Thermoplastic starch and starch-based biodegradable film

Abstract

A multi-stage modified thermoplastic starch (TPS) masterbatch is obtained by four-stage modification treatment as follows: (i) 100 parts of starch with a moisture content of 15% to 30% are added to a high-speed mixer and stirred under room temperature; (ii) Heated to 50° C. to 70° C., polybutadiene (PB), plasticizer and a chemical modifier are added. The mixture is then stirred a second time; (iii) Heated to 75° C. to 95° C., tackifier, lubricant, filler and chain extender are added. The mixture is again stirred a third time. (iv) A biodegradable resin is added at this temperature, and the resulting mixture is stirred a fourth time. After the stirring is completed, the resulting mixture is incubated at this temperature for a predetermined time, and then added to a twin-screw extruder for melt extrusion. The present invention also discloses a preparation method and use.

Claims

1. A multi-stage modified thermoplastic starch (TPS) masterbatch, prepared by the following raw materials, in parts by weight: a first starch with a moisture content of 15% to 30%: 100 parts a plasticizer: 10 to 30 parts polybutadiene (PB): 0.1 to 3 parts a chemical modifier: 0.5 to 3 parts a tackifier: 1 to 10 parts a lubricant: 1 to 5 parts a filler: 1 to 10 parts a chain extender: 0.5 to 2 parts a first biodegradable resin: 5 to 25 parts, wherein the first biodegradable resin is for masterbatch a second starch that is a modified starch: 1 to 10 parts; wherein, the starch is subjected to a four-stage modification treatment; and the four-stage modification treatment is specifically as follows: 100 parts of the starch with the moisture content of 15% to 30% and the modified starch are added to a high-speed mixer to obtain a mixed starch and a first stirring is performed on the mixed starch at a first predetermined speed under room temperature; the mixed starch is heated to a first temperature of 50° C. to 70° C., and the PB, the plasticizer, and the chemical modifier are added to the mixed starch to obtain a first resulting mixture, and a second stirring is performed on the first resulting mixture at a second predetermined speed; the first resulting mixture is heated to a second temperature of 75° C. to 95° C., and the tackifier, the lubricant, the filler, and the chain extender are added to the first resulting mixture to obtain a second resulting mixture, and a third stirring is performed on the second resulting mixture at a third predetermined speed; the first biodegradable resin is added to the second resulting mixture at the second temperature to obtain a third resulting mixture, and a fourth stirring is performed on the third resulting mixture at a fourth predetermined speed; and after the fourth stirring is stopped, an incubation is performed on the third resulting mixture at the second temperature for a period of time to obtain an incubated mixture, and then the incubated mixture is added to a twin-screw extruder for a melt extrusion to obtain the multi-stage modified thermoplastic starch (TPS) masterbatch; wherein, the modified starch is at least one selected from the group consisting of oxidized starch and hydroxypropyl starch; wherein, the first biodegradable resin for masterbatch is at least one selected from the group consisting of PBAT and PBSA; wherein, the PB is at least one selected from the group consisting of hydroxyl-terminated polybutadiene (HTPB), epoxidized polybutadiene (EPB), and 1,2-polybutadiene homopolymer; wherein, the chemical modifier is at least one selected from the group consisting of maleic anhydride, citric acid, and glycidyl methacrylate (GMA).

2. The multi-stage modified TPS masterbatch according to claim 1, wherein, the plasticizer is at least one selected from the group consisting of glycerol, sorbitol, and epoxy soybean oil (ESBO); the tackifier is at least one selected from the group consisting of polyvinyl acetate (PVAc) and ethylene-ethyl acrylate copolymer (EEA); the lubricant is at least one selected from the group consisting of calcium stearate, oleamide, and erucamide; the filler is at least one selected from the group consisting of talc powder, calcium carbonate, barium sulfate, montmorillonite, and mica powder; and the chain extender is at least one selected from the group consisting of an isocyanate chain extender, an epoxy chain extender, and an oxazoline chain extender.

