Degradable bio-based soft foaming material as well as preparation method and application thereof

Abstract

The invention discloses a degradable bio-based soft foaming material as well as a preparation method and application thereof, and belongs to the field of soft foaming materials. According to the technical scheme, the preparation method comprises the following steps: foaming a composite material, wherein the composite material is prepared from polylactic acid, polycaprolactone and a nano filler; the nanofiller is a stripped and modified single-layer zirconium hydrogen phosphate two-dimensional nanosheet. The PLA soft foaming material is applied to the aspects of packaging and transportation packaging materials of electronic and electrical products, solves the problem that an existing PLA soft foaming material is difficult to meet the foaming forming performance and the rapid biodegradability at the same time, and has the rapid degradation rate and the excellent directional foaming forming performance.

Description

Technical Field

[0001] This invention belongs to the field of flexible foam materials, and particularly relates to a biodegradable bio-based flexible foam material, its preparation method and application. Background Technology

[0002] With the formulation of various environmental protection and packaging regulations and the increasing environmental awareness of the public, more and more packaging materials are developing towards green and lightweight directions. Typical foaming materials include polyurethane (PU) foam, polystyrene (PS) foam, polyolefin foam, polyvinyl chloride (PVC) foam, and phenolic foam. However, most of these materials are petroleum-based, resulting in high carbon emissions, difficult and costly recycling, and poor biodegradability after disposal. The resulting white pollution and microplastics pose a significant threat to the ecological environment and human health.

[0003] PLA (polylactic acid) flexible foam material, as a biodegradable and environmentally friendly material, has broad prospects in packaging, cushioning, and medical fields. However, its technological development faces the following core challenges: PLA molecular chains are highly rigid and have poor melt viscoelasticity, making it difficult to effectively encapsulate gas during foaming, which easily leads to cell collapse and tensile strength <1MPa; the cell nucleation density is low, and during supercritical CO2 foaming, PLA has poor compatibility with non-polar foaming agents, resulting in a foaming ratio <20%; it exhibits significant brittleness, with a compression set >40% after foaming at room temperature, making it difficult to meet the requirements of flexible cushioning materials; and there is a contradiction between strength and degradation, requiring cross-linking or blending modification to improve tensile strength, but at the cost of sacrificing biodegradability. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the technical problem to be solved by the present invention is to overcome the problem that existing PLA soft foam materials cannot simultaneously meet the requirements of foaming and molding performance and rapid biodegradability. The present invention proposes a biodegradable bio-based soft foam material with rapid degradation rate and excellent directional foaming and molding performance, its preparation method and application.

[0005] To solve the technical problem, the technical solution adopted by the present invention is as follows:

[0006] This invention provides a biodegradable bio-based soft foam material obtained by foaming a composite material, which includes polylactic acid, polycaprolactone, and nanofillers; the nanofillers are exfoliated modified single-layer zirconium hydrogen phosphate two-dimensional nanosheets.

[0007] In some embodiments, the aspect ratio of the exfoliated modified monolayer zirconium hydrogen phosphate two-dimensional nanosheets is not less than 600:1.

[0008] In some embodiments, the exfoliated modified monolayer zirconium hydrogen phosphate two-dimensional nanosheets are organic amine intercalated modified zirconium hydrogen phosphate nanosheets, wherein the organic amine is selected from at least one of methylamine, n-butylamine, isooctylamine, tetraethylenepentamine, octadecyl dimethyl benzyl ammonium chloride, 3-aminopropyl dimethyl ethoxysilane, and aliphatic polyamines.

[0009] In some embodiments, the molar ratio of organic amine-intercalated modified nano-zirconium hydrogen phosphate to organic amine is 1:5-15.

[0010] In some embodiments, polylactic acid is a copolymer of L-polylactic acid and D-polylactic acid with a melt index of 1.5-10 g / min; polycaprolactone has a melt index of 2-15 g / min.

[0011] In some embodiments, the amount of polylactic acid is selected from any value of 45-70 parts by weight, the amount of polycaprolactone is selected from any value of 30-55 parts, and the nanofiller is selected from any value of 0.5-10 parts.

[0012] In some embodiments, the composite material further includes a compatibilizer and an antioxidant;

[0013] The amount of compatibilizer and antioxidant is selected from any value of 0.5-2 parts by weight.

