Biodegradable resin / nano titanium dioxide composite material, reflective film and preparation method of reflective film

Abstract

The invention relates to a biodegradable resin / nano titanium dioxide composite material, a reflective film and a preparation method of the reflective film. The preparation method of the biodegradable resin / nano titanium dioxide composite material comprises the following steps that biodegradable resin, a titanium dioxide precursor and a catalyst are mixed to obtain a mixture, and the catalyst comprises one or more of alkoxy metal salt, alkyl metal salt and alkyl acid metal salt; and carrying out extrusion treatment on the mixture. The biodegradable resin / nano titanium dioxide composite material prepared by the preparation method is high in degradation rate and can be better matched with the coloring period of crops.

Description

Technical Field

[0001] This application relates to the field of polymer composite materials technology, and in particular to a biodegradable resin / nano titanium dioxide composite material, a reflective film, and a method for preparing the same. Background Technology

[0002] Agricultural reflective film is widely used in agricultural planting. For example, during the fruit coloring period, reflective film can be laid on the ground to enhance the reflection of sunlight and improve the light conditions in the lower and inner parts of the tree canopy, so that the fruit in these parts can also be fully colored, thereby improving the appearance quality of the fruit.

[0003] Agricultural reflective films typically consist of a base film and a metal (such as aluminum) layer deposited on the surface of the base film. With increasing environmental pressures, the base film needs to be replaced with biodegradable resins. However, the coloring cycle of commonly used crops is only one month, and the degradation rate of traditional biodegradable resins is difficult to match, necessitating the addition of materials that catalyze degradation, such as nano-titanium dioxide.

[0004] However, titanium dioxide needs to be at the nanoscale to exert its photocatalytic degradation activity, and as an inorganic material, it is difficult to disperse when mixed with biodegradable resins, thus hindering its catalytic activity. Therefore, the base film of traditional agricultural reflective films still suffers from slow degradation rates. Summary of the Invention

[0005] Based on this, this application provides a biodegradable resin / nano titanium dioxide composite material, a reflective film, and a method for preparing the same. The biodegradable resin / nano titanium dioxide composite material prepared by this method exhibits a high degradation rate.

[0006] A first aspect of this application provides a method for preparing a biodegradable resin / nano-titanium dioxide composite material, comprising the following steps:

[0007] A mixture is obtained by mixing a biodegradable resin, a titanium dioxide precursor, and a catalyst, wherein the catalyst comprises one or more of alkoxy metal salts, alkyl metal salts, and alkyl acid metal salts.

[0008] The mixture is then extruded.

[0009] The above preparation method, in the process of extruding materials containing biodegradable resin and titanium dioxide precursor, can generate nano-titanium dioxide in situ by using a specific type of catalyst, thereby obtaining a biodegradable resin / nano-titanium dioxide composite material in which nano-titanium dioxide is uniformly distributed in the biodegradable resin. This method can fully exert the photocatalytic degradation activity of nano-titanium dioxide and shorten the degradation cycle.

[0010] The biodegradable resin / nano titanium dioxide composite material prepared by this method is particularly suitable as a base film for reflective films, such as agricultural reflective films, so that the biodegradation process of agricultural reflective films can be better matched with the coloring cycle of crops.

[0011] In one embodiment, the catalyst comprises one or more of C1-C5 alkoxy metal salts, C1-C5 alkyl metal salts, and C1-C5 alkyl acid metal salts, wherein the metal element comprises one or more of aluminum, zinc, magnesium, and calcium.

[0012] In one embodiment, the extrusion processing conditions include: extrusion in a screw extruder at a screw speed of 150 rpm to 300 rpm, using segmented temperature control, with the temperature distribution of the melting and homogenizing sections within the range of 140°C to 200°C. By controlling appropriate temperature and shear effect (screw speed), in-situ generation of nano-titanium dioxide in biodegradable resin is facilitated, further improving its dispersibility and photocatalytic activity.

[0013] Optionally, the temperature distribution of the segmented temperature control is within the range of 60℃ to 200℃.

[0014] Alternatively, the temperature distribution of the melting section and the homogenization section in the segmented temperature control is within the range of 140℃ to 160℃.

