阅读说明：本技术 一种面向包装领域的生物降解复合珠粒发泡材料及其制备方法 (Biodegradable composite bead foaming material for packaging field and preparation method thereof ) 是由 朱晨杰 龙浩宇 梁国伟 庄伟� 梁国超 肖红杰 李明 欧阳平凯 于 2021-08-17 设计创作，主要内容包括：本发明公开了一种面向包装领域的生物降解复合珠粒发泡材料及其制备方法,将含聚己二酸对苯二甲酸丁二醇酯与低结晶性聚乳酸的物料制备得到的共混粒子置于高压模具中,以发泡气体为发泡剂,进行模压发泡。本发明使用低结晶性PLA和PBAT复合的方法,不加入成核剂即可产生良好的发泡效果。(The invention discloses a biodegradable composite bead foaming material for the packaging field and a preparation method thereof. The invention uses a method of compounding low-crystallinity PLA and PBAT, and can generate good foaming effect without adding a nucleating agent.)

1. A preparation method of a biodegradable composite bead foaming material for the packaging field is characterized in that a blended particle prepared from materials containing polybutylene adipate terephthalate and low-crystallinity polylactic acid is placed in a high-pressure die, and foaming gas is used as a foaming agent for die pressing foaming.

2. The production method according to claim 1, wherein the mass ratio of polybutylene adipate terephthalate to low-crystalline polylactic acid is (90-60): (10-40).

3. The preparation method according to claim 1, wherein the mass of the polybutylene adipate terephthalate and the low-crystallinity polylactic acid accounts for 90-99.9% of the total mass of the material.

4. The method of claim 1, wherein the material further comprises a compatibilizing agent; the compatilizer accounts for 0.1-10% of the total mass of the materials.

5. The preparation method according to claim 4, wherein the compatilizer is any one or combination of epoxy compatilizers, oxazoline compatilizers and isocyanate compatilizers.

6. The preparation method according to claim 1, wherein the material containing polybutylene terephthalate adipate and polylactic acid with low crystallinity is subjected to blending extrusion by a twin-screw underwater pelletizer and underwater granulation to obtain blended particles.

7. The preparation method according to claim 6, wherein the extrusion temperature of the twin-screw underwater pelletizer is 100-190 ℃, and the screw rotation speed is 30-100 r/min; the rotating speed of the granulator is 1000-.

8. The method of claim 1, wherein the foaming gas is supercritical CO₂Supercritical N₂Any one or a combination of several of n-pentane and n-butane.

9. The preparation method according to claim 1, characterized in that the blended particles are placed in a high-pressure die at a temperature of 80-160 ℃ and the total volume of the blended particles is ensured to be less than 1/3 of the volume of the high-pressure die, 10-20MPa of foaming gas is injected into the high-pressure die, and the constant temperature and pressure are maintained for 10-30 min.

10. The method according to claim 1, wherein the high-pressure die is subjected to a pressure release rate of 10 to 20 MPa/s.

Technical Field

The invention relates to the field of biodegradable polymer materials, in particular to a biodegradable composite bead foaming material for the field of packaging and a preparation method thereof.

Background

The polymer foaming material is a polymer/gas composite material taking a high polymer as a matrix, has the advantages of low cost, light weight, high impact strength, good heat insulation and sound insulation and the like, and is widely applied to the fields of packaging, buildings, electric appliances and the like. Most polymer products are derived from fossil fuels and are non-degradable wastes in the environment. The landfill of large amounts of foam waste has become a serious global problem. Therefore, efforts are being made to create green polymers using renewable resources in the world, and today's society is increasingly paying attention to environmental protection.

Biodegradable foaming materials such as poly (butylene adipate terephthalate) (PBAT), polylactic acid (PLA) and various composite materials thereof have better thermal stability and mechanical property, can be widely used in the fields of packaging materials, disposable daily necessities, heat insulation materials and the like, and is an important way for solving the problem of white pollution of plastics.

Currently, physical foaming is broadly classified into extrusion foaming, injection foaming, bead foaming, mold foaming, and the like. Among them, extrusion foaming efficiency is high, but moldability is poor, and only simple sheets can be made; the injection-molded foaming foam has high density and belongs to a low-foaming process; water in the conventional kettle pressure bead foaming is used as a medium to degrade the degradable material, so that the biodegradable material can be degraded at high temperature, and the performance of the foaming material is adversely affected.