[0014] The compatibilizer is selected from at least one of aliphatic diesters, polycyclic epoxy oligomers, polyol esters, tributyl citrate, and ethylene-methyl acrylate-glycidyl methacrylate; the antioxidant is selected from at least one of epoxy compounds, mono / polycarbodiimides, antioxidant 1010, and antioxidant 1076.

[0015] Another aspect of the present invention provides a method for preparing a biodegradable bio-based flexible foam material according to any of the above-mentioned technical solutions, comprising:

[0016] The nanofiller preparation steps are as follows: nano-zirconium hydrogen phosphate is added to anhydrous ethanol and stirred, then an organic amine solution is added, ultrasonically stirred for 0.5-1.0 h, separated, washed, and dried at 55-65℃ to obtain the nanofiller.

[0017] In the granulation step, polylactic acid, polycaprolactone, compatibilizer, and antioxidant are added to a high-speed mixer for pre-stirring, then nanofillers are added and mixed, followed by melt blending and granulation to obtain the composite material.

[0018] In the extrusion foaming molding step, the composite material is fed into a physical foaming extruder and continuously extruded to obtain foamed material.

[0019] In some embodiments, the melt blending temperature in the granulation step is 165-180°C, and the screw speed is 100-400 r / min;

[0020] The foaming process conditions for the extrusion foaming molding step are: the temperature of the foaming extruder is 120-180℃, and the carbon dioxide injection pressure is 10-25MPa.

[0021] This invention also provides the application of biodegradable bio-based soft foam materials of any of the above technical solutions as packaging materials in the packaging and transportation of electronic and electrical products.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] This invention provides a biodegradable bio-based soft foam material. It is prepared by organically modified zirconium hydrogen phosphate / polylactic acid / polycaprolactone composite. The two-dimensional zirconium hydrogen phosphate nanosheets exfoliated into a single layer have a higher specific surface area and surface activity. As a heterogeneous foaming nucleation orientation template, it optimizes the crystallization performance of PLA, increases the SC crystallization ratio of the resin matrix, significantly improves melt strength and foaming performance, and thus enhances the cell nucleation rate and cell size uniformity.

[0024] This invention provides a method for preparing a biodegradable bio-based soft foam material. Organically modified zirconium hydrogen phosphate, as a two-dimensional nanomaterial, has better compatibility with carbon dioxide, a physical foaming agent. Homogeneous high foaming ratio (>30 times) foam material can be obtained through supercritical carbon dioxide foaming. The prepared soft foam material has a compression set of <20%, a tensile strength of >1.5MPa, and rapid degradation performance. Compared with EPE at the same foaming ratio, it has better compressive strength and tensile modulus, while reducing carbon emissions by more than 65%. After disposal, the biodegradation cycle is 90% or more and only 24 weeks. Attached Figure Description

[0025] Figure 1 This is a diagram illustrating the preparation mechanism of the PLA / OZrP composite material provided in the embodiments of the present invention.

[0026] Figure 2 This is a schematic diagram of the mechanism by which OZrP promotes heterogeneous nucleation of PLA, provided in an embodiment of the present invention.

[0027] Figure 3 This is a diagram illustrating the mechanism by which OZrP improves the directional foaming molding of PLA, as provided in an embodiment of the present invention. Detailed Implementation

[0028] The technical solutions in specific embodiments of the present invention will be described in detail and completely below. Obviously, the described embodiments are only some specific implementations of the overall technical solution of the present invention, and not all implementations. Based on the overall concept of the present invention, all other embodiments obtained by those skilled in the art fall within the protection scope of the present invention.

[0029] This invention provides a biodegradable bio-based soft foam material, obtained by foaming a composite material, the composite material including polylactic acid.

[0030] PLA (polylactic acid) flexible foam material, as a biodegradable and environmentally friendly material, has broad prospects in packaging, cushioning, and medical fields. However, its technological development faces the following core challenges: PLA molecular chains are highly rigid and have poor melt viscoelasticity, making it difficult to effectively encapsulate gas during foaming, which easily leads to cell collapse and tensile strength <1MPa; the cell nucleation density is low, and during supercritical CO2 foaming, PLA has poor compatibility with non-polar foaming agents, resulting in a foaming ratio <20%; it exhibits significant brittleness, with a compression set >40% after foaming at room temperature, making it difficult to meet the requirements of flexible cushioning materials; and there is a contradiction between strength and degradation, requiring cross-linking or blending modification to improve tensile strength, but at the cost of sacrificing biodegradability.