[0015] In addition, it is understandable that after extrusion in a screw extruder, the process includes steps such as strand cooling and cutting.

[0016] In one embodiment, the biodegradable resin includes one or more of polybutylene terephthalate (PBAT), polylactic acid (PLA), polyglycolic acid (PGA), polyhydroxyalkanoate (PHA), and polybutylene succinate (PBS).

[0017] In one embodiment, the titanium dioxide precursor comprises one or more of tetrabutyl titanate, tetraethyl titanate, triethyl titanate, and isopropyl titanate.

[0018] In one embodiment, the method for preparing the biodegradable resin / nano-titanium dioxide composite material has one or two of the following features:

[0019] (1) The titanium dioxide precursor is 4 to 10 parts by weight, based on 100 parts by weight of the biodegradable resin;

[0020] (2) The catalyst is 0.1 to 1 part by weight, based on 100 parts by weight of the biodegradable resin.

[0021] In one embodiment, the mixture also includes a film opening aid.

[0022] Optionally, the film opening aid is 0.1 to 2 parts by weight, based on 100 parts by weight of the biodegradable resin.

[0023] Optionally, the film opening aid includes one or more of oleamide, erucamide, and ethylene bis-stearamide.

[0024] A second aspect of this application provides a biodegradable resin / nano titanium dioxide composite material prepared by the preparation method described in the first aspect.

[0025] A third aspect of this application provides a reflective film, comprising a base film and a metal layer disposed on the surface of the base film, wherein the base film comprises the biodegradable resin / nano titanium dioxide composite material described in the second aspect.

[0026] Optionally, the material of the metal layer includes one or both of aluminum and zinc; more preferably, the material of the metal layer includes aluminum.

[0027] Optionally, the reflective film is an agricultural reflective film. More preferably, the agricultural reflective film is used for coloring crops.

[0028] A fourth aspect of this application provides a method for preparing a reflective film, comprising the following steps:

[0029] The biodegradable resin / nano titanium dioxide composite material described in the second aspect is subjected to film-forming treatment to prepare a base film;

[0030] A metal layer is formed on the surface of the base film.

[0031] Optionally, the material of the metal layer includes one or both of aluminum and zinc; more preferably, the material of the metal layer includes aluminum.

[0032] Optionally, the film-forming process includes blow molding.

[0033] Optionally, the method of forming a metal layer on the surface of the base film includes vapor deposition. Detailed Implementation

[0034] The following detailed description, with reference to specific embodiments, further illustrates the biodegradable resin / nano-titanium dioxide composite material, reflective film, and preparation method thereof of this application. This application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application.

[0035] Unless otherwise defined, 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 application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0036] In this application, "one or more" means any one, two or more of the listed items.

[0037] In this application, terms such as "first aspect," "second aspect," "third aspect," and "fourth aspect" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, terms such as "first," "second," "third," and "fourth" serve only as a non-exhaustive enumeration and should be understood not to constitute a closed limitation on quantity.

[0038] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0039] In this application, numerical ranges are referred to as continuous unless otherwise specified, and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0040] In this application, "within the range" means selecting an appropriate range value within that range, including the endpoint values ​​of that range.

[0041] Unless otherwise specified, the percentage content mentioned in this application refers to mass percentage for solid-liquid mixtures and solid-phase-solid mixtures, and volume percentage for liquid-phase-liquid mixtures.

[0042] Unless otherwise specified, all percentage concentrations mentioned in this application refer to the final concentration. The final concentration refers to the proportion of the added component in the system after the addition of that component.

[0043] Unless otherwise specified, the temperature parameters in this application may be either constant temperature processing or processing within a certain temperature range. The constant temperature processing allows for temperature fluctuations within the precision range controlled by the instrument.

[0044] Unless otherwise specified in this application, all steps are performed at room temperature, which generally refers to 4℃~30℃, and preferably 20±5℃.

[0045] Some examples of this application provide a method for preparing a biodegradable resin / nano titanium dioxide composite material, including the following steps:

[0046] A mixture is obtained by mixing a biodegradable resin, a titanium dioxide precursor, and a catalyst, wherein the catalyst comprises one or more of alkoxy metal salts, alkyl metal salts, and alkyl acid metal salts.

[0047] The mixture is then extruded.