3. The multi-stage modified TPS masterbatch according to claim 2, wherein, the first stirring is conducted at the first predetermined speed of 600 rpm to 1,000 rpm for 1 min to 5 min; the second stirring is conducted at the second predetermined speed of 800 rpm to 1,200 rpm for 5 min to 20 min; the third stirring is conducted at the third predetermined speed of 800 rpm to 1,200 rpm for 5 min to 15 min; the fourth stirring is conducted at the fourth predetermined speed of 800 rpm to 1,200 rpm for 1 min to 5 min; and the incubation lasts for the period of time of 2 h to12 h.

4. The multi-stage modified TPS masterbatch according to claim 2, wherein, the PB is a mixture of the HTPB and the EPB, and the HTPB and the EPB are mixed at a weight ratio of 3:1 to 1:1.

5. The multi-stage modified TPS masterbatch according to claim 4, wherein, the first stirring is conducted at the first predetermined speed of 600 rpm to 1,000 rpm for 1 min to 5 min; the second stirring is conducted at the second predetermined speed of 800 rpm to 1,200 rpm for 5 min to 20 min; the third stirring is conducted at the third predetermined speed of 800 rpm to 1,200 rpm for 5 min to 15 min; the fourth stirring is conducted at the fourth predetermined speed of 800 rpm to 1,200 rpm for 1 min to 5 min; and the incubation lasts for the period of time of 2 h to12 h.

6. The multi-stage modified TPS masterbatch according to claim 2, wherein, the tackifier is a copolymer of the PVAc and the EEA, and the PVAc and the EEA are mixed at a weight ratio of 3:1 to 1:1.

7. The multi-stage modified TPS masterbatch according to claim 6, wherein the first biodegradable resin for masterbatch consists of PBSA or PBSA and PBAT, wherein in the PBSA, succinic acid has a copolymerization percent of 30% to 45%, adipic acid has a copolymerization percent of 15% to 30%, and butylene glycol has a copolymerization percent of 40% to 55%.

8. The multi-stage modified TPS masterbatch according to claim 7, wherein, the first stirring is conducted at the first predetermined speed of 600 rpm to 1,000 rpm for 1 min to 5 min; the second stirring is conducted at the second predetermined speed of 800 rpm to 1,200 rpm for 5 min to 20 min; the third stirring is conducted at the third predetermined speed of 800 rpm to 1,200 rpm for 5 min to 15 min; the fourth stirring is conducted at the fourth predetermined speed of 800 rpm to 1,200 rpm for 1 min to 5 min; and the incubation lasts for the period of time of 2 h to12 h.

9. The multi-stage modified TPS masterbatch according to claim 6, wherein, the first stirring is conducted at the first predetermined speed of 600 rpm to 1,000 rpm for 1 min to 5 min; the second stirring is conducted at the second predetermined speed of 800 rpm to 1,200 rpm for 5 min to 20 min; the third stirring is conducted at the third predetermined speed of 800 rpm to 1,200 rpm for 5 min to 15 min; the fourth stirring is conducted at the fourth predetermined speed of 800 rpm to 1,200 rpm for 1 min to 5 min; and the incubation lasts for the period of time of 2 h to12 h.

10. The multi-stage modified TPS masterbatch according to claim 1, wherein, the first stirring is conducted at the first predetermined speed of 600 rpm to 1,000 rpm for 1 min to 5 min; the second stirring is conducted at the second predetermined speed of 800 rpm to 1,200 rpm for 5 min to 20 min; the third stirring is conducted at the third predetermined speed of 800 rpm to 1,200 rpm for 5 min to 15 min; the fourth stirring is conducted at the fourth predetermined speed of 800 rpm to 1,200 rpm for 1 min to 5 min; and the incubation lasts for the period of time of 2 h to12 h.

11. A method for preparing the multi-stage modified TPS masterbatch according to claim 1, comprising: (1) subjecting 100 parts of the starch with the moisture content of 15% to 30% and the modified starch to the first stirring at room temperature to obtain the mixed starch; (2) heating the mixed starch to the first temperature of 50° C. to 70° C., then adding the plasticizer, the PB, and the chemical modifier to the mixed starch to obtain the first resulting mixture, and subjecting the first resulting mixture to the second stirring; (3) heating the first resulting mixture to the second temperature of 75° C. to 95° C., then adding the tackifier, the lubricant, the filler, and the chain extender to the first resulting mixture to obtain the second resulting mixture, and subjecting the second resulting mixture to the third stirring; (4) adding the first biodegradable resin to the second resulting mixture to obtain the third resulting mixture, and subjecting the third resulting mixture to the fourth stirring; (5) stopping the fourth stirring, and conducting the incubation on the third resulting mixture to obtain the incubated mixture; and (6) adding the incubated mixture to the twin-screw extruder to obtain the multi-stage modified TPS masterbatch through extruding, air cooling and granulating.

