Ultraviolet-cured castor oil-based polylactic acid and preparation method thereof

Abstract

The invention relates to ultraviolet-cured castor oil-based polylactic acid and a preparation method thereof. According to the technical scheme, the preparation method comprises the following steps: adding castor oil, lactide and a catalyst into an ampere flask, vacuumizing, carrying out magnetic stirring reaction at 90-150 DEG C for 5-12 hours, adding a cross-linking agent, a photoinitiator and a solvent, pouring to form a film after the system is uniformly dissolved, and curing for 5 seconds to 1 hour under the condition of ultraviolet irradiation, so as to prepare the ultraviolet-cured castor oil-based polylactic acid. The preparation method has the characteristics of abundant raw material sources, simple process, high curing efficiency, low cost, low toxicity, environment friendliness and suitability for industrial production, and the prepared ultraviolet-cured castor oil-based polylactic acid has good flexibility and light transmission, is safe and low in toxicity, and has wide application prospects in the aspects of food packaging, electronic devices, biomedical treatment and the like.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of bio-based polymer materials. Specifically relates to a kind of ultraviolet light cured castor oil-based polylactic acid and its preparation method. BACKGROUND

[0002] Polylactic acid (PLA) has good biodegradability and recyclability, and its raw material is derived from renewable plants. The characteristics of environmental friendliness, good biocompatibility and high strength make PLA widely studied in many fields such as food packaging, biomedical and textile.

[0003] However, the brittle, low elongation at break and poor light transmission of PLA limit its application range. In order to improve the performance of PLA and solve the environmental problems caused by the use of petroleum-based materials, the introduction of vegetable oil into PLA has attracted the interest of many scientists. The patent technology "a low-cost toughened polylactic acid composite material and its preparation method" (CN106317816B) four components of 54.3-81.9wt% polylactic acid, 8-15wt% epoxidized vegetable oil, 10-30wt% inorganic filler without surface treatment and peroxide initiator, after drying and mixing, through one-step melt blending modification by double screw extruder, extrusion granulation to prepare bio-based polyester composite material, its elongation at break is 243%, tensile strength is 30MPa. The patent technology "preparation method of a polylactic acid / epoxy vegetable oil full bio-based composite material" (CN202110153339), polylactic acid, epoxy vegetable oil, acid anhydride and organic peroxide catalyst are mixed uniformly and then melt blended, then epoxy vegetable oil is added and chemical grafting reaction occurs under the catalysis of organic amine catalyst, and the grafting product is washed and dried to obtain the polylactic acid / epoxy vegetable oil full bio-based composite material. Its tensile strength is increased from 35.3MPa to 50.3MPa, and the elongation at break is increased from 3.1% to 4.4%. Shohei Matsuda et al. used stannous octoate as catalyst, castor oil, LLA / DLA and hexamethylene diisocyanate (HDI) as raw materials (Tsujimoto T, Nishio S, Uyama H. Bio-based branched polymer bearing castor oil core as anucleating agent for poly(l-lactic acid) [J]. Journal of Polymers and the Environment, 2015, 23(4): 559-565.), and obtained a material containing crosslinked network through ring-opening polymerization and thermal crosslinking curing. The tensile strength of the crosslinked network is reduced, and the elongation at break is increased to 300%.

[0004] The above invention and research both obtain the PLA material containing plant oil modification, because of the introduction of plant oil, the performance of PLA is improved, such as increasing the toughness and biodegradability of PLA. But there are still some problems: (1) the utilization of plant oil is limited to the hydroxyl group initiated ring opening, and the double bond on the plant oil is not fully developed; (2) the addition of inorganic filler in the preparation process will affect the compatibility of the material; (3) the light transmission performance of PLA is not improved; (4) the composite material prepared by melt blending, thermal crosslinking and curing method has the problems of complex process, long reaction time, low curing efficiency, high energy consumption and the like. SUMMARY

[0005] The present application aims to overcome the defects of the prior art, and aims to provide a castor oil-based polylactic acid with rich raw material sources, simple process, high curing efficiency, low cost, easy-to-control polymer structure and low toxicity and environmental protection, and a preparation method thereof. The castor oil-based polylactic acid prepared by the method has good flexibility and light transmission, is safe and low in toxicity, and has wide application prospects in food packaging, electronic devices and biological medical treatment.