[0048] The above preparation method can generate nano-titanium dioxide in situ in biodegradable resin, thereby obtaining a biodegradable resin / nano-titanium dioxide composite material in which nano-titanium dioxide is uniformly distributed in the biodegradable resin. This composite material can fully exert the photocatalytic degradation activity of nano-titanium dioxide, shorten the degradation cycle, and is suitable as a base film for reflective films, especially for agricultural reflective films, so that the biodegradation process of agricultural reflective films can better match the coloring cycle of crops.

[0049] In some examples, the extrusion conditions include: extrusion in a screw extruder at a screw speed of 150 rpm to 300 rpm, using segmented temperature control, with the temperature distribution of the melting and homogenizing sections within the segmented temperature control ranging from 140°C to 200°C. By controlling the appropriate temperature and shear effect (screw speed), in-situ generation of nano-titanium dioxide in the biodegradable resin is facilitated, further improving its dispersibility and photocatalytic activity. Further, the temperature distribution of the melting and homogenizing sections within the segmented temperature control ranges from 140°C to 160°C, or from 160°C to 190°C, or from 180°C to 200°C.

[0050] Specifically, the screw speed includes, but is not limited to: 150 rpm, 200 rpm, 250 rpm, 300 rpm, or any range between the two mentioned above.

[0051] Understandably, during segmented temperature control, a lower temperature can be used in the feeding section, for example, within the range of 60℃ to 100℃, while a higher temperature can be used in the melting and homogenization sections, for example, within the range of 140℃ to 200℃. Without limitation, the temperature range for segmented temperature control can be 60℃ to 200℃.

[0052] In some examples, the temperature can be zoned according to the type of screw extruder, for example, zone 1 temperature 80℃~90℃, zone 2 temperature 100℃~110℃, zone 3 temperature 140℃~150℃, zone 4 temperature 160℃~170℃, zone 5 temperature 160℃~170℃, zone 6 temperature 160℃~170℃, zone 7 temperature 160℃~170℃, zone 8 temperature 160℃~170℃, zone 9 temperature 160℃~170℃, zone 10 temperature 160℃~170℃, and zone 11 temperature 160℃~170℃.

[0053] In addition, it is understandable that after extrusion in a screw extruder, the process includes steps such as strand cooling and cutting.

[0054] In some examples, the biodegradable resin comprises one or more of polybutylene adipate terephthalate (PBAT), polylactic acid (PLA), polyglycolic acid (PGA), polyhydroxyalkanoates (PHA), and polybutylene succinate (PBS). Further, the biodegradable resin comprises PBAT. Without limitation, the biodegradable resin may be entirely PBAT or a mixture of biodegradable resins containing 30 wt% or more PBAT.

[0055] In some examples, the catalyst comprises one or more of C1-C5 alkoxy metal salts, C1-C5 alkyl metal salts, and C1-C5 alkyl acid metal salts, wherein the metal element comprises one or more of aluminum, zinc, magnesium, and calcium. Specifically, "C1-C5 alkoxy" includes, but is not limited to, C1 alkoxy, C2 alkoxy, C3 alkoxy, C4 alkoxy, C5 alkoxy, or any range thereof; "C1-C5 alkyl" and "C1-C5 alkyl acid" are similar and will not be described further.

[0056] Without limitation, the catalyst includes one or more of triethoxyaluminum, trimethylaluminum, zinc acetate, magnesium acetate, zinc ethyl compound (diethylzinc), magnesium ethyl compound (diethylmagnesium), and calcium ethyl compound (diethylcalcium).

[0057] In some examples, the catalyst is 0.1 to 1 part by weight per 100 parts by weight of the biodegradable resin. Specifically, the parts by weight of the catalyst include, but are not limited to: 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1 part by weight, or any range between the foregoing.

[0058] In some of these examples, the titanium dioxide precursor comprises one or more of tetrabutyl titanate, tetraethyl titanate, triethyl titanate, and isopropyl titanate.