12. The method for preparing the multi-stage modified TPS masterbatch according to claim 11, wherein, the first stirring is conducted at the first predetermined speed of 600 rpm to 1,000 rpm for 1 min to 5 min; the second stirring is conducted at the second predetermined speed of 800 rpm to 1,200 rpm for 5 min to 20 min; the third stirring is conducted at the third predetermined speed of 800 rpm to 1,200 rpm for 5 min to 15 min; the fourth stirring is conducted at the fourth predetermined speed of 800 rpm to 1,200 rpm for 1 min to 5 min; and the incubation lasts for the period of time of 2 h to12 h.

13. The method for preparing the multi-stage modified TPS masterbatch according to claim 10, wherein, in step (6), the twin-screw extruder is adopted for the melt extrusion; the melt extrusion is conducted with an aspect ratio of 44:1 to 60:1, a temperature of 110° C. to 160° C., and a screw speed of 150 rpm to 600 rpm; and the twin-screw extruder has a vacuum exhaust function module on an end of the twin-screw extruder.

14. The method for preparing the multi-stage modified TPS masterbatch according to claim 11, wherein, the plasticizer is at least one selected from the group consisting of glycerol, sorbitol, and epoxy soybean oil (ESBO); the tackifier is at least one selected from the group consisting of polyvinyl acetate (PVAc) and ethylene-ethyl acrylate copolymer (EEA); the lubricant is at least one selected from the group consisting of calcium stearate, oleamide, and erucamide; the filler is at least one selected from the group consisting of talc powder, calcium carbonate, barium sulfate, montmorillonite, and mica powder; and the chain extender is at least one selected from the group consisting of an isocyanate chain extender, an epoxy chain extender, and an oxazoline chain extender.

15. The method for preparing the multi-stage modified TPS masterbatch according to claim 14, wherein, the PB is a mixture of the HTPB and the EPB, and the HTPB and the EPB are mixed at a weight ratio of 3:1 to 1:1.

16. A starch-based biodegradable film, prepared by the following raw materials, in parts by weight: the multi-stage modified TPS masterbatch according to claims 1: 40 to 80 parts, and a second biodegradable resin: 40 to 55 parts.

17. The starch-based biodegradable film according to claim 16, wherein the second biodegradable resin is at least one selected from the group consisting of PLA, PBSA, PBAT, and PPC.

18. A method for preparing the starch-based biodegradable film according to claim 16, comprising the following steps: blending the multi-stage modified TPS masterbatch with the second biodegradable resin, and conducting a blow molding to produce the starch-based biodegradable film.

19. The method for preparing the starch-based biodegradable film according to claim 18, wherein the blown molding is conducted at 145° C. to 175° C., and a blow-up ratio (BUR) of the blow molding is 3:1 to 5.5:1.

20. A process for the use of the multi-stage modified TPS masterbatch according to claim 1 comprising preparing a starch-based biodegradable film with the multi-stage modified TPS masterbatch of claim 1.

Description

DETAILED DESCRIPTION OF THE EMBODIMENTS

(1) Epoxy chain extender: The following structural formula may be adopted:

(2) ##STR00001##
and in an embodiment of the present invention, KL-E4370 of Shanxi Institute of Chemical Industry is adopted.

(3) Oxazoline chain extender: The following structural formula may be adopted:

(4) ##STR00002##
and in an embodiment of the present invention, B1511 of TCI (Shanghai) Development Co., Ltd. is adopted.

(5) Isocyanate chain extender: In an embodiment of the present invention, hexamethylene diisocyanate (HDI) is adopted.

(6) Hydroxyl-terminated polybutadiene (HTPB) has the following structural formula:

(7) ##STR00003##
and in an embodiment of the present invention, G-1000 of Nippon Soda is adopted.