[0031] This invention provides a biodegradable bio-based flexible foam material obtained by foaming a composite material, the composite material including polycaprolactone (PCL). PCL, as a biodegradable polymer, has important applications in the development of flexible foam materials due to its excellent biocompatibility, flexibility, and processability. PCL can be blended with PLA to improve foaming performance; however, the addition of PCL still cannot overcome the aforementioned problems existing when PLA (polylactic acid) is used as a flexible foam material.

[0032] This invention provides a biodegradable bio-based soft foam material, which is obtained by foaming a composite material, the composite material including nanofillers; the nanofillers are exfoliated modified single-layer zirconium hydrogen phosphate two-dimensional nanosheets.

[0033] The zirconium hydrogen phosphate / polylactic acid / polycaprolactone composite material exhibits rapid degradation and excellent directional foaming molding performance, with a degradation cycle of <24 weeks, a compression set of <20% after foaming at room temperature, and a tensile strength >1 MPa. Among these components, exfoliated modified monolayer zirconium hydrogen phosphate two-dimensional nanosheets act as a foaming nucleating agent, dispersing bubbles during the foaming process, ensuring uniform bubble distribution within the material, preventing bubble aggregation, and improving material performance. This invention utilizes exfoliated modified monolayer zirconium hydrogen phosphate two-dimensional nanosheets as foaming nuclei to achieve directional foaming and ensure uniform distribution, which is crucial for improving the compressive performance of the soft foam material of this invention.

[0034] like Figure 1As shown, firstly, the interlayer spacing is increased by pre-intercalating ZrP (zirconium hydrogen phosphate) with organic amines, and the intercalation effect weakens the van der Waals forces that cause interlayer adhesion. Then, PLA resin and OZrP are melt-blended, and under shear force, OZrP is exfoliated into few-layer or monolayer structures, forming two-dimensional nanosheets with higher aspect ratio and larger specific surface area, further increasing the contact area between PLA and OZrP. In addition, the organic amine grafted on the OZrP surface increases the binding energy with PLA molecular chains, improving interfacial compatibility.

[0035] like Figure 2 As shown, on the one hand, OZrP increases the nucleation density and relative content of SC crystals during cooling and isothermal processes, thereby increasing the crystallization rate and inhibiting HC crystallization; on the other hand, the hydroxyl groups on the surface of OZrP form hydrogen bonds with the carbonyl groups on the PLA molecular chain, which can induce the nucleation of SC crystals. In summary, this leads to an increase in the proportion of SC crystals and a decrease in the proportion of HC crystals.

[0036] This invention utilizes an organically modified zirconium hydrogen phosphate / polylactic acid / polycaprolactone composite to prepare a rapidly degradable bio-based soft foam material. The two-dimensional zirconium hydrogen phosphate nanosheets, exfoliated into a single layer, have a higher specific surface area and surface activity. As a directional template for heterogeneous foaming nucleation, this invention optimizes the crystallization performance of PLA, increases the SC crystallization ratio of the resin matrix, significantly improves melt strength and foaming performance, and thus enhances the cell nucleation rate and cell size uniformity.

[0037] In some embodiments, the aspect ratio of the exfoliated modified monolayer zirconium hydrogen phosphate two-dimensional nanosheets is not less than 600:1. OZrP is used as an inorganic foaming nucleating agent, wherein OZrP with a high aspect ratio (600:1) is oriented under the shearing action of PLA melt, which can induce the directional arrangement of cells and make the cell size more uniform and controllable.

[0038] In some embodiments, the exfoliated modified monolayer zirconium hydrogen phosphate two-dimensional nanosheets are organic amine intercalated modified zirconium hydrogen phosphate nanosheets. The organic amine is selected from at least one of methylamine, n-butylamine, isooctylamine, tetraethylenepentamine, octadecyl dimethyl benzyl ammonium chloride, 3-aminopropyl dimethylethoxysilane, and aliphatic polyamines. OZrP, as a heterogeneous crystal nucleating agent, has a large number of organic amine molecules orderly grafted onto its surface, which can serve as a nucleation template to further increase the nucleation sites and nucleation rate of PLA. The formation of SC crystals improves the melt strength, thereby enhancing the stability and uniformity of bubble formation.

[0039] In some embodiments, the molar ratio of organic amine-intercalated modified nano-zirconium hydrogen phosphate to organic amine is 1:5-15. It is understood that the molar ratio of organic amine-intercalated modified nano-zirconium hydrogen phosphate to organic amine can also be any value within the range of 1:6, 1:7, 1:8, 1:9, 1:10, 1:11, 1:12, 1:13, 1:14, etc.

