TPS/PLA/PBAT BLEND MODIFIED BIODEGRADABLE RESIN PREPARED BY USING CHAIN EXTENDER AND PREPARATION METHOD THEREOF

Abstract

A thermoplastic starch (TPS)/polylactic acid (PLA)/poly(butylene adipate-co -terephthalate) (PBAT) blend modified biodegradable resin is prepared by using a chain extender, and is prepared from the following raw materials: 20-30 parts by weight of TPS; 20-30 parts by weight of PLA; 40-60 parts by weight of PBAT; and 0.5-0.9 parts by weight of a chain extender KL-E. The preparation method is a two-step method: blending the TPS with the PBAT in a twin screw for granulating; mixing TPS/PBAT mixed granules with PLA granules, and dissolving the chain extender KL-E into an ethyl acetate solution. The chain extender KL-E can be uniformly distributed in PLA and TPS/PBAT mixed granules by using a spraying method, and the remaining short-chain molecules and terminal carboxyl molecules in the mixed granules can be changed into long-chain molecules.

Claims

1. (canceled)

2. A method for preparing a TPS/PLA/PBAT blend modified biodegradable resin by using a chain extender, comprising the steps of: (1) adding a chain extender KL-E into an ethyl acetate solution, and stirring until the chain extender KL-E is dissolved; (2) weighing and mixing TPS granules and PBAT granules, feeding mixed granules into a twin-screw extrusion granulator, blending in a twin screw in a high-temperature and high-shear manner, extruding the mixed granules out of a die orifice, stretching, air-cooling, and cold-cutting to obtain TPS/PBAT blend modified biodegradable resin granules; and (3) mixing the TPS/PBAT blend modified biodegradable resin granules with PLA granules, spraying the solution obtained in step (1) on a surface of the mixed granules by a spraying method, feeding the mixed granules into the twin-screw extrusion granulator, blending in the twin screw in the high-temperature and high-shear manner, extruding, stretching, and cold-cutting to obtain TPS/PLA/PBAT blend modified biodegradable resin granules.

3. The method for preparing the TPS/PLA/PBAT blend modified biodegradable resin by using the chain extender according to claim 2, wherein in step (1), the chain extender KL-E is added into one-fold mass of the ethyl acetate solution.

4. The method for preparing the TPS/PLA/PBAT blend modified biodegradable resin by using the chain extender according to claim 3, wherein in step (2), the twin-screw extrusion granulator is conducted at a temperature of 130-165° C., a screw speed of 300 r/min, and a granulation capacity of 250 kg/h.

5. The method for preparing the TPS/PLA/PBAT blend modified biodegradable resin by using the chain extender according to claim 4, wherein in step (3), the twin-screw extrusion granulator is conducted at a temperature of 140-175° C., and a screw speed of 260-300 r/min, and a granulation capacity of 220-250 kg/h.

6. A method for making a TPS/PLA/PBAT blend modified packaging bag prepared by using a chain extender, comprising the steps of: (1) adding a chain extender KL-E into an ethyl acetate solution, and stirring until dissolved; (2) weighing and mixing dried TPS granules and PBAT granules, feeding mixed granules into a twin-screw extrusion granulator, blending in a twin screw in a high-temperature and high-shear manner, extruding the mixed granules out of a die orifice, stretching, air-cooling, and cold-cutting to obtain TPS/PBAT blend modified biodegradable resin granules; (3) mixing the TPS/PBAT blend modified biodegradable resin granules with PLA granules, spraying the solution obtained in step (1) on a surface of the mixed granules by a spraying method, feeding the mixed granules into the twin-screw extrusion granulator, blending in the twin screw in the high-temperature and high-shear manner, extruding out of the die orifice, stretching, air-cooling, and cold-cutting to obtain TPS/PLA/PBAT blend modified biodegradable resin granules; (4) blowing the TPS/PLA/PBAT blend modified biodegradable resin granules directly into a film by a film blowing machine, wherein the film blowing machine is a low-density film blowing machine, having a die gap of 00.5-2 mm, a blowing temperature of 140-155° C., and a blow-up ratio of 1:4; and (5) making a film obtained in step (4) into a packaging bag by printing and bagmaking.

7. The method for making the TPS/PLA/PBAT blend modified packaging bag prepared by using the chain extender according to claim 6, wherein in step (1), the chain extender KL-E is added into one-fold mass of the ethyl acetate solution.

8. The method for making the TPS/PLA/PBAT blend modified packaging bag prepared by using the chain extender according to claim 7, wherein in step (2), the twin-screw extrusion granulator is conducted at a temperature of 130-165° C., screw speed is 300 r/min, and granulation capacity is 250 kg/h.

