Polylactic acid antibacterial film containing pericarpium citri reticulatae essential oil and preparation method of polylactic acid antibacterial film

Abstract

The invention relates to a polylactic acid antibacterial film containing dried orange peel essential oil. The polylactic acid antibacterial film is prepared from the following components: polylactic acid, a ternary polylactic acid copolymer, modified nano silicon dioxide, the dried orange peel essential oil and an auxiliary agent, wherein the ternary polylactic acid segmented copolymer is a product obtained by polymerizing lactide, glycolide and RNS-E, and the modified nano silicon dioxide is a blend of hydroxylated nano silicon dioxide and common nano silicon dioxide. According to the polylactic acid antibacterial film containing the dried orange peel essential oil, the thermal stability and the tensile strength of the film are gradually improved along with the increase of the content of the ternary polylactic acid copolymer, the stability and the dispersity of the film are further enhanced by the added modified nano silicon dioxide, and the film has good thermal stability, mechanical property and antibacterial property.

Description

Technical Field

[0001] The invention relates to the field of packaging material processing, and in particular to a polylactic acid antibacterial film containing tangerine peel essential oil and a preparation method thereof. Background Art

[0002] Polylactic acid (PLA) film is a new type of biodegradable material. In recent years, it has been widely used in packaging, agriculture, biomedicine, textiles and other fields. With its unique biocompatibility and environmental safety, it has become an important force in promoting green development. Major scientific research institutions and companies around the world have increased their investment in the research and production of polylactic acid films.

[0003] At present, adding antibacterial agents to polylactic acid films to make the films have antibacterial properties is a new development direction. However, in the preparation methods commonly used in industrial large-scale production, fillers such as inorganic particles are usually added in the process of preparing polylactic acid films with antibacterial properties. However, the compatibility of inorganic particles with polylactic acid or other organic matter is poor, and the inorganic particles cannot be evenly dispersed in polylactic acid or other organic matter, which leads to a decrease in the mechanical properties of the polylactic acid film with antibacterial properties, such as a decrease in tensile strength, which makes the polylactic acid film with antibacterial properties easily torn under the action of external forces. If the polylactic acid film with antibacterial properties is used in an extremely high temperature environment, its thermal stability will be reduced and it will be more prone to decomposition, which will eventually lead to the polylactic acid film with antibacterial properties being unable to continue to be used.

[0004] Therefore, there is an urgent need to develop a polylactic acid film with better antibacterial properties. Summary of the invention

[0005] Based on this, the present invention provides a polylactic acid antibacterial film containing tangerine peel essential oil and a preparation method thereof to overcome the deficiencies of the prior art.

[0006] An object of the present invention is to provide a polylactic acid antibacterial film containing tangerine peel essential oil, wherein the polylactic acid antibacterial film containing tangerine peel essential oil comprises the following components in parts by weight:

[0007]

[0008] The ternary polylactic acid block copolymer is a product of polymerization of lactide, glycolide and RNS-E, and the modified nano-silica is a blend of hydroxylated nano-silica and ordinary nano-silica.

[0009] Furthermore, the particle size of the modified nano-silicon dioxide is 15-25 nm.

[0010] Furthermore, the auxiliary agent is selected from one or more of a dispersant, a plasticizer, an antioxidant, a lubricant, and a film-forming agent.

[0011] Furthermore, the dispersant is selected from one or more of stearic acid, zinc stearate, and white oil.

[0012] Furthermore, the plasticizer is selected from PEG200.

[0013] The present invention also provides a method for preparing the polylactic acid antibacterial film containing tangerine peel essential oil, comprising the following steps:

[0014] S1, blending lactide, glycolide and RNS-E, adding a catalyst under inert atmosphere protection, heating for reaction, and recrystallization to obtain a ternary polylactic acid copolymer;

[0015] S2, hydroxylating the nano-silicon dioxide to obtain hydroxylated nano-silicon dioxide, and adding ordinary nano-silicon dioxide to blend to obtain modified nano-silicon dioxide;

[0016] S3, blending the ternary polylactic acid copolymer, modified nano-silica, polylactic acid, tangerine peel essential oil, and additives, putting them into a screw extruder, heating and extruding them into a film, and obtaining a polylactic acid antibacterial film containing tangerine peel essential oil.

[0017] Furthermore, the mass ratio of lactide, glycolide and RNS-E is 1:(1-10):(0.02-0.05).

[0018] Furthermore, the mass ratio of the hydroxylated nano-silicon dioxide to the common nano-silicon dioxide is 1:(1-2).

[0019] Furthermore, the RNS-E is nano-silicon dioxide with epoxy groups, and the particle size is 15-25nm.

