A biodegradable quaternary copolymer foam plastic and a preparation method thereof

Abstract

The application discloses a kind of biodegradable quaternary copolymer foamed plastics and preparation method thereof, by following mass fraction component composition: carbon dioxide-based polyester-polycarbonate quaternary copolymer 88-95 parts, physical foaming agent 5-12 parts;The physical foaming agent is one or two of n-pentane or isopentane.Foaming agent n-pentane or isopentane in PPC-X The desorption rate is extremely low, can reach good storage effect, by kettle pressure foaming method, with n-pentane or isopentane as foaming agent, saturation temperature is 75 DEG C, adjust the saturation pressure of reaction kettle in 1.0MPa-5.0MPa, saturation time is 6h-24h, can obtain pentane adsorption amount greater than 7%, the PPC-X foamed particle of easy storage, when foaming in 60~80 DEG C hot water, PPC-X foamed bead with foaming ratio 10-40 can be easily obtained, and have uniform and dense cell structure, and the obtained PPC-X foam product is non-brittle foam, with good flexibility.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high polymer foam materials, in particular to a biodegradable foam plastic and a preparation method thereof. BACKGROUND

[0002] Foam is a lightweight material, due to its sound and heat insulation properties and damping performance, it is widely used in the cushioning and packaging industry. Most of the foams used and discarded at present (such as polystyrene foam and polyethylene foam, etc.) are non-biodegradable, causing serious environmental problems, so the urgency of developing biodegradable foam is increasing. However, most biodegradable polymers, such as semi-crystalline polymer poly(lactic acid) (PLA), show low melt strength, resulting in a low foaming ratio (less than 10 times) of the prepared foam, not only the cost is much higher than that of most polyethylene or polystyrene foams with a foaming ratio of more than 30 times, but also the resilience is poor.

[0003] In 2022, we prepared a non-brittle carbon dioxide-based polyester-polycarbonate (PPC-P) foam with a foaming ratio of 10-50 using autoclave foaming method with CO2 as foaming agent (Chinese patent CN 115651382A, Nanomaterials .2024, 14(13), 1120), the prepared PPC-P foam has uniform and dense cells. The disadvantage is that the PPC-P glass transition temperature (40-55℃) is relatively low, which is easy to deform at high temperature, so the size stability of the obtained PPC-P foam is poor, and because the diffusion speed of CO2 gas itself in the foam is fast, it further makes the foam easy to shrink. Thus, to a large extent, it limits its application in the field of foaming materials

[0004] In 2024, we prepared a carbon dioxide-based polyester-polycarbonate quaternary copolymer (PPC-X) by copolymerizing phthalic anhydride, tetrachlorophthalic anhydride, propylene oxide and carbon dioxide (Chinese patent CN 118206728A), the prepared PPC-X has good light transmission performance, high barrier property, and the mechanical strength can reach 49 MPa, and its T g is 69-75℃, which is much higher than that of carbon dioxide-based polyester-polycarbonate (PPC-P) T g (40-55℃). SUMMARY

[0005] The present application aims at overcoming the deficiencies of the prior art, and first uses a carbon dioxide-based polyester-polycarbonate quaternary copolymer (PPC-X) to prepare a biodegradable foamed plastic, thereby obtaining a biodegradable quaternary copolymer foamed plastic with high foaming ratio, relatively uniform and dense cell structure, and certain flexibility and resilience.

[0006] In order to achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0007] A biodegradable quaternary copolymer foamed plastic is composed of the following components in mass fraction:

[0008] 88-95 parts of a carbon dioxide-based polyester-polycarbonate quaternary copolymer,

[0009] 5-12 parts of a physical foaming agent;

[0010] The physical foaming agent is one or both of n-pentane and isopentane;

[0011] The carbon dioxide-based polyester-polycarbonate quaternary copolymer (PPC-X) is a high-molecular polymer obtained by quaternary copolymerization of phthalic anhydride, tetrachlorophthalic anhydride, propylene oxide and carbon dioxide, and has a number average molecular weight of 50000-150000; its structure is shown in formula (1); wherein m≥1, n≥1, k≥0, j≥0; m, n, k and j are all integers;

[0012]

[0013] As a preferred, in the above-mentioned biodegradable quaternary copolymer foamed plastic, an organic filler is additionally added, and the added weight of the organic filler is 1-40% of the biodegradable quaternary copolymer foamed plastic.

