阅读说明：本技术 一种淀粉基塑料母料的制备方法 (Preparation method of starch-based plastic master batch ) 是由 刘一帆 于 2021-07-21 设计创作，主要内容包括：本发明披露了一种淀粉基塑料母料的制备方法,其步骤是：(1)将淀粉的含水量干燥至5％以下,得到干淀粉,(2)干淀粉在不添加淀粉塑化剂的情形下与塑料母粒熔融混合,得到淀粉基塑料母料。本发明克服了技术偏见,在制备淀粉基塑料制品时,不添加淀粉塑化剂。本发明还同时解决了淀粉基塑料制品增塑剂析出的技术问题,本发明的产品具有力学性能好、成本低的优点。(The invention discloses a preparation method of a starch-based plastic master batch, which comprises the following steps: (1) drying the water content of the starch to be below 5% to obtain dry starch, and (2) melting and mixing the dry starch with the plastic master batch under the condition of not adding a starch plasticizer to obtain the starch-based plastic master batch. The invention overcomes the technical prejudice, and does not add starch plasticizer when preparing starch-based plastic products. The invention also solves the technical problem of plasticizer precipitation of starch-based plastic products, and the product has the advantages of good mechanical property and low cost.)

1. A preparation method of starch-based plastic master batch comprises the following steps:

(1) drying the starch to a moisture content of less than 5% to obtain dry starch,

(2) melting and mixing the dry starch and the plastic master batch to obtain starch-based plastic master batch,

the method is characterized in that when the dry starch and the plastic master batch are mixed in a melting way, the added starch plasticizer is not more than 5% of the dry starch by mass.

2. The method of claim 1, wherein the dry starch is melt mixed with the plastic masterbatch without the addition of a starch plasticizer.

3. The method for preparing a starch-based plastic masterbatch according to claim 1, wherein the drying manner in the step (1) is microwave oven drying.

4. The method for preparing a starch-based plastic masterbatch according to claim 1 wherein the drying in step (1) is performed by applying a compressive force and a shearing force to the starch while heating.

5. The method of preparing a starch-based plastic masterbatch according to claim 1 wherein the starch in step (1) is pregelatinized starch.

6. The method of preparing a starch-based plastic masterbatch according to claim 1 wherein step (1) is preceded by a gelatinization treatment of the starch.

7. The method for preparing a starch-based plastic masterbatch according to any one of claims 1-6 wherein the dry starch is further pulverized to a particle size of 80 mesh or more before step (2).

Technical Field

The invention relates to the field of plastic master batches, in particular to a preparation method of a starch-based plastic master batch.

Background

With the increasing of the environmental protection requirement and the implementation of the environmental protection policy, and the urgent requirements of 'carbon neutralization and carbon peak reaching', in the field of plastics, especially biodegradable plastics, the renewable natural polymer materials are required to be applied to plastic products as much as possible, so that the cost is reduced, and the use of petroleum-based biodegradable plastic materials is saved. There are many prior arts disclosing the addition of natural high molecular starch to biodegradable materials such as PLA, PBAT, etc., but starch is a relatively rigid material, and its melting point is even higher than its carbonization point, so that starch is difficult to be mixed and melted with traditional plastics such as PE, PP, PLA, PBAT, etc. For this reason, the prior art has taken the technical route of plasticizing starch by combining starch with a plasticizer for blending. For example, the technologies of the publication No. CN 111548536A, the name of a thermoplastic starch biodegradable material and a patent for preparing the thermoplastic starch biodegradable material, the name of an authorized publication No. CN103992517B, the name of a continuously producible fully degradable starch-based plastic alloy and a preparation method thereof, the publication No. CN104448402A, the name of a starch-based plastic and a preparation method thereof, the name of a U.S. Pat. No. US7608649B2 and the like all adopt a mode of adding a plasticizer to apply starch to the field of biodegradable plastics. Commonly used plasticizers are, as disclosed in CN103992517B, water, glycerol, formamide, urea, sorbitol, low molecular weight polyethylene glycol, and the like. Although the plasticizer can plasticize starch into thermoplastic starch at higher temperature, the adverse effect is that when the thermoplastic starch is used for making products, the plasticizer can be slowly separated out of the products, which causes poor quality strain and narrow application range, and the technical difficulty which can not be overcome by the prior art at present is solved. In addition, the thermoplastic starch product inevitably has the technical defect of retrogradation and brittleness due to incomplete water treatment in the thermoplastic starch.