9. The method for making the TPS/PLA/PBAT blend modified packaging bag prepared by using the chain extender according to claim 7, wherein in step (3), the twin-screw extrusion granulator is conducted at a temperature of 140-175° C., a screw speed of 260-300 r/min, and a granulation capacity of 220-250 kg/h.

10. The method for making the TPS/PLA/PBAT blend modified packaging bag prepared by using the chain extender according to claim 7, wherein in step (4), a thickness of the film begins with 0.01 mm.

Description

DETAILED DESCRIPTION OF THE EMBODIMENTS

Example 1

[0032] A method for preparing a TPS/PLA/PBAT blend modified biodegradable resin by using a chain extender was provided, including the following steps:

[0033] step 1, a chain extender KL-E4370 (Shanxi Provincial Institute of Chemical Industry) was added into one-fold mass of ethyl acetate solution, and stirred until dissolved, to obtain a solution;

[0034] step 2, TPS granules and PBAT granules weighed and mixed, mixed granules were fed into a twin-screw extrusion granulator, extruded, air-cooled, stretched, and cold-cut to obtain TPS/PBAT blend modified biodegradable resin granules; herein, 30 parts of TPS and 70 parts of PBAT were fed; twin-screw extrusion was conducted at a temperature of 130° C., a screw speed of 300 r/min, and a granulation capacity of 250 kg/h;

[0035] step 3, 80 parts of the TPS/PBAT blend modified biodegradable resin granules and 20 parts of PLA granules were dried and mixed; the solution obtained in step 1 was sprayed on the surface of the mixed granules; the mixed granules were fed into a twin-screw extrusion granulator, extruded, air-cooled, stretched, and cold-cut to obtain TPS/PLA/PBAT blend modified biodegradable resin granules; in step 3, the PLA was 4032D (Nature Work, USA), the twin-screw extrusion was conducted at a temperature of 140° C., a screw speed of 250 r/min, and a granulation capacity of 220 kg/h.

[0036] The properties of the TPS/PLA/PBAT blend modified biodegradable resin granules were determined as follows: melt flow rate was 0.5 g/10 min, 190° C./2.16 kg; density was 1.25 g/cm.sup.3; and volatile matter was less than 0.4%.

[0037] The TPS/PLA/PBAT blend modified biodegradable resin granules were directly blown into a film by a film blowing machine. When the film thickness was 0.035 mm, the properties of the film were measured according to GB/T1040.3; the tensile strength of the film (vertical+horizontal)/2 was at 30 MPa, the elongation at break (vertical+horizontal)/2 was 250%, and the tear strength was 100 N/15 mm.

[0038] The film was made into a packaging bag by printing and bagmaking.

Example 2

[0039] A method for preparing a TPS/PLA/PBAT blend modified biodegradable resin by using a chain extender was provided, including the following steps:

[0040] step 1, a chain extender KL-E4370 (Shanxi Provincial Institute of Chemical Industry) was added into one-fold mass of ethyl acetate solution, and stirred until dissolved, to obtain a solution;

[0041] step 2, TPS granules and PBAT granules weighed and mixed, mixed granules were fed into a twin-screw extrusion granulator, extruded, air-cooled, stretched, and cold-cut to obtain TPS/PBAT blend modified biodegradable resin granules; herein, 40 parts of TPS and 60 parts of PBAT were fed; twin-screw extrusion was conducted at a temperature of 165° C., screw speed was 300 r/min, and granulation capacity was 250 kg/h;

[0042] step 3, 70 parts of the TPS/PBAT blend modified biodegradable resin granules and 30 parts of PLA granules were mixed; the solution obtained in step 1 was sprayed on the surface of the mixed granules; the mixed granules were fed into a twin-screw extrusion granulator, extruded, air-cooled, stretched, and cold-cut to obtain TPS/PLA/PBAT blend modified biodegradable resin granules; in step 3, the PLA was 4032D (Nature Work, USA), the twin-screw extrusion was conducted at a temperature of 175° C., a screw speed of 280 r/min, and a granulation capacity of 230 kg/h.

[0043] The properties of the TPS/PLA/PBAT blend modified biodegradable resin granules were determined as follows: melt flow rate was 1 g/10 min, 190° C./2.16 kg; density was 1.29 g/cm.sup.3; and volatile matter was less than 0.4%.

[0044] The TPS/PLA/PBAT blend modified biodegradable resin granules were directly blown into a film by a film blowing machine. The properties of the film were measured according to GB/T1040.3; the tensile strength of the film (vertical+horizontal)/2 was at 34 MPa, the elongation at break (vertical+horizontal)/2 was 220%, and the tear strength was 95 N/15 mm.