[0059] In some examples, the titanium dioxide precursor is 4 to 10 parts by weight per 100 parts by weight of the biodegradable resin. Specifically, the weight parts of the titanium dioxide precursor include, but are not limited to: 4 parts by weight, 4.5 parts by weight, 5 parts by weight, 5.5 parts by weight, 6 parts by weight, 6.5 parts by weight, 7 parts by weight, 7.5 parts by weight, 8 parts by weight, 8.5 parts by weight, 9 parts by weight, 9.5 parts by weight, 10 parts by weight, or any range between the foregoing.

[0060] Additionally, in some examples, the mixture also includes a film opening aid. The addition of a film opening aid enhances the processing properties of the material, facilitating processes such as stretching and extrusion during production, thereby improving production efficiency and product quality.

[0061] In some examples, the film opening aid includes one or more of oleamide, erucamide, and ethylene bis-stearamide.

[0062] In some examples, the film opening aid is 0.1 to 2 parts by weight per 100 parts by weight of the biodegradable resin. Specifically, the parts by weight of the film opening aid include, but are not limited to: 0.1 parts by weight, 0.5 parts by weight, 0.8 parts by weight, 1 part by weight, 1.2 parts by weight, 1.5 parts by weight, 2 parts by weight, or any range between the foregoing.

[0063] Other examples of this application provide biodegradable resin / nano titanium dioxide composite materials prepared by the preparation method described above. In these biodegradable resin / nano titanium dioxide composite materials, the nano titanium dioxide exhibits good dispersibility in the biodegradable resin and has a short degradation cycle, making it particularly suitable as a base film for reflective films with degradation requirements, such as agricultural reflective films, and allowing the biodegradation process of agricultural reflective films to better match the coloring cycle of crops.

[0064] In other examples of this application, a reflective film is provided, comprising a base film and a metal layer disposed on the surface of the base film, wherein the base film comprises the biodegradable resin / nano titanium dioxide composite material as described above.

[0065] In some of these examples, the material of the metal layer includes one or both of aluminum and zinc, and more preferably, the material of the metal layer includes aluminum.

[0066] In some of these examples, the reflective film is an agricultural reflective film. Optionally, the agricultural reflective film is used for coloring crops.

[0067] Other examples of this application provide a method for preparing a reflective film, comprising the following steps:

[0068] The biodegradable resin / nano titanium dioxide composite material described above is subjected to film-forming treatment to prepare a base film;

[0069] A metal layer is formed on the surface of the base film.

[0070] In some of these examples, the material of the metal layer includes one or both of aluminum and zinc, and more preferably, the material of the metal layer includes aluminum.

[0071] Without limitation, film-forming processes include blow molding.

[0072] Without limitation, methods for forming a metal layer on the surface of the base film include vapor deposition.

[0073] For experimental parameters not specified in the following specific embodiments, please refer to the guidelines given in this application document first, or refer to experimental manuals or other experimental methods known in the art, or refer to the experimental conditions recommended by the manufacturer.

[0074] The raw materials and reagents used in the following specific embodiments are commercially available or can be prepared by those skilled in the art using known methods. Some raw material information is shown in Table 1 below:

[0075] Table 1

[0076]

[0077] Example 1

[0078] This embodiment describes a biodegradable resin / nano titanium dioxide composite material, the preparation method of which is as follows:

[0079] (1) Mix 100 parts by weight of PBAT, 4 parts by weight of tetrabutyl titanate, 0.1 parts by weight of trimethylaluminum and 1 part by weight of erucamide to obtain a mixture;

[0080] (2) A Ruiya TSE-35-44-600 co-rotating twin-screw extruder was used, with the screw speed set to 150 rpm and the temperature set as shown in Table 2 below;

[0081] Table 2 Extruder Temperature (°C)

[0082]

[0083] (3) The mixture prepared in step (1) is fed into the twin-screw extruder in step (2) through a metering feeder for extrusion;

[0084] (4) The extruded material is cooled and cut by stretching and cutting to obtain a biodegradable resin / nano titanium dioxide composite material.

[0085] Example 2

[0086] This embodiment is a biodegradable resin / nano titanium dioxide composite material, and its preparation method is the same as that in Example 1. The main difference is that the biodegradable resin PBAT is replaced with an equal amount of PBS.

[0087] Example 3

[0088] This embodiment is a biodegradable resin / nano titanium dioxide composite material, and its preparation method is the same as that in Example 1. The main difference is that the catalyst trimethylaluminum is replaced by triethoxyaluminum in equal amounts.

