阅读说明：本技术 一种高淀粉含量可降解塑料的制备方法 (Preparation method of degradable plastic with high starch content ) 是由 雷彩红 徐睿杰 于 2020-12-04 设计创作，主要内容包括：本发明公开了一种高淀粉含量可降解塑料的制备方法,先将淀粉、淀粉去分支酶、增塑剂、扩链剂、润滑剂和软化调节剂经过球磨预处理和陈化放置,再采用二级挤出装置,将树脂混合物和淀粉混合物分别于两台一级挤出机平行挤出,控制挤出速度比,通过混合器进入二级挤出机实现混合,挤出造粒。本发明的高淀粉含量可降解塑料的制备方法可以实现淀粉的充分分散均匀,制备得到的可降解塑料淀粉含量达到60%以上,具有优异的力学性能。(The invention discloses a preparation method of high-starch-content degradable plastic, which comprises the steps of firstly carrying out ball-milling pretreatment and aging placement on starch, starch debranching enzyme, plasticizer, chain extender, lubricant and softening regulator, then adopting a secondary extrusion device to extrude a resin mixture and a starch mixture in parallel in two primary extruders respectively, controlling the extrusion speed ratio, mixing the resin mixture and the starch mixture in the secondary extruders through a mixer, and carrying out extrusion granulation. The preparation method of the degradable plastic with high starch content can realize the full and uniform dispersion of starch, and the starch content of the prepared degradable plastic reaches more than 60 percent, so that the degradable plastic has excellent mechanical properties.)

1. The preparation method of the high-starch-content degradable plastic comprises the following components in parts by weight: 100 parts of degradable resin; 150-200 parts of plant starch; 0.05-0.5 part of starch debranching enzyme; 30-50 parts of a plasticizer; 5-10 parts of a chain extender; 3-5 parts of a lubricant; 1-5 parts of a softening regulator; 20-40 parts of a filler; the method is characterized by comprising the following steps:

a. ball milling pretreatment: adding plant starch, starch debranching enzyme, plasticizer, chain extender, lubricant and softening regulator into a ball milling tank, and carrying out ball milling at the temperature of 40-70 ℃ and the speed of 300-3000 rpm for 15-30 minutes to obtain a starch mixture; during ball milling, the humidity in the ball milling tank is controlled to be 30-50%;

b. aging: standing the ball-milled starch mixture in an oven at the temperature of 30-45 ℃ for 36-72 hours, and controlling the humidity of the oven at 20-45%;

c. and (3) extruding and granulating: a secondary extrusion device is adopted; the primary extruder is two parallel double-screw extruders, and the length-diameter ratio of the extruders is 24-30; the secondary extruder is a double-screw extruder, and the length-diameter ratio of the extruder is 44-54; the tail end of the first-stage extruder enters a second-stage extruder through a mixer; adding degradable resin and filler into one primary extruder for mixing and extruding, adding an aged starch mixture into the other primary extruder for extruding, wherein the extrusion temperature of the resin mixture is set to be 170-230 ℃, the extrusion temperature of the starch mixture is set to be 120-150 ℃, the extrusion speed ratio of the resin mixture to the starch mixture is 1: 1.5-1: 2, feeding the mixture into a secondary extruder through a mixer, the secondary extrusion temperature is set to be 170-230 ℃, and performing secondary extrusion granulation to obtain the high-starch-content degradable plastic.

2. The method for preparing the degradable plastic with high starch content according to claim 1, wherein the humidity in the ball milling tank in the ball milling pretreatment stage in the step a is controlled to be 35-45%.

3. The method for preparing the degradable plastic with high starch content according to claim 1, wherein the humidity of the oven in the aging stage of the step b is controlled to be 30-40%.

4. The method for preparing degradable plastic with high starch content according to claim 1, wherein the degradable resin is selected from one or more of PLA resin, PGA resin and PBAT resin.

5. The method for preparing the degradable plastic with high starch content according to claim 1, wherein the plant starch is selected from one or more of corn starch, potato starch, sweet potato starch and pea starch.

6. The method for preparing the degradable plastic with high starch content according to claim 1, wherein the starch debranching enzyme is selected from any one or more of 4-alpha-glucosidase transferase, starch-1, 6-glucose transferase, limit dextrinase, pullulanase or isoamylase.