[0020] Furthermore, the catalyst is selected from stannous octoate.

[0021] Furthermore, the added amount of the catalyst is 0.5-2% of the total mass of lactide, glycolide and RNS-E.

[0022] Furthermore, the temperature of the heating reaction is 130-150°C.

[0023] Furthermore, the temperature of the heated extrusion is 145-175°C.

[0024] The present invention has the following beneficial effects:

[0025] The polylactic acid antibacterial film containing dried orange peel essential oil of the present invention adopts ternary polylactic acid copolymer as component, and this component is reacted with the polymer of lactide and glycolide through RNS-E, so that RNS-E is grafted with polymer chain segment, thus the effect of compatibilizer is brought into play, and the affinity between silicon dioxide and polylactic acid resin can be improved, so as to improve the dispersion effect of inorganic filler, and silicon dioxide has more active groups after hydroxylation modification, and increases the crosslinking degree between components after compounding with ternary polylactic acid copolymer, so that molecules are closely combined, and stability is enhanced. In addition, the hydroxyl group in modified nano silicon dioxide can form hydrogen bonds with ternary polylactic acid copolymer and polylactic acid, so as to form a stable network, improve material strength, and can also form hydrogen bonds with groups such as amino, ester group, hydroxyl group in dried orange peel essential oil, further improve stability, and promote the improvement of multiple performances.

[0026] Therefore, in summary, the polylactic acid antibacterial film containing tangerine peel essential oil of the present invention has good thermal stability and mechanical properties, and also has good antibacterial properties. DETAILED DESCRIPTION

[0027] In order to more clearly illustrate the technical solution of the present invention, the following examples are listed. Unless otherwise stated, the raw materials, reactions and post-treatment methods shown in the examples are common raw materials on the market and technical methods well known to those skilled in the art.

[0028] It should be understood that, except in any operating examples, or where otherwise indicated, all numbers expressing, for example, the amounts of ingredients used in the specification and claims should be understood to be modified in all cases by the term "about". Therefore, unless indicated to the contrary, the numerical parameters set forth in the following specification and the appended claims are approximate values ​​that vary depending on the desired properties to be obtained by the present invention.

[0029] In the following examples, unless otherwise specified, all preparations and tests took place at 25°C.

[0030] Polylactic acid, brand 4032D, was purchased from Dongguan Yingde Plastic Raw Materials Co., Ltd.

[0031] Tangerine peel essential oil was purchased from Jiangxi Chuanhui Herbal Biotechnology Co., Ltd.

[0032] White oil, dispersant, was purchased from Maoming Petrochemical Shihua Co., Ltd.

[0033] RNS-E, nano-silica with epoxy groups, with a particle size of 15-25 nm, was purchased from Xi'an Qiyue Biotechnology Co., Ltd.

[0034] Example 1

[0035] A polylactic acid antibacterial film containing tangerine peel essential oil comprises the following components in parts by weight:

[0036]

[0037] The method for preparing the polylactic acid antibacterial film containing tangerine peel essential oil comprises the following steps:

[0038] S1. Add lactide, glycolide and RNS-E in a mass ratio of 1:10:0.04 into a container, evacuate and pass nitrogen, then add a toluene solution of stannous octoate (1.0wt%, the mass of stannous octoate is 2% of the total mass of the reaction system), evacuate and pass nitrogen again, repeat three times, seal the container, and then place it in an oil bath heated to 135°C to react for 24 hours, dissolve the solid product with dichloromethane, add excess methanol for precipitation, then filter with suction, and dry for 24 hours to obtain a ternary polylactic acid copolymer;

[0039] S2, adding nano-silica to a mixture of concentrated sulfuric acid and hydrogen peroxide (the concentration of hydrogen peroxide is 30wt%, and the mass ratio of concentrated sulfuric acid to hydrogen peroxide is 7:3), heating to 70°C, reacting for 1h to obtain hydroxylated nano-silica, adding ordinary nano-silica (the mass ratio of hydroxylated nano-silica to ordinary nano-silica is 1:1) and blending to obtain modified nano-silica;

[0040] S3, by above-mentioned mass fraction, described ternary polylactic acid copolymer, modified nano silica, polylactic acid, dried orange peel essential oil, white oil are blended, drop into twin screw extruder (twin screw extruder 1-7 district temperature is respectively 145,155,160,165,175,175,175 ℃, rotating speed is 45r / min) heating and extruding, after extruding, film bubble is blown by blower fan, after stabilizing the size of film bubble, regulating blow-up ratio is 3.0, makes film width reach 1m, by regulating main engine speed and traction rate, regulating film thickness is 15 μm, obtains the polylactic acid antibacterial film containing dried orange peel essential oil.

