KR19980032323A - Recycling method of waste rigid polyurethane foam and producing polyurethane foam with improved thermal insulation from recycled polyol obtained by this method - Google Patents

Abstract

The present invention provides a method for efficient recycling of waste polyurethane foam, which method comprises the steps of: (1) grinding the waste polyurethane foam to obtain a powder; (2) adding 15 to 100 parts by weight of glycol and 0.01 to 10 parts by weight of a specific catalyst to 100 parts by weight of the waste polyurethane foam powder obtained in (1) into a reactor equipped with a cooler; (3) reacting for 30 minutes to 15 hours at a reaction temperature of 120 ° C to 300 ° C under a nitrogen atmosphere to produce regenerated polyols; (4) removing impurities contained in the recycled polyol; (5) mixing the impurity-removing regenerated polyol obtained in step (4) in an amount of 10-30% by weight based on the total weight of the mixture of the pure polyol and the regenerated polyol to obtain a mixed polyol; And (6) reacting the mixed polyol of step (5) with diisocyanate to obtain a polyurethane foam.

The polyurethane foams produced by the process according to the invention have the advantage of superior thermal insulation properties and dimensional stability compared to polyurethane foams made only of pure polyols.

Description

Recycling method of waste rigid polyurethane foam and producing polyurethane foam with improved insulation from recycled polyol obtained by this method

The present invention relates to a method for regenerating waste polyurethane foam, and more specifically, to produce a recycled polyol by depolymerization of the waste polyurethane foam using glycol, and then mixed with a pure polyol in a fixed ratio. The present invention relates to a process for producing rigid polyurethane foams having good thermal insulation properties by reacting with diisocyanate.

Rigid Polyurethane Foams (hereinafter referred to as PURs) are thermosetting polymers that have been used primarily as insulation for refrigerators, freezers and buildings. Recently, there has been a growing interest in recycling waste PUR because PUR is released in large quantities as waste during the recycling process of waste refrigerators. PUR is regulated as a designated waste, and its disposal is tightly regulated. However, the treatment of the waste PUR has a difficult problem. The reason is that it is impossible to simply recycle PUR, a thermosetting polymer, by remelting, and the treatment method of incineration to recover waste heat not only causes secondary pollution due to toxic gases emitted during incineration, but also incineration facilities. This is because the treatment by incineration is not easy because of problems such as corrosion. In addition, since PUR is a foamable material, the volume required for treatment is greatly increased, which makes the treatment of PUR waste more difficult.

The recycling methods of conventional waste PUR are described in more detail as follows:

First, the mechanical recycling method using finely crushed waste PUR as a filler for injection or extrusion molding products or as an enhancer for polyurethane-based adhesives, or by appropriately crushing and compressing it as a rebonded foam. (Eg USP 5,451,376). Second, there is a chemical recycling method that depolymerizes polyurethane using various solvents, which is hydrolyzed by water, glycolysis by glycols, and depolymerization by amines. aminolysis), and the like (eg USP 4,159,972). The third method is feedstock recycling, which may include pyrolysis, hydrogenation and gasification. Lastly, energy recovery methods include incineration with municipal solid waste to recover waste heat, and rotary kiln method.

Each of these conventional methods has the following disadvantages:

In the first method, since the PUR used as a filler is a foam and a thermosetting polymer, there is no interaction between the interfaces with the matrix resin used in the manufacture of injection or extrusion molded products, and thus the mechanical properties of the molded products manufactured by blending the PUR are significantly reduced. There is a problem that is not successful commercialization.

The third method is not currently used due to the toxic gases emitted during incineration.

On the other hand, the second method is the most economical and practical method among them is being actively researched. The hydrolysis method of chemical regeneration method has been studied a lot, but it is disadvantageous in terms of economics because the conversion rate of the reaction is low, the regeneration polyol is prepared by depolymerization of polyurethane using a glycol depolymerization reaction, these Attention has been paid to recycling the recycled polyols with diisocyanates and recycling them as raw materials for producing polyoleethane foams.

Further, as described above, a method of decomposing a polyurethane by a chemical method and recycling the decomposition product in the production of a polyurethane is known. For example, US Pat. No. 3,404,103 describes a process for degrading polyurethane foams in the presence of amines and alkali metal oxides or hydroxides, or alkaline earth metal oxides or hydroxides. U. S. Patent No. 3,708, 440 describes a process for degrading a polyisocyanurate foam powder by heating to about 175-250 [deg.] C. in the presence of a mixture of aliphatic diols having 2-6 carbon atoms and dialkanolamines having 4-8 carbon atoms. U.S. Patent No. 4,110,266 discloses the conversion of polyurethane foams to polyols by reacting with ammonia or amines to decompose them, and the decomposition products containing mixtures of polyols, ureas and amines in an autoclave at about 120-140 ° C. Described is a method for converting amines to polyols by reacting with ethylene oxide.

