KR20230041371A - Polymer polyols by recycling rigid urethane foams and a method of manufacturing the same - Google Patents

Abstract

The present invention provides a method for manufacturing recycled polymer polyols. The invention comprises: a first step of obtaining a primary liquefied depolymerization product by performing a glycolysis reaction by adding 50 to 150 parts by weight of glycol to 100 parts by weight of rigid polyurethane foam scrap collected from rigid polyurethane foam products; a second step of adding 50 to 150 parts by weight of an isocyanate component based on 100 parts by weight of the first liquefied depolymerization obtained in the first step, and reacting a relatively highly reactive compound with the isocyanate component and gradually exhausting the relatively highly reactive compound to obtain a secondary liquefied depolymerization product with uniform reactivity; and a third step of obtaining a recycled polymer polyol by adding and mixing 25 to 150 parts by weight of the secondary liquefied depolymerization obtained in the second step with respect to 100 parts by weight of the new polyol. Accordingly, the present invention can improve productivity.

Description

Polymer polyols by recycling rigid urethane foams and a method of manufacturing the same}

The present invention relates to a recycled polymer polyol and a method for producing the same, and more particularly, to obtain a depolymerized product through glycolysis using scraps of rigid urethane foam, and processing the depolymerized product again to produce urethane in a conventional manner. It relates to a recycled polymer polyol that can stably and efficiently produce high-quality rigid polyurethane foam products even when a reaction or urea reaction proceeds, and a manufacturing method thereof.

Today, the proper treatment technology of various wastes generated after use has emerged as a very important task in terms of global environmental protection for the future of mankind. In the case of polyurethane, hard polyurethane foam scraps are most typically used as insulation materials in waste refrigerators and are generally collected at home appliance recycling centers, and soft polyurethane foam scraps are recovered from automobile seats or bed mattresses. It is known that they reach 40,000 tons per year based on domestic standards, and most of them are incinerated. This is because most polyurethane products are cross-linked polymers with a network structure, making it difficult to recycle through physical melting. However, when polyurethane is burned, the amount of hydrogen cyanide and carbon monoxide is fatal, so it is very careful to operate the incineration facility. (Reference: McKenna and Hull, Fire Science Reviews , 5, 3 (2016))

Rigid polyurethane foam has excellent thermal insulation performance and mechanical strength and is used in the manufacture of refrigerator insulation materials, frozen and refrigerated container insulation materials, and construction insulation materials. Used hard polyurethane foam scrap can be recycled by manufacturing polyol that can be used to manufacture polyurethane foam insulation again through chemical treatment.

Rigid polyurethane foam used as various insulation materials is based on a chemically cross-linked structure, so it is not easy to recycle after use. Therefore, glycol is often added to solid polyurethane scrap to liquefy by depolymerization through glycolysis at around 200 ° C, and if necessary, recycled polyol is produced through a denaturation process to be used as a raw material for polyurethane foam production. The reaction accompanying the depolymerization process of urethane and urea groups through glycolysis can be shown as shown in FIGS. 1 and 2 [Reference 1, Reference 2].

When the recycled polyol contains primary amine and secondary amine generated in the glycolysis reaction and they are involved in the reaction, it becomes difficult to control the reaction in the manufacturing process due to high reactivity when used in the production of polyurethane foam. Therefore, mixing with new polyol is inevitable, and increasing the content of recycled polyol is limited. Therefore, in order to control the high reactivity due to these amine compounds, a method of converting to a hydroxyl group by adding a compound such as propylene oxide or ethylene oxide is possible, but requires a high-pressure reactor [Reference 2]. On the other hand, a compound having an epoxy group can be used for the same purpose, but has a disadvantage in terms of economical efficiency [Reference 3]. Therefore, the problem of high reactivity due to amine compounds included in depolymerization products through glycolysis is a problem to be solved when using recycled polyols for preparing urethanes.

In the refrigerator manufacturing process using rigid polyurethane foam as an insulator and the insulator foam manufacturing process such as building board or sandwich panel, the internal temperature rises to over 150 °C due to high reaction heat [4]. In the manufacture of such a rigid polyurethane foam insulator, when rapid cooling is performed, residual stress is generated due to a difference in cooling rate depending on the part and causes deformation, so it is required to secure an appropriate cooling time to prevent this. On the other hand, in order to reduce the calorific value in the manufacturing process of rigid polyurethane foam insulators, hydrocarbons with low boiling points, methyl formate, and hydrogen fluoride compounds as auxiliary foaming agents are used. Nevertheless, if the calorific value can be lowered, productivity can be improved, so it is necessary to improve the calorific value control technology.

