Terpene alcohol ester full-bio-based polylactic acid plasticizer and application thereof

Abstract

The invention discloses a terpene alcohol ester full-bio-based polylactic acid plasticizer and application thereof, and belongs to the technical field of functional high polymer materials, the terpene alcohol ester full-bio-based polylactic acid plasticizer is an oligomer prepared from terpene alcohol and lactide as raw materials through ring-opening polymerization reaction, and has the advantages of full-bio-based carbon, green and environment-friendly effects, high-temperature resistance and the like. The polylactic acid plasticizer has good plasticizing and toughening effects on polylactic acid, can reduce the glass transition temperature, the cold crystallization temperature and the melting point of polylactic acid, and also can significantly improve the elongation at break of polylactic acid. Besides, the terpene alcohol ester full-bio-based polylactic acid plasticizer has good compatibility with a polylactic acid matrix, can maintain high transparency of polylactic acid, has excellent migration resistance and durability, and has wide application prospects in the field of bioplastics.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of functional polymer materials, and particularly relates to a terpene alcohol ester type full-bio-based polylactic acid plasticizer and application thereof. BACKGROUND

[0002] Traditional petroleum-based plastics are usually difficult to degrade naturally, and their waste often causes environmental problems such as soil degradation and water pollution, and is accompanied by carbon emissions in the whole life cycle (production, use to waste). With the increasing attention to ecological environment protection and resource conservation, bioplastics (i.e. high molecular weight materials derived from renewable resources and having biodegradability) are being vigorously developed and applied, thereby replacing traditional petroleum-based plastics. Polylactic acid (PLA) as a biodegradable polymer plastic is gradually becoming a sustainable alternative to traditional petroleum-based plastics, however, PLA is hard and brittle, and the elongation at break is only about 5%, which greatly limits its application range.

[0003] The toughness of PLA can be improved by adding plasticizers, such as small molecule ester plasticizers or oligomer plasticizers with flexible segments. Acetyl tri-n-butyl citrate (ATBC) and polyethylene glycol (PEG) oligomer are currently more commonly used PLA plasticizers. However, due to the small molecular weight and poor compatibility with PLA, they are prone to precipitation and have poor durability. Increasing the molecular weight of PEG will reduce the plasticizing efficiency. Therefore, it is urgent to develop a PLA plasticizer with high plasticizing efficiency, good migration resistance and green environmental protection.

[0004] Chinese patent document with publication number CN115028814A discloses a citric acid ester type bio-based plasticizer. The invention obtains a specific structure of citric acid ester type bio-based plasticizer through step-by-step ring-opening polymerization reaction of citric acid and polymer monomers under the action of tin catalyst. The citric acid ester type bio-based plasticizer can enhance the melt strength of polylactic acid. However, it uses acid as raw material, has low yield and uncontrollable structure. The multiple carboxyl groups at the end of the plasticizer increase the acid value, which may promote the degradation of PLA during processing and use, thereby affecting the performance.

[0005] Chinese patent document with publication number CN118745284A discloses a method for plasticizing PLA by using a bio-based plasticizer. The plasticizer used in the invention is cashew phenol ethyl ester and / or epoxidized cashew phenol ethyl ester. The plasticizer, auxiliary agent and antioxidant are added in the PLA raw material to improve the plasticizing effect on PLA and reduce the migration and volatility of the plasticizer. However, it may have the problems of easy precipitation and poor durability.

[0006] PLA oligomer also has good plasticizing effect on PLA, and with the same lactic acid structural unit, PLA oligomer has good compatibility with PLA without obvious phase separation. However, some PLA oligomer plasticizers are not completely renewable compounds, the initiator or end-capping agent thereof is a petroleum-based compound, and some thereof has certain toxicity (such as CN119528735A and the like). Meanwhile, some PLA oligomers are synthesized by polycondensation and a strong acid catalyst is used, so that acid residue is inevitably caused, and the plasticizer with high acid value will affect the performance of the PLA matrix and cause damage to the equipment.

[0007] Therefore, it is necessary to develop a full-biological PLA oligomer for plasticizing PLA. SUMMARY

[0008] The present application provides a terpene alcohol ester full-biological PLA plasticizer to solve the problems of easy precipitation, low plasticizing efficiency and non-sustainability of the conventional plasticizer. The plasticizer has full-biological carbon, can maintain the sustainability and degradability of the PLA matrix resin, can significantly improve the toughness of the PLA matrix resin, and has good migration resistance and durability.