Further, US Pat. No. 4,148,908 describes carboxylate catalysts for preparing polyurethane foams from amines and alkylene oxides. This catalyst can be prepared by reacting tertiary amines, alkylene oxides and carboxylic acids.

U.S. Patent No. 5,556,889 discloses a process for preparing a recycled polyol by reacting a polyurethane foam with a short-chain hydroxyl group-containing compound, in which at least one epoxidized natural fatty oil is added to the reaction mixture after completion of the reaction. Add.

Under these circumstances, the present inventors have conducted extensive research for the purpose of providing a more efficient regeneration method of waste polyurethane foam and a process for producing a polyurethane foam from recycled polyol, and as a result, the waste polyurethane in the presence of a specific catalyst It is possible to produce regenerated polyols in a short time by pulverization and glycol-depolymerization, and furthermore, the above-mentioned object can be achieved by mixing the regenerated polyols thus obtained with a specific ratio of pure polyols and reacting them with polyisocyanates. To discover and complete the present invention.

Accordingly, the present invention provides a method for producing a recycled polyol by glycol-depolymerization of the waste polyurethane foam.

The present invention also provides an efficient method of making polyurethanes using recycled polyols.

The present invention provides a catalyst for use in the glycol-depolymerization of polyurethane foams.

The present invention further obtains a mixed polyol by mixing a regenerated polyol obtained by glycol-depolymerization of a polyurethane foam with a specific ratio of virgin polyol, and then reacting it with a diisocyanate to improve thermal insulation properties. Provided are methods for making improved rigid polyurethane foams.

1 is a flow chart showing a process for producing a polyurethane foam with improved thermal insulation properties from the waste rigid polyurethane foam according to the method of the present invention.

Figure 2 is a graph showing the initial heat insulating properties according to the content of the regenerated polyol in the polyurethane foam with improved heat insulating properties prepared according to the method of the present invention.

Figure 3 is a graph showing the change over time of the thermal insulation properties according to the content of the recycled polyol in the polyurethane foam with improved thermal insulation properties prepared according to the method of the present invention.

4 and 5 are graphs showing the dimensional stability at 70 ℃ and -20 ℃ according to the content of the regenerated polyol in the polyurethane foam with improved thermal insulation properties prepared according to the method of the present invention, respectively.

6a to 6d are scanning electron microscope (SEM) photographs showing the cell structure of the polyurethane foam prepared according to the method of the present invention.

Specifically, the regeneration method of the polyurethane foam according to the present invention

(1) grinding the waste polyurethane foam to obtain a powder;

(2) adding 15 to 100 parts by weight of glycol and 0.01 to 10 parts by weight of catalyst with respect to 100 parts by weight of the waste polyurethane foam powder obtained in (1) to a reactor with a cooler; And

(3) reacting for 30 minutes to 15 hours at a reaction temperature of 120 ° C to 300 ° C under a nitrogen atmosphere to produce regenerated polyols;

The catalyst of step (2) comprises a Lewis acid catalyst such as zinc chloride, iron chloride, aluminum chloride, mercury chloride; Carboxylic acids such as acetic acid, formic acid, propionic acid, butyric acid and benzoic acid; Inorganic acetates such as magnesium acetic acid, lead acetic acid, calcium acetic acid, potassium acetic acid, zinc acetic acid, sodium acetic acid, phosphoric acetic acid and the like; And an alkali catalyst selected from the group consisting of sodium carbonate, sodium bicarbonate, calcium hydroxide, potassium hydroxide or sodium hydroxide and the like.

In addition, a method for obtaining a polyurethane foam from the recycled polyol according to the present invention is

(1) grinding the waste polyurethane foam to obtain a powder;

(2) adding 15 to 100 parts by weight of glycol and 0.01 to 10 parts by weight of catalyst with respect to 100 parts by weight of the waste polyurethane foam powder obtained in (1) to a reactor with a cooler;

(3) reacting for 30 minutes to 15 hours at a reaction temperature of 120 ° C to 300 ° C under a nitrogen atmosphere to produce regenerated polyols;

(4) removing impurities contained in the recycled polyol;

(5) mixing the impurity-removing regenerated polyol obtained in step (4) in an amount of 10-30% by weight based on the total weight of the mixture of the pure polyol and the regenerated polyol to obtain a mixed polyol; And

(6) reacting the mixed polyol of step (5) with diisocyanate to obtain a polyurethane foam

The catalyst of step (2) comprises a Lewis acid catalyst such as zinc chloride, iron chloride, aluminum chloride, mercury chloride; Carboxylic acids such as acetic acid, formic acid, propionic acid, butyric acid and benzoic acid; Inorganic acetates such as magnesium acetic acid, lead acetic acid, calcium acetic acid, potassium acetic acid, zinc acetic acid, sodium acetic acid, phosphoric acetic acid and the like; And an alkali catalyst selected from the group consisting of sodium carbonate, sodium bicarbonate, calcium hydroxide, potassium hydroxide or sodium hydroxide and the like.

