Polyol recycling method of polyurethane foam
A novel polyol recycling method for polyurethane foam addresses the issue of amine compounds by separating and regenerating polyols without them, enabling efficient and economical recycling and usage in new polyurethane production.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- LOOPSOL CO LTD
- Filing Date
- 2026-01-16
- Publication Date
- 2026-07-23
AI Technical Summary
Existing methods for recycling polyols from waste polyurethane foam result in the presence of amine compounds that react quickly with isocyanates, making it difficult to control the polyurethane foam manufacturing reaction and reducing the recycling rate to less than 10% by weight, especially when combined with virgin polyols.
A method involving depolymerization of polyurethane foam with a depolymerization polyol, followed by adding an acid-containing substance to separate into layers, using chromatography-like separation with specific solvents and particles to obtain a pure polyol extract, and finally regenerating the polyol without amine compounds.
The method allows for the economic recycling of polyols from waste polyurethane foam, applicable to all types, with the regenerated polyol being equivalent to new polyols, containing less than 1000 ppm of amine compounds, and enabling at least 30% by weight usage in new polyurethane production.
Smart Images
Figure KR2026000986_23072026_PF_FP_ABST
Abstract
Description
Polyol recycling method for polyurethane foam
[0001] The present invention relates to a method for recycling polyols in polyurethane foam, and more specifically, to a method for recycling polyols in polyurethane foam that can economically regenerate polyols from waste polyurethane foam, which is an environmental pollutant, and can be applied to all types of polyurethane foam without limitation, such as rigid, semi-rigid, and flexible types, and can use the regenerated polyols equivalent to new polyols by not including amine-containing compounds.
[0002] The following description merely provides background information related to the present invention and does not constitute prior art.
[0003] Polyurethane foam can take the form of rigid foam used as insulation, semi-rigid foam used for shoe soles, and soft foam used for cushions. Since polyurethane foam is difficult to recycle on its own and acts as a source of environmental pollution when discarded, most of it is currently treated as scrap and incinerated or landfilled.
[0004] Accordingly, methods are being researched to regenerate polyols from discarded polyurethane foam through chemical treatment so that they can be reused in the manufacture of polyurethane foam.
[0005] Specifically, methods are being developed to regenerate polyols by depolymerizing discarded polyurethane foam. Methods of depolymerization include hydrolysis, glycolysis, aminolysis, pyrolysis, phosphorolysis, biological degradation, or supercritical reactions. Currently, the most widely attempted method in industry is the glycolysis reaction.
[0006] However, when polyols are simply separated and regenerated from depolymers using a glycolysis reaction, a large amount of amine compounds are present in the regenerated polyol, and when the regenerated polyol is used to manufacture polyurethane foam, there is a problem in that the amine compounds react too quickly with isocyanates, making it impossible to control the polyurethane foam manufacturing reaction.
[0007] To solve this problem, U.S. Patent No. 5,300,530 discloses a method for controlling the reactivity with isocyanates by treating a glycolysis depolymer with alkylene oxide, and Korean Published Patent Application No. 10-2023-0042812 presents a method for producing a rigid polyurethane-modified regenerated polyol by adding an aldehyde compound to the depolymer, reacting a relatively highly reactive compound with the aldehyde compound, and as a result, gradually depleting the highly reactive compound to obtain a secondary liquid depolymer with controlled reactivity. However, when polyurethane foam is manufactured using polyols regenerated by the above methods, it is difficult to achieve the desired physical properties of the polyurethane foam due to the increased molecular weight; consequently, it is used in combination with virgin polyols, and the recycling rate is significantly reduced as the regenerated polyol is less than 10% by weight.
[0008] Accordingly, there is an urgent need for a polyurethane foam polyol recycling method that can economically regenerate polyol from waste polyurethane foam, which is an environmental pollutant, and can be applied without limitation to all types of polyurethane foam, such as rigid, semi-rigid, and flexible foams, and allows the regenerated polyol to be used as equivalent to new polyol because it does not contain amine-containing compounds.
[0009] [Prior Art Literature]
[0010] [Patent Literature]
[0011] (Patent Document 1) 1. U.S. Patent No. 5,300,530 (April 5, 1994)
[0012] (Patent Document 2) 2. Korean Published Patent 10-2023-0042812 (March 30, 2023)
[0013] The technical problem that the present invention aims to solve is to solve the problems of the past, and to provide a polyol recycling method for polyurethane foam and a recycled polyol produced by said method, which can economically regenerate polyol from waste polyurethane foam, which is an environmental pollutant, and can be applied without limitation to rigid, semi-rigid, and flexible polyurethane foams, and can use the recycled polyol equivalently to new polyol because the recycled polyol does not contain amine-containing compounds.