[0041] Example 2

[0042] A polylactic acid antibacterial film containing tangerine peel essential oil comprises the following components in parts by weight:

[0043]

[0044] The method for preparing the polylactic acid antibacterial film containing tangerine peel essential oil comprises the following steps:

[0045] S1. Add lactide, glycolide and RNS-E in a mass ratio of 1:10:0.04 into a container, evacuate and pass nitrogen, then add a toluene solution of stannous octoate (1.0wt%, the mass of stannous octoate is 2% of the total mass of the reaction system), evacuate and pass nitrogen again, repeat three times, seal the container, and then place it in an oil bath heated to 135°C to react for 24 hours, dissolve the solid product with dichloromethane, add excess methanol for precipitation, then filter with suction, and dry for 24 hours to obtain a ternary polylactic acid copolymer;

[0046] S2, adding nano-silica to a mixture of concentrated sulfuric acid and hydrogen peroxide (the concentration of hydrogen peroxide is 30wt%, and the mass ratio of concentrated sulfuric acid to hydrogen peroxide is 7:3), heating to 70°C, reacting for 1h to obtain hydroxylated nano-silica, adding ordinary nano-silica (the mass ratio of hydroxylated nano-silica to ordinary nano-silica is 1:1) and blending to obtain modified nano-silica;

[0047] S3, by above-mentioned mass fraction, described ternary polylactic acid copolymer, modified nano silica, polylactic acid, dried orange peel essential oil, white oil are blended, drop into twin screw extruder (twin screw extruder 1-7 district temperature is respectively 145,155,160,165,175,175,175 ℃, rotating speed is 45r / min) heating and extruding, after extruding, film bubble is blown by blower fan, after stabilizing the size of film bubble, regulating blow-up ratio is 3.0, makes film width reach 1m, by regulating main engine speed and traction rate, regulating film thickness is 15 μm, obtains the polylactic acid antibacterial film containing dried orange peel essential oil.

[0048] Example 3

[0049] A polylactic acid antibacterial film containing tangerine peel essential oil comprises the following components in parts by weight:

[0050]

[0051] The method for preparing the polylactic acid antibacterial film containing tangerine peel essential oil comprises the following steps:

[0052] S1. Add lactide, glycolide and RNS-E in a mass ratio of 1:10:0.04 into a container, evacuate and pass nitrogen, then add a toluene solution of stannous octoate (1.0wt%, the mass of stannous octoate is 2% of the total mass of the reaction system), evacuate and pass nitrogen again, repeat three times, seal the container, and then place it in an oil bath heated to 135°C to react for 24 hours, dissolve the solid product with dichloromethane, add excess methanol for precipitation, then filter with suction, and dry for 24 hours to obtain a ternary polylactic acid copolymer;

[0053] S2, adding nano-silica to a mixture of concentrated sulfuric acid and hydrogen peroxide (the concentration of hydrogen peroxide is 30wt%, and the mass ratio of concentrated sulfuric acid to hydrogen peroxide is 7:3), heating to 70°C, reacting for 1h to obtain hydroxylated nano-silica, adding ordinary nano-silica (the mass ratio of hydroxylated nano-silica to ordinary nano-silica is 1:1) and blending to obtain modified nano-silica;

[0054] S3, by above-mentioned mass fraction, described ternary polylactic acid copolymer, modified nano silica, polylactic acid, dried orange peel essential oil, white oil are blended, drop into twin screw extruder (twin screw extruder 1-7 district temperature is respectively 145,155,160,165,175,175,175 ℃, rotating speed is 45r / min) heating and extruding, after extruding, film bubble is blown by blower fan, after stabilizing the size of film bubble, regulating blow-up ratio is 3.0, makes film width reach 1m, by regulating main engine speed and traction rate, regulating film thickness is 15 μm, obtains the polylactic acid antibacterial film containing dried orange peel essential oil.

[0055] Comparative Example 1

[0056] The difference between this comparative example and Example 1 is that: Step S1 is deleted, and the mass of the ternary polylactic acid copolymer is replaced by: lactide, glycolide, and RNS-E are added into a container at a mass ratio of 1:10:0.02, and the resulting mixture is stirred evenly.

[0057] Comparative Example 2

[0058] The difference between this comparative example and Example 1 is that step S2 is deleted, and the mass of modified nano-silicon dioxide is replaced by unmodified nano-silicon dioxide.

[0059] Test Example 1

[0060] The film samples of Examples 1-3 and Comparative Examples 1-2 were tested for mechanical properties.