Disclosure of Invention

In order to solve the technical problems, the invention overcomes the technical bias and provides the preparation method of the starch-based plastic master batch, and the starch-based plastic prepared by the method can overcome the technical defects of plasticizer precipitation and starch retrogradation of starch-based plastic products. The invention is realized by the following technical scheme: a preparation method of starch-based plastic master batch comprises the following steps:

(1) drying the starch to a moisture content of less than 5% to obtain dry starch,

(2) melting and mixing the dry starch and the plastic master batch to obtain starch-based plastic master batch,

the method is characterized in that when the dry starch and the plastic master batch are mixed in a melting way, the added starch plasticizer is not more than 5% of the dry starch by mass.

Preferably, wherein the dry starch is melt mixed with the plastic masterbatch, no starch plasticizer is added.

Preferably, the drying manner in step (1) is microwave drying.

Preferably, the drying manner in step (1) is that the starch is heated while applying a pressing force and a shearing force.

Preferably, wherein the starch in step (1) is a pregelatinized starch.

Preferably, the starch is gelatinized before the step (1).

Preferably, the dry starch is further crushed to a particle size of not less than 80 meshes before the step (2).

Compared with the prior art, the theoretical basis and the innovation of the invention are as follows:

first, the present invention employs a technical route and means for applying starch to plastics that is different from the prior art.

In the prior art, when starch is applied to plastic products, the technical means adopted is that the starch is plasticized under the action of a plasticizer and then is melt-mixed with other plastic raw materials, or the starch, the plasticizer and plastic master batch are melt-mixed to obtain the starch-based plastic products. In the prior art, the selection of the plasticizer is an indispensable technical means. For example, publication numbers CN 111548536A, CN103992517B, CN104448402A and US7608649B2 all adopt a combination of plasticizer, starch and plastic resin, and the content of plasticizer is no less than 20% of the mass of starch.

The plasticizers of the starch mainly comprise water, alcohols with smaller molecular weight and amides with smaller molecular weight, such as CN103992517B, and the plasticizers adopted comprise water, glycerol, formamide, sorbitol, polyethylene glycol with low molecular weight and the like; in addition, urea, formamide, acetamide, and the like are also disclosed as plasticizers for starch. Whether water, alcohols or amides, are strongly polar molecules. Starch can be melt-plasticized at higher temperatures only under the action of the aforementioned strongly polar molecules and melt-mixed with conventional plastics at the same temperature.

However, the applicant has found that the plasticizer plasticizes starch and causes performance deterioration of plastic resins, such as PBAT, PLA, etc., mixed therewith, and even when mixed with conventional plastics, such as PP, PE, etc., the plasticizer causes performance deterioration of PP, PE. Thereby causing the mechanical property of the final plastic alloy to be poor, which is a technical defect that the prior art can not solve.

The following table shows the mechanical properties of the materials after melt mixing of starch, glycerol and PBAT. Wherein the starch has a water content of 3% and a fineness of 150 meshes; the mass ratio of the starch to the PBAT is 20: 80; the percentage of glycerol is determined by the mass of the starch.

Table one:

content of Glycerol	0	5％	10％	20％	30％	40％
							Tensile strength MPa	21.4	20.7	18.3	16.7	14.6	13.8
Elongation percentage%	189	181	167	153	141	127

As can be seen from the table, as the content of glycerin increases, both the tensile strength and the elongation of the material decrease. I.e. glycerol as plasticizer, the effect of which on the material properties is deteriorated. Thus, glycerin plasticizes starch and also deteriorates the mechanical properties of the final material. The material has the best mechanical properties at a glycerol content of 0.

In addition, the degree of plasticization of starch by plasticizers is indicated by how much starch can be mixed in the molten state with plastic masterbatch (e.g., PBAT) in the same molten state under given conditions. When the starch is fully plasticized, the two molten phases mix and the cross-section of the material is relatively homogeneous, with no starch granules being observed. When the starch is not fully or completely plasticized, granular starch is observed under an electron microscope, and the molten phase is mainly the plastic masterbatch (e.g., PBAT) phase when mixed.