(8) Epoxidized polybutadiene (EPB) has the following structural formula:

(9) ##STR00004##
and in an embodiment of the present invention, JP-200 of Nippon Soda is adopted. 1,2-polybutadiene homopolymer has the following structural formula:

(10) ##STR00005##
and in an embodiment of the present invention, B-2000 of Nippon Soda is adopted.

(11) Main Experimental Groups: Examples 1 to 8

(12) A method for preparing a TPS masterbatch includes the following steps:

(13) (1) 100 parts of starch were taken and adjusted to have a moisture content of 22%, 3 parts of oxidized starch and 4 parts of hydroxypropyl starch were added, and a resulting mixture was subjected to a first high-speed stirring at room temperature;

(14) (2) a resulting mixture was heated to 50° C. to 70° C., added with a part of additives, and then subjected to a second high-speed stirring;

(15) (3) a resulting mixture was heated to 75° C. to 95° C., added with the remaining additives, and then subjected to a third high-speed stirring;

(16) (4) a biodegradable resin for masterbatch was added, and a resulting mixture was subjected to a fourth high-speed stirring;

(17) (5) the stirring was stopped, and incubation was conducted; and

(18) (6) the incubated starch was subjected to melt extrusion to obtain a TPS masterbatch.

(19) The ingredient lists are shown in Table 1, in parts by weight, and the process parameters for each step are shown in Table 2.

(20) Corn starch was adopted here, but other starches, such as cassava starch, rice starch and potato starch, may also be adopted.

(21) TABLE-US-00001 TABLE 1 Ingredient lists for Examples 1 to 8 Biodegradable resin for Additives added the first time Additives added the second time masterbatch Example 1 glycerol: 13 parts: sorbitol: 2.6 PVAc: 4 parts; EEA: 2 parts; calcium stearate: PBSA (35% of succinic acid, parts: HTPB: 1 part; EPB: 1 3 parts; talc powder: 3 parts; calcium 18% of adipic acid, 47% of part: maleic anhydride: 0.8 carbonate: 3 parts; isocyanate chain extender: butylene glycol): 16 parts part: citric acid: 0.5 part; 1.2 parts GMA: 0.8 part Example 2 glycerol: 10 parts; HTPB: 1 EEA: 6 parts; calcium stearate: 1 part; talc PBSA (30% of succinic acid, part; EPB: 0.5 part; maleic powder: 1 part; isocyanate chain extender: 0.5 15% of adipic acid, 55% of anhydride: 0.5 part part butylene glycol): 16 parts Example 3 glycerol: 18 parts; sorbitol: 4 PVAc: 1 part; oleamide: 3 parts; barium PBSA (45% of succinic acid, parts; ESBO: 8 parts; HTPB: 1 sulfate: 3 parts; montmorillonite: 3 parts; 15% of adipic acid, 40% of part; EPB: 0.5 part; maleic epoxy chain extender: 1.2 parts butylene glycol): 16 parts anhydride: 1.2 parts; citric acid: 0.8 part; GMA: 1.0 part Example 4 ESBO: 12.6 parts; HTPB: 1 PVAc: 7.5 parts; EEA: 2.5 parts; calcium PBSA (30% of succinic acid, part; EPB: 0.5 part; maleic stearate: 3 parts; mica powder: 6 parts; 30% of adipic acid, 40% of anhydride: 0.8 part; citric acid: oxazoline chain extender: 1.2 parts butylene glycol): 16 parts 0.5 part; GMA: 0.8 part Example 5 sorbitol: 12.6 parts; HTPB: 1 PVAc: 4 parts; EEA: 2 parts; calcium stearate: PBAT: 9 parts; PBSA (35% part; EPB: 0.5 part; maleic 3 parts; talc powder: 4 parts; montmorillonite: of succinic acid. 18% of anhydride: 0.8 part; GMA: 1.3 2 parts; isocyanate drain extender: 0.8 part; adipic acid, 47% of butylene part oxazoline chain extender: 0.6 part; epoxy glycol): 16 parts chain extender: 0.6 part Example 6 glycerol: 13 parts; ESBO: 12.6 PVAc: 3 parts; EEA: 3 parts; calcium stearate: PBAT: 9 parts; PBSA (35% parts; HTPB: 1 part; EPB: 0.5 3 parts; talc powder: 3 parts; calcium of succinic acid, 18% of part; citric acid: 1.3 parts; carbonate: 3 parts; isocyanate drain extender: adipic acid, 47% of butylene GMA: 0.8 part 1.2 parts glycol): 10 parts Example 7 glycerol: 13 parts; sorbitol: 2.6 PVAc: 4 parts; EEA: 2 parts; calcium stearate: PBSA (35% of succinic acid, parts; HTPB: 1 part; EPB: 0.5 3 parts; talc powder: 3 parts; calcium 18% of adipic acid, 47% of part; maleic anhydride: 0.8 carbonate: 3 parts; epoxy chain extender: 1.2 butylene glycol): 5 parts part; citric acid: 0.5 part; parts GMA: 0.8 part Example 8 glycerol: 13 parts; sorbitol: 2.6 PVAc: 4 parts; EEA: 2 parts; calcium stearate: PBAT: 16 parts parts; HTPB: 1 part; EPB: 0.5 3 parts; barium sulfate: 6 parts; isocyanate part; maleic anhydride: 0.8 chain extender: 1.2 parts part; citric acid: 0.5 part; GMA: 0.8 part