The supercritical foaming technology is the latest and safest green environmental protection technology and is an industry key common technology which is preferentially developed by the Ministry of industry and communications. Patent CN102229707A provides PBAT mould pressing foaming material composition and a preparation method, but only PBAT is used for foaming, and the formed plate is very soft and is not suitable for being used as a packaging material; patent CN 112940468A provides a polylactic acid-based foaming particle and a preparation method thereof, but a nucleating agent is required to be added in a foaming material and a process method thereof to achieve a good foaming effect, the nucleating agent can generate adverse effects on the environment, and some nano nucleating agents are expensive; patent CN111320845A provides a method for foaming a graphene reinforced and toughened PBAT/PLA composite material, but the addition step of graphene is complicated and expensive, and a kettle pressure foaming manner is adopted, which makes the polyester biodegradable materials such as PLA, PBAT and the like easily undergo hydrolytic depolymerization under the condition of high temperature hydrothermal, and adversely affects the performance of the final product; patent CN101613486A adopts die pressing foaming and uses N₂The method for preparing PBAT foam by using the foaming agent has low foaming ratio; patent CN108003584A adopts a chemical foaming method, and the foaming ratio is low, and the residual AC foaming agent contains toxicity. Therefore, the invention provides a biodegradable composite bead foaming material oriented to the field of packaging and a preparation method thereof.

Disclosure of Invention

The purpose of the invention is as follows: the invention aims to solve the technical problem of the prior art and provides a biodegradable composite bead foaming material oriented to the packaging field and a preparation method thereof.

In order to solve the technical problems, the invention discloses a preparation method of a biodegradable composite bead foaming material for the packaging field, which comprises the steps of placing blended particles prepared from materials containing polybutylene adipate terephthalate (PBAT) and low-crystallinity polylactic acid (PLA) in a high-pressure die, and carrying out die pressing foaming by using foaming gas as a foaming agent.

Wherein the PBAT includes but is not limited to a brand number of Jinhui Luong high-tech Co., LtdThe product of (1), a product of 801T brand manufactured by Fujiwa river science and technology corporation; preferably, the PBAT is

Wherein the low-crystallinity polylactic acid is polylactic acid with optical purity less than 95L-type isomer; it is almost not crystallized in the actual forming process, the crystallization rate is very slow, the crystallinity is extremely low, and the high-viscosity amorphous transparent state is presented.

Wherein the low crystalline PLA includes, but is not limited to, LX175 brand products of darco benne corporation, thailand, Natureworks, usa, 2003D brand products, FY204, FY404, FY604, FY804 brand products of fondapaglaia polylactic acid, inc; preferably, the low crystalline PLA is LX 175.

The low-crystallinity PLA is added, so that the foaming effect can be improved, a nucleating agent is not required to be added, and the foaming effect is far better than that of semi-crystalline PLA and crystalline PLA; wherein, the semi-crystalline PLA includes but is not limited to the product with the brand number LX575 of Bien corporation of Darlco Thailand, Natureworks, USA, the brand number 4032D, and the brand numbers FY202, FY402, FY602, FY802 of Polylactic acid Limited of Fengtai, Anhui; the crystalline PLA includes, but is not limited to, products of daike bi en, tai dao, having a brand number of L105, L130, L175, products of Natureworks, usa, having a brand number of 3100HP, 2500HP, and products of fontanel polylactic acid, ltd, fengyulata, anhui, having a brand number of FY201, FY401, FY601, FY 801.

Wherein the mass ratio of the polybutylene adipate terephthalate to the low-crystallinity polylactic acid is (90-60): (10-40).

Wherein the mass of the polybutylene adipate terephthalate and the low-crystallinity polylactic acid accounts for 90-99.9% of the total mass of the material.

Wherein the material further comprises a compatibilizer; the compatilizer accounts for 0.1-10% of the total mass of the materials.

Wherein the compatilizer is any one or combination of more of epoxy compatilizers, oxazoline compatilizers and isocyanate compatilizers; preferably, the compatibilizer is an epoxy compatibilizer; further preferably, the compatibilizer isADR-4468。

Wherein, the materials containing polybutylene adipate terephthalate and low-crystallinity polylactic acid are blended and extruded by a double-screw underwater granulator, and are granulated underwater to obtain blended particles.

Wherein the extrusion section of the double-screw underwater granulator comprises 9 temperature zones, the extrusion temperature is 100-190 ℃, and the screw rotating speed is 30-100 r/min; the rotating speed of the granulator is 1000-; preferably, the pelletizer speed is 1500 rpm.

