A biodegradable polyurethane-based composite porous material and its preparation method and application

Abstract

The present invention provides a method for preparing a biodegradable polyurethane-based composite porous material, comprising: grafting treatment: grafting hydrogenated styrene-butadiene block copolymer (SEBS) or hydrogenated styrene-ethylene-propylene-styrene block copolymer (SEPS) by maleic anhydride to obtain maleic anhydride-grafted styrene-ethylene-butylene-styrene block copolymer (SEBS-g-MAH) or maleic anhydride-grafted styrene-ethylene-propylene-styrene block copolymer (SEPS-g-MAH); raw material mixing: adding SEBS-g-MAH or SEPS-g-MAH and polylactic acid (PLA) and thermoplastic polyurethane (TPU) into a stirrer, adding 1,4-dioxane solvent, stirring to obtain a mixed solution; S3: adding water after the temperature of the mixed solution drops to room temperature, stirring and standing, freezing and drying to obtain a biodegradable polyurethane-based composite porous material. The present invention also provides the above-mentioned composite porous material and its application in oil-water separation, and the composite porous material of the present invention has a good ability to absorb oil and organic pollutants.

Description

Technical Field

[0001] The invention relates to the field of preparation of polyurethane-based composite materials, and in particular to a biodegradable polyurethane-based composite porous material and a preparation method and application thereof. Background Art

[0002] With the rapid development of transportation, offshore oil extraction and modern chemical industry, human activities such as offshore oil spills, organic chemical solvent leaks, and dye wastewater discharge have caused serious damage to the local environment and ecosystem. In order to solve the pollution of crude oil and organic solvents, most of the treatment methods currently used include physical methods (oil booms, oil absorbent materials, etc.), chemical methods (in-situ combustion, dispersants, curing agents, etc.) and biological methods (biodegradation, etc.). However, these methods generally have the disadvantages of long treatment cycles, poor separation efficiency, poor recycling performance, and easy secondary pollution. In contrast, adsorbent materials have low costs, high removal rates, and simple and easy operation methods. The use of adsorbent materials has become the first choice for solving the problem of oil and organic solvent water pollution.

[0003] Thermoplastic polyurethane (TPU) plastics are widely used in packaging, sound insulation, filtration materials, and structural materials for construction, automobiles, aviation industry, and thermal insulation due to their good stability, chemical resistance, resilience, and mechanical properties. At present, my country has become the world's largest production base for polyurethane raw materials and products and the region with the most comprehensive application fields. However, the large-scale use of thermoplastic polyurethane plastics has led to the generation of a large amount of waste plastics. Due to its difficult-to-degrade characteristics, it has caused great damage to soil, water bodies, etc., and at the same time wasted a large amount of thermoplastic polyurethane plastic resources. Polyurethane has good hydrophobicity and has the potential to adsorb oil and organic pollutants, but polyurethane adsorbent materials have a strong swelling effect in organic solvents such as chloroform, resulting in the failure of polyurethane adsorbent materials to adsorb solvents such as chloroform. Therefore, there is an urgent need for a method that can modify the above-mentioned TPU material and apply it to oil-water separation. Summary of the invention

[0004] One of the technical problems to be solved by the present invention is to provide a method for preparing a biodegradable polyurethane-based composite porous material to fill the gap in this technical field and provide a method for preparing the thermoplastic polyurethane waste.

[0005] In order to solve the above problems, the present invention provides a method for preparing a biodegradable polyurethane-based composite porous material, comprising the following steps:

[0006] S1: Grafting treatment: grafting hydrogenated styrene-butadiene block copolymer or hydrogenated styrene-ethylene-propylene-styrene block copolymer with maleic anhydride to obtain maleic anhydride grafted styrene-ethylene-butylene-styrene block copolymer or maleic anhydride grafted styrene-ethylene-propylene-styrene block copolymer;

[0007] S2: mixing raw materials: adding the copolymer obtained in step S1, polylactic acid and thermoplastic polyurethane into a stirrer, and adding 1,4-dioxane solvent, stirring to obtain a mixed solution;

[0008] S3: Phase separation: After the temperature of the mixed solution drops to room temperature, water is further added, and stirring is continued. After standing, freezing and drying, water and 1,4-dioxane can be removed to obtain a biodegradable polyurethane-based composite porous material.