(22) TABLE-US-00002 TABLE 2 Process parameters for Examples 1 to 8 Step (1) Step (2) Step (3) Step (4) Rota- Rota- Rota- Rota- Step (6) tional Temper- tional Temper- tional Temper- tional Step (5) Temper- Screw speed Time ature speed Time ature speed Time ature speed Time Time Aspect ature speed Example (rpm) (min) (° C.) (rpm) (min) (° C.) (rpm) (min) (° C.) (rpm) (min) (min) ratio (° C.) (rpm) 1 900 4 60 1200 15 85 1000 12 85 1000 3 300 52:1 130 400 2 600 1 50 800 5 75 800 5 75 800 1 120 44:1 110 150 3 1000 5 70 1000 20 95 1200 15 95 1200 5 720 60:1 160 600 4 900 4 60 1200 15 85 1000 12 85 1000 3 300 52:1 130 400 5 900 4 60 1200 15 85 1000 12 85 1000 3 300 52:1 130 400 6 900 4 60 1200 15 85 1000 12 85 1000 3 300 52:1 130 400 7 900 4 60 1200 15 85 1000 12 85 1000 3 300 52:1 130 400 8 900 4 60 1200 15 85 1000 12 85 1000 3 300 52:1 130 400 Note 1: The temperature in Table 2 is shown in ° C., the rotational speed is shown in rpm, and the time is shown in min.

(23) Examples 9 to 16

(24) The TPS masterbatch samples obtained in Examples 1 to 8 were used separately to prepare starch-based biodegradable films. The preparation process was as follows: 60 parts of TPS masterbatch were blended with 25 parts of PBSA and 20 parts of PBAT, and then blow molding was conducted at 165° C. with a blow-up ratio (BUR) of 4:1 to obtain a starch-based biodegradable film. The PBSA used here had the same ingredients as the PBSA added to the TPS masterbatch.

(25) The prepared starch-based biodegradable films were tested. The test results are shown in Table 3. Test method: GB/T1040.3-2006.

(26) TABLE-US-00003 TABLE 3 Test results for Examples 9 to 16 Tensile Light Thickness strength Elongation transmittance (mm) (MPa) at break (%) (%) Example 9 0.026 35 711 64 Example 10 0.026 23 390 49 Example 11 0.026 36 632 63 Example 12 0.025 24 482 57 Example 13 0.024 26 461 53 Example 14 0.027 27 507 56 Example 15 0.026 32 644 59 Example 16 0.025 33 637 67

(27) Starch Experimental Groups: Examples 17 to 22

(28) A method for preparing a TPS masterbatch includes the following steps:

(29) (1) 100 parts of starch and a part of modified starch were taken and adjusted to have a moisture content of 15% to 30%, and then subjected to a first high-speed stirring at room temperature for 4 min, with a rotational speed of 900 rpm;

(30) (2) a resulting mixture was heated to 60° C., then added with 13 parts of glycerol, 2.6 parts of sorbitol, 1 part of HTPB, 1 part of EPB, 0.8 part of maleic anhydride, 0.5 part of citric acid and 0.8 part of GMA, and subjected to a second high-speed stirring at 1,200 rpm for 15 min;