Wherein the foaming gas is supercritical CO₂Supercritical N₂Any one or a combination of more of n-pentane and n-butane; preferably, the foaming gas contains n-butane; further preferably, the foaming gas is supercritical CO₂Supercritical N₂And n-butane; even more preferably, supercritical CO₂Supercritical N₂And n-butane at a pressure ratio of (2-6): (10-14): 1; still further preferably, supercritical CO₂Supercritical N₂And n-butane pressure ratio of 4: 12: 1.

wherein the high pressure die includes, but is not limited to, a supercritical die-pressing foaming machine.

And (3) placing the blended particles in a high-pressure die at the temperature of 80-160 ℃, ensuring that the total volume of the blended particles is less than 1/3 of the volume of the high-pressure die, injecting 10-20MPa of foaming gas into the high-pressure die, and maintaining the pressure for 10-30min at constant temperature.

Wherein the constant temperature is 90-130 ℃.

And placing the blended particles in a high-pressure die, injecting foaming gas, keeping the temperature and pressure, and quickly relieving the pressure to normal pressure to obtain the foaming material.

Wherein the pressure relief rate of the high-pressure die is 10-20 MPa/s.

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

(1) the invention adopts the die pressing bead foaming process, effectively avoids the adverse effect that water in the conventional kettle pressure bead foaming is taken as a medium to degrade degradable materials, adopts a large-size die cavity for die pressing foaming, has short foaming saturation time, can be completely saturated only in 10min generally, has high yield, improves and improves the actual foaming production efficiency, and is very easy for later-stage industrial scale-up production.

(2) The conventional crystalline PLA needs to be added with an expensive and environmentally-unfriendly nucleating agent during foaming, but the invention uses a method for compounding low-crystalline PLA and PBAT, and can generate good foaming effect without adding the nucleating agent.

(3) The pure PBAT foaming board is extremely soft after being molded and is not suitable for being used as a packaging material, the method of compounding PBAT and low-crystallinity polylactic acid (PLA) is adopted, the method is simple and convenient for actual production, the hardness, the shrinkage resistance and the compression strength of the foam molding board can be effectively improved, and the pure PBAT foaming board is green, environment-friendly and degradable and is very suitable for being applied to the fields of packaging, food and the like.

Drawings

The foregoing and/or other advantages of the invention will become further apparent from the following detailed description of the invention when taken in conjunction with the accompanying drawings.

FIG. 1 is a graph showing the results of the comparison between before and after the expansion of the particles obtained in example 1.

FIG. 2 is a cell morphology diagram of the PBAT/low-crystallinity PLA composite foamed material prepared in example 1, wherein a is 100 μm and b is 200 μm.

FIG. 3 is a diagram of a particle-formed sheet, a is a diagram of a pure PBAT-formed sheet, and b is a diagram of a PBAT/low-crystallinity PLA composite-formed sheet.

Detailed Description

The experimental methods described in the following examples are all conventional methods unless otherwise specified; the reagents and materials are commercially available, unless otherwise specified.

In the following examples, the ratio of the gases is the pressure ratio.

Example 1

(1) Drying at 70 deg.C for 10 hr(weight fraction 80%), low-crystallinity PLA-LX175 (weight fraction 18%), compatibilizerADR-4468 (weight fraction: 2%) was extruded in a twin-screw underwater pelletizing extruder, which contained nine temperature zones, the temperatures of zone one to nine being 155 ℃, 180 ℃, 180 ℃, 185 ℃, 185 ℃, 190 ℃, 190 ℃, 185 ℃, 190 ℃, 230 ℃ of the die head, and 80 revolutions per minute of the screw; the cutter was rotated at 1500 rpm and cut into 5mg pellets.

(2) Placing the obtained particles in a supercritical molding foaming machine to ensure that the total volume of the particles does not exceed 1/3(3000 cm) of the container volume³) Supercritical CO at 20MPa₂Is used as a foaming agent, is saturated for 10min at the temperature of 115 ℃, and is decompressed at the speed of 20MPa/s to obtain the biodegradable composite foaming material.

FIG. 1 is a comparison chart of the particles obtained in example 1 before and after foaming (i.e., the particles obtained in step (1) and the biodegradable foamed material obtained in step (2)), which shows that after foaming, the volume of the particles is increased, which effectively reduces the disadvantage of high cost of the degradable material, and the application range is expanded.