As a result, when today's polyurethane scrap recycling technology is applied, the reactivity of the recycled polyol is generally high, and it is difficult to obtain a high-quality polyurethane foam product unless the urethane reaction process is precisely controlled. Therefore, there is a need to devise a method of lowering the reactivity of recycled polyol.

In addition, when isocyanate is reacted with recycled polyol and water used in manufacturing rigid polyurethane foam insulation, high temperature heat is inevitably accompanied, and since a cooling process is essential, there is a disadvantage in that product shrinkage occurs. Therefore, even in the manufacturing process of polyurethane foam insulation using recycled polyol, the development of a technology capable of lowering the calorific value is extremely requested.

U.S. Patent No. 5,300,530 “Process for modifying the glycolysis reaction product of polyurethane scrap”;

J. Borda, G. Pasztor, and M. Zsuga, “Glycolysis of polyurethane foams and elastomers” Polymer Degradation and Stability, 68, 419-422 (2000); M.G. Kim, S. H. Kim, J. H. Chun, and Y. S. Lee, “Deamination of MDA in the Recycled Polyol Obtained from the Glycolyiiis of Waste MDI Based Polyurethane Foam” International Journal of Safety, 4, 14-17 (2005); R. E. Welte, “Calculation and measurement of reaction temperatures in rigid polyurethane and isocyanurate foams” Journal of cellular plastics, 5, 351 (1984); V. Zhao and G. J. Suppes, “Computational study on reaction enthalpies of urethane-forming reactions” Polymer Engineering and Science, 1421 (2015).

The present invention is to solve the problems of the prior art, by obtaining a depolymerization product through glycolysis using scrap of rigid urethane foam and processing the depolymerization product again, thereby producing a urethane reaction or urea reaction in a conventional manner. An object of the present invention is to provide a recycled polymer polyol that can stably and efficiently produce high-quality rigid polyurethane foam products and a manufacturing method thereof even when the reaction proceeds.

The present invention comprises a first step of obtaining a first liquefied depolymerized product by adding 50 to 150 parts by weight of a depolymerized polyol to 100 parts by weight of rigid polyurethane foam scrap collected from a rigid polyurethane foam product to proceed with a glycolysis reaction;

50 to 150 parts by weight of an isocyanate component is added to 100 parts by weight of the first liquefied depolymerization obtained in the first step and stirred to react a relatively highly reactive compound with the isocyanate component, and as a result, a relatively reactive a second step of gradually consuming high compounds to obtain a secondary liquefied depolymerized product having uniform reactivity;

a third step of obtaining a recycled polymer polyol by adding 25 to 100 parts by weight of the secondary liquefied depolymerization obtained in the second step to 100 parts by weight of the new polyol and mixing; contains

In the present invention, the rigid polyurethane foam scrap is subjected to a depolymerization reaction to obtain a primary liquefied depolymerization, wherein the components of the primary liquefied depolymerization have different reactivity and are relatively Faced with the fact that highly reactive materials and relatively normal reactive materials are mixed with each other, by consuming the highly reactive materials in advance before actually proceeding with the urethane reaction or urea reaction of the depolymerization in the dispersed phase, the urethane reaction or Its technical feature is to allow the urea reaction to proceed smoothly. As the relatively highly reactive compound, a compound derived from the rigid polyurethane foam scrap and having a primary amine group, a secondary amine group, or a primary hydroxyl group may be exemplified.

By realizing the present invention with these technical features, a polymer polyol compound can be obtained by chemically treating a highly reactive amine compound inevitably generated in the depolymerization reaction of rigid polyurethane foam scrap, and the polymer polyol compound and a new polyol can be obtained. Recycled polyol can be obtained by mixing, and when the reclaimed polyol is used to manufacture urethane foam again later, the problem of difficult control of reactivity can be solved.