[0006] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is:

[0007] The castor oil, lactide and catalyst are added into an ampoule, vacuumized, and magnetically stirred at 90-150 DEG C for 1-12h, then the crosslinking agent, photoinitiator and solvent are added, the system is dissolved uniformly, then poured into a film, and cured under the condition of ultraviolet light for 5s-1h, to obtain the ultraviolet light cured castor oil-based polylactic acid;

[0008] Among them:

[0009] The molar ratio of the castor oil to the lactide is (0.001-1) : 1;

[0010] The molar ratio of the catalyst to the lactide is (0.0002-0.1) : 1;

[0011] The molar ratio of the crosslinking agent to the lactide is (0.001-0.5) : 1;

[0012] The molar ratio of the photoinitiator to the lactide is (0.005-1) : 1;

[0013] The molar ratio of the solvent to the lactide is (0.1-2) : 1.

[0014] The lactide is one of L-lactide, D-lactide and D, L-lactide.

[0015] The catalyst is one of stannous octoate, dibutyltin dilaurate, dibutyltin diacetate and stannous chloride.

[0016] The crosslinking agent is one of pentaerythritol tetra (mercaptoacetic acid) ester, pentaerythritol tetra (3-mercaptopropionate), 3 trimethylolpropane tri (3-mercaptopropionate), 1, 4-butanediol di (3-mercaptopropionate) and ethoxylated trimethylolpropane tri (3-mercaptopropionate).

[0017] The photoinitiator is one of benzophenone, benzoin dimethyl ether, 2-hydroxy-2-methyl-1-phenyl-1-propanone, 2, 4, 6-trimethylbenzoyl-diphenyl phosphine oxide and phenyl bis (2, 4, 6-trimethylbenzoyl) phosphine oxide.

[0018] The solvent is one of tetrahydrofuran, dichloromethane, chloroform, dimethyl sulfoxide and N, N-dimethylformamide.

[0019] The ultraviolet light irradiation wavelength is 365nm, and the light intensity is 200-5000MJ / cm 2 .

[0020] Compared with the prior art, the application has the following positive effects:

[0021] The castor oil, lactide and catalyst are added into an ampoule, vacuumized, and then magnetically stirred at 90-150 DEG C for 1-12h, then the crosslinking agent, photoinitiator and solvent are added, the system is dissolved uniformly, then poured into a film, and then cured under ultraviolet light for 5s-1h, to obtain the ultraviolet cured castor oil-based polylactic acid.

[0022] The raw materials are abundant, renewable and low in production cost; the catalyst is low in toxicity and meets the safety certification standard of the US Food and Drug Administration, and is safe and environmentally friendly; different castor oil-based polylactic acid formulations and the types and contents of the crosslinking agent can be designed to prepare the ultraviolet cured castor oil-based polylactic acid with different structures, and the obtained polymer has good flexibility and light transmittance.

[0023] The structure of the prepared polymer is confirmed by Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy analysis, and the performance of the obtained ultraviolet cured castor oil-based polylactic acid is tested by a tensile testing machine and an ultraviolet-visible light spectrophotometer.

[0024] Therefore, the application has the characteristics of abundant raw material sources, simple process, high curing efficiency, low cost, low toxicity and environmental protection, and is suitable for industrial production, the prepared ultraviolet cured castor oil-based polylactic acid has good flexibility and light transmittance, is safe and low in toxicity, and has wide application prospects in food packaging, electronic devices and biological medical treatment. DETAILED DESCRIPTION

[0025] The application is further described in connection with the specific embodiments below, which are not intended to limit the scope of the application.

[0026] Example 1

[0027] A UV-cured castor oil-based polylactic acid and a preparation method thereof. The preparation steps are as follows:

[0028] Castor oil, lactide and a catalyst are added into an ampoule, vacuumized, and magnetically stirred at 90-105℃ for 10-12h. Then, a crosslinking agent, a photoinitiator and a solvent are added. After the system is dissolved uniformly, a film is poured and cured under UV light for 50min-1h to obtain the UV-cured castor oil-based polylactic acid. In the process, the molar ratio of the castor oil to the lactide is (0.5-1) : 1.

[0029] The molar ratio of the catalyst to the lactide is (0.05-0.1) : 1.

[0030] The molar ratio of the crosslinking agent to the lactide is (0.1-0.5) : 1.

[0031] The molar ratio of the photoinitiator to the lactide is (0.5-1) : 1.

[0032] The molar ratio of the solvent to the lactide is (1-2) : 1.

[0033] In the example, the lactide is L-lactide.

[0034] The catalyst is stannous octoate.

[0035] The crosslinking agent is pentaerythritol tetra(mercaptoacetate).