Other objects, advantages and applications of the present invention will become apparent to those skilled in the art by the following detailed description.

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

According to the process of the present invention, the waste hard polyurethane foam is ground and then depolymerized with glycol to obtain a recycled polyol. The waste rigid polyurethane foams used as raw materials in the present invention are not limited in kind, but those derived from waste refrigerators can be used.

The method of pulverizing the waste rigid polyurethane foam may be performed by a conventional method using a ball mill or a cutter, and a powder having an average particle size of about 300 mm or less, preferably about 80 μm or less by a pulverization process. Is obtained.

The waste hard polyurethane foam powder obtained by the grinding process is subjected to depolymerization using glycol. The glycols used in this depolymerization reaction are ethylene glycol (EG), diethylene glycol (DEG), 1,2-propane diol, 1,3-propane diol, dipropylene glycol (DPG), 1,4-butane diol, 1 , 3-butane diol, 1,2-butane diol, neopentyl glycol, 1,5-pentane diol, hexylene glycol, bisphenol A, 2,2-di (4-hydroxypropoxyphenyl) propane, 2,2 Dihydric glycols such as -di (4-hydroxyethoxyphenyl) propane and the like or trivalent or higher glycols such as glycerin, trihydroxy methylpropane, trimethylol ethane, pentaerythritol and the like.

Catalysts used in the depolymerization reaction according to the present invention include, for example, Lewis acid catalysts such as zinc chloride, iron chloride, aluminum chloride, mercury chloride; Carboxylic acids such as acetic acid, formic acid, propionic acid, butyric acid and benzoic acid; Inorganic acetates such as magnesium acetic acid, lead acetic acid, calcium acetic acid, potassium acetic acid, zinc acetic acid, sodium acetic acid, phosphoric acetic acid and the like; And alkali catalysts such as sodium carbonate, sodium bicarbonate, calcium hydroxide, potassium hydroxide or sodium hydroxide and the like, or a mixture of two or more thereof.

The amount of glycol and catalyst used in the depolymerization reaction with glycol is selected in the range of about 15 to 100 parts by weight and 0.01 to 10 parts by weight based on 100 parts by weight of the waste polyurethane foam powder, respectively. The reaction mixture consisting of the above amounts of components was introduced into a reactor equipped with a cooler, and then 30 minutes to 15 hours at a reaction temperature of about 120 ° C to 300 ° C, preferably about 160 ° C to 240 ° C, under a nitrogen atmosphere. By reaction to produce regenerated polyols.

Solid impurities may be present in the regenerated polyol thus prepared, and when such impurities are present, the regenerated polyol is reacted with diisocyanate to block the nozzle of the foaming machine when forming the polyurethane foam, causing molding problems. . Therefore, these solid impurities must be removed. Impurities can be removed by mounting a 50-250 mesh filter at the bottom of the reactor and purifying the reactants by gravity or through a filter under pressure after the reaction is completed.

The regenerated polyol prepared by the above method is composed of the type shown in the following formula (1), the production rate of the regenerated polyols (1) to (4) is variously determined by the reacted glycol, reaction temperature, reaction time, etc. . The ratio of regenerated polyols (1) to (4) is not a significant factor, but the hydroxy value (OH value) of the final produced regenerated polyol should be within the range as described below.

The properties of the regenerated polyols thus prepared can be specified by measuring the hydroxy value (OH value), acid value and moisture content by ASTM D2849. As a result, the hydroxy value was about 250-1,000, the acid value was 0.6-3.5, and the moisture content was 0.1-0.7 depending on the type of glycol used in the reaction and the amount added to the reaction. It was confirmed that there is no. Preferably, the hydroxy value of the regenerated polyol consisting of polyols (1)-(4) is in the range of 360-800, the acid value is 1.30-2.50, and the moisture content is in the range of 0.2-0.5.

The recycled polyols prepared by the present invention cannot be used alone to prepare PUR. That is, it should be mixed with virgin polyol. The amount of recycled polyol mixed with pure polyol can be 5 to 50% by weight based on the total weight of the polyol mixture, but a mixing ratio of about 10 to 30% by weight is the most in terms of physical properties and economics. Suitable. In particular in the range of about 10-25% by weight. When the mixing ratio of the regenerated polyol exceeds about 50% by weight, the reaction with the subsequent diisocyanate proceeds very fast, and no foam is formed. Pure polyols usable in the present invention include conventional polyols used in the polyurethane manufacturing industry and include, for example, commercially available polyols (eg, Korea Polyol CP-1106, etc.).