7. The method for preparing the degradable plastic with high starch content according to claim 1, wherein the plasticizer is selected from one or more of glycerol, diethylene glycol and sorbitol; the chain extender is polyethylene glycol; the lubricant is selected from one or more of glyceryl stearate, glyceryl laurate, stearic acid amide or oleic acid amide; the softening regulator is selected from one or more of citric acid, glycolic acid, lactic acid, malic acid or tartaric acid; the filler is selected from any one or more of sepiolite, organic montmorillonite and layered boehmite.

8. The method for preparing the degradable plastic with high starch content according to claim 7, wherein the number average molecular weight of the polyethylene glycol is 400-1000.

9. The method for preparing the degradable plastic with high starch content according to claim 1, wherein the degradable plastic with high starch content further comprises 0.1-6 parts by weight of an auxiliary agent; the auxiliary agent comprises any one or more of an antioxidant, a light stabilizer or an ultraviolet absorber.

10. The method for preparing degradable plastics with high starch content according to claim 9, wherein the auxiliary agent is added into the first-stage extruder together with the degradable resin and the filler in step c for mixing and extruding.

Technical Field

The invention relates to the technical field of degradable materials, in particular to a preparation method of degradable plastic with high starch content.

Background

High molecular polymers have been widely used in various fields related to human life, but since most of the polymers are derived from petroleum and cracked products, the waste materials thereof cannot be degraded into carbon cycle in natural environment. The huge amount of non-degradable plastics used by human beings causes serious 'white pollution', brings unmeasurable pressure to the environment and resources, and researches and developments on degradable materials as substitute materials are hot in order to deal with the problem of environmental pollution.

In recent years, with the development of degradable polymers such as polybutylene adipate terephthalate (PBAT), Polycaprolactone (PCL), polylactic acid (PLA), etc., environment-friendly plastic products have become new industrial stars in the plastic industry. Although degradable plastics can be degraded in the natural environment after being discarded, a long time is still needed for the land reclamation degradation from the viewpoint of the landfill period. In order to accelerate the soil degradation speed of the degradable plastics, biomacromolecule components such as starch, lignin, cellulose and the like are often required to be added into the degradable plastics, so that the degradation performance of the degradable plastics is accelerated, and the material cost is reduced. Starch is the most commonly used second component in view of its degradation effect, but the loading of starch is still limited at present, generally below 50% by mass. The highly filled starch composite material has the defects of uneven starch dispersion, poor mechanical property, insufficient processability and the like.

Disclosure of Invention

In order to overcome the defects in the prior art, the invention aims to provide a preparation method of degradable plastic with high starch content.

The invention is realized by the following technical scheme:

the degradable plastic with high starch content comprises the following components in parts by weight: 100 parts of degradable resin; 150-200 parts of plant starch; 0.05-0.5 part of starch debranching enzyme; 30-50 parts of a plasticizer; 5-10 parts of a chain extender; 3-5 parts of a lubricant; 1-5 parts of a softening regulator; 20-40 parts of a filler;

the preparation method of the degradable plastic with high starch content comprises the following steps:

a. ball milling pretreatment: adding plant starch, starch debranching enzyme, plasticizer, chain extender, lubricant and softening regulator into a ball milling tank, and carrying out ball milling at the temperature of 40-70 ℃ and the speed of 300-3000 rpm for 15-30 minutes to obtain a starch mixture; during ball milling, the humidity in the ball milling tank is controlled to be 30-50%;

b. aging: standing the ball-milled starch mixture in an oven at the temperature of 30-45 ℃ for 36-72 hours, and controlling the humidity of the oven at 20-45%;

c. and (3) extruding and granulating: a secondary extrusion device is adopted; the primary extruder is two parallel double-screw extruders, and the length-diameter ratio of the extruders is 24-30; the secondary extruder is a double-screw extruder, and the length-diameter ratio of the extruder is 44-54; the tail end of the first-stage extruder enters a second-stage extruder through a mixer; adding degradable resin and filler into one primary extruder for mixing and extruding, adding an aged starch mixture into the other primary extruder for extruding, wherein the extrusion temperature of the resin mixture is set to be 170-230 ℃, the extrusion temperature of the starch mixture is set to be 120-150 ℃, the extrusion speed ratio of the resin mixture to the starch mixture is 1: 1.5-1: 2, feeding the mixture into a secondary extruder through a mixer, the secondary extrusion temperature is set to be 170-230 ℃, and performing secondary extrusion granulation to obtain the high-starch-content degradable plastic.