[0009] The invention discloses a method for preparing a biodegradable polyurethane-based composite porous material. Polylactic acid (PLA) and hydrogenated styrene-ethylene-propylene-styrene block copolymer (SEPS) or hydrogenated styrene-butadiene block copolymer (SEBS) are simultaneously added to a waste TPU matrix. Since PLA contains a group -CH3, the surface energy of the material can be further reduced, and the hydrophobicity and lipophilicity of the material can be improved. PLA can be completely degraded in the natural environment, and the products are carbon dioxide and water. PLA can be used as a biodegradable green material. Adding PLA to a TPU matrix can improve the degradation performance of the TPU-based composite material and avoid secondary pollution. SEBS or SEPS has extremely high oil filling. After absorbing solvents such as chloroform, it will not be swollen by the solvent. However, since SEBS or SEPS does not contain polar and reactive groups on the molecular chain, its compatibility with TPU is poor. Therefore, before adding SEBS or SEPS to the TPU matrix, SEBS or SEPS needs to be grafted with maleic anhydride to generate maleic anhydride grafted styrene-ethylene-butylene-styrene block copolymer (SEBS-g-MAH) or maleic anhydride grafted styrene-ethylene-propylene-styrene block copolymer (SEPS-g-MAH). The compatibility of SEBS-g-MAH or SEPS-g-MAH with TPU is significantly improved, which is beneficial to the solution blending of the two.

[0010] As a preferred solution, in the step S1, the molecular weight of the hydrogenated styrene-butadiene block copolymer or the hydrogenated styrene-ethylene-propylene-styrene block copolymer is 220,000-280,000; in the step S2, the molecular weight of the polylactic acid is 40,000-100,000.

[0011] As a preferred solution, in step S2, the mass ratio of the copolymer, polylactic acid and thermoplastic polyurethane is 1:1:10.

[0012] As a preferred solution, in the step S2, the contents of the copolymer, polylactic acid and thermoplastic polyurethane in the 1,4-dioxane solvent are 3 g / L, 3 g / L and 30 g / L respectively.

[0013] As a preferred solution, in step S2, the volume ratio of water to 1,4-dioxane in the 1,4-dioxane solvent is 1:9.

[0014] As a preferred solution, in step S2, the stirring condition is: stirring at a temperature of 40°C-50°C for 3-5 hours; in step S3, the stirring time is continued for 1 hour.

[0015] As a preferred solution, in step S3, the standing condition is: standing at 0° C. for 30 minutes.

[0016] As a preferred solution, in step S3, the conditions for the freeze-drying treatment are: freezing in a -16°C refrigerator for 36 hours, and then freeze-drying in a -50°C freeze dryer.

[0017] In the components of a biodegradable polyurethane-based composite porous material, the mass ratio of maleic anhydride grafted styrene-ethylene-butylene-styrene block copolymer, polylactic acid, and thermoplastic polyurethane is selected to be 1:1:10, the volume ratio of water and 1,4-dioxane is 1:9, the content of TPU in the DO solution is 30g / L, 0℃ is allowed to stand for 30min, the freezing time at -16℃ is 36h, and the freeze-drying time at -50℃ is 48h. At this time, the absorption capacity of the composite porous material for gasoline, diesel, edible oil and other oil products and organic solvents such as toluene, carbon tetrachloride, and carbon trichloride in the water body reaches the maximum, and the cycle service life is the longest.

[0018] One of the technical problems to be solved by the present invention is to provide a biodegradable polyurethane-based composite porous material to solve the problem that thermoplastic polyurethane cannot be effectively utilized, cannot be well modified, and cannot be applied to fields related to oil-water separation.

[0019] In order to solve the above problems, the present invention provides a biodegradable polyurethane-based composite porous material, and the composite porous material is prepared by the above preparation method.

[0020] Another technical problem to be solved by the present invention is to provide an application of the above-mentioned polyurethane-based composite porous material to solve the problem that conventional thermoplastic polyurethane / modified thermoplastic polyurethane has a strong swelling effect, resulting in the failure of polyurethane adsorption materials to adsorb solvents such as chloroform.

