Method for recycling amine compound from polyurethane foams
A method for recycling amine compounds from polyurethane foam through depolymerization, acid treatment, and solvent extraction addresses the economic and applicability limitations of existing methods, allowing for high-purity amine recovery and reuse in polyurethane and epoxy curing applications.
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 fail to economically recycle amine compounds from waste polyurethane foam, which is an environmental pollutant, and are limited in applicability across different types of polyurethane foam.
A method involving depolymerization, acid treatment, solvent extraction, and chromatography steps to separate and recover amine compounds from polyurethane foam, using specific solvents and catalysts to achieve high purity.
Amine compounds are recycled economically and effectively from various types of polyurethane foam, enabling their reuse in manufacturing processes such as polyurethane production and epoxy curing agents.
Smart Images
Figure KR2026000987_23072026_PF_FP_ABST
Abstract
Description
Method for recycling amine compounds in polyurethane foam
[0001] The present invention relates to a method for recycling amine compounds in polyurethane foam, and more specifically, to a method for recycling amine compounds that can economically recycle amine compounds that have not been recycled from waste polyurethane foam, which is an environmental pollutant, and which is applicable to all types of polyurethane foam without limitation, such as rigid, semi-rigid, and flexible foam, and to a recycled amine compound recycled by said method.
[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 raw materials from discarded polyurethane foam through chemical treatment so that they can be used again 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, most conventional methods of regenerating raw materials focused on regenerating polyols, and were far from recycling amine compounds.
[0007] Specifically, while methods for changing amine compounds that are highly reactive with isocyanates into amine compounds that are less reactive have been suggested, such as treating glycolysis depolymers with alkylene oxides as described in U.S. Patent No. 5,300,530 or reacting depolymers with aldehyde compounds as described in Korean Patent Publication No. 10-2023-0042812, research on methods for recycling amine compounds from polyurethane foam is still limited.
[0008] Accordingly, there is an urgent need for an amine compound recycling method that can economically recycle amine compounds that have not been recycled from waste polyurethane foam, which is an environmental pollutant.
[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 resolve the problems of the past, and aims to provide an amine compound recycling method that can economically recycle amine compounds that have not been recycled from waste polyurethane foam, which is an environmental pollutant, and which is applicable to all types of polyurethane foam without limitation, such as rigid, semi-rigid, and flexible foam, and to provide a recycled amine compound recycled by said method.
[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 the layers into an upper layer and a lower layer centered on the interface of the intermediate;
[0018] S4) A step of introducing the lower layer material into a separation tube filled with separation particles;
[0019] S5) A step of obtaining an extract containing an amine salt by introducing a solvent soluble to the amine salt derived from polyurethane foam into a separation tube into which the lower layer material has been introduced; and
[0020] S6) A step of obtaining an amine compound from the above extract;
[0021] A method for recycling amine compounds in polyurethane foam comprising
[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 amine compound derived from the polyurethane foam in step S5) above is a polar protic solvent.
[0027] In addition, the present invention provides a regenerated amine compound regenerated by the above method.
[0028] In addition, the present invention provides an isocyanate prepared from the above-mentioned regenerated amine compound.
[0029] In addition, the present invention provides a polyol prepared from the above-mentioned regenerated amine compound.
[0030] In addition, the present invention provides a polyurethane manufactured using the above-mentioned regenerated amine compound.
[0031] In addition, the present invention provides an epoxy curing agent comprising an aliphatic amine compound prepared using the regenerated amine compound.
[0032] According to the present invention, amine compounds that have not been recycled from waste polyurethane foam, which is an environmental pollutant, can be economically recycled, and an amine compound recycling method applicable to all types of polyurethane foam without limitation, such as rigid, semi-rigid, and flexible foam, and a recycled amine compound recycled by said method can be provided.
[0033] Figure 1 shows a schematic diagram of a method for recycling amine compounds in polyurethane foam according to an embodiment of the present invention.
[0034] 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.
[0035] 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.
[0036] Figure 1 shows a schematic diagram of a method for recycling amine compounds in polyurethane foam according to an embodiment of the present invention.