It is preferable to use polyols generally having a hydroxyl value of about 400 mgKOH/g for the production of rigid polyurethane foam. In this case, about 2 phr of water generating carbon dioxide is added to polyol 100 by weight, and the amount of isocyanate added is stoichiometrically defined as the amount required for 100% reaction as Index 100, and it is recommended to add an Index value of 100 or more. desirable. Under these conditions, when Polymeric Methylene Diphenyl Diisocyanate (MDI) having an NCO content of 31% by weight is used as an isocyanate, the required amount of MDI by polyol is 104 parts by weight of a mixture in which 2 parts by weight of water is added to 100 parts by weight of polyol The amount of MDI required by water is 30 parts by weight, which is 78% and 22% in percentage, respectively. And the heat of reaction between isocyanate and polyol or water and amine is about 85 kJ/eq. If the specific heat of the reactants is assumed to be about 2 J/g without considering the cooling effect due to the vaporization of the auxiliary blowing agent, this theoretically entails a temperature rise of 178 ° C. at a similar level. Therefore, when using the above-described polymer polyol (polymer content: 50%), the reaction with isocyanate by the polyol already includes a dispersed phase formed by the polymer, so when manufacturing a rigid polyurethane foam using the polymer polyol, the calorific value by the polyol This can be reduced by up to 50%, so the heat generated by the reaction in the process can be reduced by up to about 37%, and the temperature rise can also be greatly reduced.

Unlike conventional recycled polyols, the rigid polyurethane foam recycled polymer polyol prepared according to the present invention exists as a dispersed phase in which recycled components are cross-linked in new polyol, so its reactivity is not as fast as in the prior art and can be easily controlled. There are advantages.

In addition, since the rigid polyurethane foam recycled polymer polyol produced by the present invention exists in a state in which the content of reactive components in the polyol unit mass is reduced, when a rigid polyurethane foam insulation is manufactured using this, it is naturally The heat of reaction is reduced, so the temperature rise is reduced, and thus the cooling process can be performed easily, thereby improving productivity.

1 is a reaction scheme in which, when the urethane group of polyurethane is depolymerized by glycolysis, the polymer chain is cleaved and depolymerized into hydroxyl groups and secondary amines;
2 is a reaction scheme in which, when the urea group of polyurethane is depolymerized by glycolysis, the polymer chain is cleaved and depolymerized into primary amines, hydroxyl groups, and secondary amines;
FIG. 3 schematically shows a polymer polyol obtained by dispersing a depolymerized product formed by cleavage of a polymer chain by glycolysis of polyurethane with isocyanate and dispersing it in a new polyol while proceeding the reaction.

Hereinafter, the present invention will be described more specifically and in detail. Specific numerical values or specific examples provided in the present invention are only intended to explain the technical idea of the present invention in more detail as a preferred embodiment of the present invention, and it is clear that the present invention is not limited thereto. In addition, in the specification of the present invention, detailed descriptions of parts that are known in the art and can be easily created by those skilled in the art will be omitted.

The present invention includes a first step of obtaining a first liquefied depolymer by adding 50 to 150 parts by weight of a depolymerized polyol to 100 parts by weight of rigid polyurethane foam scrap collected from a rigid polyurethane foam product to proceed with a glycolysis reaction, there is. Rigid polyurethane scrap is generated in the dismantling process of used refrigerator products and various building insulation products after use, and their raw material compositions are chemically the same in that the main ingredients are polyol and polyisocyanate. . As a specific embodiment of the present invention, scraps of used refrigerator insulation materials are used for the purpose of explanation, but various rigid polyurethane foams and elastic materials can be chemically treated using the same principle.

In the present invention, hard polyurethane scrap is depolymerized by a glycolysis reaction by introducing polyol in the range of 140 to 240 °C. The rigid polyurethane scrap may be exemplified by refrigerator insulation scrap, building insulation scrap, sandwich panel insulation scrap, and the like. The polyol is added to depolymerize the hard polyurethane scrap, and is one selected from the group consisting of ethylene glycol, propylene glycol, dipropylene glycol, low molecular weight ether-based polyol, low molecular weight ester-based polyol, and copolymerized polyol, etc. A mixture of two or more may be used.

In the present invention, in consideration of the convenience of explanation, the hard polyurethane scrap is selected and used as a refrigerator insulation scrap, and in the case of the polyol, propylene glycol will be selected and described among glycol compounds. This depolymerization reaction proceeds with a glycolysis reaction in the range of 140 to 240 ° C, and reactions such as hydrolysis and thermal decomposition may be accompanied in this process. In addition, organometallic catalysts and antioxidants may be added for effective reaction.

This glycolysis reaction is presented as a representative chemical reaction formula in FIGS. 1 and 2.

