A method for the preparation of a porous reticulated bio-based sponge from waste polyurethane foam

Abstract

The present application belongs to the technical field of polyurethane foam recycling, and particularly relates to a method for preparing porous reticular bio-based sponge by regenerating waste polyurethane foam, which comprises the following steps: firstly, crushing the waste soft polyurethane foam to a specific size; then, reacting the compounded alcoholysis agent, catalyst A and waste polyurethane foam in a reaction kettle according to a proportion to obtain a degradation liquid; further, reacting the degradation liquid, an additive and catalyst B under specific conditions to obtain bio-based polyol; finally, mixing the bio-based polyol with other raw materials to foam, and freely forming bio-based polyurethane foam at a certain temperature, which effectively solves the problem of difficult recycling of polyurethane foam waste, realizes resource recycling, and reduces resource waste and environmental threat. The combination of relatively inexpensive alcoholysis agent and catalyst reduces production cost and is more environmentally friendly and energy-saving. The prepared porous reticular bio-based sponge has unique structure and performance, and can be applied to multiple fields, and has high application value.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of polyurethane foam recycling, and particularly relates to a method for preparing porous reticular bio-based sponge by regenerating waste polyurethane foam. BACKGROUND

[0002] As an organic synthetic material with extremely wide application, polyurethane can produce products with different properties and appearances by changing the types and proportions of polyether polyols and polyisocyanate and adopting various production processes in chemical production. With excellent performance, polyurethane materials are widely used in many fields and have become one of the synthetic materials with the fastest development in recent years. With the increasing annual output of polyurethane foam, petroleum-based polyurethane foam consumes a large amount of petroleum resources, the reaction temperature is as high as 130 DEG C, and the increasing waste products bring serious challenges. Polyurethane is polymerized from isocyanate and polyol, and is difficult to be recycled by conventional methods, so that the waste polyurethane foam which is difficult to degrade can only be treated as garbage, causing resource waste and environmental threat. Therefore, developing a green and widely applicable degrading agent to degrade polyurethane foam recycling technology has become a major research topic with revolutionary significance in the field of polyurethane. At present, the chemical recycling methods include hydrolysis, pyrolysis and alcoholysis. Although the pyrolysis and hydrolysis methods are relatively simple to operate, they require high temperature and pressure and consume a large amount of energy. The alcoholysis method is relatively more green and is one of the most potential recycling methods in chemical methods.

[0003] However, most of the alcoholysis methods currently use petroleum-based polyol to prepare polyurethane products, and petroleum-based polyol is a non-renewable resource, and the high-value application of waste polyurethane foam is still not sufficient, so it is of great significance to realize the high-value application of waste polyurethane foam and the green and sustainable development of the polyurethane industry. SUMMARY

[0004] The purpose of the present application is to provide a method for preparing porous reticular bio-based sponge by regenerating waste polyurethane foam, which aims to solve the problems of difficult recycling and utilization of waste polyurethane foam, resource waste and environmental threat, and to realize the high-value application of waste polyurethane foam and the green and sustainable development of the polyurethane industry.

[0005] To achieve the above purpose, the technical scheme adopted by the present application is:

[0006] A method for preparing porous reticular bio-based sponge by regenerating waste polyurethane foam, comprising the following steps:

[0007] S1. Preparation of degradation solution: mix the alcoholysis agent, catalyst A, and polyurethane foam according to the mass ratio of 100:0.5-3:20-80, place them in a stainless steel reaction kettle, preheat to 90-160 ℃ at a rotation speed of 200-500 rpm, and then react for 120-300 min, and then keep the temperature at 30-60 ℃ for 10-20 min to obtain the degradation solution. The degradation solution contains hydroxyl groups, ester groups, tetrafluoroborate groups, butoxy groups, and silicate sheets. The hydroxyl and ester groups can promote the ester exchange reaction of the polyurethane foam, and the bioethanol can be gasified at high temperature, which helps to promote the rupture of the urea bond in the polyurethane foam and prevent the polyurethane foam from coking during the degradation process;

[0008] S2. Preparation of bio-based polyol: add the degradation solution prepared in step S1, the auxiliary agent, and catalyst B to the stainless steel reaction kettle according to the mass ratio of 100:100-300:1-5, and react at 150-210 ℃ for 180-480 min at a rotation speed of 200-500 rpm to obtain a bio-based polyol.