[0009] The specific technical solutions are as follows:

[0010] A terpene alcohol ester full-biological PLA plasticizer, the structural formula of which is shown as formula (I):

[0011]

[0012] wherein R1 is selected from * is a connection position; n is an integer between 1 and 30 (note: due to the existence of ester exchange reaction, there may be a product with only one lactic acid unit in the product, although the theoretical repeating unit is even), and the number average molecular weight is 300-2500 g / mol.

[0013] Further, the preparation method of the terpene alcohol ester full-biological PLA plasticizer comprises the following steps: under the action of a catalyst, terpene alcohol and lactide are subjected to ring-opening polymerization reaction under solvent or solvent-free conditions in an inert gas atmosphere, and the terpene alcohol ester full-biological PLA plasticizer is obtained after post-treatment.

[0014] The terpene alcohol includes geraniol, neral, linalool, citronellol, lavandulol, nerolidol, farnesol, phytol, bisabolol or menthol, and specifically, racemates, stereoisomers and the like of the above terpene alcohols can also be selected.

[0015] The lactide is at least one of L-lactide, D-lactide and meso-lactide.

[0016] The present application adopts terpene alcohol derived from animals and plants to initiate ring-opening polymerization of lactide to obtain a full-bio-based polylactic acid plasticizer, which has ecological friendliness, high efficient plasticizing and toughening effect on polylactic acid, and can achieve the purpose of plasticizing and toughening with a small amount of addition. Meanwhile, based on the same lactic acid ester structure as polylactic acid, it has good compatibility with polylactic acid, and has good resistance to migration, resistance to precipitation and durability, and in addition, does not affect the transparency of polylactic acid, and the product performance is very excellent.

[0017] Specifically, the inert gas atmosphere includes nitrogen atmosphere, argon atmosphere, etc.

[0018] Optionally, the ring-opening polymerization reaction of the terpene alcohol and the lactide is carried out at a molar ratio of 1:1-15, and preferably, the ring-opening polymerization reaction of the terpene alcohol and the lactide is carried out at a molar ratio of 1:2-5.

[0019] When the ring-opening polymerization reaction is carried out under solvent-free conditions, the ring-opening polymerization reaction conditions are: temperature 90-180℃, time 4-10h; and / or, the catalyst is selected from at least one of stannous octoate, dibutyltin dilaurate, dibutyltin, stannous chloride; and / or, the catalyst addition amount is 0.01-0.5wt% of the lactide.

[0020] Further, when the ring-opening polymerization reaction is carried out under solvent-free conditions, the post-treatment method is -100kPa reduced pressure distillation for 0-4h.

[0021] When the ring-opening polymerization reaction is carried out under solvent conditions, the solvent used includes at least one of tetrahydrofuran, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, acetonitrile, 1,4-dioxane, acetone, chloroform, dichloromethane, dichloroethane, petroleum ether, hexane, cyclohexane, preferably dichloromethane or chloroform.

[0022] When the ring-opening polymerization reaction is carried out under solvent conditions, the ring-opening polymerization reaction conditions are: temperature 25-80℃, time 1-60min; and / or, the catalyst is selected from at least one of 1,8-diazabicyclo[5.4.0]undec-7-ene, 1,5,7-triazabicyclo[4.4.0]dec-5-ene, 4-dimethylaminopyridine; and / or, the catalyst addition amount is 0.1-5mol% of the lactide.

[0023] Further, when the ring-opening polymerization reaction is carried out under solvent conditions, the post-treatment method is: after neutralization with hydrochloric acid solution, washing with saturated sodium bicarbonate solution and deionized water respectively, drying, and then removing the solvent by rotary evaporation, and further vacuum drying.

[0024] The synthesis process of the terpene alcohol ester full-bio-based polylactic acid plasticizer is simple, and all the renewable bio-based compounds used are green and environmentally friendly, which ensures that the ecological friendliness of the matrix is not destroyed when the polylactic acid is used for plasticization.

[0025] The application further provides a method for plasticizing polylactic acid by using the terpene alcohol ester full-bio-based polylactic acid plasticizer.