In the present invention, when the depolymerization reaction of the first step is completed, the first liquefied depolymerization product of hard polyurethane scraps is obtained. This primary liquefied depolymerization product is composed of a polyol, an amine compound derived from isocyanate, and residual glycol, which are usually observed uniformly. In this case, since the isocyanate is derived from the rigid polyurethane scrap, it can be seen that the amine compound is consequently derived from the scrap of the waste rigid polyurethane foam. Since the amine compound has higher reactivity than other constituents, if it is left as it is, it acts as a realistic obstacle that makes it difficult to normally control the urethane reaction or urea reaction to proceed later. In the present invention, the amine compound may be referred to as a highly reactive compound.

In the second step of the present invention, 50 to 150 parts by weight of an isocyanate compound is added to 100 parts by weight of the first liquefied depolymerized product obtained in the previous step and mixed to obtain a second liquefied depolymerized product. At this time, it is preferable to add and mix the isocyanate compound so that it can react with 50% or more of active hydrogen stoichiometrically.

In the present invention, the reason why isocyanate is added to the primary liquefaction depolymerization is that, first, the highly reactive components present in the primary liquefaction depolymerization preferentially react and exist in a dispersed state without being dissolved in the new polyol. Second, this is to maintain the reactivity of the new polyol when used as a polyol for producing polyurethane foam in a situation where the primary liquefied depolymerization reacts with isocyanate to form a polymer and is present in a dispersed state in the new polyol. Thirdly, Finally, in the reaction process for manufacturing rigid polyurethane insulation, it participates in the reaction as little as the fraction present as a polymer in polyol, thereby reducing heat generation and temperature rise due to reaction in the manufacturing process of polyurethane insulation foam, thereby facilitating cooling and improving productivity because it has suitable properties.

In the present invention, the isocyanate component may use an isocyanate component used in this technical field. For example, toluene diisocyanate (TDI) or 4,4-phenyl methane diisocyanate (MDI), or polyisocyanate containing polymeric MDI is preferably used.

According to the present invention, when isocyanate is stoichiometrically added at 50% or less with respect to 100 parts by weight of the first liquefied depolymer, there is a very high possibility that a non-crosslinked composition exists in the second liquefied depolymer, and therefore, It is undesirable because it may dissolve in the new polyol to be introduced in the next step.

In the present invention, the isocyanate addition reaction can be performed at 25 to 120 °C. At this time, the hard polyurethane scrap used as a starting material undergoes glycolysis to exist as various depolymers, and among them, a relatively highly reactive compound reacts with the isocyanate introduced in the second step. It is gradually converted into a new reactant.

In the present invention, when the second liquefied depolymerization obtained in the second step and the first liquefied depolymerization obtained in the first step are compared with each other, the highly reactive compound contained in the second liquefied depolymerization It can be seen that the composition ratio is lower and less than the composition ratio of the highly reactive compound included in the first liquefied depolymerization product.

In the third step of the present invention, 25 to 100 parts by weight of the secondary liquefied depolymerization obtained in the second step is added to 100 parts by weight of the new polyol and mixed to obtain a regenerated polymer polyol. When 25 parts by weight or less of the secondary liquefied depolymerization is included with respect to 100 parts by weight of the new polyol, the recycling rate is low, which is undesirable. It does not exhibit polyol reactivity, making it undesirable. In this case, the recycled polymer polyol exists in a form in which polyurethane-urea particles obtained from depolymerization are uniformly dispersed in the new polyol.

Figure 3 conceptually illustrates the appearance of such a recycled polymer polyol.

In order to explain the technical characteristics of the present invention more clearly, the second step and the third step have been clearly separated and described, but in actual work, the order of these is not strictly distinguished, and they are performed concurrently with each other. can be carried out. However, the stoichiometric input amount or the input ratio is not changed.

In the present invention, the material obtained in this way is named a recycled polymer polyol, but in consideration of its practical characteristics, it may be named a hard polyurethane dispersion polymer polyol.

The present invention can use the thus obtained rigid polyurethane-dispersed polymer polyol to prepare rigid polyurethane foam products by forming urethane and urea in a conventional manner.

In this case, in the rigid polyurethane-dispersed polymer polyol according to the present invention, there is little or very little of the highly reactive material. Therefore, when a final product is manufactured through a urethane reaction or a urea reaction, a stable reaction is shown, so the manufacturing process is easy to control, and an exothermic reaction occurs relatively little, so that the subsequent cooling process can be simplified or simplified.