[0036] The photoinitiator is benzophenone.

[0037] The solvent is tetrahydrofuran.

[0038] The wavelength of the UV light is 365nm, and the light intensity is 200-1000MJ / cm 2 .

[0039] Example 2

[0040] A UV-cured castor oil-based polylactic acid and a preparation method thereof. The preparation steps are as follows:

[0041] The molar ratio of the catalyst to the lactide is (0.05-0.1) : 1.

[0042] The molar ratio of the crosslinking agent to the lactide is (0.1-0.5) : 1.

[0043] The castor oil, lactide and catalyst are added into an ampoule, vacuumized, and magnetically stirred at 105-120℃ for 8-10h, then the crosslinking agent, photoinitiator and solvent are added, and after the system is dissolved uniformly, a film is poured, and then cured under ultraviolet light for 50min-1h to obtain the ultraviolet cured castor oil-based polylactic acid. Among them:

[0044] The molar ratio of the castor oil to the lactide is (0.1-0.5) : 1;

[0045] The molar ratio of the catalyst to the lactide is (0.01-0.05) : 1;

[0046] The molar ratio of the crosslinking agent to the lactide is (0.05-0.1) : 1;

[0047] The molar ratio of the photoinitiator to the lactide is (0.1-0.5) : 1;

[0048] The molar ratio of the solvent to the lactide is (0.5-1) : 1.

[0049] In this embodiment:

[0050] The lactide is D-lactide.

[0051] The catalyst is dibutyltin dilaurate.

[0052] The crosslinking agent is pentaerythritol tetra(3-mercaptopropionate).

[0053] The photoinitiator is benzoin dimethyl ether.

[0054] The solvent is dichloromethane.

[0055] The ultraviolet light irradiation wavelength is 365nm, and the light intensity is 1000-2000MJ / cm 2 .

[0056] Example 3

[0057] An ultraviolet cured castor oil-based polylactic acid and a preparation method thereof. The preparation steps are:

[0058] The castor oil, lactide and catalyst are added into an ampoule, vacuumized, and magnetically stirred at 120-130℃ for 6-8h, then the crosslinking agent, photoinitiator and solvent are added, and after the system is dissolved uniformly, a film is poured, and then cured under ultraviolet light for 10-30min to obtain the ultraviolet cured castor oil-based polylactic acid. Among them:

[0059] The molar ratio of the castor oil to the lactide is (0.05-0.1) : 1;

[0060] the molar ratio of the catalyst to the propiolactone is (0.005-0.01) : 1;

[0061] the molar ratio of the crosslinking agent to the propiolactone is (0.01-0.05) : 1;

[0062] the molar ratio of the photoinitiator to the propiolactone is (0.05-0.1) : 1;

[0063] the molar ratio of the solvent to the propiolactone is (0.1-0.5) : 1.

[0064] In this embodiment:

[0065] the propiolactone is D,L-propiolactone.

[0066] the catalyst is dibutyl tin diacetate.

[0067] the crosslinking agent is trimethylolpropane tris(3-mercaptopropionate).

[0068] the photoinitiator is 2-hydroxy-2-methyl-l-phenyl-l-propanone.

[0069] the solvent is chloroform.

[0070] the wavelength of the ultraviolet light irradiation is 365 nm, and the light intensity is 2000-3000 MJ / cm 2 .

[0071] Example 4

[0072] An ultraviolet light-cured castor oil-based polylactic acid and a preparation method thereof. The preparation steps are:

[0073] Castor oil, propiolactone and a catalyst are added to an ampoule, vacuumed, and subjected to magnetic stirring at 130-140°C for 4-6 h. Then, a crosslinking agent, a photoinitiator and a solvent are added, the system is dissolved uniformly, and a film is cast. The film is cured under ultraviolet light irradiation for 1-10 min to obtain the ultraviolet light-cured castor oil-based polylactic acid. In this embodiment:

[0074] the molar ratio of the castor oil to the propiolactone is (0.001-0.05) : 1;

[0075] the molar ratio of the catalyst to the propiolactone is (0.001-0.005) : 1;

[0076] the molar ratio of the crosslinking agent to the propiolactone is (0.001-0.01) : 1;

[0077] The molar ratio of the photoinitiator to the lactide is (0.01-0.05):1;

[0078] The molar ratio of the solvent to the lactide is (1-2):1.

[0079] In this embodiment:

[0080] The lactide is D,L-lactide.

[0081] The catalyst is stannous chloride.