FIG. 2 is a cell morphology diagram of the PBAT/low-crystallinity PLA composite foamed material prepared in example 1, wherein a is 100 μm and b is 200 μm, and it can be seen that the cell uniformity is higher after the PBAT/low-crystallinity PLA composite foamed material is foamed.

(3) And (3) using the biodegradable composite foaming material obtained in the step (2) to prepare a formed plate, specifically, sucking the biodegradable composite foaming material obtained in the step (2) into a steam forming device by using a pipeline, keeping the temperature for 10s, cooling by water for 110s and vacuum for 10s under the condition that the pressure of double sides of steam is 1MPa, and opening the die to obtain the formed biodegradable composite plate, wherein the formed plate is shown in fig. 3 b.

Comparative example 1

Drying at 70 deg.C for 10 hr(weight fraction of 80%) and low-crystallinity PLA-LX175 (weight fraction of 20%) are extruded in a double-screw underwater pelletizing extruder, and the extruder comprises nine temperature zones, wherein the temperature from one zone to nine zones is 155 ℃, 180 ℃, 180 ℃, 185 ℃, 185 ℃, 190 ℃, 190 ℃, 230 ℃ of a die head, and the screw rotating speed is 80 r/min; the cutter was rotated at 1500 rpm and cut into 5mg pellets.

Placing the obtained particles in a supercritical molding foaming machine to ensure that the total volume of the particles does not exceed 1/3(3000 cm) of the container volume³) Supercritical CO at 20MPa₂Is used as a foaming agent, is saturated for 10min at the temperature of 115 ℃, and is decompressed at the speed of 20MPa/s to obtain the biodegradable composite foaming material.

Example 2

Drying at 70 deg.C for 10 hr(70% by weight), low-crystallinity PLA-LX175 (27% by weight), and a compatibilizer(3% by weight) in a twin-screw underwater pelletizing extruder, wherein the extruder comprises nine temperature zones, the temperature of the zones from one zone to nine zone is 155 ℃, 180 ℃, 180 ℃, 185 ℃, 185 ℃, 190 ℃, 190 ℃, 185 ℃, 190 ℃, 230 ℃, the die head temperature is 230 ℃, and the screw rotation speed is 80 revolutions per minute; the pellets were cut into 5mg pellets in a twin-screw underwater pellet extruder at a pelletizer rotation speed of 1500 rpm.

Placing the obtained particles in a supercritical molding foaming machine to ensure that the total volume of the particles does not exceed 1/3(3000 cm) of the container volume³) In a total amount of 20MPa₂And supercritical CO₂The composite gas is a foaming agent and the supercritical N of the composite gas₂And supercritical CO₂The proportion is 1: and 3, saturating for 10min at the temperature of 115 ℃, and relieving pressure at the rate of 20MPa/s to obtain the biodegradable composite foaming material.

Comparative example 2

Drying at 70 deg.C for 10 hr(97% by weight) of a compatibilizerADR-4468 (3% by weight) was extruded in a twin-screw underwater pelletizing extruder, which contained nine temperature zones, the temperatures of the zones from one zone to nine being 155 ℃, 180 ℃, 180 ℃, 185 ℃, 185 ℃, 190 ℃, 190 ℃, 185 ℃, 190 ℃, 230 ℃ of the die head, and 80 revolutions per minute of the screw; the pellets were cut into 5mg pellets in a twin-screw underwater pellet extruder at a pelletizer rotation speed of 1500 rpm.

Placing the obtained particles in a supercritical molding foaming machine to ensure that the total volume of the particles does not exceed 1/3(3000 cm) of the container volume³) In a total amount of 20MPa₂And supercritical CO₂The composite gas is a foaming agent and the supercritical N of the composite gas₂And supercritical CO₂The proportion is 1: and 3, saturating for 10min at the temperature of 115 ℃, and relieving pressure at the rate of 20MPa/s to obtain the biodegradable composite foaming material.

According to the step (3) of example 1, the obtained biodegradable composite foamed material is used to prepare a formed plate, and the formed plate is shown in fig. 3 a.

Example 3

Drying at 70 deg.C for 10 hr(weight fraction of 90%), low-crystallinity PLA-LX175 (weight fraction of 8%), compatibilizerADR-4468 (2% by weight) was extruded in a twin screw underwater pelletizing extruder having nine temperature zones, 155 ℃ in one to nine zones and 180 DEG C180 ℃, 185 ℃, 185 ℃, 190 ℃, 190 ℃, 185 ℃, 190 ℃, 230 ℃ of a die head and 80 revolutions per minute of a screw; the pellets were cut into 5mg pellets in a twin-screw underwater pellet extruder at a pelletizer rotation speed of 1500 rpm.