Hereinafter, the present invention will be described in more detail by examples.

<< Example 1 >>

200 grams of pulverized polyurethane foam scraps generated in the disassembling process of used refrigerators were divided into 100 grams of propylene glycol (molecular weight: 76 g/mol) in a 1 liter reactor maintained at 200 ° C.

When solid-state scrap is put into propylene glycol, liquefaction by glycolysis proceeds at a very high speed. In general, equilibrium was reached after 4 hours of reaction, and through this, a first liquid glycolysis depolymerized product was obtained. The first liquid depolymerization had a hydroxyl value of 480 mgKOH/g and a viscosity of 10,000 cps at 25°C.

<< Example 2 >>

In Example 1, except that 200 grams of the pulverized polyurethane foam scrap and 200 grams of the propylene glycol were used, the rest was carried out in the same manner as in Example 1.

As a result, the hydroxyl value of the first liquid phase depolymerization was 720 mgKOH/g, and the viscosity at 25°C was 6,000 cps.

<< Example 3 >>

In Example 1, except that 100 grams of the pulverized polyurethane foam scrap and 150 grams of the propylene glycol were used, the rest was carried out in the same manner as in Example 1.

As a result, the hydroxyl value of the first liquid phase depolymerization was 870 mgKOH/g, and the viscosity at 25°C was 3,000 cps.

<< Example 4 >>

After mixing 50 grams of the depolymerization obtained in Example 1 and 25 grams of TDI, 300 grams of glycerin/sugar-type polyether polyol having a hydroxyl value of 490 was added, and the mixture was dividedly added and stirred three times.

After the final input was completed, a colloidal recycled polymer polyol was obtained in which a polymer produced by reacting rigid polyurethane foam scrap with TDI was dispersed in a new polyol. The obtained recycled polymer polyol had a hydroxyl value of 390 mgKOH/g, a viscosity of 2,000 cps, and a volume average particle diameter of the dispersed phase polymer of 0.8 microns.

<< Example 5 >>

In Example 4, the rest was carried out in the same manner as in Example 4, except that 112.5 grams of the glycerin/sugar type polyether polyol having a hydroxyl value of 490 was used.

The obtained recycled polymer polyol had a hydroxyl value of 290 mgKOH/g, a viscosity of 4,000 cps, and a volume average particle diameter of the dispersed phase polymer of 1.0 microns.

<< Example 6 >>

Except for using 75 grams of the glycerin/sugar type polyether polyol having a hydroxyl value of 490 in Example 4, the rest was carried out in the same manner as in Example 4.

The obtained recycled polymer polyol had a hydroxyl value of 243 mgKOH/g, a viscosity of 7,000 cps, and a volume average particle diameter of the dispersed phase polymer of 1.1 microns.

Below, it was intended to examine whether rigid polyurethane foam can be produced using the recycled polymer polyol obtained by the manufacturing method of the present invention and the change in internal heating temperature during the manufacturing process.

<< Example of commercialization application >>

In order to prepare a rigid polyurethane foam using the rigid polyurethane dispersion polymer polyol obtained in Example 4, the composition shown in <Table 1> below was used.

As confirmed in <Table 1> below, the additive composition was applied in the same ratio as the raw material composition of conventional polyurethane foam.

New polyol, recycled polymer polyol, and additives shown in <Table 1> were weighed at 25° C., put into a reaction cup, and mixed with a high-speed stirrer at 2000 rpm for 1 minute. After adding polymeric diphenyl methane diisocyanate in the amount determined by the composition to the mixture, it was further mixed for 10 seconds with a high-speed stirrer, and then introduced into a wooden box of 400 X 400 X 400 mm to obtain a rigid polyurethane foam. , In the course of the reaction, cream time, gel time, and tack free time were measured, and the internal temperature rise value was observed using a thermometer.