[0014] The present invention
[0015] S1) A step of obtaining a depolymer by mixing a polyurethane foam and a depolymerization polyol;
[0016] S2) A step of obtaining an intermediate by adding an acid-containing substance to the above depolymer;
[0017] S3) A step of separating into an upper layer and a lower layer centered on the interface of the intermediate;
[0018] S4) A step of introducing an upper layer material into a separation tube filled with separation particles;
[0019] S5) A step of obtaining an extract containing polyol by introducing a solvent soluble to polyol derived from polyurethane foam into a separation tube into which the upper layer material is introduced; and
[0020] S6) A step of obtaining a regenerated polyol from the above extract;
[0021] A method for recycling polyol in polyurethane foam including is provided.
[0022] Preferably, the catalyst is further mixed in step S1) above.
[0023] Specifically, the pH of the intermediate in step S2) above is 1 to 4.
[0024] Preferably, after step S2) above, a solvent soluble in the polyol derived from the polyurethane foam is further added to the intermediate.
[0025] Specifically, the particles for separation in step S4) above are powders for chromatography.
[0026] Specifically, the solvent soluble to the polyol derived from the polyurethane foam in step S5) above is a polar aprotic solvent.
[0027] In addition, the present invention provides a regenerated polyol regenerated by the above method.
[0028] Preferably, the concentration of the amine-containing compound of the regenerated polyol is 0 to 1000 ppm.
[0029] In addition, the present invention provides a polyurethane produced from the above-mentioned regenerated polyol.
[0030] According to the present invention, polyol can be economically recycled from waste polyurethane foam, which is an environmental pollutant, and can be applied without limitation to rigid, semi-rigid, and soft polyurethane foams, and the recycled polyol of polyurethane foam can be used equivalently to new polyol because the recycled polyol does not contain amine-containing compounds, and the recycled polyol recycled by said method can be provided.
[0031] Figure 1 shows a schematic diagram of a polyol recycling method for polyurethane foam according to an embodiment of the present invention.
[0032] Embodiments of the present invention are described below with reference to the attached drawings so that those skilled in the art can easily implement them. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein.
[0033] Throughout this specification, when a part is described as "comprising" a certain component, it means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.
[0034] Figure 1 shows a schematic diagram of a polyol recycling method for polyurethane foam according to an embodiment of the present invention.
[0035] The polyol recycling method of the polyurethane foam of the present invention
[0036] S1) A step of obtaining a depolymer by mixing a polyurethane foam and a depolymerization polyol;
[0037] S2) A step of obtaining an intermediate by adding an acid-containing substance to the above depolymer;
[0038] S3) A step of separating into an upper layer and a lower layer centered on the interface of the intermediate;
[0039] S4) A step of introducing an upper layer material into a separation tube filled with separation particles;
[0040] S5) A step of obtaining an extract containing polyol by introducing a solvent soluble to polyol derived from polyurethane foam into a separation tube into which the upper layer material is introduced; and
[0041] S6) A step of obtaining a regenerated polyol from the above extract;
[0042] Includes
[0043] Each step is explained in detail below.
[0044] S1) A step of obtaining a depolymer by mixing a polyurethane foam and a depolymerization polyol;
[0045] The polyurethane foam mentioned above may be waste polyurethane foam, and rigid, semi-rigid, and flexible polyurethane foams are all applicable without limitation. It is also applicable in the case of foams that are a mixture of rigid, semi-rigid, and flexible polyurethane foams. Furthermore, regarding form, compressed scrap or non-compressible foam are all applicable.
[0046] The above depolymerization polyol may be a known polyol used for the glycolysis depolymerization of polyurethane foam, and specifically, one or more selected from the group consisting of ethylene glycol, propylene glycol, dipropylene glycol, low molecular weight ether-based polyols, low molecular weight ester-based polyols, and copolymer polyols may be used in combination. Reaction Schemes 1 and 2 below represent the glycolysis reaction. In Reaction Schemes 1 and 2 below, R 1 , R 2 are functional groups included in the polyurethane chains of waste polyurethane foam, respectively, and R 3 is a functional group derived from depolymerized polyol.
