A bio-based recyclable polyurethane foam and a method of making the same

Abstract

The application discloses a kind of bio-based recyclable polyurethane foam and its preparation method.The bio-based recyclable polyurethane foam of the application is composed of vegetable oil-based polyol, bio-based diol carrying reversible imine bond, silicone oil, water, zinc salt catalyst, polyurethane catalyst and diisocyanate.The preparation method is to mix all raw materials uniformly, solidify after standing and foaming, and prepare bio-based recyclable polyurethane foam.The bio-based recyclable polyurethane foam of the application has the characteristics of renewable raw materials, environmental friendly, recyclable;And after being regulated by zinc salt catalyst, the bio-based recyclable polyurethane foam of the application has the characteristics of easy to recycle and good quality of recycled goods;In addition, the bio-based recyclable polyurethane foam of the application has simple preparation process, mild reaction condition, little pollution, wide raw material source, low cost, and is suitable for industrialization promotion.

Description

TECHNICAL FIELD

[0001] The present application relates to a polyurethane foam and a method for preparing the same, in particular, a bio-based recyclable polyurethane foam and a method for preparing the same BACKGROUND

[0002] Polyurethane foam is widely used in building insulation, commodity packaging, sound insulation and textile industry due to its excellent thermal insulation, porosity, low density and high specific strength. However, the raw materials for producing polyurethane foam at present are mostly non-renewable petroleum resources, and there is a lack of efficient and environmentally friendly methods for recycling waste polyurethane foam. Therefore, it is of great significance to develop recyclable polyurethane foam based on renewable raw materials.

[0003] At present, the main treatment methods for waste polyurethane foam include incineration, landfill, physical recycling and chemical recycling. Incineration treatment will produce greenhouse gases and harmful smoke, causing air pollution; landfill treatment will cause waste of land resources and petroleum resources. Physical recycling is to crush waste polyurethane foam and then compound it with other polymer materials. However, since polyurethane foam itself is a cross-linked polymer with poor processability, the recycling process always causes structural damage, resulting in performance degradation of the recycled material. Chemical recycling is a way of reusing polyurethane foam after controlled degradation, for example, the invention patent (CN 113817221B) obtains recycled polyether polyol by crushing and drying waste polyurethane foam, followed by alcoholysis and acidolysis. However, most of the chemical recycling methods have the problems of complex procedures, harsh conditions and high cost.

[0004] Introducing reversible covalent bonds into the polyurethane foam network can endow the polyurethane foam with thermoplastic processability. Sheppard et al. introduced excess dibutyltin dilaurate into the cross-linked polyurethane foam to catalyze the dynamic exchange reaction of urethane, thereby realizing the extrusion processing of polyurethane foam [ACS Cent. Sci., 2020, 6, 921-927]. The existing patent (publication number: CN111116864) also introduces dynamic disulfide bonds into the polyurethane foam network, and the prepared polyurethane foam can be recycled into polyurethane sheet after hot pressing. Liu et al. introduced dynamic urethane and dynamic disulfide bonds into polyurethane foam, and the prepared material has good thermal processing performance [ACS Appl. Polym. Mater., 2022, 4, 5056-5067].

[0005] However, the polyurethane foams containing dynamic covalent bonds reported so far are all based on non-renewable petroleum-based raw materials, and do not solve the problem of non-renewable raw materials of such materials. Although the existing patents (CN112126036A), (CN115926722A), (CN115772278A) and the literature "Preparation and performance of bio-based self-repairing recyclable polyurethane based on dynamic imine bond" disclose the preparation of polyurethane materials containing dynamic covalent bonds using renewable raw materials, the materials are all dense resins or elastomers, not foams. The bio-based materials containing dynamic covalent bonds reported in the prior art cannot be used to produce easy-to-recycle bio-based recyclable polyurethane foams. SUMMARY

[0006] The purpose of the present application is to provide a bio-based recyclable polyurethane foam and a preparation method thereof. The bio-based recyclable polyurethane foam of the present application has the characteristics of renewable raw materials, environmental friendliness and recyclability. After being regulated by a zinc salt catalyst, the bio-based recyclable polyurethane foam of the present application has the characteristics of easy recycling and good quality of recycled products. In addition, the preparation process of the bio-based recyclable polyurethane foam of the present application is simple, the reaction conditions are mild, the pollution is small, the raw materials are widely available, the cost is low, and it is suitable for industrialization.

