Environmentally friendly strong and tough barrier films and methods for making the same

Abstract

The application discloses an environment-friendly tough barrier film and a preparation method thereof, and comprises the following raw materials in parts by weight: 60-90 parts of polybutylene adipate terephthalate, 10-40 parts of polyglycolic acid, and 0.5-5 parts of PGA / PBAT Janus nanosheet. The PGA / PBAT Janus nanosheet is prepared by taking SiO2 hollow spheres as a template, and polyglycolic acid and polybutylene adipate terephthalate are respectively modified on two sides of the template. The raw materials are melt-blended, and then formed, so that the environment-friendly tough barrier film is obtained. The PGA / PBAT Janus nanosheet is prepared by taking SiO2 hollow spheres as a template and carrying out in-situ melting reaction, and the PGA / PBAT Janus nanosheet can be better dispersed at the interface of two phases when being added into the PBAT / PGA matrix, so that the compatibilization efficiency of the blend is effectively improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of functional materials, in particular to an environment-friendly tough barrier film and a preparation method thereof. BACKGROUND

[0002] At present, a single polymer cannot meet the requirements of mechanical properties, functionality and the like in industrial applications. A common method for improving the performance of a single polymer is blending modification. Polybutylene adipate terephthalate (PBAT) is a thermoplastic biodegradable plastic, which is copolymerized from adipic acid, butanediol and terephthalic acid, and has the properties of PBA and PBT, and has good ductility, elongation at break and the like. Polyglycolic acid (PGA) is a high-performance aliphatic polyester material, which has excellent gas barrier property, high mechanical strength and biodegradability. Blending of PGA and PBAT is expected to further improve the strength, modulus and barrier property of the two and further improve the performance and application field of PBAT material. However, the two have poor compatibility in the blending process, which affects the quality and application range of the final product. Therefore, a universal strategy for improving compatibility is to add a compatibilizer. However, the traditional compatibilizer has the problems of large addition amount, low efficiency and lack of functionality. SUMMARY

[0003] In view of the above problems existing in the prior art, the present application provides an environment-friendly tough barrier film and a preparation method thereof. In the present application, SiO2 hollow spheres are used as templates and in-situ melting reaction is carried out to prepare PGA / PBAT Janus nanosheets, which can be better dispersed at the interface of the two phases when added to the PBAT / PGA matrix, so that the compatibilization efficiency of the blend is effectively improved.

[0004] The technical scheme of the present application is as follows:

[0005] The first object of the present application is to provide PGA / PBAT Janus nanosheets, in which SiO2 hollow spheres are used as templates and polyglycolic acid and polybutylene adipate terephthalate are modified on the two sides of the templates, respectively.

[0006] The second object of the present application is to provide a preparation method of PGA / PBAT Janus nanosheets, which comprises the following steps:

[0007] (1) PGA is blended with 4,4'-methylenebis(phenyl isocyanate) (MDI), curcumin and SiO2 hollow spheres, after the reaction is completed, unreacted PGA is washed away with hexafluoroisopropanol to prepare SiO2 hollow spheres grafted with PGA on the outer surface;

[0008] (2) The SiO2 hollow spheres grafted with PGA on the outer surface are broken by ultrasonic to obtain SiO2-PGA nanosheets, and then the SiO2-PGA nanosheets are reacted with glycidyl methacrylate (GMA) and PBAT to obtain the PGA / PBAT Janus nanosheets.

[0009] In an embodiment of the present application, in step (1), the molar ratio of PGA to MDI is 1:2-4, and the mass ratio of curcumin to PGA is 1:15-25.

[0010] In an embodiment of the present application, in step (1), the particle size of the SiO2 hollow spheres is 2.5-3.5 μm, and the mass ratio of the SiO2 hollow spheres to PGA is 1:30-50.

[0011] In an embodiment of the present application, in step (1), the blending temperature is 220-240 °C, the blending time is 5-6 min, and the rotating speed is 80-100 rpm.

[0012] In an embodiment of the present application, in step (1), the specific process is as follows: the PGA, MDI, curcumin and SiO2 hollow spheres which are dried sufficiently are melt-blended at 220-240 °C for 5-6 min, and the rotating speed is 80-100 rpm. Then the product after blending is dissolved sufficiently with hexafluoroisopropanol, and the free PGA is washed away. Finally, the SiO2 hollow spheres grafted with PGA are obtained by centrifugal washing.

[0013] In an embodiment of the present application, in step (2), the ultrasonic breaking condition is 500-550 W ultrasonic treatment for 1-1.5 h.

[0014] In an embodiment of the present application, in step (2), the mass ratio among the SiO2-PGA nanosheets, PBAT and GMA is 1:30-50:15-25.

[0015] In an embodiment of the present application, in step (2), the blending temperature is 140-160 °C, the blending time is 7-9 min, and the blending rotating speed is 50-60 rpm.

[0016] In an embodiment of the present application, in step (2), the specific process is as follows:

[0017] The SiO2 hollow spheres grafted with PGA on the outer surface are dispersed in anhydrous ethanol, and are treated by ultrasonic at 500-550 W for 1-1.5 h to break the hollow spheres into nanosheets, thereby obtaining SiO2-PGA nanosheets. Then the SiO2-PGA nanosheets are melt-blended with glycidyl methacrylate (GMA) and PBAT at 140-160 °C for 7-9 min. Then the free PBAT is removed by washing with chloroform and centrifugal washing to obtain PGA / PBAT Janus nanosheets.

