the transparency of the polylactic acid, and simultaneously playing a toughening effect. The polylactic acid composition provided by the embodiment of the invention can effectively improve the toughness of polylactic acid, the elongation at break can reach more than 200%, and the transparency of the toughened polylactic acid is kept more than 80%.

The polylactic resin can be levorotatory polylactic resin and/or dextrorotatory polylactic resin.

The optical purity of the levorotatory polylactic resin is 5-20%, the molecular weight is 150 kg/mol-200 kg/mol, and the molecular weight distribution is 1.2-1.6.

The optical purity of the dextrorotation polylactic resin is 95-100%, the molecular weight is 30-50 kg/mol, and the molecular weight distribution is 1.3-1.7.

These resins can be easily obtained by melt ring-opening polymerization of lactide as a raw material, in addition to commercially available resins. As commercially available polylactic acid resins, there may be used Nature Works4032D, Nature Works2003D, Luminy PLA L175 and the like as L-polylactic acid resins manufactured by Nature Works, and Luminy PDLA D120, Luminy PDLA D070 and the like as D-polylactic acid resins.

By controlling the optical purity, the molecular weight and the molecular weight distribution of the polylactic acid resin to be specific conditions, the polylactic acid resin can be better matched with the refractive index of the toughening agent and can also be better compatible with the toughening agent, so that the crystallinity in the polylactic acid molding process can be further reduced, the phenomena of leaching and atomization cannot occur, and the transparency of the material is further improved.

In a preferred embodiment, the polylactic acid resin is preferably a combination of the levorotatory polylactic acid resin and the dextrorotatory polylactic acid resin. Wherein the mass ratio of the levorotatory polylactic resin to the dextrorotatory polylactic resin is 1: (0.1 to 1). The composition of the levorotatory polylactic resin and the dextrorotatory polylactic resin can further provide the flexibility of materials, give consideration to the strength and the flexibility of the polylactic resin composition and improve the heat resistance.

In the polylactic acid composition, the mass percentage of the polylactic acid resin may be 75% to 95%, preferably 75% to 90%, and more preferably 75% to 85%.

The epoxy oils may include one or more of epoxidized soybean oil, epoxidized linseed oil, epoxidized sunflower oil, epoxy modified silicone oil. Epoxy-modified silicone oils having a refractive index of 1.471 to 1.478 are exemplified by epoxy phenyl silicone oils and epoxy methyl ethoxy silicone oils. The difference between the refractive indexes of the toughening agent and the polylactic acid can cause the atomization of the material, and the epoxidized soybean oil, the epoxidized linseed oil, the epoxidized sunflower seed oil, the epoxidized phenyl silicone oil and the epoxy methyl ethoxy silicone oil are used for toughening in cooperation with the polyether polyol, so that the atomization of the material can be further reduced or avoided.

In the polylactic acid composition, the mass percentage of the epoxy oil may be 0.6% to 10%, preferably 4% to 10%, and more preferably 4% to 6%.

As a result of intensive studies, the present inventors have found that epoxy-based oils exhibit better effects when used in combination with polyether polyols than when used alone. The epoxy base oil contains epoxy functional groups and ester groups at proper positions, the polyether polyol contains a plurality of hydroxyl groups, the epoxy base oil can easily perform ring opening reaction with terminal carboxyl groups and terminal hydroxyl groups of the polylactic acid, the hydroxyl groups in the polyether polyol can be used as hydrophilic groups to better disperse the epoxy base oil, the sliding of the molecules is improved, the mobility of molecular chains including entanglement and disentangling of the molecules can be improved, the epoxy base oil is fully contacted with the polylactic acid to perform the ring opening reaction, and the distance between two ester groups in a polylactic acid chain segment is increased.

The polyether polyol may include polyoxyethylene polyol such as polyethylene glycol, polyoxypropylene polyol such as polypropylene glycol, polytetramethylene glycol, polytetrahydrofuran and its copolymer polyol such as polytetrahydrofuran glycol, tetrahydrofuran-oxypropylene copolymer glycol, and the like.