[0040] In some embodiments, polylactic acid is a copolymer of L-polylactic acid and D-polylactic acid with a melt index of 1.5-10 g / min; polycaprolactone has a melt index of 2-15 g / min.

[0041] In some embodiments, the amount of polylactic acid (PLA) is selected from any value of 45-70 parts by weight, the amount of polycaprolactone (PVC) is selected from any value of 30-55 parts by weight, and the amount of nanofiller is selected from any value of 0.5-10 parts by weight. It is understood that the amount of PLA can also be any value within the range of 50, 55, 60, 65 parts; the amount of PVC can also be any value within the range of 35, 40, 45 parts; and the amount of nanofiller can also be any value within the range of 1, 2, 3, 4, 5, 6, 7, 8, 9 parts.

[0042] In some embodiments, the composite material further includes a compatibilizer, the amount of which, by weight, is selected from any value between 0.5 and 2 parts. The compatibilizer is selected from at least one of aliphatic diesters, polycyclic epoxy oligomers, polyol esters, tributyl citrate, and ethylene-methyl acrylate-glycidyl methacrylate. The compatibilizer is added at a ratio of 0.5-2% of the matrix material. It is understood that the amount of compatibilizer can also be any value within the range of 1.0, 1.5, and so on.

[0043] In some embodiments, the composite material further includes an antioxidant, the amount of which, by weight, is selected from any value of 0.5 to 2 parts, and the antioxidant is selected from at least one of epoxy compounds, mono / polycarbodiimides, antioxidant 1010, and antioxidant 1076. It is understood that the amount of antioxidant can also be any value within the range of 1.0, 1.5, and so on.

[0044] This invention provides a method for preparing a biodegradable bio-based soft foam material, including a nanofiller preparation step. The nanofiller preparation step includes: adding nano-zirconium hydrogen phosphate into anhydrous ethanol and stirring, then adding an organic amine solution, ultrasonically stirring for 0.5-1.0 h, separating and washing, and drying at 55-65℃ to obtain the nanofiller.

[0045] The above process utilizes ultrasound to exfoliate ZrP, preparing exfoliated modified monolayer zirconium hydrogen phosphate two-dimensional nanosheets with a large specific surface area and dispersion stability. The organic amine pre-intercalation is a key process; by pre-treating zirconium hydrogen phosphate with ultrasonic organic amines, the interlayer spacing can be expanded, significantly improving the exfoliation of multilayer zirconium hydrogen phosphate into a monolayer structure. The above technical solution limits the ultrasonic time and drying temperature because suitable ultrasonic temperature and time can significantly improve the exfoliation efficiency, with better exfoliation results. However, exceeding a certain time or excessively high temperature will not significantly increase the exfoliation efficiency and may even lead to damage to the layered structure and solvent evaporation, thus reducing the exfoliation efficiency. It can be understood that the ultrasonic stirring time can be any value within the range of 0.6h, 0.7h, 0.8h, 0.9h, and 56℃, 57℃, 58℃, 59℃, 60℃, 61℃, 62℃, 63℃, 64℃, and 56℃.

[0046] This invention provides a method for preparing a biodegradable bio-based flexible foam material, including a granulation step. The granulation step includes: adding polylactic acid, polycaprolactone, a compatibilizer, and an antioxidant to a high-speed mixer for pre-stirring, then adding nanofillers and mixing, followed by melt blending and granulation to obtain the composite material. In some embodiments, the melt blending temperature in the granulation step is 165-180℃, and the screw speed is 100-400 r / min. This technical solution specifies that polylactic acid, polycaprolactone, a compatibilizer, and an antioxidant are pre-stirred before adding the nanofillers, rather than mixing polylactic acid, polycaprolactone, a compatibilizer, an antioxidant, and nanofillers together. This is because it prioritizes optimizing matrix compatibility and prevents the nanofillers from consuming functional additives. If the fillers are added too early, the compatibilizer may be adsorbed on the filler surface instead of acting on the PLA / PCL interface, reducing compatibility efficiency. In addition, the pre-mixed PLA / PCL matrix has a lower viscosity after melting, improving the dispersion effect of the nanofillers.

[0047] It is understandable that the melt blending temperature in the granulation step can be any value within the range of 166℃, 168℃, 170℃, 172℃, 174℃, 176℃, 178℃, 180℃, and so on; the screw speed can also be any value within the range of 150℃, 200℃, 250℃, 300℃, 350℃, and so on.