[0018] A third object of the present application is to provide an environmentally friendly strong barrier film, comprising the following raw materials in parts by weight: polybutylene adipate terephthalate (PBAT) 60-90 parts, polyglycolic acid (PGA) 10-40 parts, PGA / PBAT Janus nanosheet 0.5-5 parts;

[0019] The PGA / PBAT Janus nanosheet is prepared by using SiO2 hollow sphere as a template, and polyglycolic acid (PGA) and polybutylene adipate terephthalate (PBAT) are respectively modified on both sides of the template.

[0020] A fourth object of the present application is to provide a preparation method of the above-mentioned environmentally friendly strong barrier film, comprising the following steps:

[0021] The 60-90 parts of polybutylene adipate terephthalate, 10-40 parts of polyglycolic acid, and 0.5-5 parts of PGA / PBAT Janus nanosheet are melt-blended, and then formed into a PBAT / PGA blend film, i.e. the environmentally friendly strong barrier film.

[0022] In an embodiment of the present application, the specific steps of the preparation method of the environmentally friendly strong barrier film are as follows:

[0023] The 60-90 parts of polybutylene adipate terephthalate, 10-40 parts of polyglycolic acid, and 0.5-5 parts of PGA / PBAT Janus nanosheet are blended at 220-240℃ for 5-6min, and then extruded into a film or sheet, and then rapidly cooled to below 20℃ to make the crystallinity less than 15%; then the cooled film or sheet is subjected to biaxial stretching at 50-55℃ by using a flat film biaxial stretching process, and then subjected to heat treatment at 55-75℃ to obtain the environmentally friendly strong barrier film.

[0024] Alternatively,

[0025] The 60-90 parts of polybutylene adipate terephthalate, 10-40 parts of polyglycolic acid, and 0.5-5 parts of PGA / PBAT Janus nanosheet are blended at 220-240℃ for 7-9min, and then formed into a tube embryo by using a tube die, and then rapidly cooled to below 20℃ to make the crystallinity less than 15%; then the cooled tube embryo is subjected to inflation, drawing, and setting at 50-55℃ by using a tube film biaxial stretching process to obtain the environmentally friendly strong barrier film.

[0026] A fifth object of the present application is to provide an application of the above-mentioned environmentally friendly strong barrier film, which is used in the fields of textiles, fire protection, packaging bags, or agricultural films.

[0027] The beneficial technical effect of the present application is that:

[0028] The PGA / PBAT Janus nanosheet prepared by in-situ melting reaction has higher grafting efficiency, and the formed covalent bond is more stable, thereby playing an excellent compatibilization effect. The grafted curcumin in the blending process endows the blend film with good ultraviolet resistance and ammonia response performance, thereby widening the application range thereof.

[0029] Through flat film biaxial stretching or tubular film biaxial stretching, the mechanical properties of the blend film are obviously improved. In addition, due to the action of the stretching force field, the orientation of the PGA / PBAT Janus nanosheet in the blend and the crystallization of PGA synergistically improve the barrier property of the blend film, which is beneficial to the application of the blend film in the fields of packaging and mulching, thereby effectively widening the application field of the blend. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 Atomic force microscope images of the nanosheet at different stages in Example 1;

[0031] Among them, (a) SiO2nanosheet after ultrasonic crushing of ungrafted SiO2(3μm) hollow sphere; (b) SiO2-PGA nanosheet; (c) PGA / PBAT Janus nanosheet. DETAILED DESCRIPTION

[0032] The present application will be specifically described below in combination with the drawings and examples.

[0033] Example 1:

[0034] A PGA / PBAT Janus nanosheet preparation method comprises the following steps:

[0035] (1) 50g of fully dried PGA, 12.5g of MDI, 3g of curcumin and 0.6g of SiO2hollow sphere with a particle size of 2.5μm are weighed and placed in a torque rheometer mixing chamber for pre-mixing for 5min, and the blending temperature and rotation speed are 220℃ and 80rpm respectively, to obtain a PGA / SiO2blend; then the PGA-grafted SiO2hollow sphere is washed with deionized water and hexafluoroisopropanol, and dried by centrifugation to obtain the PGA-grafted SiO2hollow sphere;

[0036] (2) The PGA-grafted SiO2hollow sphere is dispersed in anhydrous ethanol and treated by ultrasonic (500W) for 1h to break it into a sheet, to obtain a SiO2-PGA nanosheet;

[0037] (3) Take 30 g of fully dried PBAT, 15 g of GMA and 1 g of SiO2-PGA nanosheet into the torque rheometer mixing chamber and pre-mix for 7 min, the blending temperature and rotation speed are 140℃ and 50 rpm respectively, to obtain PBAT / SiO2-PGA blend; then washed with chloroform and centrifuged to remove free PBAT, to obtain the final Janus nanosheet.

[0038] By Figure 1 It can be seen that the surface roughness of the nanosheet increases from 0.3 nm to 2.5 nm, indicating that the PGA and PBAT molecular chains are grafted on the surface respectively, proving the successful synthesis of PGA / PBAT Janus nanosheet. At the same time, the thickness of the nanosheet also increases from 5.1 nm to 6.4 nm, further proving the success of the synthesis.