[0026] The application further provides a high-toughness full-bio-based polylactic acid composite material comprising polylactic acid and the terpene alcohol ester full-bio-based polylactic acid plasticizer, wherein the mass of the terpene alcohol ester full-bio-based polylactic acid plasticizer accounts for 5-30 wt% of the total mass of the polylactic acid and the terpene alcohol ester full-bio-based polylactic acid plasticizer.

[0027] The terpene alcohol ester full-bio-based polylactic acid plasticizer not only has good plasticizing effect, but also can significantly reduce the glass transition temperature, cold crystallization temperature and melting temperature of polylactic acid, and can significantly improve the elongation at break of polylactic acid.

[0028] Preferably, the high-toughness full-bio-based polylactic acid composite material comprises 5-30 wt% of the terpene alcohol ester full-bio-based polylactic acid plasticizer and 70-95 wt% of polylactic acid.

[0029] Further preferably, the high-toughness full-bio-based polylactic acid composite material comprises 10-20 wt% of the terpene alcohol ester full-bio-based polylactic acid plasticizer and 80-90 wt% of polylactic acid.

[0030] Preferably, the glass transition temperature of the high-toughness full-bio-based polylactic acid composite material is ≤47℃, and the elongation at break is ≥100%.

[0031] Further preferably, the glass transition temperature of the high-toughness full-bio-based polylactic acid composite material is ≤35℃, and the elongation at break is ≥400%.

[0032] The application further provides a preparation method of the high-toughness full-bio-based polylactic acid composite material, which comprises drying raw materials including the terpene alcohol ester full-bio-based polylactic acid plasticizer and polylactic acid, and then mixing, melt-extruding and granulating to obtain the high-toughness full-bio-based polylactic acid composite material.

[0033] Preferably, the drying temperature of polylactic acid is 80-110℃, and the drying temperature of the terpene alcohol ester full-bio-based polylactic acid plasticizer is 50-70℃; and the drying time is 4-10h.

[0034] Further preferably, the polylactic acid drying temperature is 80℃, and the terpene alcohol ester type full-biological polylactic acid plasticizer drying temperature is 60℃.

[0035] Preferably, the melt extrusion temperature is 150-180℃, and the melt extrusion preferably adopts a twin-screw extruder with a screw length-diameter ratio of 35-45:1.

[0036] Compared with the prior art, the present application has the beneficial effects that:

[0037] (1) The full-biological polylactic acid plasticizer prepared by the present application with terpene alcohol and lactide as raw materials has 100% biological carbon, and has the characteristics of green environmental protection and renewable compared with other plasticizers, and can reduce carbon emissions.

[0038] (2) The terpene alcohol ester type full-biological polylactic acid plasticizer of the present application has high plasticizing effect on polylactic acid, and can reduce the glass transition temperature of polylactic acid to below 47℃ and the elongation at break to above 200% at a low addition amount. At the same time, the plasticizer has good compatibility with polylactic acid, can maintain the transparency of the PLA-based composite material, has good migration resistance, is not easy to precipitate, and can maintain the plasticizing and toughening effect for a long time.

[0039] (3) The high-toughness full-biological polylactic acid composite material prepared by the present application has good compatibility with polylactic acid due to the green environmental protection, low addition amount and good compatibility of the plasticizer, which enhances the ecological friendly properties of polylactic acid, reduces pollution caused by precipitation of the plasticizer, and fully meets the green and sustainable application requirements of polylactic acid in the fields of packaging and disposable products. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 The FT-IR spectrum of the terpene alcohol ester type full-biological polylactic acid plasticizer prepared in Example 2 and Example 4 is shown in the following figure: 1 H NMR spectrum;

[0041] Figure 2 The FT-IR spectrum of the terpene alcohol ester type full-biological polylactic acid plasticizer prepared in Example 2 and Example 4 is shown in the following figure:

[0042] Figure 3 The thermal gravimetric curve of the samples of Example 2, Example 4, Application Examples 1-3 and Comparative Examples 1 is shown in the following figure:

[0043] Figure 4 The tensile curve of Application Examples 1-3 and Comparative Examples 1-2 is shown in the following figure:

[0044] Figure 5 The migration resistance test figure of Application Examples 1-3 and Comparative Examples 1-2 is shown in the following figure. DETAILED DESCRIPTION

[0045] In order to make the purposes, features and advantages of the present application more obvious and easy to understand, the following will be described in detail through specific embodiments. In the following description, a large number of specific details are set forth in order to fully understand the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the spirit of the present application, so the present application is not limited to the specific embodiments disclosed below. The technical features in each embodiment of the present application can be combined accordingly without conflict.