[0048] This invention provides a method for preparing a biodegradable bio-based soft foam material, including an extrusion foaming step. The extrusion foaming step includes feeding the composite material into a physical foaming extruder for continuous extrusion to obtain the foam material. The foaming process conditions for the extrusion foaming step are: extruder temperature of 120-180℃ and carbon dioxide injection pressure of 10-25MPa.

[0049] The above-mentioned technical solution of the present invention uses supercritical carbon dioxide as a foaming agent. Organically modified zirconium hydrogen phosphate, as a two-dimensional nanomaterial, has better compatibility with the physical foaming agent carbon dioxide. Homogeneous foamed materials with high foaming ratios (>30 times) can be obtained through supercritical carbon dioxide foaming. For example... Figure 3 As shown, OZrP, as a heterogeneous crystal nucleating agent, has a large number of organic amine molecules orderly grafted onto its surface, which can serve as a nucleation template to further increase the nucleation sites and nucleation rate of PLA. The formation of SC crystals improves the melt strength, thereby enhancing the nucleation stability and uniformity of the cells. In addition, as an inorganic foaming nucleating agent, OZrP with a high aspect ratio (600:1) aligns and oriented under the shearing action of PLA melt, which can induce the directional alignment of cells, resulting in more uniform and controllable cell size. In summary, a soft foam material with high foaming ratio and excellent mechanical properties (>30 times) is obtained.

[0050] The soft foam material prepared by the above-mentioned technical solution of the present invention has a compression set of <20%, a tensile strength of >1.5MPa, and the insertion of two-dimensional nano-zirconium hydrogen phosphate improves the resin's antioxidant properties. It also has rapid degradation performance. Compared with EPE of the same foaming ratio, it has better compressive strength and tensile modulus. Compared with PE of the same foaming ratio, it reduces carbon emissions by more than 65%, and the biodegradation cycle after disposal is 90% or more in just 24 weeks.

[0051] This invention also provides the application of biodegradable bio-based soft foam materials of any of the above technical solutions as packaging materials in the packaging and transportation of electronic and electrical products.

[0052] To provide a clearer and more detailed description of the biodegradable bio-based soft foam material, its preparation method, and its application provided in the embodiments of the present invention, the following description will be based on specific embodiments.

[0053] Example 1

[0054] A rapidly degradable bio-based soft foam material is prepared from 70 parts PLA, 30 parts PCL, 0.5 parts compatibilizer, 0.5 parts antioxidant, and 5 parts nanofiller, wherein the nanofiller is intercalated modified zirconium hydrogen phosphate.

[0055] The compatibilizer is a multi-element epoxy oligomer, and the antioxidant is a polycarbodiimide.

[0056] (1) Preparation of intercalated modified zirconium hydrogen phosphate:

[0057] 100g of nano-zirconium hydrogen phosphate was added to 200ml of anhydrous ethanol and stirred for 1 hour. Then, an organic amine solution was added and ultrasonically stirred for 0.5 hours. After cooling, the mixture was centrifuged to remove the supernatant. The precipitate was washed 5 times with deionized water and dried in an oven at 60℃ for 24 hours before being taken out for use.

[0058] Among them, the organic amine is isooctylamine.

[0059] (2) Preparation of composite materials:

[0060] First, PLA was dried at 60℃ for 6 hours, and PCL was dried at 50℃ for 6 hours. PLA, PCL, compatibilizer, and antioxidant were then added to a high-speed mixer for pre-stirring. Next, intercalated modified zirconium hydrogen phosphate was added and mixed, followed by melt blending and granulation to obtain the composite material. The melt blending temperature was set at 180℃, and the screw speed was 100 r / min. The composite material was then fed into a physical foaming extruder for continuous extrusion to obtain the foamed material. The foaming process conditions were: extruder temperature 180℃, and carbon dioxide injection pressure 25 MPa.

[0061] Example 2

[0062] A rapidly degradable bio-based soft foam material is prepared from 60 parts PLA, 40 parts PCL, 1 part compatibilizer, 0.5 parts antioxidant, and 5 parts nanofiller, wherein the nanofiller is intercalated modified zirconium hydrogen phosphate.

[0063] The compatibilizer is a polyol ester, and the antioxidant is an epoxy compound.