[0039] Example 2:

[0040] A PGA / PBAT Janus nanosheet preparation method comprises the following steps:

[0041] (1) Take 50 g of fully dried PGA, 25 g of MDI, 2 g of curcumin and 1 g of SiO2 hollow sphere with a particle size of 3.5 μm into the torque rheometer mixing chamber and pre-mix for 6 min, the blending temperature and rotation speed are 240℃ and 100 rpm respectively, to obtain PGA / SiO2 blend; then washed with deionized water, hexafluoroisopropanol and centrifuged to dry, to obtain PGA grafted SiO2 hollow sphere on the outer surface.

[0042] (2) The PGA grafted SiO2 hollow sphere on the outer surface is dispersed in anhydrous ethanol and treated with ultrasonic (550 W) for 1.5 h to break it into pieces, to obtain SiO2-PGA nanosheet;

[0043] (3) Take 50 g of fully dried PBAT, 25 g of GMA and 1 g of SiO2-PGA nanosheet into the torque rheometer mixing chamber and pre-mix for 9 min, the blending temperature and rotation speed are 160℃ and 60 rpm respectively, to obtain PBAT / SiO2-PGA blend; then washed with chloroform and centrifuged to remove free PBAT, to obtain the final Janus nanosheet.

[0044] Example 3:

[0045] A PGA / PBAT Janus nanosheet preparation method comprises the following steps:

[0046] (1) Take 50 g of fully dried PGA, 12.5 g of MDI, 3 g of curcumin, and 1 g of SiO2 hollow spheres with a particle size of 3 μm into a torque rheometer mixing chamber and pre-mix for 8 min, with a blending temperature and speed of 235℃ and 50 rpm respectively, to obtain a PGA / SiO2 blend; then wash with deionized water and hexafluoroisopropanol, centrifuge and dry, to obtain SiO2 hollow spheres grafted with PGA on the outer surface.

[0047] (2) Disperse the SiO2 hollow spheres grafted with PGA on the outer surface in anhydrous ethanol and treat with ultrasonic waves (550 W) for 1 h to break them into pieces, to obtain SiO2-PGA nanosheets;

[0048] (3) Take 25 g of fully dried PBAT, 15 g of GMA, and 1 g of SiO2-PGA nanosheets into a torque rheometer mixing chamber and pre-mix for 8 min, with a blending temperature and speed of 150℃ and 50 rpm respectively, to obtain a PBAT / SiO2-PGA blend; then wash with chloroform and centrifuge to remove free PBAT, to obtain the final Janus nanosheets.

[0049] Example 4:

[0050] A method for preparing PGA / PBAT Janus nanosheets, comprising the following steps:

[0051] (1) Take 25 g of fully dried PGA, 12.5 g of MDI, 1 g of curcumin, and 1 g of SiO2 hollow spheres with a particle size of 3 μm into a torque rheometer mixing chamber and pre-mix for 8 min, with a blending temperature and speed of 235℃ and 50 rpm respectively, to obtain a PGA / SiO2 blend; then wash with deionized water and hexafluoroisopropanol, centrifuge and dry, to obtain SiO2 hollow spheres grafted with PGA on the outer surface.

[0052] (2) Disperse the SiO2 hollow spheres grafted with PGA on the outer surface in anhydrous ethanol and treat with ultrasonic waves (550 W) for 1 h to break them into pieces, to obtain SiO2-PGA nanosheets;

[0053] (3) Take 25 g of fully dried PBAT, 15 g of GMA, and 1 g of SiO2-PGA nanosheets into a torque rheometer mixing chamber and pre-mix for 8 min, with a blending temperature and speed of 150℃ and 50 rpm respectively, to obtain a PBAT / SiO2-PGA blend; then wash with chloroform and centrifuge to remove free PBAT, to obtain the final Janus nanosheets.

[0054] Application Example 1

[0055] A method for preparing an environmentally friendly strong and tough barrier film, comprising the following steps:

[0056] PBAT 70 parts, PGA 30 parts, PGA / PBAT Janus nanosheets prepared in Example 1 0.5 parts, after being fully dried, were stirred in a high-speed blender for 2 min, and were then put into an extruder for continuous melt extrusion and granulation, with a screw temperature of 235°C, a screw rotation speed of 200 rpm, and an extrusion time of 5 min. The dried granules were extruded into thin sheets by a screw extruder and were rapidly cooled to 20°C. The cooled thin sheets were subjected to biaxial stretching using a flat film biaxial stretching process, and were then subjected to heat treatment and cooling to room temperature to obtain the environmentally friendly strong and tough barrier film, wherein the stretching temperature was 50°C, the heat treatment temperature was 60°C, the transverse stretching ratio was 3 times, and the longitudinal stretching ratio was 3 times.

