Polyethylene terephthalate-2,5-furandicarboxylate glycol copolyester foam and method of making

Abstract

The application relates to a polyethylene glycol-2,5-furandicarboxylic acid terephthalate copolymer foaming material and a preparation method thereof, and the preparation method comprises the following steps: melting polyethylene glycol-2,5-furandicarboxylic acid terephthalate copolymer, and then performing quenching treatment to obtain sheet material; performing annealing treatment on the sheet material, wherein the annealing treatment temperature is (T-25) DEG C to (T+5) DEG C, T is the cold crystallization starting temperature of the polyethylene glycol-2,5-furandicarboxylic acid terephthalate copolymer, and the annealing treatment time is 3 min to 30 min; the sheet material after the annealing treatment is adsorbed and saturated in a foaming gas to obtain a saturated system, and the saturated system is foamed in a foaming medium to obtain the polyethylene glycol-2,5-furandicarboxylic acid terephthalate copolymer foaming material. The polyethylene glycol-2,5-furandicarboxylic acid terephthalate copolymer foaming material obtained by the application has a cell size of 2 mu m to 200 mu m and an expansion ratio of 1.5 times to 15 times, and has a good application prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of foamed materials, in particular to a poly(ethylene 2,5-furandicarboxylate) foamed material and a preparation method thereof. BACKGROUND

[0002] The mass production and use of traditional petroleum-based polymer foamed materials such as poly(ethylene terephthalate) (PET) have brought great convenience to human life, but also led to the problem of resource shortage. In addition, poly(ethylene terephthalate) with linear molecular chain structure usually exhibits low melt strength and slow crystallization rate, etc., so it is easy to cause bubble rupture and bubble wall collapse during foaming, and it is difficult to obtain foamed materials with small and uniform cell size and excellent performance.

[0003] Moreover, the conditions for preparing microcellular foamed materials with small cell size (1-10 μm) and high cell density are often harsh, such as high saturation pressure and high pressure release rate, which puts high requirements on the safety and reliability of the equipment. At the same time, during the foaming process, how to control the cell morphology of the foamed material by promoting cell nucleation and controlling cell growth is also a great challenge. SUMMARY

[0004] Therefore, it is necessary to provide a poly(ethylene 2,5-furandicarboxylate) foamed material and a preparation method thereof to solve the above problems. The poly(ethylene 2,5-furandicarboxylate) foamed material obtained by the preparation method has uniform cell size and appropriate expansion ratio, even reaching the category of microcellular foamed materials, and has good application prospects in the fields of packaging materials, daily necessities, household appliances, sports, building transportation and separation membranes, etc. At the same time, the use of biologically derived 2,5-furandicarboxylic acid partially reduces the dependence of organic polymer materials on petrochemical resources.

[0005] A preparation method of a poly(ethylene 2,5-furandicarboxylate) foamed material, comprising the following steps:

[0006] melting the poly(ethylene 2,5-furandicarboxylate) and then performing quenching treatment to obtain a sheet material;

[0007] performing annealing treatment on the sheet material, wherein the temperature of the annealing treatment is (T-25)℃-(T+5)℃, T is the cold crystallization onset temperature of the poly(ethylene 2,5-furandicarboxylate), and the time of the annealing treatment is 3-30 min;

[0008] performing adsorption saturation on the sheet material after the annealing treatment in a foaming gas to obtain a saturated system;

[0009] foaming the saturated system in a foaming medium, and cooling to obtain a poly(ethylene-co-2,5-furandicarboxylate) foamed material.

[0010] In one embodiment, the quenching medium is selected from ice water or liquid nitrogen.

[0011] In one embodiment, the poly(ethylene-co-2,5-furandicarboxylate) is a random copolymer, wherein the comonomer 2,5-furandicarboxylic acid is within 20% of the total molar amount of diacids in the poly(ethylene-co-2,5-furandicarboxylate).

[0012] In one embodiment, the sheet material has a thickness greater than 0.5 mm and less than 2 mm.

[0013] In one embodiment, the annealing temperature is (T-20) °C to T °C.

[0014] In one embodiment, the step of saturating the annealed sheet material in a foaming gas is performed at a pressure of 2 MPa to 6 MPa for 24 h to 120 h.