[0021] In order to solve the above problems, the present invention provides an application of a biodegradable polyurethane-based composite porous material, which includes applying the biodegradable polyurethane-based composite porous material to oil-water separation to adsorb oil and organic pollutants therein.

[0022] SEBS and SEPS are both new styrene-based thermoplastic elastomers, containing low surface energy groups -CH2CH2-, and are hydrophobic. SEBS and SEPS also have excellent mechanical properties and oil-filling properties. The molecular structure of SEBS is shown below:

[0023]

[0024] The molecular structure of SEPS is shown below:

[0025]

[0026] Polylactic acid (PLA) contains low surface energy groups -CH3, which are hydrophobic. The molecular structure of PLA is as follows Figure 2 As shown. PLA can also be completely degraded in the natural environment, and the products are carbon dioxide and water. It can be used as a biodegradable green material. Its structural formula is shown below:

[0027]

[0028] Therefore, SEBS or SEPS with low surface energy structure and PLA are used to modify the TPU matrix together, which can synergistically improve the hydrophobicity of TPU-based composite materials; at the same time, due to the excellent oil filling properties of SEBS and SEPS, the swelling effect of the adsorbed material in solvents such as chloroform is significantly reduced after SEBS or SEPS is added to the TPU matrix; PLA is easily biodegradable, so after being added to the TPU matrix, the degradation performance of the TPU-based composite material can be improved and secondary pollution can be avoided. The two modifiers can be added together to the waste TPU plastic matrix to achieve the purpose of "treating waste with waste".

[0029] The invention discloses a method for preparing a biodegradable polyurethane-based composite porous material. The method adopts discarded TPU plastics in the fields of packaging, sound insulation, filter materials, and structural materials such as construction, automobiles, aviation, and thermal insulation as a matrix. Compared with conventional TPU matrices, the TPU matrices are mostly industrial and domestic wastes, with a wide source and low price. The method adopts a green water-assisted thermally induced phase separation method, gradually cools and cools to induce phase separation, removes the solvent by freeze drying, and finally prepares the modified biodegradable polyurethane-based composite porous material. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is the surface morphology of pure TPU porous material;

[0031] Figure 2 This is the surface morphology of SEBS-g-MAH / PLA / TPU composite porous material. DETAILED DESCRIPTION

[0032] The technical solution of the present invention will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] In the above and below contents of the present invention, the SEBS is a styrene-ethylene-butylene-styrene block copolymer, SEBS-g-MAH is a maleic anhydride grafted styrene-ethylene-butylene-styrene block copolymer, SEPS is a styrene-ethylene-propylene-styrene block copolymer, SEPS-g-MAH is a maleic anhydride grafted styrene-ethylene-propylene-styrene block copolymer, PLA is polylactic acid, and TPU is thermoplastic polyurethane.

[0034] The present invention provides a method for preparing a biodegradable polyurethane-based composite porous material, comprising the following steps:

[0035] S1: Grafting treatment: grafting hydrogenated styrene-butadiene block copolymer or hydrogenated styrene-ethylene-propylene-styrene block copolymer with maleic anhydride to obtain maleic anhydride grafted styrene-ethylene-butylene-styrene block copolymer or maleic anhydride grafted styrene-ethylene-propylene-styrene block copolymer;

[0036] S2: mixing raw materials: adding the copolymer obtained in step S1, polylactic acid and thermoplastic polyurethane into a stirrer, and adding 1,4-dioxane solvent, stirring to obtain a mixed solution;

[0037] S3: Phase separation: After the temperature of the mixed solution drops to room temperature, water is further added, and stirring is continued. After standing, freezing and drying, water and 1,4-dioxane are removed to obtain a biodegradable polyurethane-based composite porous material.

[0038] As a preferred solution, in the step S1, the molecular weight of the hydrogenated styrene-butadiene block copolymer or the hydrogenated styrene-ethylene-propylene-styrene block copolymer is 220,000-280,000; in the step S2, the molecular weight of the polylactic acid is 40,000-100,000.

[0039] As a preferred solution, in step S2, the mass ratio of the copolymer, polylactic acid and thermoplastic polyurethane is 1:1:10.