The degree of plasticization is directly related to the amount of plasticizer added. For example, when glycerol is used as a plasticizer for starch: when the glycerol content is 0, the starch is not plasticized, but is dispersed in plastic master batches (such as PBAT) in the form of additives and kept in the original state. Therefore, under an electron microscope, the cross section of the alloy material can be observed to have a large amount of starch granules; when the content of glycerin reaches 5% of the starch, the number of starch granules begins to decrease, and from table one, the mechanical property of the alloy begins to decline; when the glycerol content reaches 30% of the starch, granular starch granules are hardly observed and the starch is fully plasticized, but it can also be seen from table one that the mechanical properties of the material alloy are greatly reduced.

Besides glycerin, plasticizers of starch such as urea, ethylene glycol, formamide, acetamide and the like have basically similar effects on materials.

It has been proved by experiments that when the starch, glycerin, PP and PE are blended, the properties of the blend are changed in the same way as the above-mentioned blend of starch, glycerin and PBAT, i.e. when the starch is added to the plastic, the starch plasticizer can homogenize the material, but the starch plasticizer can deteriorate the mechanical properties of the material alloy.

In order to ensure that the starch-based plastic has better mechanical properties, the invention requires no plasticizer or slightly plasticizer when preparing the starch-based plastic master batch. The technical route of the invention is obviously different from the prior art. The invention has the advantages that the plastic master batch has better mechanical property, the cost and the process of the plasticizer are saved, and the cost is reduced. More importantly, the technical scheme of the invention can solve the problem of plasticizer precipitation which is a problem which puzzles the prior art. Without plasticizer, there is naturally no problem of plasticizer precipitation.

And secondly, the water content of the starch is strictly limited, and the retrogradation phenomenon of the starch and the reduction of the mechanical property of the material are prevented.

In the prior art, when starch is combined with other plastics, the starch is plasticized and forms a new plastic alloy with other plastics. Since water is an ideal plasticizer for starch, the removal of water from starch is often not critical and sometimes a certain water content is deliberately retained. However, in the present invention, the combination of starch and other plastics is that starch granules are dispersed in other plastics, and the mechanical properties of the combined material are seriously affected by the presence of moisture, so the present invention requires that the starch has low moisture content.

Table two is the properties of starch based plastic masterbatches formed from 80% PBAT and 20% starch of different moisture content:

table two:

water content	0	1％	2％	3％	5％	6％
							Tensile strength MPa	21.4	21.1	20.7	18.4	18.1	16.8
Elongation percentage%	189	189	184	177	171	163
							Retrogradation phenomenon	Is free of	Is free of	Is free of	Fine and minute	Is lighter	Is more obvious

As can be seen from the table, the mechanical property of the starch-based plastic master batch is gradually reduced along with the increase of the water content in the starch, and in addition, when the water content in the starch is lower than 3 percent, the retrogradation phenomenon of the starch-based plastic master batch can not occur, and the reduction of the material property is small; when the water content in the starch reaches 6%, retrogradation and embrittlement occur. Therefore, in each technical scheme of the invention, the water content of the starch is required to be less than or equal to 5 percent.

Thirdly, special technical means are adopted to remove the water in the starch and change the internal structure of the starch.

1. Conventional starch drying means have difficulty removing moisture from the starch.

The moisture content of the existing commercial starch is about 13 percent. The applicants believe that water is present in starch in two states: one is free water, which is loosely bound to the starch molecules. When dried, the free water can be dried from the starch relatively easily, using conventional drying means; the other is bound water, which is represented by the fact that water and starch molecules are bound into fixed hydrate in the form of hydrogen bonds. When starch is dried by conventional methods, such as drying ovens, fluid bed drying, etc., bound water is difficult to separate from the starch due to the effect of hydrogen bonding. The water content of the existing commercial starch is 13%, and experiments show that when the water content of the starch is reduced to 6-7% by drying the starch in a dryer, the starch is difficult to reduce again, and the energy consumption is huge. The applicant believes that this is due to the effect of the bound water.

2. The starch is dried while bearing the extrusion force and the shearing force, so that the moisture can be easily removed.