[0037] The method for recycling amine compounds in polyurethane foam of the present invention
[0038] S1) A step of obtaining a depolymer by mixing a polyurethane foam and a depolymerization polyol;
[0039] S2) A step of obtaining an intermediate by adding an acid-containing substance to the above depolymer;
[0040] S3) A step of separating the layers into an upper layer and a lower layer centered on the interface of the intermediate;
[0041] S4) A step of introducing the lower layer material into a separation tube filled with separation particles;
[0042] S5) A step of obtaining an extract containing an amine salt by introducing a solvent soluble to the amine salt derived from polyurethane foam into a separation tube into which the lower layer material has been introduced; and
[0043] S6) A step of obtaining an amine compound from the above extract;
[0044] Includes
[0045] Each step is explained in detail below.
[0046] S1) A step of obtaining a depolymer by mixing a polyurethane foam and a depolymerization polyol;
[0047] 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.
[0048] 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.
[0049] [Reaction Equation 1]
[0050]
[0051] [Reaction Equation 2]
[0052]
[0053] 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.
[0054] 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.
[0055] 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, or Mg(OH)2, used alone or in a mixture of two or more.
[0056] 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.
[0057] S2) A step of obtaining an intermediate by adding an acid-containing substance to the above depolymer;
[0058] The depolymer of step S1) above includes polyols derived from polyurethane foam, primary amines, secondary amines, depolymerized polyols, and other materials.
[0059] In the present invention, a method for separating amine compounds and polyols derived from polyurethane foam from the above depolymer, which has not been attempted before, is developed. To this end, an acid-containing substance is added to the above depolymer to obtain an intermediate. The intermediate contains primary amines and secondary amines, 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.
[0060] 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.
[0061] If necessary, in order to separate the amine compound derived from the polyurethane foam from the intermediate with high purity, the present invention may further add a solvent soluble to the polyol derived from the polyurethane foam to the intermediate. Preferably, the solvent may be the same or equivalent to the solvent soluble to the polyol derived from the polyurethane foam, and a solvent that is insoluble or extremely low in solubility for the amine salt contained in the intermediate but highly soluble in the polyol derived from the 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 the polyurethane foam. 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.
[0062] S3) A step of separating into an upper layer and a lower layer centered on the interface of the intermediate;
[0063] In this step, if the intermediate, and if necessary, a solvent soluble in polyols derived from polyurethane foam, is further added and the intermediate is left to stand for a certain period of time, layer separation of the intermediate occurs around the interface.
[0064] 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.
[0065] Afterwards, a regenerated polyol can be obtained from the upper layer and a regenerated amine can be obtained from the lower layer.
[0066] S4) A step of introducing the lower layer material into a separation tube filled with separation particles;
[0067] In the present invention, in order to separate the amine compound derived from the polyurethane foam from the intermediate, the step of introducing the lower layer into a separation tube filled with separation particles is performed.
[0068] 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.
[0069] 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.
[0070] S5) A polyurethane foam-derived amine salt (R) into the separation tube into which the above lower layer is introduced 1 -N + H3X - By adding a solvent soluble in ) amine salt (R 1 -N + H3X - A step of obtaining an extract containing );
[0071] In the present invention, in order to separate only the amine compound derived from the polyurethane foam from the lower layer, an amine salt (R) derived from the polyurethane foam 1 -N + H3X - By adding a solvent soluble in ) amine salt (R 1 -N + H3X - The step of obtaining an extract containing ) is performed.
[0072] Preferably, the amine salt (R) derived from the polyurethane foam of step S4) above. 1 -N + H3X - A solvent soluble to ) is insoluble or extremely low in solubility for a substance (e.g., NaCl) derived from an acid-containing substance (e.g., HCl) contained in the intermediate, while soluble in an amine salt (R) derived from polyurethane foam. 1 -N + H3X - For ), a highly soluble solvent may be used, and as a specific example, a polar protic solvent may be used, and more specifically, methanol, ethanol, propanol, etc. may be used alone or in a mixture of two or more. The above solvent may be used in an amount sufficient to dissolve the amine salt derived from the polyurethane foam.