[0040] As a preferred solution, in the step S2, the contents of the copolymer, polylactic acid and thermoplastic polyurethane in the 1,4-dioxane solvent are 3 g / L, 3 g / L and 30 g / L respectively.

[0041] As a preferred solution, in step S2, the volume ratio of water to 1,4-dioxane in the 1,4-dioxane solvent is 1:9.

[0042] As a preferred solution, in step S2, the stirring condition is: stirring at a temperature of 40°C-50°C for 3-5 hours; in step S3, the stirring time is continued for 1 hour.

[0043] As a preferred solution, in step S3, the standing condition is: standing at 0° C. for 30 minutes.

[0044] As a preferred solution, in step S3, the conditions for the freeze-drying treatment are: freezing in a -16°C refrigerator for 36 hours, and then freeze-drying in a -50°C freeze dryer.

[0045] The present invention also provides the biodegradable polyurethane-based composite porous material, which is prepared by the above-mentioned preparation method, and the application of the composite porous material, which includes applying the biodegradable polyurethane-based composite porous material to oil-water separation to adsorb oil and organic pollutants therein.

[0046] In the following embodiments of the present invention, the copolymers used include maleic anhydride grafted styrene-ethylene-propylene-styrene block copolymer (SEPS-g-MAH) and styrene-ethylene-butylene-styrene block copolymer (SEBS-g-MAH), both of which can be used in the preparation of the present invention.

[0047] The following provides a description of the above-mentioned solution of the present invention in combination with specific embodiments and experiments:

[0048] Embodiment 1:

[0049] A biodegradable polyurethane-based composite porous material, wherein the composite porous material is prepared by the following formula and preparation method:

[0050] S1: Grafting treatment: grafting hydrogenated styrene-butadiene block copolymer or hydrogenated styrene-ethylene-propylene-styrene block copolymer with maleic anhydride to obtain maleic anhydride grafted styrene-ethylene-butylene-styrene block copolymer or maleic anhydride grafted styrene-ethylene-propylene-styrene block copolymer; the molecular weight of the hydrogenated styrene-butadiene block copolymer or hydrogenated styrene-ethylene-propylene-styrene block copolymer is 220000;

[0051] S2: Mixing raw materials: Add the copolymer obtained in step S1, polylactic acid and thermoplastic polyurethane into a stirrer, add 1,4-dioxane solvent, and stir at 40°C for 4 hours to obtain a mixed solution; the molecular weight of the polylactic acid is 40,000. The mass ratio of the copolymer, polylactic acid and thermoplastic polyurethane is 1:1:10, and the contents of the copolymer, polylactic acid and thermoplastic polyurethane in the 1,4-dioxane solvent are 3g / L, 3g / L and 30g / L respectively. In the 1,4-dioxane solvent, the volume ratio of water to 1,4-dioxane is 1:9;

[0052] S3: Phase separation: After the temperature of the mixed solution drops to room temperature, water is further added, stirring is continued for 1 hour, and the mixture is allowed to stand at 0°C for 30 minutes, and then frozen in a -16°C refrigerator for 36 hours. After that, the mixture is placed in a -50°C freeze dryer for freeze drying to remove water and 1,4-dioxane, thereby obtaining a biodegradable polyurethane-based composite porous material.

[0053] Embodiment 2:

[0054] A biodegradable polyurethane-based composite porous material, wherein the composite porous material is prepared by the following formula and preparation method:

[0055] S1: Grafting treatment: grafting hydrogenated styrene-butadiene block copolymer or hydrogenated styrene-ethylene-propylene-styrene block copolymer with maleic anhydride to obtain maleic anhydride grafted styrene-ethylene-butylene-styrene block copolymer or maleic anhydride grafted styrene-ethylene-propylene-styrene block copolymer; the molecular weight of the hydrogenated styrene-butadiene block copolymer or hydrogenated styrene-ethylene-propylene-styrene block copolymer is 250000;

[0056] S2: Mixing raw materials: Add the copolymer obtained in step S1, polylactic acid and thermoplastic polyurethane into a stirrer, add 1,4-dioxane solvent, and stir at 45°C for 3 hours to obtain a mixed solution; the molecular weight of the polylactic acid is 70,000. The mass ratio of the copolymer, polylactic acid and thermoplastic polyurethane is 1:1:10, and the contents of the copolymer, polylactic acid and thermoplastic polyurethane in the 1,4-dioxane solvent are 3g / L, 3g / L and 30g / L respectively. In the 1,4-dioxane solvent, the volume ratio of water to 1,4-dioxane is 1:9;