Placing the obtained particles in a supercritical molding foaming machine to ensure that the total volume of the particles does not exceed 1/3(3000 cm) of the container volume³) In a total amount of 15MPa₂And supercritical CO₂The composite gas is a foaming agent and the supercritical N of the composite gas₂And supercritical CO₂The proportion is 1: and 3, saturating for 30min at the temperature of 110 ℃, and relieving pressure at the rate of 20MPa/s to obtain the biodegradable composite foaming material.

Example 4

And (3) just changing the foaming saturation time to be 10min, and keeping the rest consistent to obtain the biodegradable composite foaming material.

Example 5

As in example 1, only the compatibilizerADR-4468 (weight fraction 2%) becomes a compatibilizerADR-4368C (weight fraction 2%) to obtain the biodegradable composite foam material.

Example 6

As in example 1, only the compatibilizerADR-4468 (weight fraction 2%) becomes a compatibilizerADR-4370 (weight fraction 2%) to obtain the biodegradable composite foam material.

Comparative example 3

Just replacing low-crystalline PLA with semi-crystalline PLA-LX575 as in example 1, the biodegradable composite foamed material was obtained.

Comparative example 4

Just replacing the low crystalline PLA with the crystalline PLA-L175 as in example 1, the biodegradable composite foam was obtained.

Comparative example 5

As in example 1, the biodegradable composite foam was obtained by replacing only the low crystalline PLA with the semi-crystalline PLA-LX575 while adding the nucleating agent TMC-300 (1% by weight).

Comparative example 6

As in example 1, only the low crystalline PLA was replaced with crystalline PLA-L175, and at the same time, the nucleating agent TMC-300 (weight fraction: 1%) was added to obtain a biodegradable composite foam.

Example 7

Drying at 70 deg.C for 10 hr(70% by weight), low-crystallinity PLA-LX175 (25% by weight), and a compatibilizerADR-4468 (weight fraction: 5%) was extruded in a twin-screw underwater pelletizing extruder, which contained nine temperature zones, the temperatures of zone one to nine being 155 ℃, 180 ℃, 180 ℃, 185 ℃, 185 ℃, 190 ℃, 190 ℃, 185 ℃, 190 ℃, 230 ℃ of the die head, and 80 revolutions per minute of the screw; the pellets were cut into 5mg pellets in a twin-screw underwater pellet extruder at a pelletizer rotation speed of 1500 rpm.

Placing the obtained granules in a supercritical molding foaming machine to ensure that the total volume of the granules does not exceed 1/3(3000 cm) of the container volume³) In a total amount of 15MPa₂Supercritical CO₂N-butane composite gas as foaming agent, its supercritical N₂And supercritical CO₂And n-butane ratio of 4: 12: 1, saturating for 20min at the temperature of 110 ℃, and decompressing at the rate of 20MPa/s to obtain the biodegradable composite foaming material.

Example 8

As in example 7, only the supercritical N is added in a total amount of 15MPa₂Supercritical CO₂N-butylChanging alkane composite gas as foaming agent into supercritical N with total amount of 15MPa₂Supercritical CO₂The composite gas is a foaming agent and the supercritical N of the composite gas₂And supercritical CO₂The proportion is 1: and 3, obtaining the biodegradable composite foaming material.

Example 9

As in example 7, only the supercritical N is added in a total amount of 15MPa₂Supercritical CO₂The total amount of the foaming agent of n-butane composite gas is changed into the supercritical CO with the total amount of 15MPa₂The gas is used as a foaming agent to obtain the biodegradable composite foaming material.

The biodegradable composite foamed materials prepared in the above examples and comparative examples were tested, and the results are shown in table 1.

TABLE 1

From the data of table 1 and the phenomena during the experiment, the following conclusions can be drawn:

(1) compared with the comparative example 1, the example 1 can find that the foaming ratio of the biodegradable composite bead foaming material for the packaging box, which is obtained after the compatilizer is added, is greatly improved, and proves that the melt strength and the compatibility of the biodegradable composite bead foaming material are improved, so that the foaming performance of the biodegradable material is improved, and the biodegradable material still has good biodegradation performance.