[0057] Application Example 2

[0058] A method for preparing an environmentally friendly strong and tough barrier film, comprising the following steps:

[0059] PBAT 60 parts, PGA 40 parts, PGA / PBAT Janus nanosheets prepared in Example 1 0.5 parts, after being fully dried, were stirred in a high-speed blender for 2 min, and were then put into an extruder for continuous melt extrusion and granulation, with a screw temperature of 220°C, a screw rotation speed of 200 rpm, and an extrusion time of 5 min. The dried granules were extruded into thin sheets by a screw extruder and were rapidly cooled to 20°C. The cooled thin sheets were subjected to biaxial stretching using a flat film biaxial stretching process, and were then subjected to heat treatment and cooling to room temperature to obtain the environmentally friendly strong and tough barrier film, wherein the stretching temperature was 50°C, the heat treatment temperature was 55°C, the transverse stretching ratio was 3 times, and the longitudinal stretching ratio was 3 times.

[0060] Application Example 3

[0061] A method for preparing an environmentally friendly strong and tough barrier film, comprising the following steps:

[0062] PBAT 90 parts, PGA 10 parts, PGA / PBAT Janus nanosheets prepared in Example 1 5 parts, after being fully dried, were stirred in a high-speed blender for 2 min, and were then put into an extruder for continuous melt extrusion and granulation, with a screw temperature of 240°C, a screw rotation speed of 200 rpm, and an extrusion time of 6 min. The dried granules were extruded into thin sheets by a screw extruder and were rapidly cooled to 20°C. The cooled thin sheets were subjected to biaxial stretching using a flat film biaxial stretching process, and were then subjected to heat treatment and cooling to room temperature to obtain the environmentally friendly strong and tough barrier film, wherein the stretching temperature was 55°C, the heat treatment temperature was 75°C, the transverse stretching ratio was 3 times, and the longitudinal stretching ratio was 3 times.

[0063] Application Example 4

[0064] A method for preparing an environmentally friendly tough barrier film, comprising the following steps:

[0065] PBAT 70 parts, PGA 30 parts, PGA / PBAT Janus nanosheets prepared in Example 2 0.5 parts, after being fully dried, were stirred in a high-speed blender for 2 min, and then were put into an extruder for continuous melt extrusion and granulation, with a screw temperature of 235°C and a screw rotation speed of 200 rpm, and extruded for 5 min. The dried granules were extruded into a sheet by a screw extruder and were quickly cooled to 20°C. The cooled sheet was subjected to biaxial stretching using a flat film biaxial stretching process, and then was subjected to heat treatment and cooled to room temperature to obtain the environmentally friendly tough barrier film, wherein the stretching temperature was 50°C, the heat treatment temperature was 60°C, the transverse stretching ratio was 3 times, and the longitudinal stretching ratio was 3 times.

[0066] Application Example 5

[0067] A method for preparing an environmentally friendly tough barrier film, comprising the following steps:

[0068] PBAT 70 parts, PGA 30 parts, PGA / PBAT Janus nanosheets prepared in Example 3 0.5 parts, after being fully dried, were stirred in a high-speed blender for 2 min, and then were put into an extruder for continuous melt extrusion and granulation, with a screw temperature of 235°C and a screw rotation speed of 200 rpm, and extruded for 5 min. The dried granules were extruded into a sheet by a screw extruder and were quickly cooled to 20°C. The cooled sheet was subjected to biaxial stretching using a flat film biaxial stretching process, and then was subjected to heat treatment and cooled to room temperature to obtain the environmentally friendly tough barrier film, wherein the stretching temperature was 50°C, the heat treatment temperature was 60°C, the transverse stretching ratio was 3 times, and the longitudinal stretching ratio was 3 times.

[0069] Application Example 6

[0070] A method for preparing an environmentally friendly tough barrier film, comprising the following steps:

[0071] PBAT 70 parts, PGA 30 parts, PGA / PBAT Janus nanosheets prepared in Example 4 0.5 parts, after being fully dried, were stirred in a high-speed blender for 2 min, and then were put into an extruder for continuous melt extrusion and granulation, with a screw temperature of 235°C and a screw rotation speed of 200 rpm, and extruded for 5 min. The dried granules were extruded into a sheet by a screw extruder and were quickly cooled to 20°C. The cooled sheet was subjected to biaxial stretching using a flat film biaxial stretching process, and then was subjected to heat treatment and cooled to room temperature to obtain the environmentally friendly tough barrier film, wherein the stretching temperature was 50°C, the heat treatment temperature was 60°C, the transverse stretching ratio was 3 times, and the longitudinal stretching ratio was 3 times.

[0072] Application Example 7

[0073] A method for preparing an environmentally friendly tough barrier film, comprising the following steps:

[0074] PBAT 70 parts, PGA 30 parts, PGA / PBAT Janus nanosheets prepared in Example 1 1.5 parts, after being fully dried, were stirred in a high-speed blender for 2 min, and were then put into an extruder for continuous melt extrusion and granulation, with a screw temperature of 235°C and a screw rotation speed of 200 rpm, and were extruded for 5 min. The dried granules were extruded into a sheet by a screw extruder and were rapidly cooled to 20°C. The cooled sheet was subjected to biaxial stretching using a flat film biaxial stretching process, and was then subjected to heat treatment and cooled to room temperature to obtain the environmentally friendly tough barrier film, wherein the stretching temperature was 50°C, the heat treatment temperature was 60°C, the transverse stretching ratio was 3 times, and the longitudinal stretching ratio was 3 times.