[0007] The technical solution of the present application is a bio-based recyclable polyurethane foam, which consists of the following components by weight:

[0008] Plant oil-based polyol: 60-210 parts;

[0009] Bio-based diol carrying reversible imine bond: 20-80 parts;

[0010] Silicone oil: 0.1-10 parts;

[0011] Water: 0.3-5 parts;

[0012] Zinc salt catalyst: 0.1-10 parts;

[0013] Polyurethane catalyst: 0.1-4 parts;

[0014] Diisocyanate: 100 parts.

[0015] The bio-based recyclable polyurethane foam described above consists of the following components by weight:

[0016] Plant oil-based polyol: 80 parts;

[0017] Bio-based diol carrying reversible imine bond: 25 parts;

[0018] Silicone oil: 5 parts;

[0019] Water: 3 parts;

[0020] Zinc salt catalyst: 1 part;

[0021] Polyurethane catalyst: 1.5 parts;

[0022] Diisocyanate: 100 parts.

[0023] The aforementioned bio-based recyclable polyurethane foam, the plant oil-based polyol is one or any of castor oil-based polyol, soybean oil-based polyol, palm oil-based polyol, glycerol-based polyol, rosin ester-based polyol, rapeseed oil-based polyol, coconut oil-based polyol or derivatives of the plant oil-based polyol.

[0024] The aforementioned bio-based recyclable polyurethane foam, the preparation method of the bio-based diol carrying reversible imine bond is: dissolving one of vanillin, syringaldehyde, 5-hydroxymethyl furfural or p-hydroxybenzaldehyde in a solvent, and reacting with equimolar amount of vanillin amine hydrochloride or p-aminophenol to obtain bio-based diol carrying reversible imine bond after filtration and washing.

[0025] The aforementioned bio-based recyclable polyurethane foam, the solvent is one or any mixed solvent of water, ethanol, methanol or isopropanol.

[0026] The aforementioned bio-based recyclable polyurethane foam, the reaction conditions are nitrogen atmosphere, 10-50℃ reaction for 12-48h.

[0027] The aforementioned bio-based recyclable polyurethane foam, the zinc salt catalyst is one or any of zinc chloride, zinc sulfate, zinc nitrate, zinc fluorosilicate, zinc fluoroborate, zinc acetate or zinc bromide.

[0028] The aforementioned bio-based recyclable polyurethane foam, the polyurethane catalyst is one or any of dibutyltin dilaurate, stannous octoate, dibutyltin diacetate, dibutyltin mercaptan, dibutyltin sulfate, triethylenediamine or tetramethylbutanediamine.

[0029] A preparation method of the aforementioned bio-based recyclable polyurethane foam, plant oil-based polyol, bio-based diol carrying reversible imine bond, silicone oil, water, zinc salt catalyst and polyurethane catalyst are uniformly mixed; then diisocyanate is added to make all raw materials uniformly mixed, and the bio-based recyclable polyurethane foam is prepared after foaming and curing.

[0030] The aforementioned preparation method of bio-based recyclable polyurethane foam, the temperature during mixing is 10-40℃; the temperature during foaming and curing is 10-85℃; the foaming time is 5-20min; and the curing time is 1-24h.

[0031] Advantages of the present application

[0032] 1. The application has the advantages of renewable raw materials, wide raw material sources, environmental friendliness and low cost by using plant oil-based polyols as biomass raw materials.

[0033] 2. The application realizes the recyclable function of polyurethane foam by adding bio-based diols carrying reversible imine bonds in the polyurethane foam and through the action of dynamic imine bonds.

[0034] 3. The application adds bio-based diols carrying reversible imine bonds, and also uses Zn 2+ to control the dynamic behavior of dynamic imine bonds and promote the polyurethane network reconstruction process in the recycling process, overcoming the problem of material performance degradation caused by structure damage in the traditional physical recycling process, so that the polyurethane foam of the application has the advantages of easier recycling and better quality of recycled products.