[0082] The crosslinking agent is 1,4-butanediol di(3-mercaptopropionate).

[0083] The photoinitiator is 2,4,6-trimethylbenzoyl-diphenylphosphine oxide.

[0084] The solvent is dimethyl sulfoxide.

[0085] The wavelength of the ultraviolet light irradiation is 365 nm, and the light intensity is 3000-4000 MJ / cm 2 .

[0086] Example 5

[0087] An ultraviolet light-cured castor oil-based polylactic acid and a preparation method thereof. The preparation steps are:

[0088] Castor oil, lactide and a catalyst are added to an ampoule, vacuumed, and magnetically stirred at 140-150°C for 1-4 h. Then, a crosslinking agent, a photoinitiator and a solvent are added, the system is dissolved uniformly, and a film is poured. The ultraviolet light-cured castor oil-based polylactic acid is prepared by curing under ultraviolet light irradiation for 5 s-1 min. In this embodiment:

[0089] The molar ratio of the castor oil to the lactide is (0.001-0.01):1;

[0090] The molar ratio of the catalyst to the lactide is (0.0002-0.001):1;

[0091] The molar ratio of the crosslinking agent to the lactide is (0.001-0.01):1;

[0092] The molar ratio of the photoinitiator to the lactide is (0.005-0.01):1;

[0093] The molar ratio of the solvent to the lactide is (0.5-1):1.

[0094] In this embodiment:

[0095] The lactide is L-lactide.

[0096] The catalyst is stannous octoate.

[0097] The crosslinking agent is ethoxylated trimethylolpropane tri(3-mercaptopropionate).

[0098] The photoinitiator is phenyl bis(2,4,6-trimethylbenzoyl) phosphine oxide.

[0099] The solvent is N,N-dimethylformamide.

[0100] The wavelength of the ultraviolet light irradiation is 365 nm, and the light intensity is 4000-5000 MJ / cm 2 .

Claims

1. A UV-curable castor oil-based polylactic acid and its preparation method, characterized in that... The preparation method is: The castor oil, lactide and catalyst are added into an ampoule, vacuumized, and magnetically stirred at 90-150℃ for 1-12h, then the crosslinking agent, photoinitiator and solvent are added, and after the system is dissolved uniformly, a film is poured, and then cured under ultraviolet light for 5s-1h to obtain the ultraviolet cured castor oil-based polylactic acid; The molar ratio of the castor oil to the lactide is (0.001-1) : 1; The molar ratio of the catalyst to the lactide is (0.0002-0.1) : 1; The molar ratio of the crosslinking agent to the lactide is (0.001-0.5) : 1; The molar ratio of the photoinitiator to the lactide is (0.005-1) : 1; The molar ratio of the solvent to the lactide is (0.1-2) :

1. The lactide is one of L-lactide, D-lactide and D,L-lactide.

2. The UV-cured castor oil-based polylactic acid according to claim 1, characterized by The catalyst is one of stannous octoate, dibutyltin dilaurate, dibutyltin diacetate and stannous chloride.

3. The UV-cured castor oil-based polylactic acid according to claim 1, characterized by The crosslinking agent is one of pentaerythritol tetra(mercaptoacetate), pentaerythritol tetra(3-mercaptopropionate), trimethylolpropane tri(3-mercaptopropionate), 1,4-butanediol di(3-mercaptopropionate) and ethoxylated trimethylolpropane tri(3-mercaptopropionate).

4. The UV-cured castor oil-based polylactic acid according to claim 1, characterized by The photoinitiator is one of benzophenone, benzoin dimethyl ether, 2-hydroxy-2-methyl-1-phenyl-1-propanone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide and phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide.

5. The UV-cured castor oil-based polylactic acid according to claim 1, characterized by The solvent is one of tetrahydrofuran, dichloromethane, trichloromethane, dimethyl sulfoxide and N,N-dimethylformamide.

6. The ultraviolet light cured castor oil based polylactic acid according to claim 1, characterized by The ultraviolet cured castor oil-based polylactic acid is the ultraviolet cured castor oil-based polylactic acid prepared according to the ultraviolet cured castor oil-based polylactic acid and the preparation method thereof in any one of claims 1-7.

7. The UV-cured castor oil-based polylactic acid according to claim 1, characterized by The wavelength of the ultraviolet light irradiation is 365 nm, and the light intensity is 200-5000 MJ / cm 2 .

8. An ultraviolet light cured castor oil based polylactic acid characterized in that ​