[0089] Example 4

[0090] This embodiment is a biodegradable resin / nano titanium dioxide composite material, and its preparation method is the same as that in Example 1. The main difference is that the catalyst trimethylaluminum is replaced by zinc acetate in an equal amount.

[0091] Example 5

[0092] This embodiment is a biodegradable resin / nano titanium dioxide composite material, and its preparation method is the same as that in Example 1. The main difference is that the catalyst trimethylaluminum is replaced by an equal amount of calcium ethyl compound.

[0093] Example 6

[0094] This embodiment is a biodegradable resin / nano titanium dioxide composite material, and its preparation method is the same as that in Example 1. The main difference is that different weight parts are used, specifically: 100 parts by weight of PBAT, 10 parts by weight of tetrabutyl titanate, 0.4 parts by weight of trimethylaluminum, and 1 part by weight of erucamide.

[0095] Example 7

[0096] This embodiment is a biodegradable resin / nano titanium dioxide composite material, and its preparation method is the same as that in Example 1. The main difference is that different weight parts are used, specifically: 100 parts by weight of PBAT, 6 parts by weight of tetrabutyl titanate, 1 part by weight of trimethylaluminum, and 1 part by weight of erucamide.

[0097] Example 8

[0098] This embodiment is a biodegradable resin / nano titanium dioxide composite material. Its preparation method is the same as that in embodiment 1. The main difference is that the screw speed and temperature settings in step (2) are different. Specifically, the screw speed is set to 300 rpm and the temperature is set as shown in Table 3 below.

[0099] Table 3 Extruder Temperature (°C)

[0100]

[0101] Example 9

[0102] This embodiment is a biodegradable resin / nano titanium dioxide composite material. Its preparation method is the same as that in embodiment 1. The main difference is that the screw speed and temperature settings in step (2) are different. Specifically, the screw speed is set to 100 rpm and the temperature is set as shown in Table 4 below.

[0103] Table 4 Extruder Temperature (°C)

[0104]

[0105] Comparative Example 1

[0106] This comparative example is a biodegradable resin material, and its preparation method is the same as that in Example 1. The main difference is that tetrabutyl titanate and trimethylaluminum were not added in step (1).

[0107] Comparative Example 2

[0108] This comparative example is a biodegradable resin material, which is prepared in the same way as in Example 1, except that the catalyst trimethylaluminum is replaced by sodium hydroxide in equal amounts.

[0109] Comparative Example 3

[0110] This comparative example is a biodegradable resin material, and its preparation method is the same as that in Example 1. The main difference is that tetrabutyl titanate and trimethylaluminate were not added in step (1), and 4 parts by weight of nano titanium dioxide were added. Specifically, it consists of 100 parts by weight of PBAT, 4 parts by weight of nano titanium dioxide, and 1 part by weight of erucamide.

[0111] Test example:

[0112] The biodegradable resin / nano titanium dioxide composite material prepared in the examples and the material prepared in the comparative examples were used to prepare biodegradable agricultural reflective films, respectively, and the steps are as follows:

[0113] (1) Add the material to the blown film machine, blow it into a film, pull and wind it up to form a film material.

[0114] (2) Place the film material prepared in step (1) in a vacuum evaporation machine to perform aluminum deposition to obtain a biodegradable agricultural reflective film.

[0115] The prepared biodegradable agricultural reflective film was subjected to performance testing, and the testing methods are as follows:

[0116] According to the standard ASTM G154, the prepared biodegradable agricultural reflective film was subjected to QUV accelerated aging test with aging cycles of 24h, 48h, 72h, 96h and 120h; then the film tensile test was carried out, and the elongation at break was tested according to the test specification ISO-1184.

[0117] The test results are shown in Table 5 below:

[0118] Table 5

[0119]

[0120] As can be seen, compared with Comparative Examples 1-3, Examples 1-9, by using specific types of catalysts to generate nano-titanium dioxide in situ during the extrusion process, can significantly improve the degradation rate of the composite material, thereby better matching the coloring cycle of crops.