The applicants believe that the bound water in starch is present predominantly in the crystalline regions of the starch granules, while the free water is present predominantly in the amorphous regions. When the crystalline region of the starch is broken and destroyed, the bound water in the original crystalline region can be changed into free water, and the free water is easily removed from the starch granules. Experiments show that the crystalline regions inside the starch granules can be broken up by extruding and shearing the starch. The specific means can be that the two rollers rotate in an unequal contact manner, and can extrude and shear starch between the rollers; the gears are meshed with each other, the racks are meshed with each other or the threads are meshed with each other, and extrusion and shearing can be provided for starch between tooth surfaces; starch between the contact surfaces of the stator and the rotor can be extruded and sheared. The starch is heated while undergoing extrusion and shearing, wherein moisture is easily removed. The conventional apparatuses such as a kneader, a mixer, and an internal mixer can provide the above-mentioned extrusion force and shearing force, and thus can be used as an apparatus for drying starch in the present invention.

The following table shows the conditions for drying (a) a commercial starch in a dryer and (b) in an internal mixer (drying temperature 110 ℃ C.):

table two:

time (minutes)	0	15	20	30	40	70
							a water content%	13.15	10.67	8.21	6.34	5.27	2.41
b water content%	13.15	6.21	4.16	3.23	1.97	1.22

3. The starch is dried by microwave, so that the moisture can be removed easily.

Applicants have found that microwaves are capable of drying not only free water in the amorphous regions of the starch granule, but also bound water in the crystalline regions within the starch granule. Because of the directional osmotic energy, the microwave can directly act on water molecules in a crystallization area and excite the water molecules, so that the water molecules are separated from the constraint of hydrogen bonds and released from the interior of the starch, and the aim of drying is fulfilled. Thus, the microwave drying method is one of drying methods that can be employed in the present invention. The commonly used microwave heating equipment mainly comprises a box type microwave heater and a tunnel type microwave heater, and the commonly used microwave frequency is 915MHz and 2450 MHz. The microwave drying has the characteristics of high speed, good effect and the like, for example, 200g of commercial starch is dried in a household microwave heater, and the water content can be dried to 2.1 percent within 3 minutes.

4. Other methods involve first destroying the crystalline regions within the starch granules and then drying them.

(1) Pregelatinized starches are useful in the present invention.

There are two methods of starch pre-gelatinization, the physical method: mixing raw starch with a certain amount of water, heating, swelling and pasting starch granules, breaking intermolecular hydrogen bonds, and eliminating a crystalline structure; and then quickly drying and removing the water to obtain the starch without an obvious crystalline structure, namely the pregelatinized starch. The chemical method comprises the following steps: firstly, uniformly stirring the original starch in an alkali liquor with a certain pH value, swelling and pasting starch granules, breaking intermolecular hydrogen bonds, and eliminating a crystalline structure; and then quickly drying and removing the moisture to obtain the starch without an obvious crystalline structure, namely the alkaline pregelatinized starch.

The production process for preparing the pregelatinized starch commonly used in industry specifically comprises the following steps: drum drying, spray drying, extrusion, pulse jet, and the like.

The moisture content of commercial pregelatinized starch is about 10-14%.

Because the pregelatinized starch granules have no obvious crystalline structure inside, the moisture in the pregelatinized starch granules is easy to dry and remove, and the pregelatinized starch granules can be dried to be below 5 percent and below 2 percent by conventional drying means, such as a dryer, a fluidized drying bed and the like.

(2) According to the pre-gelatinization principle and the method, the original starch can be pre-gelatinized first, then deep drying is carried out in the corresponding drying link for preparing the pre-gelatinized starch, and the pre-gelatinized starch is directly dried to be less than 5 percent.

Fourthly, the dried starch has strong brittleness and is easy to be thinned, and the high-fineness starch is obtained.

As analyzed previously, dried starch has low moisture content and the internal texture of the starch is largely amorphous, which determines that dried starch is very easy to break and refine. Experiments have shown that it is possible to refine dry starch to a particle size of over 150 mesh with less time and power spent in the micronizer. Under the same conditions, commercial starch cannot be thinned to the same mesh size in a micronizer. According to inspection, no starch with more than 150 meshes is found in the existing starch commodity. In an ultrafine pulverizer (such as a jet pulverizer), dry starch can be made into more than 500 meshes, which is not possible for commercial starch (with high water content). This is also one of the features of the present invention that distinguishes it from the prior art.

Compared with the prior art, the preferable scheme of the invention requires higher mesh number of the starch, because when the dry starch is combined with other plastic resins into an alloy, the dry starch is not plasticized, the size of the dry starch particle size influences the performance of the alloy, and the smaller the dry starch particle size, the better the performance.