[0014] As a preferred, in the above-mentioned biodegradable quaternary copolymer foamed plastic, the organic filler is selected from one or more of corn starch, wheat starch, sweet potato starch and lignin fiber powder.

[0015] A preparation method of a biodegradable quaternary copolymer foamed plastic includes the following steps:

[0016] (1) using a wire rod extruder to cut the carbon dioxide-based polyester-polycarbonate quaternary copolymer tow into microparticles;

[0017] (2) placing the microparticles in a high-pressure reaction kettle, first loading a dispersion medium, a physical foaming agent and a release agent, then injecting N2, and setting the saturation pressure, saturation time and saturation temperature in the kettle to obtain a homogeneous material with different foaming agent adsorption contents;

[0018] (3) After the physical foaming agent is adsorbed and saturated, the reaction kettle is first cooled at low temperature, then slowly depressurized at low temperature, and after the depressurization is completed, the adsorption amount of the physical foaming agent is confirmed on an analytical balance, and then the physical foaming agent is transferred to a hot water bath for foaming, and then the foamed beads after foaming are collected and molded into a foam molding body by molding.

[0019] As preferred, in the above-mentioned preparation method of the biodegradable tetrapolymer foam plastic, the length / diameter ratio of the micro-particles is 0.5-2, and the average weight of the micro-particles is 0.1-20 mg.

[0020] As preferred, in the above-mentioned preparation method of the biodegradable tetrapolymer foam plastic, the saturation temperature is 75°C; the saturation pressure is 2.0 MPa-5.0 MPa; the saturation time is 6 h-24 h; and the temperature of the hot water bath is 55°C-85°C.

[0021] As preferred, in the above-mentioned preparation method of the biodegradable tetrapolymer foam plastic, the dispersion medium is deionized water, and the release agent is calcium phosphate.

[0022] Since the carbon dioxide-based polyester-polycarbonate tetrapolymer has a high glass transition temperature, after adsorbing pentane under high temperature and high pressure conditions, the foaming agent n-pentane or isopentane can be stored in the material body, and when used, it can be foamed by increasing the temperature. This undoubtedly reduces the cost and the difficulty of industrial application. By adjusting the pressure during adsorption to 1.0 MPa-2.0 MPa, a foamed material with a foaming ratio of 10-40 times can be easily obtained, and has a uniform and dense cell structure, and the obtained foam product is a non-brittle foam, which has a certain flexibility and resilience. Under higher pressure, such as 3.0 MPa-5.0 MPa, the saturation time of n-pentane or isopentane in the polymer PPC-X can be greatly shortened, and the industrialization efficiency can be greatly improved.

[0023] Compared with the prior art, the present application has the following beneficial effects:

[0024] (1) In common EPS foaming, the selection principle of the physical foaming agent is that the compatibility of pentane and PS is very good. In the present application, based on the structural characteristics of PPC-X, it is not difficult to find that the compatibility of pentane and PPC-X is general, but through designed experiments, we can achieve a high adsorption amount (>7%) of pentane in PPC-X particles. Although the compatibility of pentane and PPC-X is general, unexpectedly, the foamed PPC-X has a high foaming ratio (10-45 times), a small cell size (~40 μm), and a dense and uniform cell structure (the cell density can reach ~1.5×10 7 cells / cm 3) and certain resilience, etc. On the other hand, for most biodegradable polymers, the common physical foaming agent is CO2, and the fast desorption rate of CO2 gas limits the foaming behavior of them, and the pre-foaming phenomenon often occurs after the physical foaming agent is adsorbed, which obviously increases the requirements for the material foaming process and storage conditions. In the present application, the desorption rate of the foaming agent n-pentane or isopentane in PPC-X is extremely low, which can achieve good storage effect, which provides the possibility for long-term storage of the foaming particles containing the foaming agent. The present application can obtain the PPC-X foaming particles with n-pentane adsorption amount greater than 7% and convenient storage by the autoclave foaming method, with n-pentane or isopentane as the foaming agent, the saturation temperature of 75℃, the saturation pressure of the reaction kettle adjusted to 1.0MPa-5.0MPa, and the saturation time of 6h-24h. When foaming in 60-80℃ hot water, the PPC-X foaming beads with foaming ratio of 10-40 can be easily obtained, and have uniform and dense cell structure, and the obtained PPC-X foam product is non-brittle foam, and has good flexibility.