[0015] In one embodiment, the foaming gas is selected from carbon dioxide or nitrogen.

[0016] In one embodiment, the step of foaming the saturated system in a foaming medium is performed at a temperature of 130 °C to 230 °C for 10 s to 30 s.

[0017] In one embodiment, the foaming medium is selected from dimethyl silicone oil, glycerol, vegetable oil, or motor oil.

[0018] A poly(ethylene-co-2,5-furandicarboxylate) foamed material obtained by the above-mentioned method, wherein the cell size of the poly(ethylene-co-2,5-furandicarboxylate) foamed material is 2 μm to 200 μm, and the expansion ratio is 1.5 to 15.

[0019] In the preparation method of the poly(ethylene terephthalate-2,5-furandicarboxylate) copolyester foam material of the present invention, after the molten poly(ethylene terephthalate-2,5-furandicarboxylate) copolyester is quenched to room temperature, the molecular chains do not have time to arrange themselves in a regular manner, and the crystallinity of the system is extremely low, almost amorphous. However, when heated to a suitable temperature, the chain segments can move, the molecular chains arrange themselves in a regular manner, and cold crystallization occurs. Therefore, after annealing, crystalline regions will form inside the sheet material. Among them, the nucleation energy barrier at the interface between the crystalline and amorphous regions is low, which can promote cell nucleation, increase the nucleation density, and generate fine and uniform cells. At the same time, by controlling the cold crystallization through the annealing process, sheet materials with different crystallinities can be obtained, thus laying the foundation for controllable cell morphology. Furthermore, the solid-state intermittent foaming method can achieve precise control of the cell structure, resulting in polyethylene terephthalate-2,5-furandicarboxylate copolyester foamed materials with uniform cell size, appropriate expansion ratio, and even reaching the category of microporous foamed materials. These materials have promising application prospects in packaging materials, daily necessities, home appliances, sports, construction and transportation, and separation membranes.

[0020] Meanwhile, in the polyethylene terephthalate-2,5-furandicarboxylate copolyester foaming material of the present invention, a portion of polyethylene 2,5-furandicarboxylate is used to replace polyethylene terephthalate, which can alleviate the problem of petroleum resource shortage. Moreover, the foaming method of the present invention has low equipment requirements, simple process and low energy consumption. Attached Figure Description

[0021] Figure 1 This is a cross-sectional scanning electron microscope image of the polyethylene terephthalate-2,5-furandicarboxylic acid copolyester foam material obtained in Example 1 of the present invention.

[0022] Figure 2 This is a cross-sectional scanning electron microscope image of the polyethylene terephthalate-2,5-furandicarboxylate copolyester foam material obtained in Example 2 of the present invention.

[0023] Figure 3 for Figure 2 Enlarged image;

[0024] Figure 4 This is a cross-sectional scanning electron microscope image of the polyethylene terephthalate-2,5-furandicarboxylate copolyester foam material obtained in Example 3 of the present invention.

[0025] Figure 5 This is a cross-sectional scanning electron microscope image of the polyethylene terephthalate-2,5-furandicarboxylate copolyester foam material obtained in Example 4 of the present invention.

[0026] Figure 6Cross-sectional scanning electron microscope image of the foamed sample of polyethylene terephthalate-2,5-furandicarboxylate glycol copolymer obtained for the inventive comparative example 1;

[0027] Figure 7 Cross-sectional scanning electron microscope image of the foamed sample of polyethylene terephthalate-2,5-furandicarboxylate glycol copolymer obtained for the inventive comparative example 3;

[0028] Figure 8 Differential scanning calorimetry heating curve of polyethylene terephthalate glycol quenched from the melt and polyethylene terephthalate-2,5-furandicarboxylate glycol copolymer quenched from the melt used in the inventive examples. DETAILED DESCRIPTION

[0029] The polyethylene terephthalate-2,5-furandicarboxylate glycol copolymer foamed material provided by the present application and the preparation method thereof will be further described below.

[0030] Polyethylene 2,5-furandicarboxylate (PEF) is a bio-based polyester synthesized by 2,5-furandicarboxylic acid (FDCA) and ethylene glycol through polycondensation reaction. Compared with polyethylene terephthalate (PET), polyethylene 2,5-furandicarboxylate not only greatly reduces the consumption of petrochemical resources and the emission of greenhouse gases in the production process, but also has similar structure, performance and terephthalic acid (TPA) to 2,5-furandicarboxylic acid. Therefore, polyethylene 2,5-furandicarboxylate is expected to become a new furan-based polyester to replace polyethylene terephthalate.