[0073] If necessary, in the step of introducing the lower layer material into the separation tube filled with separation particles in S4) of the present invention; the amine salt (R) derived from the polyurethane foam in step S5). 1 -N + H3X - A solvent that is soluble in ) may also be mixed and added.
[0074] In addition, if necessary, the polyol may be removed first by introducing a solvent soluble to the polyol derived from the polyurethane foam into the column into which the lower layer is introduced. The solvent soluble to the polyol derived from the polyurethane foam may be a solvent 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 individually or in a mixture of two or more types. The solvent may be used in an amount sufficient to dissolve the polyol derived from the polyurethane foam. It may be used in an amount of 1 to 300 parts by weight of solvent per 100 parts by weight of polyurethane foam.
[0075] S6) A step of obtaining an amine compound from the above extract;
[0076] The above extract contains amine salts (R) derived from polyurethane foam. 1 -N + H3X - It contains ) and a solvent, and there may also be substances derived from substances containing acid.
[0077] In the present invention, a step (S6-1) of evaporating a solvent from the extract to obtain an amine compound from the extract; and an ionic form derived from an acid-containing substance (for example, Cl - The method may include a step of separating layers by mixing a substance of ) with a basic aqueous solution (e.g., an aqueous NaOH solution) containing a counterion (S6-2); and a step of separating an amine compound from the layered mixture (S6-3).
[0078] The above step (S6-1) may be performed later after step (S6-2); and step (S6-3) have been performed first.
[0079] The step of evaporating the solvent from the above extract (S5-1) can be carried out through a conventional heating process.
[0080] Ionic forms derived from substances containing the above acid (for example, Cl - A step (S5-2) of separating layers by mixing a basic aqueous solution (e.g., an NaOH aqueous solution) containing a counterion with a substance of ); wherein the amine salt (R) contained in the extract is mixed with a basic aqueous solution containing a counterion. 1 -N + H3X - ) amine compound (R 1 It changes into -NH2) and a substance in ionic form derived from strong acid (X - , for example, Cl - ) is converted into the form of a compound (e.g., NaCl). The basic aqueous solution converts the amine salt (R) contained in the extract. 1 -N + H3X - All of ) are amine compounds (R 1 It changes into -NH2) and an ionic substance (X) derived from an acid-containing substance. - , for example, Cl - A sufficient amount can be used to convert ) into the form of a compound (e.g., NaCl), and preferably, the mixture is mixed such that the pH of the mixture is 8 to 13. More preferably, the pH is 9 to 13. Within the above range, a higher purity amine compound can be obtained.
[0081] As the above (S6-2) step proceeds, the mixture is an ionic substance (X) derived from a substance containing acid in the lower layer. - , for example, Cl - A compound containing ) (e.g., NaCl) is located in a dissolved state in water, and an amine compound (R) is located in the upper layer. 1 If -NH2) is located, or if step (S5-1) is performed later, the amine compound (R 1 -NH2) and the solvent are mixed and positioned.
[0082] Subsequently, through the step (S5-3) of separating the amine compound from the layered separated mixture, the amine compound (R 1 -NH2) can be obtained. If step (S5-1) is performed later, the solvent is evaporated through heating to obtain the amine compound (R 1 -NH2) can be separated from the solvent.
[0083] In addition, the present invention provides a regenerated amine compound regenerated by the above method. Preferably, the content of polyol in the regenerated amine compound is 0 to 1000 ppm.
[0084] The above-mentioned regenerated amine compound can be used in an equivalent manner to the new amine compound. Specifically, the above-mentioned regenerated amine compound can be used as a raw material for isocyanates used in the manufacture of polyurethane (Use 1), can be converted into a polyol by reacting with alkylene oxide (Use 2), and can be converted into an aliphatic amine through a hydrogenation reaction and used as a raw material for an epoxy curing agent (Use 3).
[0085] Known methods may be applied to the method of preparing a regenerated amine compound into an isocyanate, and specifically, the regenerated amine compound may be reacted with COCl2.