[0075] Application Example 8

[0076] A method for preparing an environmentally friendly tough barrier film, comprising the following steps:

[0077] PBAT 70 parts, PGA 30 parts, PGA / PBAT Janus nanosheets prepared in Example 1 3 parts, after being fully dried, were stirred in a high-speed blender for 2 min, and were then put into an extruder for continuous melt extrusion and granulation, with a screw temperature of 235°C and a screw rotation speed of 200 rpm, and were extruded for 5 min. The dried granules were extruded into a sheet by a screw extruder and were rapidly cooled to 20°C. The cooled sheet was subjected to biaxial stretching using a flat film biaxial stretching process, and was then subjected to heat treatment and cooled to room temperature to obtain the environmentally friendly tough barrier film, wherein the stretching temperature was 50°C, the heat treatment temperature was 60°C, the transverse stretching ratio was 3 times, and the longitudinal stretching ratio was 3 times.

[0078] Application Example 9

[0079] A method for preparing an environmentally friendly tough barrier film, comprising the following steps:

[0080] PBAT 70 parts, PGA 30 parts, PGA / PBAT Janus nanosheets prepared in Example 1 5 parts, after being fully dried, were stirred in a high-speed blender for 2 min, and were put into an extruder for continuous melt extrusion and granulation, with a screw temperature of 235°C and a screw rotation speed of 200 rpm, and were extruded for 5 min. The dried granules were extruded into a sheet by a screw extruder and were rapidly cooled to 20°C. The cooled sheet was subjected to biaxial stretching by using a flat film biaxial stretching process, and then was heat treated and cooled to room temperature to obtain the environmentally friendly strong and tough barrier film, wherein the stretching temperature was 50°C, the heat treatment temperature was 60°C, the transverse stretching ratio was 3 times, and the longitudinal stretching ratio was 3 times.

[0081] Application Example 10

[0082] A method for preparing an environmentally friendly strong and tough barrier film, comprising the following steps:

[0083] PBAT 70 parts, PGA 30 parts, PGA / PBAT Janus nanosheets prepared in Example 1 5 parts, after being fully dried, were stirred in a high-speed blender for 2 min, and were put into an extruder for continuous melt extrusion and granulation, with a screw temperature of 235°C and a screw rotation speed of 200 rpm, and were extruded for 5 min. The dried granules were extruded into a sheet by a screw extruder and were rapidly cooled to 20°C. The cooled sheet was subjected to biaxial stretching by using a flat film biaxial stretching process, and then was heat treated and cooled to room temperature to obtain the environmentally friendly strong and tough barrier film, wherein the stretching temperature was 50°C, the heat treatment temperature was 60°C, the transverse stretching ratio was 3 times, and the longitudinal stretching ratio was 3 times.

[0084] Application Example 11

[0085] A method for preparing an environmentally friendly strong and tough barrier film, comprising the following steps:

[0086] PBAT 70 parts, PGA 30 parts, PGA / PBAT Janus nanosheets prepared in Example 1 5 parts, after being fully dried, were stirred in a high-speed blender for 2 min, and were put into an extruder for continuous melt extrusion and granulation, with a screw temperature of 235°C and a screw rotation speed of 200 rpm, and were extruded for 5 min. The dried granules were extruded into a sheet by a screw extruder and were rapidly cooled to 20°C. The cooled sheet was subjected to biaxial stretching by using a flat film biaxial stretching process, and then was heat treated and cooled to room temperature to obtain the environmentally friendly strong and tough barrier film, wherein the stretching temperature was 50°C, the heat treatment temperature was 60°C, the transverse stretching ratio was 3 times, and the longitudinal stretching ratio was 3 times.

[0087] Application Example 12

[0088] A method for preparing an environmentally friendly tough barrier film, comprising the following steps:

[0089] PBAT 90 parts, PGA 10 parts, PGA / PBAT Janus nanosheets prepared in Example 1 0.5 parts, after being fully dried, were stirred in a high-speed blender for 2 min, and were put into an extruder for continuous melt extrusion and granulation, with a screw temperature of 240°C, a screw rotation speed of 150 rpm, and an extrusion time of 9 min. After granulation, the granules were dried in a vacuum oven. A sheet was prepared by using a casting machine and was rapidly cooled by cooling water, with a screw temperature of 240°C and a screw rotation speed of 200 rpm. The above-mentioned tube blank was simultaneously blown and stretched at 55°C by using a tube-film two-way stretching process, and then was heat-treated and cooled to room temperature to obtain the environmentally friendly tough barrier film, with a heat treatment temperature of 75°C, a blowing ratio of 3 times, and a stretching ratio of 5 times.

[0090] Application Example 13

[0091] A method for preparing an environmentally friendly tough barrier film, comprising the following steps:

[0092] PBAT 70 parts, PGA 30 parts, PGA / PBAT Janus nanosheets prepared in Example 1 1.5 parts, after being fully dried, were stirred in a high-speed blender for 2 min, and were put into an extruder for continuous melt extrusion and granulation, with a screw temperature of 235°C, a screw rotation speed of 150 rpm, and an extrusion time of 7 min. After granulation, the granules were dried in a vacuum oven. A sheet was prepared by using a casting machine and was rapidly cooled by cooling water, with a screw temperature of 240°C and a screw rotation speed of 200 rpm. The above-mentioned tube blank was simultaneously blown and stretched at 50°C by using a tube-film two-way stretching process, and then was heat-treated and cooled to room temperature to obtain the environmentally friendly tough barrier film, with a heat treatment temperature of 60°C, a blowing ratio of 3 times, and a stretching ratio of 5 times.