[0025] (2) When n-pentane or isopentane is used as a physical foaming agent, the low solubility of n-pentane or isopentane in biodegradable polymer limits its use. Through the design experiment, the present application can easily realize the adsorption amount of the foaming agent in PPC-X greater than 7% by using n-pentane or isopentane as a physical foaming agent, so as to obtain a PPC-X foam material with high foaming ratio. The foaming ratio of the biodegradable foam plastic of the present application can be more than 40 times, which is a very high foaming ratio in the field of biodegradable plastic foaming, especially in the method of autoclave foaming.

[0026] (3) The polymer used in the present application is synthesized from carbon dioxide, which utilizes the greenhouse gas carbon dioxide and has the significance of carbon reduction and green environmental protection.

[0027] (4) The biodegradable foam material prepared by the present application has high foaming ratio, relatively uniform and dense cell structure, and certain flexibility and resilience. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 It is the scanning electron microscope graph of the cross section of the foaming material obtained in Example 3 of the present application;

[0029] Figure 2 It is the scanning electron microscope graph of the cross section of the foaming material obtained in Example 4 of the present application. DETAILED DESCRIPTION Example 1:

[0030] The carbon dioxide-based polyester-polycarbonate quaternary copolymer (PPC-X) was dried in a vacuum oven at 80°C, then cut into particles using a wire extruder, with the wire extruder 1 zone temperature at 145°C and the 2 zone temperature at 160°C, to obtain microparticles with a length / diameter ratio of 0.9-1.1 and an average weight of 1-3 mg. Then, the microparticles with a mass m0 of 0.1086 g were placed in a reaction kettle, 45 ml of deionized water, 5 ml of n-pentane, and 0.5 g of calcium phosphate were added to the reaction kettle, and then N2 gas was used to pressurize to 1.5 MPa, with a saturation time of 24 h, a saturation temperature of 75°C, and a magnetic stirrer stirring rate of 800 rpm. After saturation was completed, the reaction kettle was first cooled in a low-temperature ice water bath for 30 min, then the temperature in the reaction kettle was maintained below 10°C, and then low-temperature slow pressure relief was performed. After pressure relief was completed, the microparticles were collected and the surface moisture was wiped off, then transferred to an analytical balance to weigh the mass of PPC-X / n-pentane as m1: 0.1191 g (calculated, n-pentane adsorption amount: 9.7%), and then quickly transferred to a 60°C hot water bath for foaming experiment, to obtain biodegradable foam beads after 1 min, and then the foam molded body was prepared by molding. It was tested that the biodegradable foam plastic prepared had a foaming ratio of 22 times, a cell size of 38 μm, a cell density of 1.5×10 7 3 / cm, a compressive strength of 302 kPa, a tensile strength of 930 kPa, and an elongation at break of 216.3%.

[0031] Example 2:

[0032] ​The carbon dioxide-based polyester-polycarbonate quaternary copolymer (PPC-X) was dried in a vacuum oven at 80°C, then cut into particles using a wire extruder, with the wire extruder 1 zone temperature at 145°C and the 2 zone temperature at 160°C, to obtain microparticles with a length / diameter ratio of 0.9-1.1 and an average weight of 1-3 mg. The mass m0 of the microparticles was 0.4396 g, which were placed in a reaction kettle, 45 ml of deionized water, 5 ml of n-pentane, and 0.5 g of calcium phosphate were added to the reaction kettle, and then N2 gas was used to pressurize to 1.5 MPa, with a saturation time of 24 h, a saturation temperature of 75°C, and a magnetic stirrer stirring rate of 800 rpm. After saturation was complete, the reaction kettle was first cooled in a low-temperature ice water bath for 30 min, then the temperature in the reaction kettle was maintained below 10°C, and then low-temperature slow pressure relief was performed. After pressure relief was complete, the microparticles were collected and the surface moisture was wiped off, transferred to an analytical balance to weigh the mass of PPC-X / n-pentane as m1: 0.4801 g (calculated n-pentane adsorption amount: 9.2%), and quickly transferred to a 70°C hot water bath for foaming experiments. Biodegradable foam beads were prepared after 1 min, and a foam molded body was prepared by molding. Testing showed that the biodegradable foam plastic prepared had a foaming ratio of 31 times, a cell size of 52 μm, a cell density of 1.1 x 10 7 3 cm-3, a compressive strength of 275 kPa, a tensile strength of 620 kPa, and an elongation at break of 157.6%.

[0033] Example 3:

[0034] ​The carbon dioxide-based polyester-polycarbonate quaternary copolymer (PPC-X) was dried in a vacuum oven at 80°C, then cut into particles using a wire extruder, with the wire extruder 1 zone temperature at 145°C and the 2 zone temperature at 160°C, to obtain microparticles with a length / diameter ratio of 0.9-1.1 and an average weight of 1-3 mg. Then, the microparticles with a mass m0 of 0.2086 g were placed in a reaction kettle, 45 ml of deionized water, 5 ml of n-pentane, and 0.5 g of calcium phosphate were added to the reaction kettle, and then N2 gas was used to pressurize to 2.5 MPa, with a saturation time of 16 h and a saturation temperature of 75°C, and a magnetic stirrer stirring rate of 800 rpm. After saturation was completed, the reaction kettle was first cooled in a low-temperature ice water bath for 30 min, then the temperature in the reaction kettle was maintained below 10°C, and then low-temperature slow pressure relief was performed, after which the microparticles were collected and the surface moisture was wiped off, transferred to an analytical balance to weigh the mass of PPC-X / n-pentane as m1: 0.2309 g (calculated, n-pentane adsorption amount: 10.7%), and quickly transferred to a 70°C hot water bath for foaming experiment, and biodegradable foam beads were prepared after 1 min, and a foam molded body was prepared by molding. Testing showed that the biodegradable foam plastic prepared had a foaming ratio of 36 times, a cell size of 55 μm, a cell density of 6.7 x 10 6 3 , a compressive strength of 256 kPa, a tensile strength of 600 kPa, and an elongation at break of 150.1%.

[0035] Example 4:

[0036] ​Carbon dioxide-based polyester-polycarbonate tetromer (PPC-X) was dried in a vacuum drying oven at 80℃, and then pelletized using a wire extruder. The temperature of zone 1 of the wire extruder was 145℃, and the temperature of zone 2 was 160℃, yielding microparticles with a length / diameter ratio of 0.9-1.1 and an average weight of 1-3 mg. Microparticles with a mass m0 of 0.3877 g were weighed and placed in a reaction vessel. 45 ml of deionized water, 5 ml of n-pentane, and 0.5 g of calcium phosphate were added to the reaction vessel. The pressure was then increased to 3.0 MPa using N2 gas, and the saturation time was 12 h. The saturation temperature was 75℃, and the magnetic stirring speed was 800 rpm. After saturation, the reactor was first cooled in a low-temperature ice-water bath for 30 minutes, maintaining the temperature below 10°C. Then, the pressure was slowly released at low temperature. After depressurization, the microparticles were collected, their surface moisture wiped dry, and transferred to an analytical balance. The mass of PPC-X / n-pentane was weighed to be m1: 0.4311 g (calculated, the n-pentane adsorption capacity was 11.2%). The mixture was then quickly transferred to a 70°C hot water bath for foaming experiments. Biodegradable foam beads were obtained after 1 minute, and foam molded bodies were prepared by compression molding. Testing showed that the prepared biodegradable foam plastic had a foaming ratio of 38 times, a cell size of 70 μm, and a cell density of 6.2 × 10⁻⁶. 6 Bubble size / cm 3 The compressive strength is 240 kPa, the tensile strength is 571 kPa, and the elongation at break is 146.7%.