The following table shows the effect of starch fineness on mechanical properties (PBAT 80%; dry starch 20%; starch moisture 1%):

starch particle size (mesh)	50	80	100	150	250
						Tensile strength MPa	15.3	18.1	20.6	21.4	24.7
Elongation percentage%	132	154	175	189	213

As can be seen from the table, the mechanical properties of the dry starch and the plastic resin are better and better with the increase of the mesh number. When the mesh number of the dry starch reaches 80 meshes, the tensile strength of the alloy is equivalent to that of the PBAT, and when the mesh number reaches 100 meshes, the strength of the alloy exceeds that of the PBAT resin (about 18-20 MPa). In addition, from the appearance of the resulting material alloy, the higher the mesh number of starch, the higher the smoothness. Therefore, the invention has the requirement of reaching 80 meshes, preferably exceeding 100 meshes.

In addition, after the starch is subjected to the processes such as extrusion shearing, pre-gelatinization, microwave treatment and the like, the particle size of the starch obtained by some processes is increased. For example, a commercial starch has a 87% pass through a 80 mesh screen prior to microwave treatment, but only 34% pass through after microwave treatment. A preferred embodiment of the present invention therefore requires the dry starch to be thinned to above 80 mesh.

The following is a further description of step (2) of the present invention

The process of the step (2) is a process of mixing dry starch and plastic master batches. This process is often done in a plastic molding machine. The method comprises the following steps: the dry starch and the plastic master batch are mixed and then enter a plastic forming machine or are added into the plastic forming machine simultaneously, the plastic master batch is melted in a spiral cavity in the forming machine under the action of high temperature, high pressure and shearing force, and the dry starch is dispersed into the melted plastic. This is essentially the same as the current method of adding calcium carbonate powder to plastics. Sometimes, for processing convenience, a small amount of a processing aid such as paraffin or the like may be added. Polar starch plasticizers are preferably not added, and if added, should be less, preferably less.

The plastic master batch can be biodegradable plastics such as PLA, PBAT, PHA and the like, and can also be traditional petroleum-based plastics such as PP, PE, PVC, PET and the like. When the dry starch and biodegradable plastics such as PLA, PBAT, PHA and the like form starch-based plastic master batch, the obtained plastic product is a completely biodegradable plastic product; when the dry starch and petroleum-based plastics such as PP, PE, PVC, PET and the like form starch-based plastic master batches, the obtained plastic products are partially biodegradable plastic products.

Because the dry starch is recyclable material and has low price, the plastic can play a role in reducing carbon emission and product cost as long as the dry starch is added into the plastic. Moreover, because no starch plasticizer is added, the mechanical property of the starch-based plastic master batch cannot be affected by the weakening of the starch plasticizer, and the thinned starch granules can also play a role in improving the strength of the material.

In practical application, the addition amount of the dry starch can be determined according to the requirements of different plastic types, different degradation requirements, product functions and the like.

For disposable degradable plastic products, the addition amount of dry starch is generally between 10 and 30 percent, the addition amount is small, the advantages of the starch cannot be reflected, but when the addition amount of the starch exceeds 30 percent, the plasticity, toughness and the like of the starch-based plastic master batch formed by the dry starch, PBAT, PLA and the like cannot meet the requirements;

when the starch-based plastic master batch is used for manufacturing the plate, a large amount of the starch-based plastic master batch can be added. For example, 50% of dry starch can be combined with PP to prepare a starch plastic plate, and the processing technology and the application thereof are similar to those of a commercial wood plastic plate. However, when the dry starch content exceeds 70%, the existing processing equipment and process cannot process the starch, so the invention requires that the addition amount of the dry starch does not exceed 70% at most.

Even if a small amount of dry starch is added to the plastic masterbatch, the dry starch will also provide reinforcement: experiments show that when 3% of starch-based plastic master batch with the water content of 1% and the mesh number of 250 meshes is added into PE, the tensile strength of the PE can be improved by about 23%.

Has the advantages that:

compared with the prior art, the invention has the advantages that:

1. the invention overcomes the technical prejudice, and when preparing the starch-based plastic product, the starch plasticizer is not added, so that the product performance is better and the cost is lower;

2. the invention solves the problem of plasticizer precipitation in the prior degradable plastic technology and solves the problem of starch-based product regeneration.