[0046] The raw materials used in the following specific embodiments are all purchased from the market. The melt index of polylactic acid is 16.0 g / 10 min (at 190°C, under a load of 2.16 kg), and the molecular weight is 126000 g / mol.

[0047] Example 1

[0048] Under a nitrogen atmosphere, 1 mol of geraniol and 2 mol of L-lactide were added to a 1L three-necked round-bottom flask equipped with magnetic stirring. The temperature was raised to 110°C, and after the lactide was completely melted, 0.1wt% of the catalyst stannous octoate based on the mass fraction of lactide was added. After 6h of reaction, the product was obtained by distillation under reduced pressure of -100kPa for 1h, which was a colorless transparent liquid, i.e., a terpene alcohol ester-based fully biobased polylactic acid plasticizer, the structural formula of which is shown below, and the number average molecular weight is 450g / mol, wherein the theoretical value of n is 4 (the product contains multiple structures, which are normally distributed, and the non-integer is calculated according to the number average molecular weight, the same below).

[0049]

[0050] Example 2

[0051] Under a nitrogen atmosphere, 1 mol of geraniol and 2 mol of L-lactide were added to a 1L three-necked round-bottom flask equipped with magnetic stirring. After dissolving the lactide in 500mL of dichloromethane, 0.1% of the catalyst 1,8-diazabicyclo[5.4.0]undec-7-ene based on the molar fraction of lactide was added, and the reaction was carried out at room temperature (about 25°C) for 30min. After stopping the reaction by adding hydrochloric acid aqueous solution to the reaction solution, the solution was washed with saturated sodium bicarbonate aqueous solution and deionized water for 3 times respectively, and then dried. After removing the solvent by rotary evaporation and drying in a vacuum oven, the colorless transparent liquid product was obtained, i.e., a terpene alcohol ester-based fully biobased polylactic acid plasticizer, the structural formula of which is shown below, and the number average molecular weight is 450g / mol, wherein the theoretical value of n is 4.

[0052]

[0053] Example 3

[0054] A 1 L three-necked round-bottom flask equipped with magnetic stirring was charged with 1 mol of geraniol and 2 mol of D-lactide under nitrogen atmosphere. After the addition of 500 mL of dichloromethane to dissolve lactide, 0.1% (molar fraction) of catalyst 1,8-diazabicyclo[5.4.0]undec-7-ene was added to react for 30 min at room temperature (about 25 °C). After the reaction was stopped by adding aqueous hydrochloric acid solution to the reaction solution, it was washed with saturated aqueous sodium bicarbonate solution and deionized water for 3 times, respectively. After drying, the solvent was removed by rotary evaporation, and the product was obtained as a colorless transparent liquid after drying in a vacuum oven. The structure of the terpene alcohol ester-based fully bio-based polylactic acid plasticizer is shown below, and the number average molecular weight is 450 g / mol, where n is 4 in theory.

[0055]

[0056] Example 4

[0057] A 2 L three-necked round-bottom flask equipped with magnetic stirring was charged with 1 mol of geraniol and 6 mol of L-lactide under nitrogen atmosphere. After the addition of 1 L of dichloromethane to dissolve lactide, 0.1% (molar fraction) of catalyst 1,8-diazabicyclo[5.4.0]undec-7-ene was added to react for 30 min at room temperature (about 25 °C). After the reaction was stopped by adding aqueous hydrochloric acid solution to the reaction solution, it was washed with saturated aqueous sodium bicarbonate solution and deionized water for 3 times, respectively. After drying, the solvent was removed by rotary evaporation, and the product was obtained as a colorless viscous liquid after drying in a vacuum oven. The structure of the terpene alcohol ester-based fully bio-based polylactic acid plasticizer is shown below, and the number average molecular weight is 980 g / mol, where n is 12 in theory.