(31) (3) a resulting mixture was heated to 85° C., then added with 4 parts of PVAc, 2 parts of EEA, 3 parts of calcium stearate, 3 parts of talc powder, 3 parts of calcium carbonate and 1.2 parts of isocyanate chain extender, and subjected to a third high-speed stirring at 1,000 rpm for 12 min;

(32) (4) at 85° C., 16 parts of PBSA (35% of succinic acid, 18% of adipic acid and 47% of butylene glycol) were added, and a resulting mixture was subjected to a fourth high-speed stirring at 1,000 rpm for 3 min;

(33) (5) the stirring was stopped, and incubation lasted for 300 min; and

(34) (6) the incubated starch was subjected to melt extrusion to obtain a TPS masterbatch, where, the melt extrusion was conducted with an aspect ratio of 52:1, a temperature of 130° C., and a screw speed of 400 rpm, and the twin-screw extruder had a vacuum exhaust function module on the end thereof.

(35) The ingredient lists are shown in Table 4, in parts by weight, and the process parameters for each step are shown in Table 2.

(36) Corn starch was adopted in this example.

(37) TABLE-US-00004 TABLE 4 Ingredient lists for Examples 17 to 22 Starch Example 17 Commercial starch with a moisture content of 15%: 100 parts Example 18 Commercial starch with a moisture content of 22%: 100 parts Example 19 Commercial starch with a moisture content of 30%: 100 parts Example 20 Commercial starch with a moisture content of 22%: 100 parts; oxidized starch: 1 part Example 21 Commercial starch with a moisture content of 22%: 100 parts; oxidized starch: 3 part; hydroxypropyl starch: 4 parts Example 22 Commercial starch with a moisture content of 22%: 100 parts; oxidized starch: 10 parts

(38) Examples 23 to 28

(39) The TPS masterbatch samples obtained in Examples 17 to 22 were used separately to prepare starch-based biodegradable films. The preparation process was as follows: 60 parts of TPS masterbatch were blended with 25 parts of PBSA and 20 parts of PBAT, and then blow molding was conducted at 165° C. with a BUR of 4:1 to obtain a starch-based biodegradable film. The PBSA used in this example had the same ingredients as the PBSA added to the TPS masterbatch.

(40) The prepared starch-based biodegradable films were tested. The test results are shown in Table 5. Test method: GB/T1040.3-2006.

(41) TABLE-US-00005 TABLE 5 Test results for Examples 23 to 28 Tensile Light Thickness strength Elongation transmittance (mm) (MPa) at break (%) (%) Example 23 0.028 25 437 42 Example 24 0.026 24 461 47 Example 25 0.025 22 422 43 Example 26 0.027 27 493 51 Example 27 0.026 35 711 64 Example 28 0.026 28 502 55

(42) It can be seen that the addition of modified starch can further increase the tensile strength and elongation of a starch-based biodegradable film.

(43) PB Experimental Groups: Examples 29 to 34 and Comparative Example 1

(44) A method for preparing a TPS masterbatch includes the following steps:

(45) (1) 100 parts of starch were taken and adjusted to have a moisture content of 22%, 3 parts of oxidized starch and 4 parts of hydroxypropyl starch were added, and a resulting mixture was subjected to a first high-speed stirring at room temperature;

(46) (2) a resulting mixture was heated, added with a part of additives, and then subjected to a second high-speed stirring;

(47) (3) a resulting mixture was heated, added with 4 parts of PVAc, 2 parts of EEA, 3 parts of calcium stearate, 3 parts of talc powder, 3 parts of calcium carbonate and 1.2 parts of isocyanate chain extender, and then subjected to a third high-speed stirring;

(48) (4) 16 parts of PBSA (35% of succinic acid, 18% of adipic acid and 47% of butylene glycol) were added, and a resulting mixture was subjected to a fourth high-speed stirring;

(49) (5) the stirring was stopped, and incubation was conducted; and

(50) (6) the incubated starch was subjected to melt extrusion to obtain a TPS masterbatch.

(51) The ingredient lists are shown in Table 6, in parts by weight, and the process parameters for each step refer to Example 17.

(52) Corn starch was adopted in this example.