Best mode for carrying out the invention

Example 1

200g of commercial starch (water content 13.2%) were dried in a test dryer at 120 ℃. After 140 minutes, the starch moisture content was measured to be 4.2% and a dry starch was obtained. Mixing dry starch and 800g of PBAT plastic master batch uniformly in a mixer, and then uniformly adding the mixture into an extruder for test, wherein the parameters set by the extruder are as follows: 35mm single screw, rotational speed 10rpm, three heating zones, the heating temperature is in proper order: the diameter of the die orifice is 1mm at 140 ℃, 130 ℃ and 80 ℃. Cooling and dicing the extruded material by a dicing cutter to obtain granular starch-based plastic master batch.

Example 2

200g of commercial starch (water content 13.2%) are placed in an experimental internal mixer with the following parameters: capacity 1L, temperature range: normal temperature is 300 ℃; heating by an electric heating pipe; the heating power is 2.4KW, and the speed ratio of the rotor is 1: 1.27-1.4; flip angle 110 °, rotor speed: 0-85 rpm. The heating temperature was set at 110 ℃ and the rotational speed was set at 50rpm, and the internal mixer was provided with an exhaust port. Banburying for 30 minutes, discharging to obtain dry starch, and measuring the water content of the dry starch to be 3.2%. Mixing dry starch and 800g of PBAT plastic master batch uniformly in a mixer, and then uniformly adding the mixture into an extruder for test, wherein the parameters set by the extruder are as follows: 35mm single screw, rotational speed 10rpm, three heating zones, the heating temperature is in proper order: the diameter of the die orifice is 1mm at 140 ℃, 130 ℃ and 80 ℃. Cooling and dicing the extruded material by a dicing cutter to obtain granular starch-based plastic master batch.

Example 3

200g of commercial pregelatinized starch (water content 11.7%, passing rate of 50 mesh sieve 23.6%) was placed in a test dryer and dried at 120 ℃. After 30 minutes, the starch moisture content was measured to be 3.6% to give a dry starch. The dry starch was ground in a ball mill for 0.5 hours with a throughput of 91% in a 180 mesh screen. Uniformly mixing the ground dry starch and 800g of LPE plastic master batch in a mixer, and uniformly adding the mixture into an extruder for testing, wherein the parameters set by the extruder are as follows: 35mm single screw, rotational speed 15rpm, three heating zones, the heating temperature is in proper order: die size was 0.3 x 10mm at 130 ℃, 120 ℃, 70 ℃. Cooling the extruded material to obtain the flaky starch-based plastic master batch.

Example 4

200g of commercial starch (with the water content of 13.2%) and 400g of water are mixed in a stirring kettle, the mixture is heated to 70 ℃ while being stirred, after starch gelatinization, the mixture is poured out and placed in an open container to be dehydrated and dried, and the drying temperature is 80 ℃, so that blocky pre-gelatinized starch is obtained. The water content of the pregelatinized starch was 15.6%. And (3) primarily crushing the pregelatinized starch, and then putting the crushed pregelatinized starch into a drying oven for drying at the drying temperature of 120 ℃ for 30 minutes to obtain dry starch with the water content of 2.7%. The dry starch was pulverized in a jet mill and taken out after 20 minutes, and the passing rate in a 270-mesh sieve was 84%. The dry starch and 800g of LPE plastic master batch are uniformly mixed in a mixer, and then the mixture is uniformly added into an extruder for testing, wherein the parameters set by the extruder are as follows: 35mm single screw, rotational speed 10rpm, three heating zones, the heating temperature is in proper order: the diameter of the die orifice is 1mm at 140 ℃, 130 ℃ and 80 ℃. Cooling and dicing the extruded material by a dicing cutter to obtain granular starch-based plastic master batch.

Example 5

200g of commercial starch (water content 13.2%, passing rate of 100 mesh sieve 68%) was dried in a microwave oven at 2450 MHz. After drying for 4 minutes, the starch was found to have a water content of 1.37% to give a dry starch. The dry starch was pulverized in a jet mill for 15 minutes and taken out, and the passing rate in a 300-mesh sieve was 79%. Mixing dry starch and 800g of PBAT plastic master batch uniformly in a mixer, and then uniformly adding the mixture into an extruder for test, wherein the parameters set by the extruder are as follows: 35mm single screw, rotational speed 10rpm, three heating zones, the heating temperature is in proper order: the diameter of the die orifice is 1mm at 140 ℃, 130 ℃ and 80 ℃. Cooling and dicing the extruded material by a dicing cutter to obtain granular starch-based plastic master batch.