[0064] (1) Preparation of intercalated modified zirconium hydrogen phosphate:

[0065] 100g of nano-zirconium hydrogen phosphate was added to 200ml of anhydrous ethanol and stirred for 1 hour. Then, an organic amine solution was added and ultrasonically stirred for 0.5 hours. After cooling, the mixture was centrifuged to remove the supernatant. The precipitate was washed 5 times with deionized water and dried in an oven at 60℃ for 24 hours before being taken out for use.

[0066] The organic amine is n-butylamine.

[0067] (2) Preparation of composite materials:

[0068] First, PLA was dried at 60℃ for 6 hours, and PCL was dried at 50℃ for 6 hours. PLA, PCL, compatibilizer, antioxidant, and modifier were added to a high-speed mixer for pre-stirring. Then, intercalated modified zirconium hydrogen phosphate was added and mixed. The mixture was then melt-blended and granulated to obtain the composite material. The melt-blending temperature was set at 170℃, and the screw speed was 120 r / min. The composite material was fed into a physical foaming extruder for continuous extrusion to obtain the foamed material. The foaming process conditions were: extruder temperature 170℃, and carbon dioxide injection pressure 205 MPa.

[0069] Example 3

[0070] A rapidly degradable bio-based soft foam material is prepared from 50 parts PLA, 50 parts PCL, 1.5 parts compatibilizer, 0.5 parts antioxidant, and 10 parts nanofiller, wherein the nanofiller is intercalated modified zirconium hydrogen phosphate.

[0071] The compatibilizer is tributyl citrate, and the antioxidant is antioxidant 1010.

[0072] (1) Preparation of intercalated modified zirconium hydrogen phosphate:

[0073] 100g of nano-zirconium hydrogen phosphate was added to 200ml of anhydrous ethanol and stirred for 1 hour. Then, an organic amine solution was added and ultrasonically stirred for 0.5 hours. After cooling, the mixture was centrifuged to remove the supernatant. The precipitate was washed 5 times with deionized water and dried in an oven at 60℃ for 24 hours before being taken out for use.

[0074] The organic amine is n-butylamine.

[0075] (2) Preparation of composite materials:

[0076] First, PLA was dried at 60℃ for 6 hours, and PCL was dried at 50℃ for 6 hours. PLA, PCL, compatibilizer, antioxidant, and modifier were added to a high-speed mixer and pre-stirred. Then, intercalated modified zirconium hydrogen phosphate was added and mixed, followed by melt blending and granulation to obtain the composite material. The melt blending temperature was set at 175℃, and the screw speed was 80 r / min. The composite material was fed into a physical foaming extruder for continuous extrusion to obtain the foamed material. The foaming process conditions were: extruder temperature 175℃, and carbon dioxide injection pressure 15 MPa.

[0077] Example 4

[0078] A rapidly degradable bio-based soft foam material is prepared from 60 parts PLA, 40 parts PCL, 1 part compatibilizer, 0.5 parts antioxidant, and 7.5 parts nanofiller, wherein the nanofiller is intercalated modified zirconium hydrogen phosphate.

[0079] The compatibilizer is an aliphatic diester, and the antioxidant is monocarbodiimide.

[0080] (1) Preparation of intercalated modified zirconium hydrogen phosphate:

[0081] 100g of nano-zirconium hydrogen phosphate was added to 200ml of anhydrous ethanol and stirred for 1 hour. Then, an organic amine solution was added and ultrasonically stirred for 0.5 hours. After cooling, the mixture was centrifuged to remove the supernatant. The precipitate was washed 5 times with deionized water and dried in an oven at 60℃ for 24 hours before being taken out for use.

[0082] The organic amine is tetraethylenepentamine.

[0083] (2) Preparation of composite materials:

[0084] First, PLA was dried at 60℃ for 6 hours, and PCL was dried at 50℃ for 6 hours. PLA, PCL, compatibilizer, antioxidant, and modifier were added to a high-speed mixer and pre-stirred. Then, intercalated modified zirconium hydrogen phosphate was added and mixed, followed by melt blending and granulation to obtain the composite material. The melt blending temperature was set at 180℃, and the screw speed was 60 r / min. The composite material was fed into a physical foaming extruder for continuous extrusion to obtain the foamed material. The foaming process conditions were: extruder temperature 160℃, and carbon dioxide injection pressure 10 MPa.

[0085] Example 5

[0086] A rapidly degradable bio-based soft foam material is prepared from 60 parts PLA, 40 parts PCL, 1 part compatibilizer, 0.5 parts antioxidant, and 2.5 parts nanofiller, wherein the nanofiller is intercalated modified zirconium hydrogen phosphate.