[0031] However, in the foaming process, polyethylene 2,5-furandicarboxylate has strong gas barrier property, which makes the diffusion rate of the gas foaming agent in the polymer matrix slow and the solubility very low. In addition, polyethylene 2,5-furandicarboxylate is expensive, has slow crystallization rate, poor impact toughness and is not easy to process, which seriously restricts the application of polyethylene 2,5-furandicarboxylate in the foaming field.

[0032] On the other hand, polyethylene terephthalate-2,5-furandicarboxylate glycol (PEFT) copolymer molecular chain also contains terephthalic acid units, which can also endow the material with better crystallinity, toughness, gas adsorption and processability. Therefore, by partially replacing polyethylene terephthalate with polyethylene 2,5-furandicarboxylate, the polyethylene terephthalate-2,5-furandicarboxylate glycol copolymer prepared by copolymerization has more excellent physical properties.

[0033] Therefore, the application provides a preparation method of poly(ethylene 2,5-furandicarboxylate) foamed material, which comprises the following steps.

[0034] S1, melt poly(ethylene 2,5-furandicarboxylate), and then perform quenching treatment to obtain a sheet material;

[0035] S2, perform annealing treatment on the sheet material, wherein the annealing treatment is performed at a temperature of (T-25)℃-(T+5)℃, T is the cold crystallization onset temperature of the poly(ethylene 2,5-furandicarboxylate), and the annealing treatment is performed for 3-30 minutes;

[0036] S3, perform adsorption saturation on the sheet material after the annealing treatment in a foaming gas to obtain a saturated system;

[0037] S4, foam the saturated system in a foaming medium, and obtain poly(ethylene 2,5-furandicarboxylate) foamed material after cooling.

[0038] In step S1, the preparation of the sheet material is specifically as follows: provide a mold for the sheet material, place poly(ethylene 2,5-furandicarboxylate) in the mold, heat-press the poly(ethylene 2,5-furandicarboxylate) into a preform in a molten state, then place the mold carrying the preform in a medium for quenching treatment, rapidly quench the preform to below the glass transition temperature, and obtain the sheet material.

[0039] Optionally, the quenching treatment medium is selected from ice water or liquid nitrogen.

[0040] Optionally, the thickness of the sheet material is greater than 0.5 mm and less than 2 mm, so that the foaming gas can better diffuse in step S3, the saturation adsorption time is shortened, and the speed of the foaming gas escaping in the foaming process in step S4 can be better controlled, so as to ensure the cell size of the foamed material.

[0041] Optionally, the poly(ethylene 2,5-furandicarboxylate) is a random copolymer, and the content of the comonomer 2,5-furandicarboxylic acid accounts for 20% or less of the total molar amount of the diacids in the poly(ethylene 2,5-furandicarboxylate), so as to better ensure the crystallization ability of the poly(ethylene 2,5-furandicarboxylate), and further facilitate the regulation of the cold crystallization by the annealing process to endow the sheet material with different crystallinities.

[0042] Optionally, the poly(ethylene 2,5-furandicarboxylate) is prepared by an esterification polycondensation method.

[0043] The structure and properties of poly(ethylene 2,5-furandicarboxylate) are greatly influenced by the thermal history of the polymer. The poly(ethylene 2,5-furandicarboxylate) has a rigid molecular chain and a slow crystallization rate. The poly(ethylene 2,5-furandicarboxylate) obtained by quenching from the melt has a disordered molecular chain segment and a very low crystallinity, almost in an amorphous state. When heated to a suitable temperature, the molecular chain moves and arranges regularly, and cold crystallization occurs.

[0044] Therefore, above the glass transition temperature, the crystallization perfection can be controlled by annealing treatment. However, if the annealing treatment temperature is too low, the molecular chain movement ability is relatively small, and the crystallinity after annealing treatment does not change too much, which has little effect on the foaming behavior. If the annealing treatment temperature is too high, the molecular chain movement ability is too strong, which can cause the crystallinity to increase rapidly, resulting in a decrease in gas solubility and a significant increase in the rigidity of the matrix, thereby limiting the cell nucleation and growth, resulting in a large number of unfoamed areas in the foamed material, or even completely unable to foam, so the suitable annealing treatment temperature range is extremely critical.