According to the preparation method, the starch is subjected to ball milling pretreatment, so that the formation of amylose and the gelatinization of the starch can be accelerated, and the absorption of the starch to the auxiliary agent is further accelerated through an aging stage. In the ball milling stage and the aging stage, starch gelatinization is controlled by controlling humidity, and the strength of a starch melt is weakened due to overhigh humidity, so that the extrusion stability is reduced. Preferably, the humidity in the ball milling tank in the ball milling pretreatment stage in the step a is controlled to be 35-45%; and b, controlling the humidity of the oven in the aging stage of the step b to be 30-40%.

The processing performance of the starch is obviously improved after ball milling and aging treatment, and then a secondary extrusion device is adopted, and the extrusion speed ratio of the resin mixture and the starch mixture is controlled, so that the starch can be well dispersed in the resin mixture, and the stable preparation of the degradable composite material with high starch content is realized.

The degradable resin is selected from any one or more of PLA resin, PGA resin or PBAT resin.

The plant starch is selected from one or more of corn starch, potato starch, sweet potato starch and pea starch.

The starch debranching enzyme is selected from any one or more of 4-alpha-glucosyltransferase, starch-1, 6-glucosyltransferase, limit dextrinase, pullulanase or isoamylase.

The plasticizer is selected from one or more of glycerol, diethylene glycol or sorbitol.

The chain extender is polyethylene glycol; the number average molecular weight of the polyethylene glycol is 400-1000.

The lubricant is selected from one or more of glyceryl stearate, glyceryl laurate, stearic acid amide or oleic acid amide.

The softening regulator is one or more selected from citric acid, glycolic acid, lactic acid, malic acid or tartaric acid.

The filler is selected from any one or more of sepiolite, organic montmorillonite and layered boehmite.

According to the material performance requirement, the high-starch-content degradable plastic also comprises 0.1-6 parts of an auxiliary agent in parts by weight; the auxiliary agent comprises any one or more of an antioxidant, a light stabilizer or an ultraviolet absorber. In the preparation process, the auxiliary agent is added into a primary extruder together with the degradable resin and the filler in the step c for mixing and extruding.

The antioxidant is selected from one or more of antioxidant 1010, antioxidant 1076 or antioxidant T501; the light stabilizer is selected from one or more of light stabilizer 770, light stabilizer 944, light stabilizer 622, light stabilizer 2002, light stabilizer 783 and light stabilizer 2020; the ultraviolet absorbent is selected from any one or more of UV531, UV234, UV326, UV327, UV328, UV329 or UV 1130.

Compared with the prior art, the invention has the following beneficial effects:

according to the preparation method of the high-starch-content degradable plastic, the starch is subjected to ball milling and aging treatment, then the resin mixture and the starch mixture are extruded in parallel in two primary extruders respectively by adopting a secondary extrusion device, and the resin mixture and the starch mixture enter the secondary extruder through a mixer to be mixed, extruded and granulated, so that the degradable plastic with the starch content of more than 60% is prepared, and the degradable plastic has excellent mechanical properties. The preparation method can realize the full and uniform dispersion of high-content starch in the degradable resin, and solves the problems of non-uniform dispersion and poor mechanical property of the highly filled starch composite material caused by poor dispersion of the starch in the degradable resin in the prior art.

Detailed Description

The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that variations and modifications can be made by persons skilled in the art without departing from the spirit of the invention. All falling within the scope of the present invention.

The raw materials used in the examples of the present invention and the comparative examples are commercially available, but are not limited to these materials.

Testing of tensile Strength: the test standard is GB/T1040-.

Example 1

a. Ball milling pretreatment: adding 150 parts of corn starch, 0.05 part of 4-alpha-glucosyltransferase, 30 parts of glycerol, 5 parts of polyethylene glycol (molecular weight 400), 3 parts of oleamide and 1 part of tartaric acid into a ball milling tank, and carrying out ball milling at the speed of 300rpm at 60 ℃ for 15 minutes to obtain a starch mixture; during ball milling, the humidity in the ball milling tank is controlled at 30%;

b. aging: standing the ball-milled starch mixture in an oven for 48 hours, and controlling the humidity of the oven at 30%;

c. and (3) extruding and granulating: a secondary extrusion device is adopted; the primary extruder is two parallel double-screw extruders, and the length-diameter ratio of the extruders is 26; the secondary extruder is a double-screw extruder, and the length-diameter ratio of the extruder is 48; the tail end of the first-stage extruder enters a second-stage extruder through a mixer; adding 100 parts of PLA resin, 20 parts of organic montmorillonite, 0.1 part of antioxidant 1076, 0.1 part of light stabilizer 944 and 0.1 part of UV234 into one primary extruder for mixing and extruding, adding the aged starch mixture into the other primary extruder for extruding, wherein the extrusion temperature of the resin mixture is set to be 190-210 ℃, the extrusion temperature of the starch mixture is set to be 120-150 ℃, the speed ratio of the extrusion of the resin mixture to the extrusion of the starch mixture is 1:1.5, feeding the mixture into a secondary extruder through a mixer, setting the secondary extrusion temperature to be 190-210 ℃, and performing secondary extrusion granulation to prepare the degradable plastic with high starch content; the tensile strength was 48 MPa.