[0058]

[0059] Example 5

[0060] A 2 L three-necked round-bottom flask equipped with magnetic stirring was charged with 1 mol of geraniol and 6 mol of L-lactide under nitrogen atmosphere. After the addition of 1 L of dichloromethane to dissolve lactide, 0.1% (molar fraction) of catalyst 1,8-diazabicyclo[5.4.0]undec-7-ene was added to react for 30 min at room temperature (about 25 °C). After the reaction was stopped by adding aqueous hydrochloric acid solution to the reaction solution, it was washed with saturated aqueous sodium bicarbonate solution and deionized water for 3 times, respectively. After drying, the solvent was removed by rotary evaporation, and the product was obtained as a colorless viscous liquid after drying in a vacuum oven. The structure of the terpene alcohol ester-based fully bio-based polylactic acid plasticizer is shown below, and the number average molecular weight is 980 g / mol, where n is 12 in theory.

[0061]

[0062] Example 6

[0063] Under nitrogen atmosphere, 1 mol L-menthol and 2 mol L-lactide were added into a 1 L three-necked round-bottom flask with magnetic stirring. After dissolving in 500 mL dichloromethane, 0.1% (molar fraction) of catalyst 1,8-diazabicyclo[5.4.0]undec-7-ene was added. The reaction was carried out at room temperature (about 25°C) for 30 min. After stopping the reaction by adding aqueous hydrochloric acid solution, the reaction solution was washed with saturated aqueous sodium bicarbonate solution and deionized water for 3 times respectively. After drying, the solvent was removed by rotary evaporation. After drying in a vacuum oven, the colorless transparent liquid product was obtained, which was a terpene alcohol ester type fully biobased polylactic acid plasticizer, and its structural formula was as shown below. The number average molecular weight was 430 g / mol, and the theoretical value of n was 4.

[0064]

[0065] Example 7

[0066] Under nitrogen atmosphere, 1 mol farnesol and 2 mol L-lactide were added into a 1 L three-necked round-bottom flask with magnetic stirring. After dissolving in 500 mL dichloromethane, 0.1% (molar fraction) of catalyst 1,8-diazabicyclo[5.4.0]undec-7-ene was added. The reaction was carried out at room temperature (about 25°C) for 30 min. After stopping the reaction by adding aqueous hydrochloric acid solution, the reaction solution was washed with saturated aqueous sodium bicarbonate solution and deionized water for 3 times respectively. After drying, the solvent was removed by rotary evaporation. After drying in a vacuum oven, the colorless transparent liquid product was obtained, which was a terpene alcohol ester type fully biobased polylactic acid plasticizer, and its structural formula was as shown below. The number average molecular weight was 520 g / mol, and the theoretical value of n was 4.

[0067]

[0068] Application Example 1

[0069] Polylactic acid 90 kg, terpene alcohol ester type fully biobased polylactic acid plasticizer prepared in Example 2 10 kg. The polylactic acid and the terpene alcohol ester type fully biobased polylactic acid plasticizer were dried at 80°C and 60°C respectively for 8 h. After mixing, they were added into a twin-screw extruder for melt blending. The screw temperature was set at 120°C, 150°C, 160°C, 170°C, 175°C, 170°C in stages. After cooling and granulation, a high-toughness fully biobased polylactic acid composite material was obtained.

[0070] Application Example 2

[0071] Take 80 kg of polylactic acid, 20 kg of terpene alcohol ester full-bio-based polylactic acid plasticizer prepared in Example 2. Dry the polylactic acid and the terpene alcohol ester full-bio-based polylactic acid plasticizer at 80°C and 60°C respectively for 8 hours. After mixing the dried raw materials, add them to the twin-screw extruder for melt blending. The screw temperature is set in stages at 120°C, 150°C, 160°C, 170°C, 175°C, and 170°C. After cooling and granulation, a high-toughness full-bio-based polylactic acid composite material is obtained.

[0072] Application Example 3

[0073] Take 80 kg of polylactic acid, 20 kg of terpene alcohol ester full-bio-based polylactic acid plasticizer prepared in Example 4. Dry the polylactic acid and the terpene alcohol ester full-bio-based polylactic acid plasticizer at 80°C and 60°C respectively for 8 hours. After mixing the dried raw materials, add them to the twin-screw extruder for melt blending. The screw temperature is set in stages at 120°C, 150°C, 160°C, 170°C, 175°C, and 170°C. After cooling and granulation, a high-toughness full-bio-based polylactic acid composite material is obtained.