In a preferred embodiment, the polyether polyol is polyethylene glycol. The polyethylene glycol includes, but is not limited to, for example, PEG-200, PEG-400, PEG-600, PEG-800, PEG-1000, PEG-1500, PEG-2000, PEG-4000, PEG-6000, PEG-8000, PEG-10000, PEG-20000. Preferably, the molecular weight of the polyethylene glycol is 200-6000, and the hydroxyl value is 18-650 mgKOH/g. For example, PEG-200, PEG-400, PEG-600, PEG-800, PEG-1000, PEG-1500, PEG-2000, PEG-4000 and PEG-6000 can better disperse epoxy oils and improve the compatibility of each phase.

In the polylactic acid composition, the polyether polyol may be present in an amount of 1.5 to 15% by weight, preferably 10 to 15% by weight.

In the toughening agent, the mass ratio of the polyether polyol to the epoxy oil is 5 (2-3), and may be, for example, 5:2, 5:2.2, 5:2.5, 5:2.8, or 5: 3.

In one embodiment, the other auxiliary agent comprises a cross-linking agent. The crosslinking agent may include an organic peroxide and one or more of a multifunctional anhydride-type or epoxy-type organic small molecule or oligomer. In the polylactic acid composition, the mass percentage of the cross-linking agent is 0.1-3%. The cross-linking agent can fix the toughening agent, prevent the toughening agent from migrating, effectively increase the elongation at break of the material, promote the compatibility of microphase in a system and further improve the transparency of the material.

In yet another embodiment, the other adjuvant further comprises an antioxidant. The antioxidant can comprise one or more of antioxidant 168, antioxidant 1010, antioxidant 618, antioxidant 1330, antioxidant 245 and antioxidant 626. In the polylactic acid composition, the antioxidant accounts for 0.1-1% by weight. The antioxidant can reduce oxidative degradation of the material during processing and use, and increase the weather resistance of the material.

The polylactic acid composition of the present embodiment may contain, in addition to the plasticizer, the crosslinking agent, and the antioxidant of the present invention, an anti-hydrolysis agent, an antistatic agent, a light stabilizer, an ultraviolet absorbing material, a pigment, an antibacterial agent, an antifungal agent, a foaming agent, a flame retardant, and the like, within a range that does not impair toughness and transparency which are the objects of the present invention. Examples of the hydrolysis-resistant agent include carbodiimide compounds such as polycarbodiimide compounds, and polycarbodiimide compounds obtained by the reaction of monocarbodiimide such as dicyclohexylcarbodiimide or diisopropylcarbodiimide with an organic diisocyanate.

The embodiment of the invention also provides a toughened transparent material formed by the polylactic acid composition.

The toughened transparent material may comprise a wire, film or sheet-like shaped body. Such as polylactic acid fibers, polylactic acid films, and polylactic acid sheets. The strand, film or sheet-like molded article may be used for producing various molded articles by injection molding, extrusion molding, blow molding, or the like. The molded article referred to in the present embodiment includes a container, a bag, a tube, a cup, a bottle, a tray, and the like, and is not limited in shape, size, thickness, and the like. Particularly, there are mentioned containers such as blister packs, food trays, lunch boxes, beverage cups, and the like; other various molded articles for packaging, and the like. The obtained molded article can directly have excellent properties of the polylactic acid composition such as mechanical properties and transparency.

The embodiment of the invention further provides a preparation method of the toughened transparent material, which comprises the following steps:

s10, melting and mixing polylactic resin, polyether polyol, epoxy oil or polylactic resin, polyether polyol, epoxy oil and other auxiliary agents to obtain a toughened transparent material prefabricated body;

s20, extruding and granulating or extruding and molding the obtained toughened transparent material preform.

In step S10, the temperature in the melt kneading step is 140 to 240 ℃.

The components can be mixed by a known and common method or kneading technique. For example, when a powdery or granular polylactic acid resin is extrusion-kneaded and pelletized using a twin-screw extruder, a polyether polyol, an epoxy oil, and other additives may be added, heated, and sheared to enable mixing and extrusion-kneading and pelletization. The supply to the twin-screw extruder may be carried out by feeding the polyether polyol, the epoxy oil and other additives together with the polylactic acid, or by using a side-feed pump or a liquid injection pump as required.