[0047] [Reaction Equation 1]
[0048]
[0049] [Reaction Equation 2]
[0050]
[0051] The mixing ratio of the polyurethane foam and the depolymerized polyol can be arbitrarily adjusted, and may be 30 to 1,000 parts by weight of depolymerized polyol mixed with 100 parts by weight of polyurethane foam.
[0052] To obtain the above depolymer, the temperature may be raised to 120 to 300°C, and if necessary, a catalyst may be further mixed in step S1). The catalyst may be a known catalyst that serves to break down the polyurethane chains or promote the reaction, and the amount used may be adjusted arbitrarily and may be used in an amount of 0.01 to 10 parts by weight per 100 parts by weight of polyurethane foam.
[0053] Specific examples of catalysts may include basic inorganic compounds or organometallic compounds. Preferably, the catalyst may be NaOH, LiOH, KOH, dibutyl tin oxide (DBTO), (Ca(OH)2, Mg(OH)2), or a mixture of two or more types.
[0054] If necessary, after proceeding with S1) the step of mixing a polyurethane foam and a depolymerization polyol to obtain a depolymer; a filtration step may be performed to remove solid impurities contained in the depolymer before proceeding to the next step. The filtration may utilize a conventional filtration device that separates the liquid depolymer from solid impurities. Alternatively, solid impurities may be separated using centrifugation.
[0055] S2) A step of obtaining an intermediate by adding an acid-containing substance to the above depolymer;
[0056] The depolymer of step S1) above includes polyols derived from polyurethane foam, primary amines, secondary amines, depolymerized polyols, and other materials.
[0057] In the present invention, a method has been developed to separate only pure polyol derived from polyurethane foam from the above depolymer, which has not been attempted before. To this end, an acid-containing substance is added to the above depolymer to obtain an intermediate. The intermediate contains primary amines and secondary amine salts (R 1 -N + H3X - It is changed into ) and included. Here, the above X - is an anion derived from a substance containing the above acid.
[0058] Preferably, the acid-containing substance of step S2) is added in an amount capable of making the pH of the intermediate 1 to 4. More preferably, the pH is 1 to 3. Within the above range, the regenerated polyol does not contain amine-containing compounds and can be used equivalently to the new polyol. Specifically, the acid-containing substance is hydrochloric acid, sulfuric acid, nitric acid, organic acid, or an aqueous solution thereof, but is not limited thereto, and gas may be used as needed.
[0059] If necessary, in order to separate the polyol derived from polyurethane foam from the intermediate with high purity, the present invention may further add a solvent soluble to the polyol derived from polyurethane foam to the intermediate. Preferably, the solvent may be the same or equivalent to the solvent soluble to the polyol derived from polyurethane foam in step S5) described later. A solvent that has no or extremely low solubility for the amine salt contained in the intermediate but high solubility for the polyol derived from polyurethane foam may be used. Specific examples include polar aprotic solvents, and more specifically, methyl acetate, ethyl acetate, butyl acetate, THF, acetonitrile, etc., may be used alone or in a mixture of two or more. The solvent may be used in an amount sufficient to dissolve the polyol derived from polyurethane foam when combined with the amount used in step S5) described later. Preferably, 10 to 300 parts by weight of solvent can be used per 100 parts by weight of polyurethane foam so that the separation of the intermediate interface can be clearly distinguished.
[0060] S3) A step of separating into an upper layer and a lower layer centered on the interface of the intermediate;
[0061] In this step, if the intermediate, and if necessary, a solvent soluble in polyols derived from polyurethane foam, is further added and left to stand for a certain period of time, the intermediate undergoes layer separation around the interface.
[0062] When the above layer separation is performed, the upper layer may contain a polyol and a solvent, and the lower layer may contain an amine salt (R 1 -N + H3X - It may include ), water and other substances.
[0063] Afterwards, a regenerated polyol can be obtained from the upper layer and a regenerated amine can be obtained from the lower layer.
[0064] S4) A step of introducing the upper layer material into a separation tube filled with separation particles;
[0065] In the present invention, the step of introducing the upper layer into a separation tube filled with particles for separation is performed to separate the polyol derived from the polyurethane foam from the intermediate. If necessary, the upper layer may further include a solvent soluble in the polyol derived from the polyurethane foam.
[0066] Specifically, the above separation column may be a column, and more specifically, a column for chromatography, and the material may not be particularly limited, and may be glass, for example.