[0037] Example 5

[0038] The carbon dioxide-based polyester-polycarbonate quaternary copolymer (PPC-X) was dried in a vacuum oven at 80°C, and then cut into particles using a wire extruder with a temperature of 145°C in zone 1 and 160°C in zone 2. The length / diameter ratio of the micro-particles was 0.9-1.1, and the average weight was 1-3 mg. The mass m0 of the micro-particles was 0.7233 g, which was placed in a reaction kettle. Deionized water (45 ml), n-pentane (5 ml), and calcium phosphate (0.5 g) were added to the reaction kettle, which was then pressurized to 3.5 MPa using N2 gas. The saturation time was 9 h, the saturation temperature was 75°C, and the magnetic stirring rate was 800 rpm. After saturation, the reaction kettle was cooled in an ice water bath for 30 min, and then slowly depressurized at a low temperature. After depressurization, the micro-particles were collected and the surface moisture was wiped off. The mass of the PPC-X / n-pentane was m1: 0.8101 g (calculated n-pentane adsorption amount: 12.0%), which was quickly transferred to a hot water bath at 70°C for foaming. Biodegradable foam beads were prepared after 1 min, and a foam molding body was prepared by molding. The biodegradable foam plastic prepared had a foaming ratio of 42, a cell size of 29 μm, a cell density of 9.1 x 10 6 3 cm-3, a compressive strength of 291 kPa, a tensile strength of 840 kPa, and an elongation at break of 186.5%.

[0039] Example 6

[0040] ​The carbon dioxide-based polyester-polycarbonate quaternary copolymer (PPC-X) was dried in a vacuum oven at 80°C, then cut into particles using a wire extruder, with the wire extruder 1 zone temperature at 145°C and the 2 zone temperature at 160°C, to obtain microparticles with a length / diameter ratio of 0.9-1.1 and an average weight of 1-3 mg. The mass m0 of the microparticles was 0.2612 g, which was placed in a reaction kettle, 45 ml of deionized water, 5 ml of n-pentane, and 0.5 g of calcium phosphate were added to the reaction kettle, and then N2 gas was used to pressurize to 2.5 MPa, with a saturation time of 16 h and a saturation temperature of 75°C, and a magnetic stirring speed of 800 rpm. After saturation was complete, the reaction kettle was first cooled in a low-temperature ice water bath for 30 min, then the temperature in the reaction kettle was maintained below 10°C, and then low-temperature slow pressure relief was performed, after which the microparticles were collected and the surface moisture was wiped off, transferred to an analytical balance to weigh the mass of PPC-X / n-pentane as m1: 0.2878 g (calculated n-pentane adsorption amount: 10.2%), and quickly transferred to a 75°C hot water bath for foaming experiments, and biodegradable foam beads were prepared after 1 min, and a foam molded body was prepared by molding. Testing showed that the biodegradable foam plastic prepared had a foaming ratio of 26 times, a cell size of 44 μm, a cell density of 1.3 x 10 7 3 cm, a compressive strength of 295 kPa, a tensile strength of 896 kPa, and an elongation at break of 202.2%.

[0041] Example 7

[0042] ​Carbon dioxide-based polyester-polycarbonate tetromer (PPC-X) was dried in a vacuum drying oven at 80℃, and then pelletized using a wire extruder. The temperature of zone 1 of the wire extruder was 145℃, and the temperature of zone 2 was 160℃, yielding microparticles with a length / diameter ratio of 0.9-1.1 and an average weight of 1-3 mg. Microparticles with a mass m0 of 0.1357 g were weighed and placed in a reaction vessel. 45 ml of deionized water, 5 ml of isopentane, and 0.5 g of calcium phosphate were added to the reaction vessel. The pressure was then increased to 1.5 MPa using N2 gas, and the saturation time was 24 h. The saturation temperature was 75℃, and the magnetic stirring speed was 800 rpm. After saturation, the reactor was first cooled in a low-temperature ice-water bath for 30 minutes, maintaining the temperature below 10°C. Then, the pressure was slowly released at low temperature. After depressurization, the microparticles were collected, their surface moisture wiped dry, and the mass of PPC-X / isopentane was weighed on an analytical balance to be m1: 0.1468 g (the calculated isopentane adsorption rate was 8.2%). The mixture was then rapidly transferred to a 75°C hot water bath for foaming experiments. Biodegradable foam beads were obtained after 1 minute, and foam molded bodies were prepared using compression molding. Testing showed that the prepared biodegradable foam plastic had a foaming ratio of 25 times, a cell size of 40 μm, and a cell density of 1.4 × 10⁻⁶. 7 Bubble size / cm 3 The compressive strength is 285 kPa, the tensile strength is 876 kPa, and the elongation at break is 207.9%.