[0035] 4. The bio-based recyclable polyurethane foam of the application has simple preparation process, mild reaction conditions, small pollution, wide raw material sources and low cost, and is suitable for industrialization. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 Figure 1 is the Fourier transform infrared spectrum of the bio-based recyclable polyurethane foam and the polyurethane sheet after hot pressing recycling in Example 7.

[0037] Figure 2 Figure 2 is a comparison of the appearance of the bio-based recyclable polyurethane foam and the polyurethane sheet after hot pressing recycling in Example 7.

[0038] Figure 3 Figure 3 is the SEM morphology of the bio-based recyclable polyurethane foam in Example 7.

[0039] Figure 4 Figure 4 is the SEM morphology of the polyurethane sheet after hot pressing recycling of the bio-based recyclable polyurethane foam in Example 7.

[0040] Figure 5 Figure 5 is the compressive stress-strain curve of the bio-based recyclable polyurethane foam in Example 7.

[0041] Figure 6 Figure 6 is the tensile stress-strain curve of the polyurethane sheet after hot pressing recycling of the bio-based recyclable polyurethane foam in Example 10 and Example 11.

[0042] Figure 7 Figure 7 is a comparison of the appearance of the polyurethane sheet after hot pressing recycling of the bio-based recyclable polyurethane foam in Example 10 and Example 11.

[0043] wherein, Figure 1 Figure 8 shows that the chemical structure of the recycled polyurethane sheet is consistent with that of the original polyurethane foam.

[0044] Figures 2-4 It is shown that the loose polyurethane foam is converted into dense polyurethane sheet after heat pressing recovery.

[0045] Figure 5 With Figure 6 It is shown that both the bio-based recyclable polyurethane foam and the recycled polyurethane sheet have good mechanical properties, which can meet the use requirements.

[0046] Figure 6 It is shown that the mechanical properties of the recycled polyurethane sheet without zinc acetate are obviously weaker than those of the recycled polyurethane sheet with zinc acetate.

[0047] Figure 7 It is shown that obvious defects can be observed on the surface of the recycled polyurethane sheet without zinc acetate.

[0048] Figure 6 And Figure 7 The phenomenon shown indicates that the addition of Zn 2+ The imine bond can be effectively controlled to overcome the problem of performance degradation in the physical recovery process of the polyurethane foam. DETAILED DESCRIPTION

[0049] The present application will be further described below in conjunction with examples, but it is not limited to the basis of the application.

[0050] Embodiments of the present application

[0051] Example 1: A bio-based recyclable polyurethane foam, consisting of the following components by weight parts:

[0052] Plant oil-based polyol: 80 parts;

[0053] Bio-based diol carrying reversible imine bond: 25 parts;

[0054] Silicone oil: 5 parts;

[0055] Water: 3 parts;

[0056] Zinc salt catalyst: 1 part;

[0057] Polyurethane catalyst: 1.5 parts;

[0058] Diisocyanate: 100 parts.

[0059] Example 2: A bio-based recyclable polyurethane foam, consisting of the following components by weight parts:

[0060] Plant oil-based polyol: 60 parts;

[0061] Bio-based diol carrying reversible imine bond: 20 parts;

[0062] Silicone oil: 0.1 parts;

[0063] Water: 0.3 parts;

[0064] Zinc salt catalyst: 0.1 parts;

[0065] Polyurethane catalyst: 0.1 parts;

[0066] Diisocyanate: 100 parts.

[0067] Example 3: A bio-based recyclable polyurethane foam consisting of the following components by weight parts:

[0068] Vegetable oil-based polyol: 210 parts;

[0069] Bio-based diol carrying reversible imine bond: 80 parts;

[0070] Silicone oil: 10 parts;

[0071] Water: 5 parts;

[0072] Zinc salt catalyst: 10 parts;

[0073] Polyurethane catalyst: 4 parts;

[0074] Diisocyanate: 100 parts.

[0075] Example 4: Preparation of bio-based diol carrying reversible imine bond: Vanillin was dissolved in water under nitrogen atmosphere, reacted with equal molar amount of vanillin amine hydrochloride at 10 °C for 48 h, then filtered and washed to obtain bio-based diol carrying reversible imine bond.