[0045] Within the suitable annealing treatment temperature range, at a higher annealing temperature, the molecular chain movement ability is larger, and the crystallinity increases faster. At a lower annealing temperature, the molecular chain needs a longer annealing time to arrange regularly, and the crystallinity increases slowly. Therefore, within the suitable annealing temperature range, the crystallization perfection of the poly(ethylene 2,5-furandicarboxylate) can be controlled by increasing the annealing temperature while reducing the annealing time, or by reducing the annealing temperature while extending the annealing time, so as to regulate the cell structure.

[0046] In addition, the content of the comonomer 2,5-furandicarboxylic acid has a great influence on the cold crystallization onset temperature of the poly(ethylene 2,5-furandicarboxylate). With the increase of the content of 2,5-furandicarboxylic acid, the cold crystallization onset temperature gradually shifts to a high temperature direction, making crystallization more difficult, and therefore a higher annealing treatment temperature is required.

[0047] Therefore, when the annealing process of step S2 of the present application is adopted, a crystalline region will be formed inside the poly(ethylene 2,5-furandicarboxylate) sheet material. The nucleation energy barrier at the interface between the crystalline region and the amorphous region is low, which can promote cell nucleation and increase the nucleation density, generating fine and uniform cells. At the same time, different crystallinity of the sheet material can be obtained by adjusting the cold crystallization through the annealing process, thereby laying a foundation for the controllable cell morphology.

[0048] Optionally, the annealing treatment temperature is (T-20)℃-T℃, so as to better control the crystallinity of the sheet material.

[0049] Optionally, the polyethylene-2,5-furandicarboxylate glycol copolyester sheet material is annealed in a temperature control device selected from an electric heating air drying oven, a vacuum drying oven, a flat plate curing machine or a constant temperature and humidity test chamber, and the process of cold crystallization is regulated by controlling the temperature and time of annealing, so that the sheet material with different crystallinity is obtained.

[0050] In step S3, the annealed sheet material is saturated and adsorbed in a foaming gas, the pressure of the foaming gas is 2-6 MPa, the pressure holding time is 24-120 h, and the foaming gas is selected from carbon dioxide or nitrogen.

[0051] The foaming gas carbon dioxide can also play a plasticizing role in the polymer matrix, increase the activity of the molecular chain, and the crystallization energy barrier of the polymer is lower, which is beneficial to increase the crystallization density to obtain uniformly distributed cells, so the foaming gas is preferably carbon dioxide.

[0052] In step S4, the saturated system is foamed in a foaming medium, the foaming temperature is 130-230 DEG C, the foaming time is 10-30 s, and the foaming medium is selected from dimethyl silicone oil, glycerol, vegetable oil or machine oil.

[0053] Therefore, the polyethylene-2,5-furandicarboxylate glycol copolyester sheet material obtained by melt quenching is almost amorphous, then the different crystallinity of the sheet material is given by regulating the cold crystallization using the annealing process, and finally the foaming material of the polyethylene-2,5-furandicarboxylate glycol copolyester sheet material with uniform cell size, suitable expansion ratio and even reaching the microcell range is prepared by the solid intermittent foaming method.

[0054] Meanwhile, in the polyethylene-2,5-furandicarboxylate glycol copolyester foaming material of the application, part of the polyethylene-2,5-furandicarboxylate glycol copolyester segment is used instead of the polyethylene terephthalate glycol copolyester segment, which can alleviate the problems of shortage of petroleum resources and environmental pollution, and the solid intermittent foaming method adopted in the application has low equipment requirements, simple process and low energy consumption.

[0055] Based on this, the application also provides the polyethylene-2,5-furandicarboxylate glycol copolyester foaming material prepared by the above preparation method, the cell size of the polyethylene-2,5-furandicarboxylate glycol copolyester foaming material is 2-200 μm, the expansion ratio is 1.5-15 times, and the polyethylene-2,5-furandicarboxylate glycol copolyester foaming material has good application prospect in the fields of packaging materials, daily necessities, household appliances, sports, building transportation and separation membranes.