Example 2

a. Ball milling pretreatment: adding 200 parts of potato starch, 0.5 part of starch-1, 6-glucose transferase, 50 parts of diethylene glycol, 10 parts of polyethylene glycol (molecular weight 1000), 5 parts of glyceryl laurate and 1 part of glycolic acid into a ball milling tank, and ball milling at the speed of 3000rpm at 60 ℃ for 30 minutes to obtain a starch mixture; during ball milling, the humidity in the ball milling tank is controlled at 50%;

b. aging: standing the ball-milled starch mixture in an oven for 48 hours, and controlling the humidity of the oven at 40%;

c. and (3) extruding and granulating: a secondary extrusion device is adopted; the primary extruder is two parallel double-screw extruders, and the length-diameter ratio of the extruders is 26; the secondary extruder is a double-screw extruder, and the length-diameter ratio of the extruder is 48; the tail end of the first-stage extruder enters a second-stage extruder through a mixer; adding 100 parts of PLA resin, 20 parts of sepiolite, 0.1 part of antioxidant 1010, 0.1 part of light stabilizer 770 and 0.1 part of UV531 into one primary extruder for mixing and extruding, adding the aged starch mixture into the other primary extruder for extruding, wherein the extrusion temperature of the resin mixture is set to be 190-230 ℃, the extrusion temperature of the starch mixture is set to be 120-150 ℃, the speed ratio of the extrusion of the resin mixture to the extrusion of the starch mixture is 1:2, feeding the mixture into a secondary extruder through a mixer, setting the secondary extrusion temperature to be 190-230 ℃, and performing secondary extrusion granulation to obtain the degradable plastic with high starch content; the tensile strength was 35 MPa.

Example 3

a. Ball milling pretreatment: adding 180 parts of pea starch, 0.2 part of limit dextrinase, 40 parts of sorbitol, 5 parts of polyethylene glycol (molecular weight 600), 4 parts of stearic acid amide and 1 part of malic acid into a ball milling tank, and carrying out ball milling at the speed of 2000rpm at 60 ℃ for 15 minutes to obtain a starch mixture; during ball milling, the humidity in the ball milling tank is controlled at 45%;

b. aging: standing the ball-milled starch mixture in an oven for 48 hours, and controlling the humidity of the oven at 40%;

c. and (3) extruding and granulating: a secondary extrusion device is adopted; the primary extruder is two parallel double-screw extruders, and the length-diameter ratio of the extruders is 26; the secondary extruder is a double-screw extruder, and the length-diameter ratio of the extruder is 48; the tail end of the first-stage extruder enters a second-stage extruder through a mixer; adding 100 parts of PBAT resin, 20 parts of lamellar boehmite, 0.1 part of antioxidant T501, 0.1 part of light stabilizer 622 and 0.1 part of UV327 into one primary extruder for mixing and extruding, adding the aged starch mixture into the other primary extruder for extruding, wherein the extrusion temperature of the resin mixture is set to be 170-200 ℃, the extrusion temperature of the starch mixture is set to be 120-150 ℃, the speed ratio of the extrusion of the resin mixture to the extrusion of the starch mixture is 1:1.8, feeding the mixture into a secondary extruder through a mixer, setting the secondary extrusion temperature to be 170-200 ℃, and performing secondary extrusion granulation to obtain the degradable plastic with high starch content; the tensile strength was 26 MPa.