[0121] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0122] The embodiments described above are merely illustrative of several implementation methods of this application, intended to facilitate a detailed understanding of the technical solutions of this application, but should not be construed as limiting the scope of protection of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the scope of protection of this application. It should be understood that technical solutions obtained by those skilled in the art based on the technical solutions provided in this application through logical analysis, reasoning, or limited experimentation are all within the scope of protection of the appended claims. Therefore, the scope of protection of this patent application should be determined by the content of the appended claims, and the specification can be used to interpret the content of the claims.

Claims

1. A method for producing a biodegradable resin / nano-titanium dioxide composite material, characterized by comprising the steps of: (1) mixing a biodegradable resin and a nano-titanium dioxide to prepare a mixture; (2) kneading the mixture; and (3) molding the mixture. The method comprises the following steps: mixing a biodegradable resin, a titanium dioxide precursor and a catalyst to obtain a mixture, the catalyst comprising one or more of a metal alkoxide, a metal alkyl and a metal alkyl acid salt; subjecting the mixture to an extrusion treatment.

2. The method for producing a biodegradable resin / nano-titanium oxide composite material according to claim 1, characterized by, The catalyst comprises one or more of a C1-C5 metal alkoxide, a C1-C5 metal alkyl and a C1-C5 metal alkyl acid salt, wherein the metal element comprises one or more of aluminum, zinc, magnesium and calcium.

3. The method for producing a biodegradable resin / nano-titanium oxide composite material according to claim 1, characterized by, The extrusion treatment is performed in a screw extruder at a screw rotation speed of 150 rpm to 300 rpm, and the temperature distribution in the temperature-controlling segments is in the range of 140°C to 200°C, wherein the temperature distribution in the melting segment and the homogenizing segment is in the range of 140°C to 200°C. Optionally, the temperature distribution in the temperature-controlling segments is in the range of 60°C to 200°C. Further optionally, the temperature distribution in the melting segment and the homogenizing segment is in the range of 140°C to 160°C.

4. The method of producing a biodegradable resin / nano-titanium oxide composite material according to claim 1, characterized by, The biodegradable resin comprises one or more of polybutylene adipate terephthalate, polylactic acid, polyglycolide, polyhydroxyalkanoate and polybutylene succinate.

5. The method of producing a biodegradable resin / nano-titanium oxide composite material according to claim 1, wherein The titanium dioxide precursor comprises one or more of tetrabutyl titanate, tetraethyl titanate, triethyl titanate and isopropyl titanate.

6. The method for producing a biodegradable resin / nano-titanium oxide composite material according to any one of claims 1 to 5, characterized by, Possess one or two of the following characteristics: (1) the titanium dioxide precursor is 4 parts by weight to 10 parts by weight based on 100 parts by weight of the biodegradable resin; (2) the catalyst is 0.1 parts by weight to 1 parts by weight based on 100 parts by weight of the biodegradable resin.

7. The method for producing a biodegradable resin / nano-titanium oxide composite material according to any one of claims 1 to 5, characterized by, The mixture further comprises a film-opening aid; Optionally, the film-opening aid is 0.1 parts by weight to 2 parts by weight based on 100 parts by weight of the biodegradable resin. Optionally, the film-opening aid comprises one or more of oleic acid amide, erucic acid amide and ethylene bis-stearamide.

8. The biodegradable resin / nano-titanium dioxide composite material prepared by the method of any one of claims 1 to 7.

9. A light reflecting film characterized by, The reflective film comprises a base film and a metal layer formed on the surface of the base film, wherein the base film comprises the biodegradable resin / nano-titanium dioxide composite material of claim 8. Optionally, the metal layer comprises one or both of aluminum metal and zinc metal, and further optionally, the metal layer comprises aluminum metal. Optionally, the reflective film is an agricultural reflective film, and further optionally, the agricultural reflective film is used for coloring crops.

10. A method of making a retroreflective film, characterized by, The method comprises the following steps: forming a base film by subjecting the biodegradable resin / nano-titanium dioxide composite material of claim 8 to a film-forming treatment; forming a metal layer on the surface of the base film; Optionally, the metal layer comprises one or both of aluminum metal and zinc metal, and further optionally, the metal layer comprises aluminum metal. Optionally, the film-forming treatment comprises blow film forming. Optionally, the method of forming the metal layer on the surface of the base film comprises evaporation.

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