[0076] Example 5: Preparation of bio-based diol carrying reversible imine bond: Safflower aldehyde was dissolved in ethanol under nitrogen atmosphere, reacted with equal molar amount of vanillin amine hydrochloride at 30 °C for 30 h, then filtered and washed to obtain bio-based diol carrying reversible imine bond.

[0077] Example 6: Preparation of bio-based diol carrying reversible imine bond: p-Hydroxybenzaldehyde was dissolved in isopropyl alcohol under nitrogen atmosphere, reacted with equal molar amount of p-amino phenol at 50 °C for 12 h, then filtered and washed to obtain bio-based diol carrying reversible imine bond.

[0078] Example 7: Preparation of bio-based recyclable polyurethane foam: 80 parts of castor oil, 25 parts of bio-based reversible imine diol monomer, 5 parts of silicone oil, 3 parts of water, 1 part of zinc acetate and 1.5 parts of dibutyltin dilaurate were added into a container and mixed uniformly at 10 °C; then 100 parts of diphenyl methane diisocyanate (trade name PM-200) was quickly added, and after quick stirring and mixing uniformly, free foaming was carried out at 10 °C for 20 min, and curing was carried out at 10 °C for 24 h to prepare bio-based recyclable polyurethane foam. The density of the bio-based polyurethane foam was 69 kg / m3. 3The bio-based polyurethane foam was pulverized and then placed on a flat vulcanizing machine and hot-pressed at 150°C and 10MPa for 90 minutes to obtain polyurethane sheets.

[0079] Example 8: Preparation of bio-based recyclable polyurethane foam: 79 parts castor oil, 33 parts bio-based reversible imine diol monomer, 4 parts silicone oil, 2.5 parts water, 1 part zinc acetate, and 1.2 parts dibutyltin dilaurate were added to a container and mixed evenly at room temperature (20°C). Then, 100 parts diphenylmethane diisocyanate (brand name PM-200) were quickly added and rapidly stirred until evenly mixed. The mixture was then allowed to foam freely at 20°C for 10 minutes and cured at 75°C for 20 hours to obtain bio-based recyclable polyurethane foam. The density of this bio-based polyurethane foam was 85 kg / m³. 3 The bio-based polyurethane foam was pulverized and then placed on a flat vulcanizing machine and hot-pressed at 150°C and 10MPa for 90 minutes to obtain polyurethane sheets.

[0080] Example 9: Preparation of Bio-based Recyclable Polyurethane Foam: 60 parts castor oil, 25 parts bio-based reversible imine diol monomer, 5 parts silicone oil, 3.5 parts water, 1 part zinc acetate, and 1.2 parts dibutyltin dilaurate were added to a container and mixed thoroughly at room temperature (25°C). Then, 100 parts diphenylmethane diisocyanate (brand name PM-200) were quickly added and rapidly stirred until homogeneous. The mixture was then allowed to foam freely at 20°C for 10 minutes and cured at 70°C for 29 hours to obtain bio-based recyclable polyurethane foam. The density of this bio-based polyurethane foam was 140 kg / m³. 3 The bio-based polyurethane foam was pulverized and then placed on a flat vulcanizing machine and hot-pressed at 150°C and 10MPa for 90 minutes to obtain polyurethane sheets.

[0081] Example 10: Preparation of bio-based recyclable polyurethane foam: 72 parts castor oil, 28 parts bio-based reversible imine diol monomer, 6 parts silicone oil, 3.6 parts water, 2 parts zinc acetate, and 1.2 parts dibutyltin dilaurate were added to a container and mixed evenly at 40°C. Then, 100 parts diphenylmethane diisocyanate (brand name PM-200) were quickly added and rapidly stirred until evenly mixed. The mixture was then allowed to foam freely at 85°C for 5 minutes and cured at 85°C for 1 hour to obtain bio-based recyclable polyurethane foam. The density of this bio-based polyurethane foam was 55 kg / m³. 3 The bio-based polyurethane foam was pulverized and then placed on a flat vulcanizing machine and hot-pressed at 150°C and 10MPa for 90 minutes to obtain polyurethane sheets.