It is preferable that the components are dried in advance before mixing them, the drying temperature is 60 to 100 ℃, and the drying time is 2 to 12 hours.

The heating temperature of the twin-screw extruder is preferably 140 to 240 ℃ although it depends on the rotation speed of the screw. When the temperature is less than 140 ℃, the mixing is insufficient, and when the temperature exceeds 240 ℃, the thermal decomposition of the polylactic acid occurs. The rotation speed of the screw is preferably 100 to 500 rpm. When the amount is less than 100pm, the mixing is insufficient, and when it exceeds 500rpm, the thermal decomposition of the polylactic acid occurs.

In addition to the twin-screw extruder, the mixing may be carried out by a method of kneading in batches using a kneader of the batch type, a kneader-extruder (kneader), or a kneader, and then granulating the kneaded material using an extruder. The polylactic acid, the polyether polyol, the epoxy oil, and other additives may be mixed together by a mixer or the like, and then the composition may be heated and melted by a twin-screw extruder and extruded into pellets.

When the polylactic acid composition contains a crosslinking agent, the polylactic acid composition of the present embodiment is preferably mixed with a crosslinking agent and an epoxy oil.

When the polyether polyol and the epoxy oil are added as the polylactic acid composition, the polyether polyol and the epoxy oil may be mixed with each additive, or 2 additives may be mixed at the same time. The polylactic acid can also be mixed with polyether polyol and epoxy oil in a small amount in batches so as to ensure that the mixture is fully reacted.

The following are specific examples. The present invention will be described more specifically with reference to the following examples, but the present invention is not limited to these examples. The properties shown in the materials of the examples were measured and evaluated by the following methods.

1. Toughness of

Elongation at break of the Material tested according to GB-T1040.1-2006

2. Transparency of

The haze value and the light transmittance were measured by an integrating sphere type light transmittance measuring apparatus specified in JIS-K7105. When the haze value is small and the light transmittance is high, the transparency is good. The haze and light transmittance referred to in the present invention refer to values when a toughened transparent material having a thickness of 0.3mm is measured by the method according to JIS-K7105. When the thickness is different from 0.3mm, the converted haze value and the light transmittance when converted to 0.3mm are expressed by the formulas defined as H0.3 (%) ═ H × 0.3/d (H0.3: 0.3mm thickness converted haze value (%), H: measured haze value of sample (%), d: sample thickness (mm) of haze measuring section).

Examples

Preparation of toughened transparent material

A twin screw extruder (manufactured by Perker, Inc., HK25D, cylinder diameter 25.2mm, rotation speed 100rpm, melt index 3 g/min-40 g/min, ejection 8 kg/hr) was used to melt-knead the raw materials of the composition shown in Table 1 at a melt-kneading temperature of 140 ℃ to 240 ℃ and strand-cutting was performed to obtain granules of a toughened transparent material, the obtained granules were dried under reduced pressure at 110 ℃ for 2 hours to reduce the moisture content to 500ppm or less, the raw materials were previously dried before being fed into the extruder at a drying temperature of 80 ℃ for a drying time of 6 hours.

Extrusion molding conditions:

the cylinder temperature of the double-shaft mixing part is 190 ℃;

the temperature of a T-shaped die (outlet) is 190 ℃;

extrusion speed: 8kg/h (cooling roller contact time up to 34 seconds);

surface temperature of cooling roll: 25 ℃;

surface temperature of heating roller: 80 ℃.

In each example, the toughened transparent material was prepared according to the formulation provided in table 1, and the raw materials in table 1 are as follows:

polylactic acid resin:

l-polylactic acid resin: optical purity 10%, molecular weight 180kg/mol, NatureWorks 4032D, available from NatureWorks.

D-polylactic resin: optical purity 98.5%, molecular weight 50kg/mol, Luminy PDLA D120, available from Total Corbion.