[0086] The method of converting a regenerated amine compound into a polyol by reacting it with an alkylene oxide (Use 2) may be applied using known methods, and specifically, the alkylene oxide may be propylene oxide or ethylene oxide. The polyol may be used in the manufacture of polyurethane foam.
[0087] The method of converting a regenerated amine compound into an aliphatic amine through a hydrogenation reaction can be applied using known methods, and specifically, it can be carried out by introducing hydrogen gas (H2) under a platinum catalyst.
[0088] In addition, the present invention provides a polyurethane prepared from the above-described regenerated amine compound. The regenerated amine compound prepared according to the present invention can be used to manufacture polyurethane with an isocyanate or a polyol.
[0089] According to the present invention, amine compounds that have not been recycled from waste polyurethane foam, which is an environmental pollutant, can be economically recycled without limitation into polyurethane foams such as semi-rigid and soft types.
[0090] 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.
[0091] [Example 1]
[0092] 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 until it was 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.
[0093] 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.
[0094] 200g of silica gel 60A was dispersed in ethyl acetate solvent and placed in a glass tube. A separation column was prepared so that the silica gel could be well packed, and the solution was separated and recovered by slowly adding the lower layer containing amine hydrochloride while adding ethanol.
[0095] After removing ethanol from the above solution by distillation, a 10% by weight aqueous sodium hydroxide solution was added until the pH reached 12 to 13. The solution to which the sodium hydroxide solution was added was transferred to a separation reactor, washed with distilled water until the pH reached 7 to 8, and then transferred to a reactor to remove water through distillation to obtain 137g of regenerated polyamine with a total amine value of 497 mgKOH / g.
[0096] [Example 2]
[0097] 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 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.
[0098] 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 became 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, separating into an upper layer containing ethyl acetate solvent containing regenerated polyol and a lower layer containing water containing amine hydrochloride.
[0099] 200g of silica gel 60A was dispersed in ethyl acetate solvent and placed in a glass tube. A separation column was prepared so that the silica gel could be well packed, and the solution was separated and recovered by slowly adding the lower layer containing amine hydrochloride while adding ethanol.
[0100] After removing ethanol from the above solution by distillation, a 10 wt% aqueous sodium hydroxide solution was added until the pH reached 12 to 13. The solution to which the sodium hydroxide solution was added was transferred to a separation reactor, washed with distilled water until the pH reached 7 to 8, and then transferred to a reactor to remove water through distillation, thereby obtaining 195 g of regenerated polyamine with a total amine value of 512 mgKOH / g. Compared to Example 1, when a catalyst was used, the depolymerization reaction time was shorter, the purity of the amine compound was higher, and the yield was higher.
[0101] 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 the layers into an upper layer and a lower layer centered on the interface of the intermediate; S4) A step of introducing the lower layer material into a separation tube filled with separation particles; S5) A step of obtaining an extract containing an amine salt by introducing a solvent soluble to the amine salt derived from polyurethane foam into a separation tube into which the lower layer material has been introduced; and S6) A step of obtaining an amine compound from the above extract; A method for recycling amine compounds in polyurethane foam comprising 2. In Paragraph 1, A method for recycling amine compounds in polyurethane foam, characterized by further mixing a catalyst in step S1) above.
3. In Paragraph 1, A method for recycling amine compounds in 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 amine compounds of 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 method for recycling amine compounds in polyurethane foam, characterized in that the separation particles in step S4) above are chromatographic powders.
6. In Paragraph 1, A method for recycling amine compounds in polyurethane foam, characterized in that the solvent soluble to the amine salt derived from the polyurethane foam in step S5) above is a polar protic solvent.
7. A regenerated amine compound regenerated by the method described in any one of paragraphs 1 to 6.
8. Isocyanate prepared from the regenerated amine compound described in Paragraph 7.
9. Polyol produced from the regenerated amine compound described in Paragraph 7.
10. Polyurethane manufactured using the regenerated amine compound described in Paragraph 7.
11. An epoxy curing agent comprising an aliphatic amine compound prepared using the regenerated amine compound described in claim 7.