[0067] Specifically, the separation particles in step S4) above may be materials used in chromatography, may be a mixture of two or more types, and more specifically, are silica particles.
[0068] S5) A step of obtaining an extract containing polyol by introducing a solvent soluble to the polyol derived from polyurethane foam into the column into which the upper layer is introduced;
[0069] In the present invention, in order to separate only the polyol derived from the polyurethane foam from the upper layer, a solvent soluble in the polyol derived from the polyurethane foam is added to obtain an extract containing the polyol. Preferably, the solvent may be one that has no or extremely low solubility for the amine salt contained in the intermediate, while having high solubility for the polyol derived from the polyurethane foam. Specific examples include polar aprotic solvents, and more specifically, methyl acetate, ethyl acetate, butyl acetate, THF, acetonitrile, etc., may be used alone or in a mixture of two or more. The solvent may be used in an amount sufficient to dissolve the polyol derived from the polyurethane foam. The solvent may be used in an amount of 10 to 300 parts by weight per 100 parts by weight of polyurethane foam.
[0070] If necessary, in the step of introducing the upper layer material into the separation tube filled with the separation particles in S4) of the present invention, a solvent soluble in the polyurethane foam-derived polyol of step S5) may be mixed and introduced.
[0071] S6) A step of obtaining a regenerated polyol from the above extract;
[0072] The above extract contains a polyol derived from polyurethane foam and a solvent, and trace amounts of amine salts may be present. In the present invention, a regenerated polyol derived from polyurethane foam can be obtained by applying a known method for separating mixed solvents with different boiling points. Specifically, the regenerated polyol can be obtained by removing the solvent through heating.
[0073] In addition, the present invention provides a regenerated polyol regenerated by the above method.
[0074] The regenerated polyol of the present invention is characterized as a polyol from which amine compounds have been removed while undergoing steps S2) to S6) described in the polyol recycling method of the polyurethane foam.
[0075] Accordingly, the amine-containing compound in the above-mentioned recycled polyol is either completely absent or, even if included, is in an extremely small amount of 1,000 ppm or less. Preferably, it is 100 ppm or less. This fundamentally differs from conventional methods, which included the amine contained in the recycled polyol in a form that converted it into other compounds.
[0076] In addition, the present invention provides a polyurethane produced from the above-described recycled polyol. The recycled polyol produced according to the present invention can be used equivalently to a new polyol, and specifically, can be used in the manufacture of polyurethane.
[0077] According to the present invention, in the manufacture of conventional polyurethane, at least 30% by weight of recycled polyol according to the present invention can be used, whereas in the manufacture of conventional polyurethane, 10% by weight or less of recycled polyol and 90% by weight or more of new polyol can be used, and if necessary, all of the polyol used in the manufacture of polyurethane may be recycled polyol according to the present invention.
[0078] Hereinafter, preferred embodiments are presented to aid in understanding the present invention; however, the following embodiments are merely illustrative of the invention and the scope of the invention is not limited to the following embodiments.
[0079] [Example 1]
[0080] A 2L four-necked flask equipped with a mechanical stirrer, temperature sensor, reflux condenser, and nitrogen injection device was placed on a heating mantle. 1,000g of diethylene glycol was added, and the mixture was heated to 180°C under a nitrogen atmosphere. Then, waste refrigerator foam, cut into pieces of approximately 1 cm³, was added. Once the foam melted, an additional 500g of waste foam was repeatedly added and completely dissolved. The temperature of the dissolved reaction solution was continuously raised to 230°C and the reaction was carried out for 12 hours to decompose the foam. After the reaction was complete, the mixture was cooled to room temperature and filtered to remove solid impurities mixed with the waste foam, thereby preparing a liquid reaction product. Subsequently, 540g of unreacted diethylene glycol was recovered through vacuum distillation, yielding 850g of the depolymerization reaction product.
[0081] The depolymerization reaction mixture was transferred to a 3L 4-neck flask, and a 15 wt% aqueous hydrochloric acid solution was added while maintaining the reaction mixture temperature at 35°C or lower until the pH of the solution reached 2. After the reaction mixture temperature stabilized, 1,000 g of ethyl acetate was added and mixed, then transferred to a separation flask and left to stand to separate into an upper layer containing ethyl acetate solvent with regenerated polyol and a lower layer containing water with amine hydrochloride. The upper layer was washed three times with distilled water.