Plasticizer:

polyethylene glycol which is a condensation product of fatty alcohol and ethylene oxide, has a molecular weight of 5500-7000, a hydroxyl value of 17.5-20 and a model of PEG-6000 and is manufactured by Shanghai Kate chemical Co.

Epoxidized soybean oil: refractive index 1.471, type: GreenSoft D epoxidized soybean oil, available from TPS corporation.

A crosslinking agent:

tert-butyl peroxybenzoate: molecular formula C₁₁H₁₄O₃Molecular weight 194.23, type: b802799, available from makelin, shanghai.

Antioxidant:

antioxidant 168: tris [ 2.4-di-tert-butylphenyl ] phosphite, type: basf antioxidant Irganox168, available from shanghai pethidi chemicals.

TABLE 1

The toughness and transparency of the toughened transparent materials prepared in the above examples and comparative examples are shown in table 2:

TABLE 2

	Elongation at Break (%)	Light transmittance (MPa)	Haze (MPa)
				Example 1	150	82	20
Example 2	200	83	21
				Example 3	280	83	25
Example 4	310	84	30
				Example 5	190	82	24
Example 6	210	83	28
				Example 7	240	82	27
Example 8	230	83	25
				Example 9	220	82	30
Comparative example 1	100	75	35
				Comparative example 2	15	75	25
Comparative example 3	250	65	35

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims

1. The polylactic acid composition is characterized by comprising the following components in percentage by mass:

75 to 95 percent of polylactic resin

6 to 20 percent of toughening agent

0.1 to 6 percent of other auxiliary agents;

wherein the toughening agent is prepared from (2-3) by mass: 5 and polyether polyol, wherein the refractive index of the epoxy oil is 1.471-1.478.

2. The polylactic acid composition according to claim 1, wherein the polylactic acid resin is a levorotatory polylactic acid resin and/or a dextrorotatory polylactic acid resin, the levorotatory polylactic acid resin has an optical purity of 5% to 20%, a molecular weight of 150kg/mol to 200kg/mol, a molecular weight distribution of 1.2 to 1.6, and the dextrorotatory polylactic acid resin has an optical purity of 95% to 100%, a molecular weight of 30kg/mol to 50kg/mol, and a molecular weight distribution of 1.3 to 1.7.

3. The polylactic acid composition according to claim 2, wherein the polylactic acid resin is a combination of the L-polylactic acid resin and the D-polylactic acid resin, and the mass ratio of the L-polylactic acid resin to the D-polylactic acid resin is 1: (0.1 to 1).

4. The polylactic acid composition according to claim 1, wherein the epoxy-based oil comprises one or more of epoxidized soybean oil, epoxidized linseed oil, epoxidized sunflower oil, epoxy-modified silicone oil.

5. A polylactic acid composition according to claim 1, wherein the polyether polyol comprises one or more of polyethylene glycol, polypropylene glycol, polybutylene glycol, polytetrahydrofuran glycol, tetrahydrofuran-propylene oxide co-glycol.

6. The polylactic acid composition according to claim 5, wherein the polyether polyol is polyethylene glycol, the polyethylene glycol has a molecular weight of 200 to 6000 and a hydroxyl value of 18 to 650 mgKOH/g.

7. The polylactic acid composition according to claim 1, wherein the other auxiliary agent comprises a cross-linking agent, the cross-linking agent comprises one or more of organic peroxide and polyfunctional anhydride or epoxy small organic molecules or oligomers, and the mass percentage of the cross-linking agent is 0.1-3%.

8. The polylactic acid composition according to claim 1, wherein the other additives further comprise an antioxidant, and the antioxidant is contained in an amount of 0.1 to 1% by mass.

9. A toughened transparent material comprising the polylactic acid composition according to any one of claims 1 to 8, which comprises a wire, a film or a sheet-like shaped body.

10. The method for preparing the toughened transparent material according to claim 9, comprising the steps of:

carrying out melt mixing on polylactic resin, polyether polyol, epoxy oil or polylactic resin, polyether polyol, epoxy oil and other auxiliaries to obtain a toughened transparent material preform, wherein the temperature of the melt mixing step is 140-240 ℃;