[0087] The compatibilizer is ethylene-methyl acrylate-glycidyl methacrylate, and the antioxidant is antioxidant 1076.

[0088] (1) Preparation of intercalated modified zirconium hydrogen phosphate:

[0089] 100g of nano-zirconium hydrogen phosphate was added to 200ml of anhydrous ethanol and stirred for 1 hour. Then, an organic amine solution was added and ultrasonically stirred for 0.5 hours. After cooling, the mixture was centrifuged to remove the supernatant. The precipitate was washed 5 times with deionized water and dried in an oven at 60℃ for 24 hours before being taken out for use.

[0090] Among them, organic amines are fatty polyamines.

[0091] (2) Preparation of composite materials:

[0092] First, PLA was dried at 60℃ for 6 hours, and PCL was dried at 50℃ for 6 hours. PLA, PCL, compatibilizer, antioxidant, and modifier were added to a high-speed mixer and pre-stirred. Then, intercalated modified zirconium hydrogen phosphate was added and mixed, followed by melt blending and granulation to obtain the composite material. The melt blending temperature was set at 165℃, and the screw speed was 50 r / min. The composite material was fed into a physical foaming extruder for continuous extrusion to obtain the foamed material. The foaming process conditions were: extruder temperature 120℃, and carbon dioxide injection pressure 25 MPa.

[0093] Comparative Example 1

[0094] A rapidly degradable bio-based soft foam material is prepared from 60 parts PLA, 40 parts PCL, 1 part compatibilizer, 0.5 parts antioxidant, and 5 parts nanofiller, wherein the nanofiller is zirconium hydrogen phosphate.

[0095] The compatibilizer is a multi-element epoxy oligomer, and the antioxidant is a polycarbodiimide.

[0096] (1) Preparation of composite materials:

[0097] First, PLA was dried at 60℃ for 6 hours, and PCL was dried at 50℃ for 6 hours. PLA, PCL, compatibilizer, antioxidant, and modifier were then added to a high-speed mixer and pre-stirred. Zirconium hydrogen phosphate was then added and mixed, followed by melt blending and granulation to obtain the composite material. The melt blending temperature was set at 180℃, and the screw speed was 100 r / min. The composite material was then fed into a physical foaming extruder for continuous extrusion to obtain the foamed material. The foaming process conditions were: extruder temperature 180℃, and carbon dioxide injection pressure 25 MPa.

[0098] Comparative Example 2

[0099] A rapidly degradable bio-based soft foam material is prepared from 60 parts PLA, 40 parts PCL, 1 part compatibilizer, 0.5 parts antioxidant, and 0 parts nanofiller.

[0100] The compatibilizer is a multi-element epoxy oligomer, and the antioxidant is a polycarbodiimide.

[0101] (1) Preparation of composite materials:

[0102] First, PLA was dried at 60℃ for 6 hours, and PCL was dried at 50℃ for 6 hours. PLA, PCL, compatibilizer, antioxidant, and modifier were then added to a high-speed mixer and mixed for 20 minutes. After melt blending, the mixture was granulated to obtain the composite material. The melt blending temperature was set at 165℃, and the screw speed was 100 r / min. The composite material was then fed into a physical foaming extruder for continuous extrusion to obtain the foamed material. The foaming process conditions were: extruder temperature 160℃, and carbon dioxide injection pressure 20 MPa.

[0103] Comparative Example 3

[0104] A rapidly degradable bio-based soft foam material is prepared from 60 parts PLA, 40 parts PCL, 1 part compatibilizer, 0.5 parts antioxidant, and 5 parts cubic zirconium hydrogen phosphate.

[0105] The compatibilizer is a multi-element epoxy oligomer, and the antioxidant is a polycarbodiimide.

[0106] (1) Preparation of modified cubic zirconium hydrogen phosphate:

[0107] Add 100g of cubic zirconium hydrogen phosphate to 200ml of anhydrous ethanol and stir for 1 hour. Then add an organic amine solution and sonicate for 0.5 hours. After cooling, centrifuge to remove the supernatant. Wash the precipitate 5 times with deionized water and dry it in a 60℃ oven for 24 hours before use.

[0108] The organic amine in question is isooctylamine.