[0043] Example 8

[0044] Carbon dioxide-based polyester-polycarbonate tetromer (PPC-X) was dried in a vacuum drying oven at 80℃, and then pelletized using a wire extruder. The temperature of zone 1 of the wire extruder was 145℃, and the temperature of zone 2 was 160℃, yielding microparticles with a length / diameter ratio of 0.9-1.1 and an average weight of 1-3 mg. Microparticles with a mass m0 of 0.2534 g were weighed and placed in a reaction vessel. 45 ml of deionized water, 5 ml of isopentane, and 0.5 g of calcium phosphate were added to the reaction vessel. The pressure was then increased to 2.5 MPa using N2 gas, and the saturation time was 16 h. The saturation temperature was 75℃, and the magnetic stirring speed was 800 rpm. After saturation, the reactor was first cooled in a low-temperature ice-water bath for 30 minutes, maintaining the temperature below 10°C. Then, the pressure was slowly released at low temperature. After depressurization, the microparticles were collected, their surface moisture wiped dry, and the mass of PPC-X / isopentane was weighed on an analytical balance to be m1: 0.2820 g (the calculated isopentane adsorption capacity was 11.3%). The mixture was then quickly transferred to a 75°C hot water bath for foaming experiments. Biodegradable foam beads were obtained after 1 minute, and foam molded bodies were prepared by compression molding. Testing showed that the prepared biodegradable foam plastic had a foaming ratio of 28 times, a cell size of 51 μm, and a cell density of 1.2 × 10⁻⁶. 7 Bubble size / cm 3 The compressive strength is 307 kPa, the tensile strength is 918 kPa, and the elongation at break is 206.1%.

[0045] Example 9

[0046] The carbon dioxide-based polyester-polycarbonate quaternary copolymer 80 parts and cassava starch 20 parts were blended in a torque blender for 10 min at 150 °C and 60 rpm to obtain a blended composite. After drying the carbon dioxide-based polyester-polycarbonate blended composite in a vacuum drying oven at 80 °C, the micro-particles with a length / diameter ratio of 0.9-1.1 and an average weight of 1-3 mg were obtained by using a wire extruder to pull strands and cut them into particles. The wire extruder had a temperature of 145 °C in zone 1 and 160 °C in zone 2. Then, 0.4258 g of the micro-particles were weighed and placed in a reaction kettle. 45 ml of deionized water, 5 ml of n-pentane, and 0.5 g of calcium phosphate were added to the reaction kettle. The reaction kettle was pressurized to 3.0 MPa using N2 gas. The saturation time was 12 h, the saturation temperature was 75 °C, and the magnetic stirrer speed was 800 rpm. After saturation was complete, the reaction kettle was cooled in an ice water bath for 30 min. The temperature in the reaction kettle was maintained below 10 °C. Then, the pressure was slowly released at low temperature. After the pressure was released, the micro-particles were collected and the surface moisture was wiped off. The mass of the PPC-X / n-pentane was m1: 0.4556 g (calculated n-pentane adsorption amount: 7.0%). The mass was quickly transferred to a hot water bath at 70 °C for foaming experiments. Biodegradable foam beads were prepared after 1 min. Foam molded bodies were prepared by molding. 6 The cell size was 90 μm, the cell density was 9.2 x 10 3 The compressive strength was 330 kPa, the tensile strength was 923 kPa, and the elongation at break was 204.7%.