[0056] Hereinafter, the poly(ethylene 2,5-furandicarboxylate) foamed material and the preparation method thereof will be further described through specific examples and comparative examples.

[0057] In the following examples and comparative examples, the mole content of the comonomer 2,5-furandicarboxylic acid in the poly(ethylene 2,5-furandicarboxylate) accounts for X% of the total mole content of the diacids in the poly(ethylene 2,5-furandicarboxylate), and is named as PEFTX%, and the intrinsic viscosity of the poly(ethylene 2,5-furandicarboxylate) is about 0.8.

[0058] wherein, Figure 8 In the following examples and comparative examples, the mole content of the comonomer 2,5-furandicarboxylic acid in the poly(ethylene 2,5-furandicarboxylate) accounts for X% of the total mole content of the diacids in the poly(ethylene 2,5-furandicarboxylate), and is named as PEFTX%, and the intrinsic viscosity of the poly(ethylene 2,5-furandicarboxylate) is about 0.8. Figure 8 It can be seen that, with the increase of the content of 2,5-furandicarboxylic acid, the cold crystallization onset temperature gradually shifts to high temperature, which indicates that the crystallization becomes more difficult, and thus a higher annealing temperature is required.

[0059] Example 1:

[0060] The plastic particles of PEFT5% were placed in a mold, and a molding machine with a temperature of 280℃ and a pressure of 10MPa was used to mold for 5min to obtain a preform in a molten state. Then, the mold carrying the preform was quickly placed in an ice water bath for quenching treatment to obtain a PEFT5% sheet material, and the thickness of the sheet material was 1mm. The cold crystallization onset temperature of PEFT5% was 115.1℃.

[0061] The PEFT5% sheet material was placed in an electric heating air drying oven for annealing treatment, and the annealing temperature was set to 108℃ and the annealing time was set to 10min.

[0062] The PEFT5% sheet material after annealing treatment was placed in an autoclave, and 4MPa of carbon dioxide gas was introduced into the autoclave, and the pressure holding time was set to 72h. After saturation was completed, the pressure in the autoclave was released to obtain a saturated system. The saturated system was transferred to dimethyl silicone oil with a temperature of 180℃ for foaming for 20s, and finally the sample was placed in an ice water bath to fix the cell morphology, to obtain a poly(ethylene 2,5-furandicarboxylate) foamed material.

[0063] The cross section of the poly(ethylene 2,5-furandicarboxylate) foamed material was scanned and analyzed, and the results were as follows: Figure 1As shown in FIG. 1 and FIG. 2, the cell size distribution of the polyethylene terephthalate-2,5-furandicarboxylate glycol copolymer foamed material is uniform, the cell size is 48.7 μm, and the expansion ratio is 5.8 times.

[0064] Example 2:

[0065] The plastic particles of PEFT 5% were placed in a mold, and a molding machine with a temperature of 280°C and a pressure of 10 MPa was used to mold for 5 min to obtain a preform in a molten state. Then, the mold carrying the preform was quickly placed in an ice water bath for quenching treatment to obtain a PEFT 5% sheet material. The thickness of the sheet material was 1 mm, and the cold crystallization onset temperature of PEFT 5% was 115.1°C.

[0066] The PEFT 5% sheet material was placed in an electric heating air drying oven for annealing treatment. The annealing temperature was set to 110°C, and the annealing time was set to 10 min.

[0067] The PEFT 5% sheet material after annealing treatment was placed in an autoclave, and 4 MPa of carbon dioxide gas was introduced into the autoclave. The pressure holding time was set to 72 h. After saturation was completed, the pressure in the autoclave was released to obtain a saturated system. The saturated system was transferred to dimethyl silicone oil at a temperature of 180°C for foaming for 20 s. Finally, the sample was placed in an ice water bath to fix the cell morphology, and a polyethylene terephthalate-2,5-furandicarboxylate glycol copolymer foamed material was obtained.

[0068] The cross section of the polyethylene terephthalate-2,5-furandicarboxylate glycol copolymer foamed material was scanned and analyzed, and the results are shown in FIG. 3 and FIG. 4. Figure 2 and Figure 3 As shown in FIG. 3 and FIG. 4, the cell size of the polyethylene terephthalate-2,5-furandicarboxylate glycol copolymer foamed material is in the micron range, the cell size is 2.8 μm, and the expansion ratio is 2.2 times.