(53) TABLE-US-00006 TABLE 6 Ingredient lists for Examples 29 to 34 and Comparative Example 1 Additives added the first time Example 29 Glycerol: 13 parts; sorbitol: 2.6 parts; HTPB: 2 parts; EPB: 1 part; maleic anhydride: 0.8 part; citric acid: 0.5 part; GMA: 0.8 part Example 30 Glycerol: 13 parts; sorbitol: 2.6 parts; HTPB: 0.6 part; EPB: 0.6 part; 1,2-polybutadiene homopolymer: 0.8 part; maleic anhydride: 0.8 part; citric acid: 0.5 part; GMA: 0.8 part Example 31 Glycerol: 13 parts; sorbitol: 2.6 parts; HTPB: 1 part; EPB: 1 part; maleic anhydride: 0.8 part; citric acid: 0.5 part; GMA: 0.8 part Example 32 Glycerol: 13 parts; sorbitol: 2.6 parts; HTPB: 1 part; EPB: 0.5 part; maleic anhydride: 0.8 part; citric acid: 0.5 part; GMA: 0.8 part Example 33 Glycerol: 13 parts; sorbitol: 2.6 parts; HTPB: 1.5 parts; EPB: 0.5 part; maleic anhydride: 0.8 part; citric acid: 0.5 part; GMA: 0.8 part Example 34 Glycerol: 13 parts; sorbitol: 2.6 parts; HTPB: 0.1 part; maleic anhydride: 0.8 part; citric acid: 0.5 part; GMA: 0.8 part Comparative Glycerol: 13 parts; sorbitol: 2.6 parts; maleic anhydride: 0.8 part; citric acid: Example 1 0.5 part; GMA: 0.8 part

(54) Examples 35 to 40 and Comparative Example 2

(55) The TPS masterbatch samples obtained in Examples 29 to 34 were used separately to prepare starch-based biodegradable films. The preparation process was as follows: 60 parts of TPS masterbatch were blended with 25 parts of PBSA and 20 parts of PBAT, and then blow molding was conducted at 165° C. with BUR of 4:1 to obtain a starch-based biodegradable film. The PBSA used here had the same ingredients as the PBSA added to the TPS masterbatch.

(56) The TPS masterbatch samples obtained in Comparative Example 1 were used separately to prepare starch-based biodegradable films. The preparation process was as follows: 60 parts of TPS masterbatch were blended with 25 parts of PBSA and 20 parts of PBAT, and then blow molding was conducted at 165° C. with BUR of 4:1 to obtain the starch-based biodegradable film of Comparative Example 2. The PBSA used here had the same ingredients as the PBSA added to the TPS masterbatch.

(57) The prepared starch-based biodegradable films were tested. The test results are shown in Table 7. Test method: GB/T1040.3-2006.

(58) TABLE-US-00007 TABLE 7 Test results for Examples 35 to 40 and Comparative Example 2 Tensile Light Thickness strength Elongation transmittance (mm) (MPa) at break (%) (%) Example 35 0.027 31 629 57 Example 36 0.027 33 640 60 Example 37 0.026 35 711 64 Example 38 0.026 35 670 63 Example 39 0.027 34 689 63 Example 40 0.027 29 493 55 Comparative 0.027 26 450 51 Example 2

(59) It can be seen that the addition of a trace amount of PB can further improve the tensile strength and elongation of a starch-based biodegradable film.

(60) Starch-based biodegradable film experimental groups: Examples 41 to 46

(61) The TPS masterbatch of Example 1 was used to prepare starch-based biodegradable films. The PBSA used here had the same ingredients as the PBSA added to the TPS masterbatch. The ingredient lists and process parameters are shown in Table 8.

(62) TABLE-US-00008 TABLE 8 Ingredient lists and process parameters for Examples 41 to 46 Blow molding TPS temperature masterbatch Biodegradable resin (° C.) BUR Example 41 60 parts PLA: 10 parts; PBSA: 15 parts; 145 3:1 PBAT: 10 parts; PPC: 15 parts Example 42 40 parts PBSA: 25 parts; PLA: 20 parts 165 4:1 Example 43 60 parts PBSA: 40 parts 155 3:1 Example 44 60 parts PBSA: 25 parts; PBAT: 20 parts 165 4:1 Example 45 70 parts PBAT: 40 parts 160 5:1 Example 46 80 parts PBSA: 25 parts; PBAT: 30 parts 175 5.5:1.sup.