[0082] 200g of silica gel 60A was dispersed in ethyl acetate solvent and placed in a glass tube. A separation column was prepared to ensure the silica gel was properly packed. An upper layer containing the regenerated polyol was mixed with acetonitrile solvent and slowly added, and the solution passing through the separation column was recovered and then distilled to remove the solvent and water, thereby obtaining 156g of regenerated polyol. The viscosity of the regenerated polyol was 382 cps / 25℃, the hydroxyl value was 412 mgKOH / g, and the total amine value was 0.39 mgKOH / g.
[0083] [Example 2]
[0084] A 2L four-necked flask equipped with a mechanical stirrer, temperature sensor, reflux condenser, and nitrogen injection device was placed on a heating mantle. 1,000g of diethylene glycol and 2.5g of dibutyl tin oxide (DBTO) catalyst were added, and the mixture was heated to 180°C under a nitrogen atmosphere. Then, waste refrigerator foam, cut into pieces of approximately 1 cm³, was added. Once the foam melted, an additional 500g of waste foam was repeatedly added and completely dissolved. The temperature of the dissolved reaction solution was continuously raised to 210°C and the reaction was carried out for 5 hours to decompose the foam. After the reaction was complete, the mixture was cooled to room temperature and filtered to remove solid impurities mixed in the waste foam, thereby preparing a liquid reaction product. Subsequently, 685g of unreacted diethylene glycol was recovered through vacuum distillation, yielding 705g of the depolymerization reaction product.
[0085] The depolymerization reaction mixture was transferred to a 3L 4-neck flask, and a 15 wt% aqueous hydrochloric acid solution was added while maintaining the temperature of the reaction mixture at 35°C or lower until the pH of the solution reached 2. After the temperature of the reaction mixture stabilized, 1,000 g of ethyl acetate was added and mixed, then transferred to a separation flask and left to stand to separate into an upper layer containing ethyl acetate solvent with regenerated polyol and a lower layer containing water with amine hydrochloride. The upper layer was washed three times with distilled water.
[0086] 200g of silica gel 60A was dispersed in ethyl acetate solvent and placed in a glass tube. A separation column was prepared to ensure the silica gel was properly packed. An upper layer containing regenerated polyol was mixed with acetonitrile solvent and slowly added to the column. The solution passing through the separation column was recovered and then distilled to remove the solvent and water, thereby obtaining 195g of regenerated polyol. The viscosity of the regenerated polyol was 525 cps / 25℃, the hydroxyl value was 382 mgKOH / g, and the total amine value was 0.31 mgKOH / g. Compared to Example 1, the depolymerization reaction time was shortened and the yield was higher when a catalyst was used.
[0087] Although embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements by those skilled in the art using the basic concept of the present invention as defined in the following claims also fall within the scope of the present invention.
Claims
1. S1) A step of obtaining a depolymer by mixing a polyurethane foam and a depolymerization polyol; S2) A step of obtaining an intermediate by adding an acid-containing substance to the above depolymer; S3) A step of separating into an upper layer and a lower layer centered on the interface of the intermediate; S4) A step of introducing an upper layer material into a separation tube filled with separation particles; S5) A step of obtaining an extract containing polyol by introducing a solvent soluble to polyol derived from polyurethane foam into a separation tube into which the upper layer material is introduced; and S6) A step of obtaining a regenerated polyol from the above extract; A method for recycling polyol in polyurethane foam including 2. In Paragraph 1, A polyol recycling method for polyurethane foam characterized by further mixing a catalyst in step S1) above.
3. In Paragraph 1, A polyol recycling method for polyurethane foam characterized in that the pH of the intermediate in step S2) is 1 to 4.
4. In Paragraph 1, A method for recycling polyol from polyurethane foam, characterized by further adding a solvent soluble to the polyol derived from the polyurethane foam to the intermediate after step S2) above.
5. In Paragraph 1, A polyol recycling method for polyurethane foam characterized in that the separation particles in step S4) above are chromatographic powders.
6. In Paragraph 1, A method for recycling polyol from polyurethane foam, characterized in that the solvent soluble to the polyol derived from the polyurethane foam in step S5) above is a polar aprotic solvent.
7. Regenerated polyol produced by the method described in any one of paragraphs 1 to 6.
8. In Paragraph 7, A recycled polyol characterized in that the concentration of the amine-containing compound of the recycled polyol is 0 to 1000 ppm.
9. Polyurethane manufactured from the recycled polyol described in Paragraph 7.