[0069] Example 3:

[0070] The plastic particles of PEFT 10% were placed in a mold, and a molding machine with a temperature of 280°C and a pressure of 10 MPa was used to mold for 5 min to obtain a preform in a molten state. Then, the mold carrying the preform was quickly placed in an ice water bath for quenching treatment to obtain a PEFT 10% sheet material. The thickness of the sheet material was 1 mm, and the cold crystallization onset temperature of PEFT 10% was 123.5°C.

[0071] The PEFT 10% sheet material was placed in an electric heating air drying oven for annealing treatment. The annealing temperature was set to 113°C, and the annealing time was set to 10 min.

[0072] The PEFT 10% sheet material after annealing treatment was placed in an autoclave, 4 MPa of carbon dioxide gas was introduced into the autoclave, the pressure holding time was set to 72 h, after saturation was completed, the pressure in the autoclave was unloaded, and a saturated system was obtained. The saturated system was transferred to dimethyl silicone oil at a temperature of 150°C for foaming for 20 s, and finally the sample was placed in an ice water bath to fix the cell morphology, and a polyethylene terephthalate-2,5-furandicarboxylate glycol copolymer foamed material was obtained.

[0073] The cross section of the polyethylene terephthalate-2,5-furandicarboxylate glycol copolymer foamed material was scanned and analyzed, and the results are shown in Figure 4 The cell size distribution of the polyethylene terephthalate-2,5-furandicarboxylate glycol copolymer foamed material was uniform, the cell size was 108.4 μm, and the expansion ratio was 4.2 times.

[0074] Example 4:

[0075] The PEFT 10% plastic particles were placed in a mold, and a molding machine with a temperature of 280°C and a pressure of 10 MPa was used to mold for 5 min to obtain a preform in a molten state. Then the mold carrying the preform was quickly placed in an ice water bath for quenching treatment to obtain a PEFT 10% sheet material. The thickness of the sheet material was 1 mm, and the cold crystallization onset temperature of the PEFT 10% was 123.5°C.

[0076] The PEFT 10% sheet material was placed in an electric heating air drying oven for annealing treatment, the annealing temperature was set to 118°C, and the annealing time was set to 10 min.

[0077] The PEFT 10% sheet material after annealing treatment was placed in an autoclave, 4 MPa of carbon dioxide gas was introduced into the autoclave, the pressure holding time was set to 72 h, after saturation was completed, the pressure in the autoclave was unloaded, and a saturated system was obtained. The saturated system was transferred to dimethyl silicone oil at a temperature of 150°C for foaming for 20 s, and finally the sample was placed in an ice water bath to fix the cell morphology, and a polyethylene terephthalate-2,5-furandicarboxylate glycol copolymer foamed material was obtained.

[0078] The cross section of the polyethylene terephthalate-2,5-furandicarboxylate glycol copolymer foamed material was scanned and analyzed, and the results are shown in Figure 5 The cell size of the polyethylene terephthalate-2,5-furandicarboxylate glycol copolymer foamed material was in the micron range, the cell size was 3.2 μm, and the expansion ratio was 2.5 times.

[0079] Example 5:

[0080] The plastic particles of PEFT15% were placed in a mold, and a molding machine with a temperature of 280℃ and a pressure of 10 MPa was used to mold for 5 min to obtain a preform in a molten state. Then, the mold carrying the preform was quickly placed in an ice water bath for quenching treatment to obtain a PEFT15% sheet material. The thickness of the sheet material was 1 mm, and the cold crystallization onset temperature of PEFT15% was 128.4℃.

[0081] The PEFT15% sheet material was placed in an electric heating air drying oven for annealing treatment. The annealing temperature was set to 115℃, and the annealing time was set to 10 min.

[0082] The PEFT15% sheet material after annealing treatment was placed in an autoclave, and 4 MPa of carbon dioxide gas was introduced into the autoclave. The pressure holding time was set to 72 h. After saturation was completed, the pressure in the autoclave was released to obtain a saturated system. The saturated system was transferred to dimethyl silicone oil at a temperature of 150℃ for foaming for 20 s. Finally, the sample was placed in an ice water bath to fix the cell morphology, and a polyethylene terephthalate-2,5-furandicarboxylate glycol copolymer foamed material was obtained.