Example 4

a. Ball milling pretreatment: adding 150 parts of sweet potato starch, 0.1 part of pullulanase, 40 parts of glycerol, 5 parts of polyethylene glycol (molecular weight 800), 5 parts of glycerol laurate and 1 part of glycolic acid into a ball milling tank, and carrying out ball milling at the speed of 3000rpm at the temperature of 60 ℃ for 30 minutes to obtain a starch mixture; during ball milling, the humidity in the ball milling tank is controlled at 35%;

b. aging: standing the ball-milled starch mixture in an oven for 48 hours, and controlling the humidity of the oven at 25%;

c. and (3) extruding and granulating: a secondary extrusion device is adopted; the primary extruder is two parallel double-screw extruders, and the length-diameter ratio of the extruders is 26; the secondary extruder is a double-screw extruder, and the length-diameter ratio of the extruder is 48; the tail end of the first-stage extruder enters a second-stage extruder through a mixer; adding 100 parts of PLA resin and 20 parts of sepiolite into one primary extruder for mixing and extruding, adding the aged starch mixture into the other primary extruder for extruding, wherein the extrusion temperature of the resin mixture is set to be 190-230 ℃, the extrusion temperature of the starch mixture is set to be 120-150 ℃, the speed ratio of the extrusion of the resin mixture to the extrusion of the starch mixture is 1:2, feeding the mixture into a secondary extruder through a mixer, the extrusion temperature of the secondary extruder is set to be 190-230 ℃, and performing secondary extrusion granulation to obtain the degradable plastic with high starch content; the tensile strength was 35 MPa.

Comparative example 1:

a. ball milling pretreatment: adding 150 parts of corn starch, 0.05 part of 4-alpha-glucosyltransferase, 30 parts of glycerol, 5 parts of polyethylene glycol (molecular weight 400), 3 parts of oleamide and 1 part of tartaric acid into a ball milling tank, and carrying out ball milling at the speed of 300rpm at 60 ℃ for 15 minutes to obtain a starch mixture; during ball milling, the humidity in the ball milling tank is controlled to be 65%;

b. aging: standing the ball-milled starch mixture in an oven for 48 hours, and controlling the humidity of the oven to be 65%;

c. and (3) extruding and granulating: a secondary extrusion device is adopted; the primary extruder is two parallel double-screw extruders, and the length-diameter ratio of the extruders is 26; the secondary extruder is a double-screw extruder, and the length-diameter ratio of the extruder is 48; the tail end of the first-stage extruder enters a second-stage extruder through a mixer; adding 100 parts of PLA resin, 20 parts of organic montmorillonite, 0.1 part of antioxidant 1076, 0.1 part of light stabilizer 944 and 0.1 part of UV234 into one primary extruder for mixing and extruding, adding the aged starch mixture into the other primary extruder for extruding, wherein the extrusion temperature of the resin mixture is set to be 190-210 ℃, the extrusion temperature of the starch mixture is set to be 120-150 ℃, the speed ratio of the extrusion of the resin mixture to the extrusion of the starch mixture is 1:1.5, feeding the mixture into a secondary extruder through a mixer, setting the secondary extrusion temperature to be 190-210 ℃, and performing secondary extrusion granulation to prepare the degradable plastic with high starch content; the tensile strength was 24 MPa.

Comparative example 2:

a. ball milling pretreatment: adding 150 parts of corn starch, 0.05 part of 4-alpha-glucosyltransferase, 30 parts of glycerol, 5 parts of polyethylene glycol (molecular weight 400), 3 parts of oleamide and 1 part of tartaric acid into a ball milling tank, and carrying out ball milling at the speed of 300rpm at 60 ℃ for 15 minutes to obtain a starch mixture; during ball milling, the humidity in the ball milling tank is controlled at 30%;

b. aging: standing the ball-milled starch mixture in an oven for 48 hours, and controlling the humidity of the oven at 30%;

c. and (3) extruding and granulating: adding 100 parts of PLA resin, 20 parts of organic montmorillonite, 0.1 part of antioxidant 1076, 0.1 part of light stabilizer 944, 0.1 part of UV234 and the starch mixture aged in the step b into a double-screw extruder, setting the length-diameter ratio of the extruder to be 48 and the extrusion temperature to be 190-210 ℃, and performing mixing, extrusion and granulation to prepare the degradable plastic with high starch content; the tensile strength was 18 MPa.

The above examples show that the high-starch-content degradable plastic prepared by the preparation method of the invention has the starch content of more than 60% and excellent mechanical properties, and the preparation method of the invention can realize the full and uniform dispersion of the high-starch-content degradable plastic in the degradable resin.

Compared with the comparative example 1, the preparation method needs to control the humidity in the ball milling pretreatment and aging stages, the strength of the starch melt is weakened due to overhigh humidity, the dispersion of the starch is influenced during the subsequent mixing and extrusion with the resin, and the prepared degradable plastic with high starch content has small tensile strength and poor mechanical property.

Comparative example 2 does not adopt a two-stage extrusion device, the starch after the aging treatment is directly mixed with the degradable resin for extrusion, the starch dispersion effect is poor, and the prepared degradable plastic has poor mechanical properties.