[0061] Test method:

[0062] The film samples of Examples 1-3 and Comparative Examples 1-2 were tested for tensile strength and elongation at break according to ASTM D638 plastic tensile properties test standard.

[0063] The test results are shown in Table 1.

[0064] Table 1 Mechanical properties test results of film samples of Examples 1-3 and Comparative Examples 1-2

[0065]

[0066]

[0067] As can be seen from Table 1, the polylactic acid antibacterial films containing tangerine peel essential oil of Examples 1-3 have good mechanical properties, and the tensile strength and elongation at break are significantly better than those of Comparative Examples 1-2. In Comparative Example 1, due to the replacement of the ternary polylactic acid copolymer, the compatibility and stability between the components are significantly reduced, the ideal synergistic effect cannot be achieved, and the strength is significantly reduced; in Comparative Example 2, the modified nano-silica is replaced, the synergistic effect between the components is also reduced, and the strength is weakened.

[0068] Test Example 2

[0069] The antibacterial performance of the film samples of Examples 1-3 and Comparative Examples 1-2 was tested.

[0070] Test method:

[0071] The antibacterial performance test of the film samples of Examples 1-3 and Comparative Examples 1-2 was performed according to ASTM E2180-07 standard.

[0072] The test results are shown in Table 2.

[0073] Table 2 Antibacterial performance test results of film samples of Examples 1-3 and Comparative Examples 1-2

[0074]

[0075] As can be seen from Table 2, Examples 1-3 have excellent antibacterial properties, with the antibacterial rates against Escherichia coli and Staphylococcus aureus reaching more than 99%, while the stability of Comparative Example 1-2 with replaced ingredients is reduced, and the antibacterial performance also decreases, and the ideal performance improvement cannot be obtained.

[0076] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention.

[0077] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A polylactic acid antibacterial film containing tangerine peel essential oil, characterized in that: The polylactic acid antibacterial film containing tangerine peel essential oil comprises the following components in parts by weight: Wherein, the ternary polylactic acid block copolymer is a product of polymerization of lactide, glycolide and RNS-E; The modified nano silicon dioxide is a blend of hydroxylated nano silicon dioxide and common nano silicon dioxide.

2. The polylactic acid antibacterial film containing tangerine peel essential oil according to claim 1, characterized in that: The particle size of the modified nano silicon dioxide is 15-25 nm.

3. The polylactic acid antibacterial film containing tangerine peel essential oil according to claim 1, characterized in that: The auxiliary agent is selected from one or more of a dispersant, a plasticizer, an antioxidant, a lubricant, and a film-forming agent.

4. The method for preparing the polylactic acid antibacterial film containing tangerine peel essential oil according to any one of claims 1 to 3, characterized in that: The preparation method of the polylactic acid antibacterial film containing tangerine peel essential oil is: S1, blending lactide, glycolide and RNS-E, adding a catalyst under inert atmosphere protection, heating for reaction, and recrystallization to obtain a ternary polylactic acid copolymer; S2, hydroxylating the nano-silicon dioxide to obtain hydroxylated nano-silicon dioxide, and adding ordinary nano-silicon dioxide to blend to obtain modified nano-silicon dioxide; S3, blending the ternary polylactic acid copolymer, modified nano-silica, polylactic acid, tangerine peel essential oil, and additives, putting them into a screw extruder, heating and extruding them into a film, and obtaining a polylactic acid antibacterial film containing tangerine peel essential oil.

5. The method for preparing the polylactic acid antibacterial film containing tangerine peel essential oil according to claim 4, characterized in that: The mass ratio of lactide, glycolide and RNS-E is 1:(1-10):(0.02-0.05).

6. The method for preparing the polylactic acid antibacterial film containing tangerine peel essential oil according to claim 4, characterized in that: The mass ratio of the hydroxylated nano-silicon dioxide to the common nano-silicon dioxide is 1:(1-2).

7. The method for preparing the polylactic acid antibacterial film containing tangerine peel essential oil according to claim 4, characterized in that: The RNS-E particle size is 15-25 nm.

8. The method for preparing the polylactic acid antibacterial film containing tangerine peel essential oil according to claim 4, characterized in that: The catalyst is selected from organotin catalysts.

9. The method for preparing the polylactic acid antibacterial film containing tangerine peel essential oil according to claim 4, characterized in that: The temperature of the heating reaction is 130-150°C.

10. The method for preparing the polylactic acid antibacterial film containing tangerine peel essential oil according to claim 4, characterized in that: The temperature of the heated extrusion is 145-175°C.

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