[0083] The cross section of the polyethylene terephthalate-2,5-furandicarboxylate glycol copolymer foamed material was scanned and analyzed. The cell size distribution of the polyethylene terephthalate-2,5-furandicarboxylate glycol copolymer foamed material was uniform, the cell size was 65.5 μm, and the expansion ratio was 6.0 times.

[0084] Comparative Example 1:

[0085] The plastic particles of PEFT5% were placed in a mold, and a molding machine with a temperature of 280℃ and a pressure of 10 MPa was used to mold for 5 min to obtain a preform in a molten state. Then, the mold carrying the preform was quickly placed in an ice water bath for quenching treatment to obtain a PEFT5% sheet material. The thickness of the sheet material was 1 mm, and the cold crystallization onset temperature of PEFT5% was 115.1℃.

[0086] The PEFT5% sheet material was directly placed in an autoclave, and 4 MPa of carbon dioxide gas was introduced into the autoclave. The pressure holding time was set to 72 h. After saturation was completed, the pressure in the autoclave was released to obtain a saturated system. The saturated system was transferred to dimethyl silicone oil at a temperature of 180℃ for foaming for 20 s. Finally, the sample was placed in an ice water bath to fix the cell morphology, and a polyethylene terephthalate-2,5-furandicarboxylate glycol copolymer foamed sample was obtained.

[0087] The cross section of the polyethylene terephthalate-2,5-furandicarboxylate glycol copolymer foamed sample was scanned and analyzed. The results are shown in Table 1. Figure 6As shown, the cell coalescence and cell wall rupture phenomenon of the polyethylene terephthalate-2,5-furandicarboxylate glycol copolymer foamed sample is very serious.

[0088] Comparative Example 2:

[0089] The plastic particles of PEFT 5% were placed in a mold, and a molding machine with a temperature of 280°C and a pressure of 10 MPa was used to mold for 5 min to obtain a preform in a molten state. Then, the mold carrying the preform was quickly placed in an ice water bath for quenching treatment to obtain a PEFT 5% sheet material. The thickness of the sheet material was 1 mm, and the cold crystallization onset temperature of the PEFT 5% was 115.1°C.

[0090] The PEFT 5% sheet material was placed in an electric heating air drying oven for annealing treatment. The annealing temperature was set to 85°C, and the annealing time was set to 10 min.

[0091] The PEFT 5% sheet material after annealing treatment was placed in an autoclave, and 4 MPa of carbon dioxide gas was introduced into the autoclave. The pressure holding time was set to 72 h. After saturation was completed, the pressure in the autoclave was released to obtain a saturated system. The saturated system was transferred to dimethyl silicone oil at a temperature of 180°C for foaming for 20 s. Finally, the sample was placed in an ice water bath to fix the cell morphology to obtain a polyethylene terephthalate-2,5-furandicarboxylate glycol copolymer foamed sample.

[0092] The cross section of the polyethylene terephthalate-2,5-furandicarboxylate glycol copolymer foamed sample was scanned and analyzed. The cell coalescence and cell wall rupture phenomenon of the polyethylene terephthalate-2,5-furandicarboxylate glycol copolymer foamed sample was very serious.

[0093] Comparative Example 3:

[0094] The plastic particles of PEFT 10% were placed in a mold, and a molding machine with a temperature of 280°C and a pressure of 10 MPa was used to mold for 5 min to obtain a preform in a molten state. Then, the mold carrying the preform was quickly placed in an ice water bath for quenching treatment to obtain a PEFT 10% sheet material. The thickness of the sheet material was 1 mm, and the cold crystallization onset temperature of the PEFT 10% was 123.5°C.

[0095] The PEFT 10% sheet material was placed in an electric heating air drying oven for annealing treatment. The annealing temperature was set to 130°C, and the annealing time was set to 10 min.

[0096] The PEFT 10% flaky material after annealing treatment was placed in an autoclave, 4 MPa of carbon dioxide gas was introduced into the autoclave, the pressure holding time was set to 72 h, after saturation was completed, the pressure in the autoclave was unloaded, and a saturated system was obtained. The saturated system was transferred to dimethyl silicone oil at a temperature of 150°C for foaming for 20 s, and finally the sample was placed in an ice water bath to fix the cell morphology, and a polyethylene terephthalate-2,5-furan dicarboxylic acid glycol copolymer foamed sample was obtained.