[0093] Application Example 14

[0094] A method for preparing an environmentally friendly tough barrier film, comprising the following steps:

[0095] PBAT 70 parts, PGA 30 parts, PGA / PBAT Janus nanosheets prepared in Example 1 3 parts, after being fully dried, were stirred in a high-speed blender for 2 min, and were put into an extruder for continuous melt extrusion and granulation, with a screw temperature of 235°C and a screw rotation speed of 150 rpm, and were extruded for 7 min. After granulation, the granules were dried in a vacuum oven. A casting machine was used to prepare a sheet, and the sheet was rapidly cooled by cooling water, with a screw temperature of 240°C and a screw rotation speed of 200 rpm. A pipe film biaxial stretching process was used to simultaneously perform inflation and stretching on the above-mentioned pipe embryo at 50°C, and then heat treatment was performed and cooled to room temperature to obtain the environmentally friendly strong and tough barrier film, with a heat treatment temperature of 60°C, an inflation ratio of 3 times, and a stretching ratio of 5 times.

[0096] Application Example 15

[0097] A method for preparing an environmentally friendly strong and tough barrier film, comprising the following steps:

[0098] PBAT 70 parts, PGA 30 parts, PGA / PBAT Janus nanosheets prepared in Example 1 5 parts, after being fully dried, were stirred in a high-speed blender for 2 min, and were put into an extruder for continuous melt extrusion and granulation, with a screw temperature of 235°C and a screw rotation speed of 150 rpm, and were extruded for 7 min. After granulation, the granules were dried in a vacuum oven. A casting machine was used to prepare a sheet, and the sheet was rapidly cooled by cooling water, with a screw temperature of 240°C and a screw rotation speed of 200 rpm. A pipe film biaxial stretching process was used to simultaneously perform inflation and stretching on the above-mentioned pipe embryo at 50°C, and then heat treatment was performed and cooled to room temperature to obtain the environmentally friendly strong and tough barrier film, with a heat treatment temperature of 60°C, an inflation ratio of 3 times, and a stretching ratio of 5 times.

[0099] Comparative Example 1

[0100] Compared with Application Example 1, no Janus nanosheets were added, and other conditions were unchanged, and the specific conditions were as follows:

[0101] PBAT 70 parts, PGA 30 parts, after being fully dried, were stirred in a high-speed blender for 2 min, and were put into an extruder for continuous melt extrusion and granulation, with a screw temperature of 235°C and a screw rotation speed of 200 rpm. The dried granules were extruded into a sheet by a screw extruder and were rapidly cooled to 20°C. A flat film biaxial stretching process was used to perform biaxial stretching on the cooled sheet, and then heat treatment was performed and cooled to room temperature to obtain a barrier film, with a stretching temperature of 50°C, a heat treatment temperature of 60°C, a transverse stretching ratio of 3 times, and a longitudinal stretching ratio of 3 times.

[0102] Comparative Example 2

[0103] Compared with application example 1, the amount of PGA / PBAT Janus nanosheets is changed to 8 parts, and other conditions remain unchanged, as follows:

[0104] PBAT 70 parts, PGA 30 parts, and Janus nanosheets prepared in Example 1 8 parts were fully dried and stirred in a high-speed mixer for 2 min, and then fed into an extruder for continuous melt extrusion and granulation. The screw temperature was 235°C, and the screw rotation speed was 200 rpm. The dried granules were extruded into a sheet by a screw extruder and rapidly cooled to 20°C. The cooled sheet was subjected to biaxial stretching using a flat film biaxial stretching process, and then heat treated and cooled to room temperature to obtain a barrier film. The stretching temperature was 50°C, the heat treatment temperature was 60°C, the transverse stretching ratio was 3 times, and the longitudinal stretching ratio was 3 times.

[0105] Comparative example 3

[0106] Compared with application example 1, the amount of PBAT and PGA is changed to 50 parts, and other conditions remain unchanged, as follows:

[0107] PBAT 50 parts, PGA 50 parts, and PGA / PBAT Janus nanosheets prepared in Example 1 0.5 parts were fully dried and stirred in a high-speed mixer for 2 min, and then fed into an extruder for continuous melt extrusion and granulation. The screw temperature was 235°C, and the screw rotation speed was 200 rpm. The dried granules were extruded into a sheet by a screw extruder and rapidly cooled to 20°C. The cooled sheet was subjected to biaxial stretching using a flat film biaxial stretching process, and then heat treated and cooled to room temperature to obtain a barrier film. The stretching temperature was 50°C, the heat treatment temperature was 60°C, the transverse stretching ratio was 3 times, and the longitudinal stretching ratio was 3 times.