[0009] S3. Preparation of reticular bio-based sponge: mix the bio-based polyol prepared in step S2, catalyst, silicon oil L580, foaming agent, pore-forming agent, isocyanate, and other materials according to the mass ratio of 100:0.1-0.6:3-5:2-10:0.2-2:90-150, and then use mechanical stirring to blend and foam. Then place it in a free-forming environment at 0-25 ℃ to obtain a bio-based polyurethane foam, which is a reticular bio-based sponge. The present application uses waste polyurethane foam to form long-chain polyether compounds and grafts with castor oil acid to form regenerated cross-linked polyol, and then prepares a reticular bio-based sponge. The reticular bio-based sponge not only provides good cushioning effect and is widely used in packaging, furniture, automobile seats, etc., providing a comfortable user experience, but also has good filtering performance, which can filter particulate matter and pollutants in the air, keeping the indoor air fresh. The reticular bio-based sponge not only realizes the high-value application of waste polyurethane foam, but also promotes the green development of the environment.

[0010] Further, the polyurethane foam in step S1 is waste soft polyurethane foam and needs to be crushed to 1-5 cm for use.

[0011] Further, the alcoholysis agent in the step S1 is compounded by the following raw materials with mass percentage: bioethanol 10-25%, crude glycerol 35-50%, furfuryl alcohol 7-15%, 1,4-butanediol 15-25%, and polylactic acid 8-20%; the compounded alcoholysis agent can promote the transesterification with the urethane groups in the polyurethane foam and the urea bond breaking reaction, and simultaneously regulate the molecular weight and viscosity of the alcoholysis product, so as to improve the performance of the alcoholysis product. Because the bioethanol can form hydrogen bond and other interactions with the crude glycerol and the furfuryl alcohol, the polarity of the whole alcoholysis system is enhanced, so as to improve the solubility to the polyurethane foam. Meanwhile, the molecular chain of the polylactic acid can also intertwine with the alcoholysis product or form a copolymer, so as to improve the structure and performance of the product.

[0012] Further, the catalyst A is at least one of dimethyl bismuth, zinc acetate, 9-cymene acridine, tetrabutyl titanate, titanium dioxide, antimony trioxide, molybdenum trioxide, and iron-based montmorillonite.

[0013] Further, the auxiliary agent in the step S2 is one of oleic acid, linoleic acid, ricinoleic acid, and linolenic acid; and the catalyst B is one of potassium hydroxide, sodium hydroxide, sodium ethoxide, and potassium ethoxide.

[0014] Further, the catalyst in the step S3 is a delayed amine catalyst A300 and stannous octoate T9, and the mass ratio of the two is 1:1-3; and the isocyanate is one of toluene diisocyanate TDI and polyphenyl polymethylene polyisocyanate PMDI.

[0015] The present application has the advantages of:

[0016] 1. The present application effectively solves the problem that the polyurethane foam waste is difficult to recycle, and by adopting the bio-based alcoholysis agent and the auxiliary agent, the waste sofa soft polyurethane foam is converted into valuable products, so that the resource recycling is realized, the resource waste is reduced, and the polyurethane industry is promoted to move towards the green and sustainable development direction.

[0017] 2. The method adopts the relatively inexpensive alcoholysis agent and catalyst combination, so that the production cost is reduced. Compared with the pyrolysis method and the hydrolysis method, the alcoholysis method has smaller energy consumption and is more environmentally friendly and energy-saving. In the preparation process, the reaction temperature and pressure are relatively low, the demand for energy is reduced, and the requirements of sustainable development are met.

[0018] 3. The present application first proposes to use waste polyurethane foam as raw material, to realize resource recycling by alcoholysis method under lower reaction temperature and pressure, to reduce the dependence on non-renewable petroleum resources and waste emissions, to be more green and energy saving, and to have unique structure and performance of the prepared sponge, low density, high porosity, high tear strength, pore size comparable to commercial petroleum-based foam, high application value and stable and reliable performance.

[0019] 4. The porous reticular bio-based sponge prepared by the method of the present application has unique structure and performance, and can be applied to filtration materials, sound-absorbing materials, cleaning supplies and other fields, and has high application value. Precise control of the reaction conditions and raw material ratio of each step ensures stable product performance and reliable quality.