[0109] (2) Preparation of composite materials:

[0110] First, PLA was dried at 60℃ for 6 hours, and PCL was dried at 50℃ for 6 hours. PLA, PCL, compatibilizer, antioxidant, and modifier were added to a high-speed mixer and pre-stirred. Then, modified cubic zirconium hydrogen phosphate was added and mixed, followed by melt blending and granulation to obtain the composite material. The melt blending temperature was set at 180℃, and the screw speed was 100 r / min. The composite material was fed into a physical foaming extruder for continuous extrusion to obtain the foamed material. The foaming process conditions were: extruder temperature 180℃, and carbon dioxide injection pressure 25 MPa.

[0111] The amounts of each substance used in the above embodiments and comparative examples are shown in Table 1.

[0112] Table 1 Summary of Material Amounts in Examples and Comparative Examples

[0113]

[0114] Performance testing

[0115] The performance of the embodiments and comparative examples was tested according to the standards in Table 2, and the test results are shown in Table 3.

[0116] Table 2 Test Standards

[0117]

[0118] Table 3 Test Results

[0119]

[0120]

Claims

1. A degradable bio-based flexible foamed material, characterized in that, The composite material is obtained by foaming, and the composite material includes polylactic acid, polycaprolactone, and nanofiller; the nanofiller is a peeled modified single-layer zirconium hydrogen phosphate two-dimensional nanosheet.

2. The degradable bio-based flexible foam material according to claim 1, characterized in that, The aspect ratio of the exfoliated modified monolayer zirconium hydrogen phosphate two-dimensional nanosheets is not less than 600:

1.

3. The degradable bio-based flexible foam material according to claim 1, wherein, The exfoliated modified monolayer zirconium hydrogen phosphate two-dimensional nanosheets are organic amine intercalated modified zirconium hydrogen phosphate nanosheets, and the organic amine is selected from at least one of methylamine, n-butylamine, isooctylamine, tetraethylenepentamine, octadecyl dimethyl benzyl ammonium chloride, 3-aminopropyl dimethyl ethoxysilane, and aliphatic polyamines.

4. The degradable bio-based flexible foam material according to claim 3, characterized in that, The molar ratio of the organic amine-intercalated modified nano-zirconium hydrogen phosphate to the organic amine is 1:5-15.

5. The degradable bio-based flexible foam material according to claim 1, wherein, The polylactic acid is a copolymer of L-polylactic acid and D-polylactic acid with a melt index of 1.5-10 g / min; the polycaprolactone has a melt index of 2-15 g / min.

6. The biodegradable bio-based flexible foam material according to claim 1, characterized in that, The amount of polylactic acid is selected from any value of 45-70 parts by weight, the amount of polycaprolactone is selected from any value of 30-55 parts, and the nanofiller is selected from any value of 0.5-10 parts.

7. The biodegradable bio-based flexible foam material according to claim 1, characterized in that, The composite material also includes a compatibilizer and an antioxidant; The amount of the compatibilizer and the amount of the antioxidant are selected from any value of 0.5-2 parts by weight. The compatibilizer is selected from at least one of aliphatic diesters, polycyclic epoxy oligomers, polyol esters, tributyl citrate, and ethylene-methyl acrylate-glycidyl methacrylate; the antioxidant is selected from at least one of epoxy compounds, mono / polycarbodiimides, antioxidant 1010, and antioxidant 1076.

8. The method for preparing the biodegradable bio-based flexible foam material according to any one of claims 1-7, characterized in that, include: The nanofiller preparation steps are as follows: nano-zirconium hydrogen phosphate is added to anhydrous ethanol and stirred, then an organic amine solution is added, ultrasonically stirred for 0.5-1.0 h, separated, washed, and dried at 55-65℃ to obtain the nanofiller; In the granulation step, the polylactic acid, the polycaprolactone, the compatibilizer, and the antioxidant are added to a high-speed mixer for pre-stirring, then the nanofiller is added and mixed and stirred, and then melt-blended and granulated to obtain the composite material. In the extrusion foaming molding step, the composite material is fed into a physical foaming extruder and continuously extruded to obtain a foamed material.

9. The method for preparing the biodegradable bio-based flexible foam material according to claim 8, characterized in that, The melt blending temperature in the granulation step is 165-180℃, and the screw speed is 100-400 r / min; The foaming process conditions for the extrusion foaming molding step are: the foaming extruder temperature is 120-180℃, and the carbon dioxide injection pressure is 10-25MPa.

10. The application of the biodegradable bio-based flexible foam material according to any one of claims 1-8 as a packaging material in the packaging and transportation of electronic and electrical products.

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