[0097] The cross section of the polyethylene terephthalate-2,5-furan dicarboxylic acid glycol copolymer foamed sample was scanned and analyzed, and the results are shown in Figure 7 The inside of the polyethylene terephthalate-2,5-furan dicarboxylic acid glycol copolymer foamed sample cannot be foamed at all.

[0098] The technical features of the above-described embodiments can be combined arbitrarily, and for the sake of brevity, all possible combinations of the technical features in the above-described embodiments are not described, however, as long as the combinations of the technical features do not contradict, they should be considered as the scope of the description.

[0099] The above-described embodiments only express several embodiments of the present application, and the description is more specific and detailed, but it should not be understood as limiting the scope of the patent. It should be noted that for ordinary skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are within the scope of the present application. Therefore, the scope of protection of the patent of the present application should be subject to the appended claims.

Claims

1. A method for producing a polyethylene-2,5-furandicarboxylate glycol copolyester foamed material, characterized by, The method comprises the following steps: melting polyethylene glycol-co-2,5-furandicarboxylic acid terephthalate, and then quenching to obtain a sheet material, wherein the polyethylene glycol-co-2,5-furandicarboxylic acid terephthalate is a random copolymer, and the content of the comonomer 2,5-furandicarboxylic acid accounts for 5%-20% of the total molar amount of the diacid in the polyethylene glycol-co-2,5-furandicarboxylic acid terephthalate; when the content of the comonomer 2,5-furandicarboxylic acid accounts for 5% of the total molar amount of the diacid in the polyethylene glycol-co-2,5-furandicarboxylic acid terephthalate, the cold crystallization onset temperature is 115.1°C, and the cold crystallization onset temperature gradually shifts to a high temperature direction with the increase of the content of 2,5-furandicarboxylic acid; annealing the sheet material, wherein the annealing temperature is (T-20)°C-T°C, T is the cold crystallization onset temperature of the polyethylene glycol-co-2,5-furandicarboxylic acid terephthalate, and the annealing time is 3 min-30 min; saturating the annealed sheet material in a foaming gas to obtain a saturated system; foaming the saturated system in a foaming medium to obtain a polyethylene glycol-co-2,5-furandicarboxylic acid terephthalate foaming material after cooling.

2. The method for preparing the polyethylene terephthalate-2,5-furandicarboxylic acid copolyester foam material according to claim 1, characterized in that, The quenching medium is selected from ice water or liquid nitrogen.

3. The method for preparing the polyethylene terephthalate-2,5-furandicarboxylic acid copolyester foam material according to claim 1, characterized in that, The thickness of the sheet material is greater than 0.5 mm and less than 2 mm.

4. The method for preparing the polyethylene terephthalate-2,5-furandicarboxylic acid copolyester foam material according to claim 1, characterized in that, In the step of saturating the annealed sheet material in a foaming gas, the pressure of the foaming gas is 2 MPa-6 MPa, and the pressure maintaining time is 24 h-120 h.

5. The method for preparing the polyethylene terephthalate-2,5-furandicarboxylate copolyester foam material according to claim 1 or 4, characterized in that, The foaming gas is selected from carbon dioxide or nitrogen.

6. The method for preparing the polyethylene terephthalate-2,5-furandicarboxylate copolyester foam material according to claim 1, characterized in that, In the step of foaming the saturated system in a foaming medium, the foaming temperature is 130°C-230°C, and the foaming time is 10 s-30 s.

7. The method for preparing the polyethylene terephthalate-2,5-furandicarboxylate copolyester foam material according to claim 1 or 6, characterized in that, The foaming medium is selected from dimethyl silicone oil, glycerol, vegetable oil or machine oil.

8. A polyethylene-2,5-furandicarboxylate glycol copolyester foam material obtainable by the process according to any one of claims 1 to 7, characterized in that, The cell size of the polyethylene glycol-co-2,5-furandicarboxylic acid terephthalate foaming material is 2 μm-200 μm, and the expansion ratio is 1.5 times-15 times.

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