(2) Comparing example 2 with comparative example 2, it can be found that adding low crystalline PLA into PBAT can effectively improve the hardness of the foamed material, and the PBAT/PLA composite material can form PBAT-g-PLA under the action of the compatibilizer, improving the foaming ratio.

(3) Comparing the embodiment 3 with the embodiment 4, the saturation time of the molding foaming is very short, the molding foaming can be basically and completely saturated within 10min, the saturation time is subsequently prolonged, the influence on the foaming is not great, meanwhile, the hydrolysis influence of the conventional bead foaming on the biodegradable material can be prevented, the biodegradable material still has good biodegradation performance, the production efficiency and the quality of the bead foam are improved, and the large-scale market application is facilitated.

(4) Example 1 was compared with examples 5 and 6 and a compatibilizer was foundADR-4468 has better chain extension compatibility on a PBAT/PLA composite system, has higher foaming ratio, and has the advantages of being amplified during molding and being easy to mold.

(5) Example 1 is compared with comparative examples 3, 4, 5 and 6, and it is found that for PBAT/PLA composite systems, low-crystallinity PLA is more favorable for foaming, good foaming effect can be achieved without adding nucleating agent, and the foaming rate is higher, while expensive and environmentally unfriendly nucleating agent needs to be added when the conventional crystalline PLA is foamed, so as to avoid cell combination phenomenon, and whether the semicrystalline and crystalline PLA added with nucleating agent generate partial crystallization phenomenon to inhibit cell growth, so that the foaming rate is low.

(6) Examples 7 to 9 show that the addition of a small amount of n-butane to the blowing gas is effective in increasing the blowing ratio.

Example 10

Like example 1, onlyThe PBAT-801T product is obtained, and the biodegradable composite foaming material is obtained.

Example 11

Just by changing the low-crystalline PLA-LX175 into a product of low-crystalline PLA-2003D as in example 1, a biodegradable composite foamed material was obtained.

Example 12

Just changing the low-crystallinity PLA-LX175 into the low-crystallinity PLA-FY204 product just as in example 1, the biodegradable composite foaming material is obtained.

Example 13

Just changing the low-crystallinity PLA-LX175 into the low-crystallinity PLA-FY404 product just as in example 1, the biodegradable composite foaming material is obtained.

Example 14

Just changing the low-crystallinity PLA-LX175 into the low-crystallinity PLA-FY604 product just as in example 1, the biodegradable composite foaming material is obtained.

Example 15

Just changing the low-crystallinity PLA-LX175 into the low-crystallinity PLA-FY804 product in the same way as in example 1 to obtain the biodegradable composite foaming material.

The biodegradable composite foam materials prepared in the above examples were tested, and the results are shown in table 2.

TABLE 2

From the data of table 2 and the phenomena during the experiment, the following conclusions can be drawn:

example 1 in comparison with examples 10-15, it was found that better foamability was achieved by changing to a different grade of PBAT including but not limited to the grade manufactured by aura-long-high tech limited and low crystalline PLAThe product of (1), a product of 801T brand manufactured by Fujiwa river science and technology corporation; further preferably, the PBAT isThe low crystalline PLA includes, but is not limited to, LX175 brand products of darco pecan, thailand, usa 2003D brand products of Natureworks, FY204, FY404, FY604, FY804 brand products of fondapaglaia, anhui; further preferably, the low crystalline PLA is LX 175.

The results of the tests of the PBAT/low-crystallinity PLA composite foamed material molded plate prepared in the above example 1 and the pure PBAT foamed material molded plate prepared in the comparative example 2 are shown in Table 3.

TABLE 3

From the data of table 3 and the phenomena during the experiment, the following conclusions can be drawn:

comparing the data of the formed sheet of example 1 with the data of the formed sheet of comparative example 2, it can be seen that the formed sheet of PBAT (fig. 3a) is extremely soft and not suitable for the packaging field, and the formed sheet of PBAT/low crystalline PLA (fig. 3b) has improved hardness, rigidity and shrinkage resistance and is suitable for the packaging field.

The present invention provides a concept and a method for a biodegradable composite bead foaming material and a preparation method thereof, which are oriented to the field of packaging, and a method and a way for implementing the technical scheme are numerous, and the above description is only a preferred embodiment of the present invention, and it should be noted that, for a person skilled in the art, a plurality of improvements and decorations can be made without departing from the principle of the present invention, and the improvements and decorations should also be regarded as the protection scope of the present invention. All the components not specified in the present embodiment can be realized by the prior art.