[0108] Comparative example 4

[0109] Compared with application example 1, no flat film biaxial stretching was performed, and other conditions remained unchanged, as follows:

[0110] PBAT 70 parts, PGA 30 parts, and PGA / PBAT Janus nanosheets prepared in Example 1 0.5 parts were fully dried and stirred in a high-speed mixer for 2 min, and then fed into an extruder for continuous melt extrusion and granulation. The screw temperature was 235°C, and the screw rotation speed was 200 rpm. The dried granules were extruded into a sheet by a screw extruder and rapidly cooled to 20°C to obtain a barrier film.

[0111] Comparative example 5

[0112] Compared with application example 10, no Janus nanosheets were added, and other conditions remained unchanged, as follows:

[0113] PBAT 70 parts, PGA 30 parts, the PGA / PBAT Janus nanosheet prepared in Example 1 0.5 parts, were fully dried and stirred in a high-speed mixer for 2 min, and then were put into an extruder for continuous melt extrusion and granulation, with a screw temperature of 235 ℃ and a screw rotation speed of 150 rpm. After granulation, the granules were dried in a vacuum oven. A sheet was prepared by using a casting machine and was rapidly cooled by cooling water, with a screw temperature of 240 ℃ and a screw rotation speed of 200 rpm. A barrier film was obtained by simultaneously performing inflation and drawing on the above-mentioned tube embryo at 50 ℃ by using a tube-film two-way stretching process, followed by heat treatment and cooling to room temperature, with a heat treatment temperature of 60 ℃, an inflation ratio of 3 times, and a drawing ratio of 5 times.

[0114] Comparative Example 6

[0115] Compared with Application Example 10, no tube-film two-way stretching was performed, and other conditions were unchanged, and the specific conditions were as follows:

[0116] PBAT 70 parts, PGA 30 parts, the PGA / PBAT Janus nanosheet prepared in Example 1 0.5 parts, were fully dried and stirred in a high-speed mixer for 2 min, and then were put into an extruder for continuous melt extrusion and granulation, with a screw temperature of 235 ℃ and a screw rotation speed of 150 rpm. After granulation, the granules were dried in a vacuum oven. A sheet was prepared by using a casting machine and was rapidly cooled by cooling water, with a screw temperature of 240 ℃ and a screw rotation speed of 200 rpm. A barrier film was obtained by simultaneously performing inflation and drawing on the above-mentioned tube embryo at 50 ℃ by using a tube-film two-way stretching process, followed by heat treatment and cooling to room temperature, with a heat treatment temperature of 60 ℃, an inflation ratio of 3 times, and a drawing ratio of 5 times.

[0117] Comparative Example 7

[0118] Compared with Application Example 1, PBAT, PGA, curcumin, and SiO2 hollow microspheres (pure nanoparticles without any modification and grafting) were added, and other conditions were unchanged, and the specific conditions were as follows:

[0119] PBAT 70 parts, PGA 30 parts, curcumin 3 parts, and SiO2 hollow microspheres 0.5 parts were fully dried and stirred in a high-speed mixer for 2 min, and then were put into an extruder for continuous melt extrusion and granulation, with a screw temperature of 235 ℃ and a screw rotation speed of 200 rpm. The dried granules were extruded into a sheet by a screw extruder and were rapidly cooled to 20 ℃. The cooled sheet was stretched in two directions by using a flat-film two-way stretching process, followed by heat treatment and cooling to room temperature, to obtain a barrier film, with a stretching temperature of 50 ℃, a heat treatment temperature of 60 ℃, a transverse stretching ratio of 3 times, and a longitudinal stretching ratio of 3 times.

[0120] The films obtained from the above application examples and comparative examples were dried sufficiently and then tested for tensile properties at room temperature according to the standard method of GB / T 1040-2006, the tensile rate was set to 10 mm / min, at least 5 sample strips of the same sample were tested and the average value was taken, the test results are shown in Table 1. The oxygen permeability of the material was tested by an oxygen permeability tester according to the standard method of GB / T 1038, the test conditions were 20℃, relative humidity 40%, sample thickness 20μm, film test area 38.48cm 2 ; the water vapor permeability of the material was tested by a water vapor permeability tester according to the standard method of GB / T 1037, the test conditions were 38℃, relative humidity 95%, sample thickness 20μm, film test area 33cm 2 ; the crystallinity was measured by DSC, the heating rate was 10℃ / min, the test results are shown in Table 2.

[0121] Table 1

[0122]

[0123]

[0124] Table 2

[0125]

[0126]