[0020] DRAWINGS

[0021] Figure 1 Optical diagram of the reticular polyurethane foam prepared in Example 1 of the present application.

[0022] Figure 2 FTIR spectrum of Example 1 and Comparative Example 4 of the present application. DETAILED DESCRIPTION

[0023] Example 1

[0024] The waste polyurethane foam was crushed to 1-3 cm, and the alcoholysis agent (biological ethanol: crude glycerol: furfuryl alcohol: 1,4-butanediol: polylactic acid in a mass ratio of 20:40:10:15:15), catalyst A (zinc acetate: tetrabutyl titanate in a mass ratio of 1:1) and waste polyurethane foam were mixed in a stainless steel reaction kettle at a mass ratio of 100:1:50, the rotating speed was controlled at 300 rpm, heated to 120℃, reacted for 240 min, cooled to 40℃, and kept for 10 min to obtain a degradation solution. The degradation solution, additive (oleic acid) and catalyst B (sodium hydroxide) were added to the stainless steel reaction kettle at a mass ratio of 100:200:3, and reacted at 200℃ for 360 min to obtain a bio-based polyol. The test results showed that the molecular weight of the bio-based polyol was 4520, the hydroxyl value was 80 mg KOH / g, and the viscosity was 500 mPa·s. The bio-based polyol, catalyst, silicon oil L580, foaming agent, opening agent and isocyanate were mixed at a mass ratio of 100:0.3:3:3:0.5:100, and then blended and foamed by mechanical stirring. After stirring for 20 s, the porous reticular bio-based polyurethane sponge was obtained by free forming at 0-25℃, and served as a filtration material. After 72 h, the density of the porous reticular bio-based polyurethane foam was 30 kg / m 3 , the porosity was 98%, the pore size was 80 PPI, and the tear strength was 15 N / cm.

[0025] Example 2

[0026] The waste polyurethane foam was crushed to 2-4 cm, and the alcoholysis agent (bioethanol: crude glycerol: furfuryl alcohol: 1,4-butanediol: polylactic acid in a mass ratio of 15:45:12:18:10), catalyst A (dimethyl bismuth: titanium dioxide in a mass ratio of 2:1) and waste polyurethane foam in a mass ratio of 100:2:60 were mixed into a stainless steel reaction kettle, the rotating speed was controlled at 400 rpm, heated to 140°C, reacted for 200 min, then cooled to 50°C, and kept for 15 min to obtain a degradation solution. The degradation solution, auxiliary agent (linoleic acid) and catalyst B (sodium ethoxide) in a mass ratio of 100:250:4 were added into a stainless steel reaction kettle, and reacted at 190°C for 400 min to obtain a bio-based polyol. The molecular weight of the bio-based polyol was 4800, the hydroxyl value was 75 mg KOH / g, and the viscosity was 550 mPa-s. The bio-based polyol, catalyst (delayed amine catalyst A300 and stannous octoate T9 in a mass ratio of 1:2), silicone oil L580, foaming agent, pore opener and isocyanate in a mass ratio of 100:0.4:4:4:0.8:120 were mixed, and mechanical stirring was used for blending and foaming. After stirring for 25 s, the porous reticular bio-based polyurethane sponge was placed at 0-25°C for free forming to serve as a filter material. After 72 h, the density of the porous reticular bio-based polyurethane sponge was 28 kg / m³, the porosity was 97%, the pore size was 86 PPI, and the tear resistance was 13 N / cm.