[0082] Example 11: Preparation of bio-based recyclable polyurethane foam: 72 parts of castor oil, 28 parts of bio-based reversible imine diol monomer, 6 parts of silicone oil, 3.6 parts of water, 0 parts of zinc acetate and 1.2 parts of dibutyl tin dilaurate were added into a container and mixed uniformly at 30°C; then 100 parts of diphenylmethane diisocyanate (trade name PM-200) was quickly added, and after mixing uniformly under rapid stirring, free foaming was carried out at 85°C for 5 min, and curing was carried out at 85°C for 1 h to prepare a bio-based recyclable polyurethane foam. The density of the bio-based polyurethane foam was 73 kg / m3. 3 The bio-based polyurethane foam was crushed and placed on a flat vulcanizing machine for hot pressing at 150°C and 10 MPa for 90 min to obtain a polyurethane sheet.

[0083] The above is only a preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can make equivalent replacements or changes within the technical scope disclosed by the present application according to the technical solutions and inventive concepts of the present application, which should be covered within the protection scope of the present application.

Claims

1. A bio-based recyclable polyurethane foam, characterized in that, By weight, it consists of the following components: Vegetable oil-based polyols: 60-210 parts; Bio-based diols carrying reversible imine bonds: 20-80 parts; Silicone oil: 0.1-10 parts; Water: 0.3-5 parts; Zinc salt catalyst: 0.1-10 parts; Polyurethane catalyst: 0.1-4 parts; Diisocyanate: 100 parts; The preparation method of the bio-based diol carrying reversible imine bonds is as follows: one of vanillin, eugenol, 5-hydroxymethylfurfural or p-hydroxybenzaldehyde is dissolved in a solvent, reacted with an equimolar amount of vanillinamine hydrochloride or p-aminophenol, and then filtered and washed to obtain the bio-based diol carrying reversible imine bonds. The zinc salt catalyst is one or any combination of zinc chloride, zinc sulfate, zinc nitrate, zinc fluorosilicate, zinc fluoroborate, zinc acetate, or zinc bromide.

2. The bio-based recyclable polyurethane foam according to claim 1, characterized in that, By weight, it consists of the following components: Vegetable oil-based polyols: 80 parts; Bio-based diols carrying reversible imine bonds: 25 parts; Silicone oil: 5 parts; Water: 3 parts; Zinc salt catalyst: 1 part; Polyurethane catalyst: 1.5 parts; Diisocyanate: 100 parts.

3. The bio-based recyclable polyurethane foam according to any one of claims 1 or 2, characterized in that: The plant oil-based polyol is one or any combination of castor oil-based polyol, soybean oil-based polyol, palm oil-based polyol, glycerol-based polyol, rosin ester-based polyol, rapeseed oil-based polyol, coconut oil-based polyol, or derivatives of the plant oil-based polyol.

4. The bio-based recyclable polyurethane foam according to claim 1, characterized in that: The solvent is one or any mixture of water, ethanol, methanol or isopropanol.

5. The bio-based recyclable polyurethane foam according to claim 1, characterized in that: The reaction is carried out under a nitrogen atmosphere at 10-50°C for 12-48 hours.

6. The bio-based recyclable polyurethane foam according to any one of claims 1 or 2, characterized in that: The polyurethane catalyst is one or any combination of dibutyltin dilaurate, stannous octoate, dibutyltin diacetate, dibutyltin thiol, dibutyltin sulfate, triethylenediamine, or tetramethylbutanediamine.

7. A method for preparing bio-based recyclable polyurethane foam according to any one of claims 1-6, characterized in that: Vegetable oil-based polyol, bio-based diol carrying reversible imine bonds, silicone oil, water, zinc salt catalyst and polyurethane catalyst are mixed evenly; then diisocyanate is added to mix all raw materials evenly, and the mixture is allowed to stand to foam and then cured to prepare bio-based recyclable polyurethane foam.

8. The method for preparing bio-based recyclable polyurethane foam according to claim 7, characterized in that: The mixing temperature is 10-40℃; the foaming and curing temperature is 10-85℃; the foaming time is 5-20 min; and the curing time is 1-24 h.

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