[0057] S3: Phase separation: After the temperature of the mixed solution drops to room temperature, water is further added, stirring is continued for 1 hour, and the mixture is allowed to stand at 0°C for 30 minutes, and then frozen in a -16°C refrigerator for 36 hours. After that, the mixture is placed in a -50°C freeze dryer for freeze drying to remove water and 1,4-dioxane, thereby obtaining a biodegradable polyurethane-based composite porous material.

[0058] Embodiment 3:

[0059] A biodegradable polyurethane-based composite porous material, wherein the composite porous material is prepared by the following formula and preparation method:

[0060] S1: Grafting treatment: grafting hydrogenated styrene-butadiene block copolymer or hydrogenated styrene-ethylene-propylene-styrene block copolymer with maleic anhydride to obtain maleic anhydride grafted styrene-ethylene-butylene-styrene block copolymer or maleic anhydride grafted styrene-ethylene-propylene-styrene block copolymer; the molecular weight of the hydrogenated styrene-butadiene block copolymer or hydrogenated styrene-ethylene-propylene-styrene block copolymer is 280000;

[0061] S2: Mixing raw materials: Add the copolymer obtained in step S1, polylactic acid and thermoplastic polyurethane into a stirrer, add 1,4-dioxane solvent, and stir at 50°C for 5 hours to obtain a mixed solution; the molecular weight of the polylactic acid is 100,000. The mass ratio of the copolymer, polylactic acid and thermoplastic polyurethane is 1:1:10, and the contents of the copolymer, polylactic acid and thermoplastic polyurethane in the 1,4-dioxane solvent are 3g / L, 3g / L and 30g / L respectively. In the 1,4-dioxane solvent, the volume ratio of water to 1,4-dioxane is 1:9;

[0062] S3: After the temperature of the mixed solution drops to room temperature, water is further added, stirring is continued for 1 hour, and the mixture is allowed to stand at 0°C for 30 minutes, and then frozen in a -16°C refrigerator for 36 hours. After that, the mixture is placed in a -50°C freeze dryer for freeze drying to remove water and 1,4-dioxane, thereby obtaining a biodegradable polyurethane-based composite porous material.

[0063] The biodegradable polyurethane-based composite porous material (SEBS-g-MAH / PLA / TPU composite porous material) prepared in Example 2 was compared with the pure TPU porous material in terms of structure and performance in the field of oil-water separation. The results of the comparison are as follows:

[0064] Compared with pure TPU porous material, the SEBS-g-MAH / PLA / TPU composite porous material prepared by the preparation method of the present invention has a more obvious three-dimensional multi-level hierarchical open pore structure, with more micro-nanopores and nanoporous microspheres on the pore wall, and the rich pore structure enables the composite material to have better porosity and mechanical properties, not only allowing oil and other organic pollutants to pass freely, but also its skeleton structure can more effectively support the weight of the absorbed oil, and has a stronger oil retention capacity, providing favorable conditions for storing a large amount of oil and organic solvents.

[0065] The SEBS-g-MAH / PLA / TPU composite porous material prepared by the present technical solution has more excellent hydrophobicity and lipophilicity, and its water contact angle is 142.06°, which is significantly increased compared with the water contact angle (108.09°) of the unmodified TPU porous material.

[0066] The SEBS-g-MAH / PLA / TPU composite porous material prepared by the technical scheme shows excellent saturated adsorption capacity and large adsorption rate for different types of oils and organic solvents, among which the maximum absorption capacity for soybean oil and chloroform is 16.5g / g and 78.5g / g respectively, and the material performance has not changed significantly after 20 cycles of adsorption, while the maximum absorption capacity of the unmodified pure TPU porous material for soybean oil is 11.4g / g, and it will soon swell to floccules after being put into chloroform solvent. This may be mainly due to the combined effect of the micro-nano pores and nanoporous microspheres of the SEBS-g-MAH / TPU porous material, the multi-level hierarchical open pore structure and the low surface energy.