[0074] Comparative Example 1

[0075] Take 100 kg of polylactic acid and dry it at 80°C for 8 hours. After drying, add it to the twin-screw extruder for melt blending. The screw temperature is set in stages at 120°C, 150°C, 160°C, 170°C, 175°C, and 170°C. After cooling and granulation, polylactic acid particles are obtained.

[0076] Comparative Example 2

[0077] Take 90 kg of polylactic acid and 10 kg of acetyl tri-n-butyl citrate. Dry the polylactic acid and the acetyl tri-n-butyl citrate plasticizer at 80°C and 60°C respectively for 8 hours. After mixing the dried raw materials, add them to the twin-screw extruder for melt blending. The screw temperature is set in stages at 120°C, 150°C, 160°C, 170°C, 175°C, and 170°C. After cooling and granulation, a composite material is obtained.

[0078] Sample Analysis

[0079] Figure 1 FT-IR spectrum of the terpene alcohol ester full-bio-based polylactic acid plasticizer prepared in Example 2 and Example 4; the molecular structure of Example 2 and Example 4 can be confirmed from the corresponding hydrogen nuclear magnetic spectrum and infrared spectrum. 1 H NMR spectrum, Figure 2 FT-IR spectrum of the terpene alcohol ester full-bio-based polylactic acid plasticizer prepared in Example 2 and Example 4; the molecular structure of Example 2 and Example 4 can be confirmed from the corresponding hydrogen nuclear magnetic spectrum and infrared spectrum.

[0080] Thermogravimetric test was performed on the geraniol lactate oligomer (i.e. terpene alcohol ester full-bio-based polylactic acid plasticizer) of Example 2 and Example 4, from which Figure 3It can be seen that the thermal stability of the terpene alcohol ester is obviously improved compared with the raw material geraniol, and the thermal stability increases with the increase of the molecular weight. The obtained geraniol lactate oligomer meets the processing conditions of polylactic acid.

[0081] Further thermogravimetric test was conducted on the polylactic acid composite obtained in application examples 1-3 and the polylactic acid particles of comparative example 1, and the results are shown in Figure 3 As shown in the figure, due to the early thermal degradation or volatilization of the geraniol lactate oligomer, the initial decomposition temperature of the polylactic acid composite of application examples 1-3 is reduced, but it does not affect the thermal decomposition of the polylactic acid material itself.

[0082] The samples obtained in application examples 1-3 and comparative examples 1-2 were injection molded into 1mm thick standard tensile samples, wherein the injection molding temperature was 165-175℃, the injection pressure was 70-90MPa, and the holding pressure was 45MPa. The tensile test was carried out according to GB / T1040.1-2018, and the test results are shown in Figure 4 , and the specific data are shown in Table 1.

[0083] Differential scanning calorimetry test was conducted on the samples obtained in application examples 1-3 and comparative examples 1-2, and the specific results are shown in Table 1.

[0084] UV-visible light transmittance test was conducted on the samples obtained in application examples 1-3 and comparative examples 1-2, and the specific results are shown in Table 1.

[0085] Table 1 Performance test results of samples obtained in application examples 1-3 and comparative examples 1-2

[0086]

[0087] From the results of the tensile test and the differential scanning calorimetry test, it can be seen that the terpene alcohol ester full-bio-based polylactic acid plasticizer has very obvious plasticizing and toughening effect on polylactic acid. The glass transition temperature, cold crystallization temperature and melting temperature of the polylactic acid composite material are obviously reduced by 43℃, 116℃ and 146℃ respectively by adding only 10wt% of the geraniol lactate oligomer of example 2. At the same time, the elongation at break is increased to 271.4%. The results are close to those of comparative example 2.

[0088] By increasing the amount of geraniol lactate oligomer of example 2, the glass transition temperature of the polylactic acid composite material can be further reduced to 31℃, and the elongation at break reaches 514.5%.

[0089] From application example 2 and application example 3, it can be seen that the low molecular weight geraniol lactate oligomer has better plasticizing and toughening effect, which shows that the structure that mainly plays the role of plasticizing may be the long non-polar chain of terpene alcohol.

[0090] The results of the ultraviolet-visible light transmittance test show that the addition of the terpene alcohol ester full-bio-based polylactic acid plasticizer does not affect the high transparency of the polylactic acid material, and also shows that the plasticizer has good compatibility with the polylactic acid.