[0027] Example 3

[0028] The waste polyurethane foam was crushed to 3-5 cm, and the alcoholysis agent (biological ethanol: crude glycerol: furfuryl alcohol: 1,4-butanediol: polylactic acid mass ratio of 18:42:11:16:13), catalyst A (9-cymene acridine: antimony trioxide mass ratio of 1:2) and waste polyurethane foam were mixed in a mass ratio of 100:1.5:70 into a stainless steel reaction kettle. The rotating speed was controlled at 350 rpm, heated to 130°C, reacted for 220 min, then cooled to 45°C, and kept for 12 min to obtain a degradation solution. The degradation solution, auxiliary agent (castor oil acid), catalyst B (potassium ethoxide) were added to the stainless steel reaction kettle in a mass ratio of 100:220:3.5, and reacted at 185°C for 380 min to obtain a bio-based polyol. The molecular weight of the bio-based polyol was 4650, the hydroxyl value was 78 mg KOH / g, and the viscosity was 520 mPa·s. The polyol, catalyst (delayed amine catalyst A300 and stannous octoate T9 mass ratio of 1:2.5), silicone oil L580, foaming agent, pore opener, isocyanate were mixed in a mass ratio of 100:0.5:3.5:5:1:110, and then mechanically stirred and blended to foam. After stirring for 30 s, the porous reticular bio-based polyurethane sponge was placed at 0-25°C to freely form and obtain a filter material. After 72 h, the density of the porous reticular bio-based polyurethane sponge was measured to be 29 kg / m³, the porosity was 96%, the pore size was 89 PPI, and the tear resistance was 12 N / cm.

[0029] Example 4

[0030] The waste polyurethane foam is crushed to 1-4 cm, and the alcoholysis agent (bioethanol: crude glycerol: furfuryl alcohol: 1,4-butanediol: polylactic acid mass ratio is 16:44:13:17:10), catalyst A (iron-based montmorillonite: molybdenum trioxide mass ratio is 3:1) and waste polyurethane foam are mixed in a mass ratio of 100:2.5:75 into a stainless steel reaction kettle. The rotating speed is controlled at 450 rpm, heated to 150 ℃, reacted for 180 min, then cooled to 55 ℃, and kept for 18 min to obtain a degradation solution. The degradation solution, additive (linolenic acid), catalyst B (sodium hydroxide) are added to the stainless steel reaction kettle in a mass ratio of 100:280:4.5, and reacted at 205 ℃ for 420 min to obtain a bio-based polyol. The molecular weight of the bio-based polyol is 4900, the hydroxyl value is 72 mg KOH / g, and the viscosity is 580 mPa·s. The bio-based polyol, catalyst (delayed amine catalyst A300 and stannous octoate T9 mass ratio is 1:1.5), silicone oil L580, foaming agent, pore opener, isocyanate are mixed in a mass ratio of 100:0.2:4.5:6:1.2:130, and then mechanically stirred and blended and foamed. After stirring for 28 s, the porous reticular bio-based polyurethane sponge is placed at 0-25 ℃ to freely form and obtain a porous reticular bio-based polyurethane sponge as a filter material. After 72 h, the density of the porous reticular bio-based polyurethane sponge is measured to be 27 kg / m³, the porosity is 98%, the pore size is 102 PPI, and the tear resistance is 10 N / cm.

[0031] Example 5

[0032] The waste polyurethane foam is crushed to 2-5 cm, and the alcoholysis agent (biological ethanol: crude glycerol: furfuryl alcohol: 1,4-butanediol: polylactic acid mass ratio is 17:43:12:15:13), catalyst A (tetrabutyl titanate: antimony trioxide mass ratio is 2:1) and waste polyurethane foam are mixed in a stainless steel reaction kettle at a mass ratio of 100:1.8:65. The rotating speed is controlled at 380 rpm, heated to 135°C, reacted for 210 min, then cooled to 48°C, and kept for 16 min to obtain a degradation solution. The degradation solution, additive (oleic acid), catalyst B (potassium ethoxide) are added to the stainless steel reaction kettle at a mass ratio of 100:240:3.8, and reacted at 195°C for 390 min to obtain a bio-based polyol. The molecular weight of the bio-based polyol is 4700, the hydroxyl value is 76 mg KOH / g, and the viscosity is 540 mPa·s. The bio-based polyol, catalyst (delayed amine catalyst A300 and stannous octoate T9 mass ratio is 1:2.2), silicone oil L580, foaming agent, pore opener, isocyanate are mixed at a mass ratio of 100:0.35:4:4.5:0.9:115, and then mechanically stirred and blended to foam. After stirring for 22 s, the porous reticular bio-based polyurethane sponge is placed at 0-25°C to freely form and obtain a filter material. After 72 h, the density of the porous reticular bio-based polyurethane sponge is measured to be 28.5 kg / m³, the porosity is 99%, the pore size is 103 PPI, and the tear resistance is 9 N / cm.