Example 3

[0045] A method for preparing a TPS/PLA/PBAT blend modified biodegradable resin by using a chain extender was provided, including the following steps:

[0046] step 1, a chain extender KL-E4370 (Shanxi Provincial Institute of Chemical Industry) was added into one-fold mass of ethyl acetate solution, and stirred until dissolved, to obtain a solution;

[0047] step 2, TPS granules and PBAT granules weighed and mixed, mixed granules were fed into a twin-screw extrusion granulator, extruded, air-cooled, stretched, and cold-cut to obtain TPS/PBAT blend modified biodegradable resin granules; herein, 50 parts of TPS and 50 parts of PBAT were fed; twin-screw extrusion was conducted at a temperature of 145° C., screw speed was 300 r/min, and granulation capacity was 250 kg/h;

[0048] step 3, 75 parts of the TPS/PBAT blend modified biodegradable resin granules and 25 parts of PLA granules were mixed; the solution obtained in step 1 was sprayed on the surface of the mixed granules; the mixed granules were fed into a twin-screw extrusion granulator, extruded, air-cooled, stretched, and cold-cut to obtain TPS/PLA/PBAT blend modified biodegradable resin granules; in step 3, the PLA was 4032D (Nature Work, USA), the twin-screw extrusion was conducted at a temperature of 150° C., a screw speed of 260 r/min, and a granulation capacity of 225 kg/h.

[0049] The properties of the TPS/PLA/PBAT blend modified biodegradable resin granules were determined as follows: melt flow rate was 0.8 g/10 min, 190° C./2.16 kg; density was 1.29 g/cm.sup.3; and volatile matter was less than 0.4%.

[0050] The TPS/PLA/PBAT blend modified biodegradable resin granules were directly blown into a film by a film blowing machine. The properties of the film were measured according to GB/T1040.3; the tensile strength of the film (vertical+horizontal)/2 was at 30 MPa, the elongation at break (vertical+horizontal)/2 was 240%, and the tear strength was 100 N/15 mm.

Comparative Example 1

[0051] A method for preparing a TPS/PLA/PBAT blend modified biodegradable resin by using a chain extender was provided, including the following steps:

[0052] step 1, a chain extender KL-E4370 (Shanxi Provincial Institute of Chemical Industry) was added into one-fold mass of ethyl acetate solution, and stirred until dissolved, to obtain a solution;

[0053] step 2, 25 parts of TPS granules, 50 parts of PBAT granules, and 25 parts of dried PLA granules were weighed and mixed; the solution obtained in step 1 was sprayed on the surface of the mixed granules; the mixed granules were fed into a twin-screw extrusion granulator, extruded, air-cooled, stretched, and cold-cut to obtain TPS/PLA/PBAT blend modified biodegradable resin granules; the twin-screw extrusion was conducted at a temperature of 165° C., a screw speed of 280 r/min, and a granulation capacity of 230 kg/h.

[0054] The TPS/PLA/PBAT blend modified biodegradable resin granules were directly blown into a film by a film blowing machine. The properties of the film were measured according to GB/T1040.3; the tensile strength of the film (vertical+horizontal)/2 was at 18 MPa, the elongation at break (vertical+horizontal)/2 was 150%, and the tear strength was 70 N/15 mm.

Comparative Example 2

[0055] Step 1, 50 parts of TPS granules and 50 parts of PBAT granules were mixed; the mixed granules were fed into a twin-screw extrusion granulator, extruded, air-cooled, stretched, and cold-cut to obtain TPS/PBAT blend modified biodegradable resin granules; the twin-screw extrusion was conducted at a temperature of 135° C., a screw speed of 300 r/min, and a granulation capacity of 250 kg/h.

[0056] Step 2, 75 parts of the TPS/PBAT blend modified biodegradable resin granules and 25 parts of PLA granules were mixed; the mixed granules were fed into a twin-screw extrusion granulator, extruded, air-cooled, stretched, and cold-cut to obtain TPS/PLA/PBAT blend modified biodegradable resin granules; the twin-screw extrusion was conducted at a temperature of 175° C., a screw speed of 280 r/min, and a granulation capacity of 230 kg/h.

[0057] The properties of the prepared TPS/PLA/PBAT blend modified biodegradable resin granules were as follows: the tensile strength of the film (vertical+horizontal)/2 was at 15 MPa, the elongation at break (vertical+horizontal)/2 was 150%; and the tear strength was 70 N/15 mm.

[0058] It is apparent from the above examples and comparative examples that the addition of a chain extender in TPS/PLA/PBAT blend has a substantial effect on properties thereof.