[0067] like Figure 1 / 2, Figure 1 This is the surface morphology of pure TPU porous material. Figure 2 This is the surface morphology of the SEBS-g-MAH / PLA / TPU composite porous material. It can be seen from the above SEM image that compared with the pure TPU porous material, the SEBS-g-MAH / PLA / TPU composite porous material prepared by the present technical scheme has a more obvious three-dimensional multi-level hierarchical open pore structure, with more micro-nanopores on the pore wall and a larger porosity; the surface of the composite porous material is rougher, the number of particles on the pore wall is significantly increased, and they are nanoporous microspheres, which have a good modification effect on the sample surface and are conducive to the adsorption of more organic pollutants such as oil.

[0068] Through the above embodiments and experiments, it is further proved that the composite porous material obtained by the preparation method of a biodegradable polyurethane-based composite porous material of the present invention has stronger oil-water separation ability and oil adsorption ability than pure TPU porous material and general modified material, and waste is treated with waste. By adding two modifiers together, the discarded TPU plastic matrix can achieve the effect of "waste treatment with waste".

[0069] Although the disclosure is disclosed as above, the protection scope of the disclosure is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the disclosure, and these changes and modifications will fall within the protection scope of the present invention.

Claims

1. A method for preparing a biodegradable polyurethane-based composite porous material, characterized in that: The following steps are involved: S1: Grafting treatment: grafting hydrogenated styrene-butadiene block copolymer or hydrogenated styrene-ethylene-propylene-styrene block copolymer with maleic anhydride to obtain maleic anhydride grafted styrene-ethylene-butylene-styrene block copolymer or maleic anhydride grafted styrene-ethylene-propylene-styrene block copolymer; S2: mixing raw materials: adding the copolymer obtained in step S1, polylactic acid and thermoplastic polyurethane into a stirrer, and adding 1,4-dioxane solvent, stirring to obtain a mixed solution; S3: Phase separation: After the temperature of the mixed solution in step S2 drops to room temperature, water is further added, and stirring is continued. After standing, freezing and drying, a biodegradable polyurethane-based composite porous material is obtained.

2. The method for preparing the biodegradable polyurethane-based composite porous material according to claim 1, characterized in that: In the step S1, the molecular weight of the hydrogenated styrene-butadiene block copolymer or the hydrogenated styrene-ethylene-propylene-styrene block copolymer is 220,000-280,000; in the step S2, the molecular weight of the polylactic acid is 40,000-100,000.

3. The method for preparing the biodegradable polyurethane-based composite porous material according to claim 2, characterized in that: In the step S2, the mass ratio of the copolymer, polylactic acid and thermoplastic polyurethane is 1:1:

10.

4. The method for preparing the biodegradable polyurethane-based composite porous material according to claim 1, characterized in that: In the step S2, the contents of the copolymer, polylactic acid, and thermoplastic polyurethane in the 1,4-dioxane solvent are 3 g / L, 3 g / L, and 30 g / L, respectively.

5. The method for preparing the biodegradable polyurethane-based composite porous material according to claim 1, characterized in that: In the step S2, the volume ratio of water to 1,4-dioxane in the 1,4-dioxane solvent is 1:

9.

6. The method for preparing the biodegradable polyurethane-based composite porous material according to claim 1, characterized in that: In the step S2, the stirring condition is: stirring at a temperature of 40°C-50°C for 3-5 hours; in the step S3, the stirring time is continued for 1 hour.

7. The method for preparing the biodegradable polyurethane-based composite porous material according to claim 1, characterized in that: In the step S3, the standing condition is: standing at 0° C. for 30 minutes.

8. The method for preparing the biodegradable polyurethane-based composite porous material according to claim 1, characterized in that: In step S3, the freeze-drying treatment conditions are: freezing in a -16°C refrigerator for 36 hours, and then freeze-drying in a -50°C freeze dryer.

9. A biodegradable polyurethane-based composite porous material, characterized in that: The composite porous material is prepared by any preparation method according to claims 1-8.

10. An application of a biodegradable polyurethane-based composite porous material, characterized in that: The application includes applying the biodegradable polyurethane-based composite porous material according to claim 9 to oil-water separation to adsorb oil and organic pollutants therein.

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