[0127] It can be seen from Table 1 and Table 2 that the breaking strength and elongation at break of polyglycolic acid, polybutylene adipate / terephthalate (comparative example 1) are significantly improved after adding Janus nanosheets (application example 1). It shows that the Janus nanosheets are uniformly dispersed at the interface of the two phases at this time, and play a good compatibilization effect, so the mechanical properties of the blend such as breaking strength and elongation at break are improved. It can be seen from the PBAT / PGA blend film with different Janus nanosheet contents (application examples 6-9, 12-15) that the compatibility is obviously improved and the mechanical properties of the blend are also significantly improved with the addition of Janus nanosheets. However, when the content of Janus nanosheets is too high (comparative example 2), the compatibility and mechanical properties of the PBAT / PGA blend film decrease to a certain extent, and the reason is that the nanosheets are not uniformly distributed at this time, and too many nanosheets are aggregated, which affects the mechanical properties of the blend. In addition, the component ratio of the blend also has a certain influence on the compatibility of the material (comparative example 3), when the mass ratio of PBAT and PGA is 1:1, the interface formed by the blend is larger, and the compatibilization efficiency is lower, so the tensile strength and elongation at break of the material are not obviously improved. On the other hand, the biaxial stretching process adopted in the application makes the barrier property of the PBAT / PGA blend film (application examples 1-15) much higher than that of the blend film without biaxial stretching (comparative examples 4, 6). Under the action of the stretching force field, the Janus nanosheets are oriented in the blend, which plays a barrier role and significantly improves the barrier property. At the same time, the stretching force field promotes the crystallization property of PGA, and cooperates with the Janus nanosheets to improve the barrier property of the blend film. Compared with the simply blended blend film (comparative example 7), the in-situ melt reaction adopted in the application makes the grafting efficiency of the Janus nanosheets higher, and the dispersion of curcumin is more uniform, so the performance is the best (application examples 1-15). In summary, the application prepares an environmentally friendly strong and tough barrier film, which is simple and practical, easy to industrialize, and is expected to be applied in the fields of film packaging materials and agricultural greenhouse film materials.

[0128] The above provided examples are not intended to limit the scope covered by the present application, and the described steps are not intended to limit the execution order. Those skilled in the art can make obvious improvements to the present application in combination with existing common knowledge, which also falls within the protection scope defined by the claims of the present application.

Claims

1. An environmentally friendly strong and tough barrier film, characterized by, The raw materials include the following by weight: 60-90 parts of polybutylene adipate terephthalate, 10-40 parts of polyglycolic acid, and 0.5-5 parts of PGA / PBAT Janus nanosheet; The PGA / PBAT Janus nanosheet is prepared by using SiO2 hollow spheres as a template, and polyglycolic acid and polybutylene adipate terephthalate are respectively modified on two sides of the template; The PGA / PBAT Janus nanosheet is prepared by the following steps: (1) PGA, 4, 4'-methylenebis(phenyl isocyanate), curcumin, and SiO2 hollow spheres are blended, after the reaction, unreacted PGA is washed away with hexafluoroisopropanol to obtain SiO2 hollow spheres grafted with PGA on the outer surface; (2) After the SiO2 hollow spheres grafted with PGA on the outer surface are ultrasonically broken, SiO2-PGA nanosheets are obtained, and then the SiO2-PGA nanosheets are reacted with glycidyl methacrylate and PBAT to obtain the PGA / PBAT Janus nanosheet.

2. The environmentally friendly strong and tough barrier film according to claim 1, wherein, In step (1), the molar ratio of PGA to MDI is 1:2-4, and the mass ratio of curcumin to PGA is 1:15-25.

3. The environmentally friendly strong and tough barrier film according to claim 1, wherein, In step (1), the particle size of the SiO2 hollow spheres is 2.5-3.5 μm, and the mass ratio of the SiO2 hollow spheres to PGA is 1:30-50.

4. The environmentally friendly strong and tough barrier film according to claim 1, wherein, In step (1), the blending temperature is 220-240℃, the blending time is 5-6 min, and the rotation speed is 80-100 rpm.

5. The environmentally friendly strong and tough barrier film according to claim 1, wherein, In step (2), the ultrasonic breaking conditions are: 500-550 W ultrasonic treatment for 1-1.5 h; the blending temperature is 140-160℃, the blending time is 7-9 min, and the blending rotation speed is 50-60 rpm.

6. The environmentally friendly strong and tough barrier film according to claim 1, wherein, In step (2), the mass ratio between the SiO2-PGA nanosheet, PBAT, and GMA is 1:30-50:15-25.

7. A method of making the environmentally friendly strong and tough barrier film of claim 1, wherein, The method comprises the following steps: 60-90 parts of polybutylene adipate terephthalate, 10-40 parts of polyglycolic acid, and 0.5-5 parts of PGA / PBAT Janus nanosheet are melt-blended, and then formed to obtain a PBAT / PGA blend film, i.e., the environment-friendly strong and tough barrier film.

8. The preparation method according to claim 7, characterized in that, The specific steps are as follows: 60-90 parts of polybutylene adipate terephthalate, 10-40 parts of polyglycolic acid, and 0.5-5 parts of PGA / PBAT Janus nanosheet are blended at 220-240℃ for 5-6 min, and then extruded into a film or sheet, and then quickly cooled to below 20℃ to make the crystallinity less than 15%; then the cooled film or sheet is subjected to biaxial stretching at 50-55℃ by using a flat film biaxial stretching process, and then subjected to heat treatment at 55-75℃ to obtain the environment-friendly strong and tough barrier film; or Blending 60-90 parts of polybutylene adipate / terephthalate, 10-40 parts of polyglycolic acid, 0.5-5 parts of PGA / PBAT Janus nanosheet at 220-240℃ for 7-9min, then forming a tube embryo through a tube die, quickly cooling the tube embryo to below 20℃ so that its crystallinity is less than 15%, and then using a tube film biaxial stretching process to blow, stretch and set the cooled tube embryo at 50-55℃, and then heat treating at 55-75℃ to obtain the environment-friendly strong and tough barrier film.

9. Use of the environmentally friendly strong and tough barrier film according to claim 1, characterized in that, For the fields of textiles, fire protection, packaging bags or agricultural films.

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