Ratio of raw materials for manufacturing rigid polyurethane foam applied with recycled polymer polyol of the present invention
sample name Composition ratio (parts by weight) A - 0 A-25 A-50 A-75 A-100 Polyol part New polyol (JOP-0585) 100.0 75.0 50.0 25.0 0 Recycled Polymer Polyol 0 25.0 50.0 75.0 100.0 antifoaming agent B-8462 2.0 2.0 2.0 2.0 2.0 Catalyst(1) HEX CEM-977 0.3 0.3 0.3 0.3 0.3 Catalyst(2) PC-8 3.0 3.0 3.0 3.0 3.0 flame retardant TCPP 15.0 15.0 15.0 15.0 15.0 Foaming agent(1) Water 2.0 2.0 2.0 2.0 2.0 Foaming agent(2) cyclopentane 20.0 20.0 20.0 20.0 20.0 Isocyanate part NCO Index 120 120 120 120 120

Based on the raw material sample having each composition ratio described in Table 1 above, the polyurethane reaction was carried out, and the reactivity data measured in the manufacturing process and the maximum value of the internal temperature rise were measured, and the results are shown in the <Table below. 2>.

This is to look at the degree of difference between the product manufactured by the method of the present invention and the product manufactured by the conventional method, and finally determine whether or not suitability as a polyurethane foam can be recognized. It was for evaluation.

Rigid polyurethane foam application of the recycled polymer polyol of the present invention Reactivity characteristic A - 0 A-25 A-50 A-75 A-100 Cream time (sec) 12 12 11 10 10 Gel time(sec) 80 79 78 76 75 Tack free time (sec) 125 124 122 121 120 Internal maximum temperature (℃) 160 150 140 130 120

As confirmed by Table 2, the reactivity in the polyurethane foam manufacturing process tends to be slightly faster according to the addition of the rigid polyurethane dispersed polymer polyol, but it was not a problem level. In addition, the increase in internal temperature due to heat generation was greatly reduced according to the amount of the recycled polymer polyol of the present invention, so that the cooling time could be shortened, and the advantage of contributing to productivity improvement was confirmed.

In conclusion, the disadvantage is that it is difficult to control due to the rapid reactivity observed when applied to rigid polyurethane foam scrap in the conventional method, but in the case of the new method according to the present invention, when applied to rigid polyurethane foam scrap It was confirmed that the problem could be overcome.

Moreover, it was empirically confirmed that the new method according to the present invention can be directly applied at the work site, and the performance of the final product is not inferior to the existing product as well as the advantage of increasing productivity.

In the above, the recycled polymer polyol and the manufacturing method thereof according to the present invention have been specifically presented, but this is only specified in the process of describing the embodiments of the present invention, and all features of the present invention are limited to being applied only to the items mentioned above. It should not be interpreted as such.

In addition, anyone skilled in the art will be able to make various modifications and imitations based on the description of the present specification, but it will be clear that this also does not deviate from the scope of the present invention.

Claims (6)

A first step of obtaining a first liquefied depolymerized product by adding 50 to 150 parts by weight of polyol to 100 parts by weight of rigid polyurethane foam scraps collected from rigid polyurethane foam products to proceed with a glycolysis reaction;
50 to 150 parts by weight of an isocyanate component is added to 100 parts by weight of the primary liquefied depolymerization obtained in the first step, and a relatively highly reactive compound is reacted with the isocyanate component. As a result, the highly reactive compound is gradually reduced. a second step of obtaining a secondary liquefied depolymerized product having uniform reactivity by exhaustion;
A third step of obtaining a recycled polymer polyol by adding 25 to 100 parts by weight of the secondary liquefied depolymerization obtained in the second step to 100 parts by weight of the new polyol and mixing them; cast
Characterized in that it contains, a method for producing a recycled polymer polyol.
According to claim 1,
The isocyanate,
Among the depolymerization products obtained in the first step, relatively highly reactive compounds react first,
In the second step, lowering the composition ratio of the highly reactive compounds
Characterized by a method for producing a recycled polymer polyol.
According to claim 1,
The method for producing a recycled polymer polyol, characterized in that the second step and the third step proceed simultaneously.
According to claim 1,
The method for producing a recycled polymer polyol, characterized in that the highly reactive compound is an amine compound derived from isocyanate contained in rigid polyurethane foam scrap.
According to claim 2,
When the secondary liquefied depolymerization obtained in the second step and the first liquefied depolymerization obtained in the first step are compared with each other, the composition ratio of the highly reactive compound contained in the second liquefied depolymerization is 1 A method for producing a recycled polymer polyol, characterized in that the composition ratio of the highly reactive compound contained in the secondary liquefied depolymerization is lower and less present.
A recycled polymer polyol prepared according to any one of claims 1 to 5.

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