[0033] Comparative Example 1

[0034] The waste polyurethane foam is crushed to the same size as in Example 1, and single biological ethanol is used as the alcoholysis agent. The alcoholysis agent, catalyst A (same as in Example 1) and waste polyurethane foam are mixed in a stainless steel reaction kettle at a mass ratio of 100:1:50, and the same rotating speed, temperature and reaction time are controlled to obtain a degradation solution. There is part of the undegraded waste polyurethane foam in the degradation solution, and the subsequent steps are the same as in Example 1. After 72 h, the density of the porous reticular bio-based polyurethane sponge is measured to be 45 kg / m³, the porosity is 42%, the pore size is 40 PPI, and the tear resistance is 6 N / cm.

[0035] Comparative Example 2

[0036] The waste polyurethane foam is crushed to the same size as in Example 1, and single 1,4-butanediol is used as the alcoholysis agent. The alcoholysis agent, catalyst A (same as in Example 1) and waste polyurethane foam are mixed in a stainless steel reaction kettle at a mass ratio of 100:1:50, and the same rotating speed, temperature and reaction time are controlled. Since the foam does not dissolve, the foam comes into contact with the wall of the reaction kettle during stirring, causing the foam to coking phenomenon, and the subsequent foaming step cannot be carried out.

[0037] Comparative Example 3

[0038] The waste polyurethane foam was crushed to the same size as in Example 1, a single furfuryl alcohol was used as the alcoholysis agent, the alcoholysis agent, catalyst A (the same as in Example 1) and waste polyurethane foam were mixed in a mass ratio of 100:1:50 into a stainless steel reaction kettle, and the same rotation speed, temperature and reaction time were controlled. The foam was not completely dissolved, and since the foam was not dissolved, the foam came into contact with the wall of the reaction kettle during stirring, resulting in coking of the foam, and the subsequent foaming step could not be carried out.

[0039] Comparative Example 4

[0040] The waste polyurethane foam was crushed to the same size as in Example 1, a single crude glycerol was used as the alcoholysis agent, the alcoholysis agent, catalyst A (the same as in Example 1) and waste polyurethane foam were mixed in a mass ratio of 100:1:50 into a stainless steel reaction kettle, and the same rotation speed, temperature and reaction time were controlled to obtain a degradation liquid. There were some undegraded waste polyurethane foams in the degradation liquid, and the subsequent steps were exactly the same as in Example 1. After being placed for 72 h, the density of the porous reticular bio-based polyurethane sponge was measured to be 68 kg / m³, the porosity was 23%, the pore size was 31 PPI, and the tear resistance was 5 N / cm.

[0041] Comparative Example 5

[0042] The waste polyurethane foam was crushed to the same size as in Example 1, a single polylactic acid was used as the alcoholysis agent, the alcoholysis agent, catalyst A (the same as in Example 1) and waste polyurethane foam were mixed in a mass ratio of 100:1:50 into a stainless steel reaction kettle, and the same rotation speed, temperature and reaction time were controlled. The foam was not dissolved and coking occurred. The subsequent foaming step could not be carried out.

[0043] Comparative Example 6

[0044] A reticular polyurethane foam sold on the market, which used petroleum-based polyols as foaming raw materials in the production process. The performance of this foam was tested according to the same test method as in Example 1. The test results showed that the density of the petroleum-based reticular foam was 35 kg / m³, the porosity was 96%, the pore size was 43 PPI, and the tear resistance was 10 N / cm.

[0045] Test Example

[0046] The test performance results of Examples 1-5 and Comparative Examples 1-6 of the present application were compared and analyzed, and the test results are shown in Table 1.

[0047] Table 1 Comparison of properties of reticular polyurethane sponge

[0048]

[0049] As shown in the above table, the alcoholysis agent used in the present application examples 1-5 can alcoholize the polyurethane soft foam, and the bio-based polyols prepared can be used to prepare the reticulated polyurethane sponge for filter material, because the bio-based polyols prepared by using the complex alcoholysis agent to degrade the waste polyurethane foam have smaller viscosity and larger molecular weight than the commercial petroleum-based polyols, so the density of the bio-based polyurethane sponge prepared is as low as 30 kg / m3, the void ratio is as high as more than 95%, and the tear strength is also greater than 9 N / cm, and the void ratio and pore size of the bio-based polyurethane sponge are comparable to those of the commercial petroleum-based foam. The comparative examples 2, 3 and 5 show that the single 1,4-butanediol, furfuryl alcohol and polylactic acid as alcoholysis agent cannot completely alcoholize the polyurethane foam, which shows that these single alcoholysis agents will be limited, and the single crude glycerol and bio-ethanol can alcoholize the polyurethane foam, but the reticulated polyurethane foam prepared by using the bio-based polyols has poor performance in filter material, with a void ratio of less than 50%, a pore size of less than 50 PPI, and a tear strength of as low as 5 N / cm, and the overall performance is greatly different from that of the reticulated polyurethane foam prepared by using the complex alcoholysis agent.