[0091] The samples obtained in Examples 1-3 and Comparative Examples 1-2 were subjected to migration resistance tests, Figure 5 The mass loss of each sample after being soaked in water and n-hexane for 24 h, and the mass loss after being placed in an oven at 70°C for 12 h.

[0092] From Figure 5 It can be seen that the mass loss of Comparative Example 1 and all the samples of Examples is less than 1 wt%, while the mass loss of Comparative Example 2 is greater than 1 wt%, which shows that the terpene alcohol ester full-bio-based polylactic acid plasticizer has good solvent migration resistance and heat migration resistance.

[0093] The above examples have been described in detail to the technical solutions of the present application, and it should be understood that the above description is only a specific embodiment of the present application and is not used to limit the present application. Any modification, supplement or similar replacement within the principle range of the present application should be included in the protection scope of the present application.

Claims

1. A terpene alcohol ester all-biobased polylactic acid plasticizer, characterized in that: Its structural formula is shown in formula (I): Wherein, R1 is selected from * is the connection position; n is an integer between 1 and 30.

2. The terpene alcohol ester all-biobased polylactic acid plasticizer according to claim 1, characterized in that: The preparation method of the terpene alcohol ester all-biobased polylactic acid plasticizer comprises the following steps: in an inert gas atmosphere, in a solvent or without solvent, allowing terpene alcohol and lactide to undergo a ring-opening polymerization reaction under the action of a catalyst, and obtaining the terpene alcohol ester all-biobased polylactic acid plasticizer through post-processing; The terpene alcohol includes geraniol, nerol, linalool, citronellol, lavandinol, nerolidol, farnesol, phytol, bisabolol or menthol; The lactide is at least one of L-lactide, D-lactide and meso-lactide.

3. The terpene alcohol ester all-biobased polylactic acid plasticizer according to claim 2, characterized in that: Terpene alcohol and lactide undergo ring-opening polymerization at a molar ratio of 1:1 to 15.

4. The terpene alcohol ester all-biobased polylactic acid plasticizer according to claim 2, characterized in that: When the ring-opening polymerization reaction is carried out under solvent-free conditions, the ring-opening polymerization reaction conditions are: temperature 90-180° C., time 4-10 hours; and / or the catalyst is selected from at least one of stannous octoate, dibutyltin dilaurate, dibutyltin, and stannous chloride; and / or the catalyst addition amount is 0.01-0.5 wt % of the lactide.

5. The terpene alcohol ester all-biobased polylactic acid plasticizer according to claim 2, characterized in that: When the ring-opening polymerization reaction is carried out under solvent conditions, the solvent used includes at least one of tetrahydrofuran, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, acetonitrile, 1,4-dioxane, acetone, chloroform, dichloromethane, dichloroethane, petroleum ether, hexane, and cyclohexane.

6. The terpene alcohol ester all-biobased polylactic acid plasticizer according to claim 2, characterized in that: When the ring-opening polymerization reaction is carried out under solvent conditions, the ring-opening polymerization reaction conditions are: temperature 25-80° C., time 1-60 min; and / or the catalyst is selected from at least one of 1,8-diazabicyclo[5.4.0]undec-7-ene, 1,5,7-triazabicyclo[4.4.0]decene-5-ene, and 4-dimethylaminopyridine; and / or the catalyst addition amount is 0.1-5 mol% of the lactide.

7. A method for plasticizing polylactic acid, characterized in that: Utilize the terpene alcohol ester all-biobased polylactic acid plasticizer described in any one of claims 1-6.

8. A high-toughness all-biobased polylactic acid composite material, characterized in that: The invention comprises polylactic acid and the terpene alcohol ester all-biobased polylactic acid plasticizer according to any one of claims 1 to 6.

9. The high-toughness all-biobased polylactic acid composite material according to claim 8, characterized in that: The components include 5-30 wt% of a terpene alcohol ester all-biobased polylactic acid plasticizer and 70-95 wt% of polylactic acid.

10. The high-toughness all-biobased polylactic acid composite material according to claim 8, characterized in that: The preparation method of the high-toughness all-biobased polylactic acid composite material is as follows: after drying the raw materials including the terpene alcohol ester all-biobased polylactic acid plasticizer and polylactic acid, the raw materials are mixed, melt-extruded and granulated to obtain the high-toughness all-biobased polylactic acid composite material.

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