[0047] Comparative Example 1

[0048] 10 phr of 4,4'-oxadiazolesulfonyl hydrazide (OBSH foaming agent) and carbon dioxide-based polyester-polycarbonate quaternary copolymer were blended in a torque blender for 10 min at 150 °C and 60 rpm to obtain a blended polymer.

[0049] Then, the blended polymer was used to pull strands and cut them into particles using a wire extruder. The wire extruder had a temperature of 145 °C in zone 1 and 160 °C in zone 2. The micro-particles with a length / diameter ratio of 0.9-1.1 and an average weight of 1-3 mg were obtained. Then, 0.1053 g of the micro-particles were weighed and placed in a forced air oven at 180 °C. The foaming time was 20 min. Biodegradable PPC-X foam beads were obtained. Foam molded bodies were prepared by molding. The biodegradable foam plastic prepared had a foaming ratio of 10 times, a cell size of 159 μm, a cell density of 3.0 x 10 6 The cell size was 90 μm, the cell density was 9.2 x 10 3The compression strength is 127 kPa, the tensile strength is 357 kPa, and the elongation at break is 93.3%.

[0050] It can be seen that the physical foaming agent (n-pentane or iso-pentane) adsorption amount in the polymer PPC-X is greater than 7% by the kettle pressure foaming method, that is, under the conditions of high pressure and high temperature, and the foaming agent is well stored in PPC-X. And by adjusting different saturation pressures, saturation times, and foaming temperatures, biodegradable foam plastics with high foaming ratios can be prepared, and the obtained foam plastics have certain flexibility and resilience.

Claims

1. A biodegradable quaternary copolymer foam, characterized in that, Composed of the following components in parts by mass composition: 88-95 parts of carbon dioxide-based polyester-polycarbonate tetromer 5-12 parts of physical foaming agent; The physical foaming agent is one or both of n-pentane and isopentane; it is a foamed plastic prepared by autoclaving. The carbon dioxide-based polyester-polycarbonate quaternary copolymer is a high molecular weight polymer obtained by quaternary copolymerization of phthalic anhydride, tetrachlorophthalic anhydride, propylene oxide and carbon dioxide, with a number average molecular weight of 50,000 to 150,000; its structure is shown in formula (1); wherein m≥1, n≥1, k>0, j≥0; m, n, k, and j are all integers; 2. The biodegradable quaternary copolymer foam according to claim 1, characterized in that, Organic fillers are also added, with the weight of the organic fillers being 1-40% of the biodegradable quaternary copolymer foam.

3. The biodegradable quaternary copolymer foam according to claim 2, characterized in that, The organic filler is selected from one or more of corn starch, wheat starch, sweet potato starch, and lignin fiber powder.

4. A method for preparing the biodegradable quaternary copolymer foam plastic according to claim 1, characterized in that, Includes the following steps: (1) Carbon dioxide-based polyester-polycarbonate quaternary copolymer was granulated into microparticles using a wire extruder; (2) Place the microparticles in a high-pressure reactor, first load the dispersion medium, physical foaming agent and separating agent, then inject N2, and obtain homogeneous materials with different foaming agent adsorption contents by setting the saturation pressure, saturation time and saturation temperature in the reactor. (3) After the physical foaming agent is saturated, the reactor is first cooled at low temperature and then slowly depressurized at low temperature. After depressurization, the mixture is transferred to an analytical balance to confirm the amount of physical foaming agent adsorbed, and then transferred to a hot water bath for foaming. The foam beads after foaming are collected and foam molded by compression molding.

5. The method for preparing biodegradable quaternary copolymer foam according to claim 4, characterized in that, The length-to-diameter ratio of the microparticles is 0.5-2, and the average weight of the microparticles is 0.1-20 mg.

6. The method for preparing biodegradable quaternary copolymer foam according to claim 4, characterized in that, The saturation temperature is 75℃; the saturation pressure is 2.0MPa-5.0MPa; the saturation time is 6h-24h; and the temperature of the hot water bath is 55℃-85℃.

7. The method for preparing biodegradable quaternary copolymer foam according to claim 4, characterized in that, The dispersion medium is deionized water, and the separating agent is calcium phosphate.

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