[0050] The product structure prepared by the present application is tested, and it can be observed from Figure 1 that the regenerated reticulated polyurethane sponge has a three-dimensional reticular open structure. Figure 2 The FTIR spectrum of the present application examples 1 and comparative example 4. In the range of 2950~2800 cm -1 , symmetric and asymmetric stretching vibrations are observed, which are related to the vibration of methylene and methyl groups in the polymer backbone. In the range of 3300 cm -1 , the stretching vibration peak indicates that the O-H group in the regenerated polyol reacts with PMDI during the polymerization process, and then forms N-H group.

[0051] In summary, bio-ethanol can form hydrogen bond interaction with alcoholysis agents such as crude glycerol and furfuryl alcohol, enhance the polarity of the entire alcoholysis system, and improve the solubility of polyurethane foam. At the same time, the molecular chain of polylactic acid can intertwine with the alcoholysis product, thereby improving the structure and performance of the product. The complex alcoholysis agent not only can alcoholize the polyurethane foam, but also the performance of the reticulated polyurethane sponge prepared by using the bio-based polyols generated by the complex alcoholysis agent is better than that of the polyurethane sponge prepared by using the single alcoholysis agent and the commercial petroleum-based foam in filter material.

Claims

1. A method for preparing porous mesh bio-based sponges using recycled waste polyurethane foam, characterized in that, Includes the following steps: S1. Preparation of degradation solution: The alcoholysis agent, catalyst A, and polyurethane foam are mixed in a mass ratio of 100:0.5~3:20~80 and placed in a stainless steel reactor. The mixture is preheated to 90~160 ℃ at 200~500 rpm and reacted for 120~300 min. The mixture is then kept at 30~60 ℃ for 10~20 min to obtain the degradation solution. The alcoholysis agent is a compound of the following raw materials in the following mass percentages: bioethanol 10~25%, crude glycerol 35~50%, furfuryl alcohol 7~15%, 1,4-butanediol 15~25%, and polylactic acid 8~20%. Catalyst A is at least one of dimethylbismuth, zinc acetate, 9-trimethylmethylacridine, tetrabutyl titanate, titanium dioxide, antimony trioxide, molybdenum trioxide, and iron-based montmorillonite. The polyurethane foam is waste soft polyurethane foam that needs to be crushed to 1~5 cm before use. S2. Preparation of bio-based polyol: The degradation solution obtained in step S1, the auxiliary agent, and catalyst B are added to a stainless steel reactor at a mass ratio of 100:100~300:1~5. The reactor is reacted at 150~210 ℃ for 180~480 min at a rotation speed of 200~500 rpm to obtain a bio-based polyol. The auxiliary agent is one of oleic acid, linoleic acid, ricinoleic acid, and linolenic acid. The catalyst B is one of potassium hydroxide, sodium hydroxide, sodium ethoxide, and potassium ethoxide. S3. Preparation of reticulated bio-based sponge: The bio-based polyol, catalyst, silicone oil L580, foaming agent, cell opener and isocyanate prepared in step S2 are mixed in a mass ratio of 100:0.1~0.6:3~5:2~10:0.2~2:90~150 and then mixed and foamed by mechanical stirring. Then, it is placed at 0~25 ℃ to freely shape and obtain bio-based polyurethane foam, i.e., reticulated bio-based sponge.

2. The method for preparing porous mesh bio-based sponge by recycling waste polyurethane foam as described in claim 1, characterized in that: The catalyst in step S3 is a delayed amine catalyst A300 and stannous octoate T9, with a mass ratio of 1:1 to 3; the isocyanate is one of toluene diisocyanate TDI and polyphenyl polymethylene polyisocyanate PMDI.

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