In the present invention, a polyurethane mixture prepared by mixing the regenerated polyol and the pure polyol prepared according to the method of the present invention is reacted with a diisocyanate to prepare a rigid polyurethane foam, and the physical properties of the prepared foam are measured as follows.

First, the proper filling amount was measured using a mold having a standard of 30 × 40 × 5 cm. Density was measured by ASTM D1622, respectively, the apparent density and the core density. Compressive strength was measured by ASTM D2126 for horizontal and vertical, respectively. Dimensional stability was measured for 24 hours at 70 ° C. or −20 ° C. under 95% relative humidity. Post expansion is related to productivity when the PUR is applied to a refrigerator or a freezing container, and is a factor that determines the demold time.

The post-expansion measurement method is as follows. PUR is formed by inserting about 20% excess raw material (over packing 120%) into the mold of 30 × 40 × 5cm size, and after 4 minutes, the PUR is removed from the mold and compared with the mold size and the size of the molded PUR. Measure the changed value. At this time, the larger the value of the later dimension, the longer the release time. If the release time value is not sufficient, the middle part of the PUR will swell or, if severe, cracks inside. And the thermal conductivity is EKO Instruments Trading Co. , Ltd. The thermal conductivity measuring apparatus (Thermal Conductivity Measuring Apparatus Model) of HC-073 was used to measure the average temperature at 23.8 ℃.

A blowing agent is required in the process for producing the polyurethane foam by reacting the polyol mixture with the diisocyanate. As the blowing agent, those commonly used in the art, for example, CFC (chlorofluorocarbon) may be used. However, in connection with the recent prohibition of the use of chlorine-based blowing agents in terms of environmental protection, cyclopentane may be used as blowing agent instead. Can be.

To prepare a polyol mixture by mixing the regenerated polyol prepared in the present invention with a pure polyol, the content of the regenerated polyol is mixed to an appropriate amount, specifically 10 to 30% by weight based on the total weight of the mixture, to prepare a polyol mixture, When the rigid polyurethane foam was prepared by reacting with diisocyanate, the heat insulating property was increased from about 8% to about 13%. The reason why the insulation properties are improved can be explained by the following theory.

When the polyurethane foam is depolymerized by glycol-glycolysis, regenerated polyols can be produced as shown in Formula 1 below:

Among the regenerated polyols, the polyol (4) has a chemical structure similar to diisocyanate, thereby increasing the compatibility with the diisocyanate.

Therefore, when producing a rigid polyurethane foam, the polyol (4) is well mixed with the diisocyanate so that the cell structure of the foam is much more dense and dense than the structure of the foam produced using only pure polyol. This is as confirmed by scanning electron microscope (SEM) in the embodiment (Fig. 6). Thus, when the cell structure of the foam becomes dense and dense, the thermal insulation properties are improved.

The ratio of mixed polyols to diisocyanates is determined by the hardness desired to be obtained in the final rigid polyurethane foam and can be expressed by the ratio of NCO equivalents of diisocyanate to OH equivalents of polyol, ie NCO index (or reaction index). In Table 1, when the reaction index is 112, the equivalent of NCO is added in an excess of 12% of the OH equivalent, and the higher the reaction index, the higher the hardness of the PUR. As already explained, the selection of the reaction index is made according to the hardness of the desired rigid polyurethane foam, which selection can be made by a person skilled in the art.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the scope of the present invention is not limited only to the following examples.

Example 1

The rigid polyurethane foam was crushed into powder so as to have an average diameter of about 80 μm with a crusher in the form of a mixer. 40 g of ethylene glycol, about 5 g of polyurethane powder, and 0.6 g of sodium hydroxide were added to a small reactor equipped with a cooler, and the inside was replaced with nitrogen, and the reaction mixture was raised to 200 ° C., and 55 g of the polyurethane foam powder was added thereto. The depolymerization reaction was carried out gradually. At this time, since the density of the rigid polyurethane is about 0.4 g / cm 3, it is about 4 times the volume of ethylene glycol to be reacted. Therefore, when the reactor is small, it may be difficult to react all the polyurethane foam powder and ethylene glycol at once in the reactor. In this case, as described above, the reaction is started by adding ethylene glycol, a catalyst, and a small amount of polyurethane powder, replacing with nitrogen, and then raising the temperature to about 200 ° C. And when the reaction of the polyurethane powder which was initially put in is completed, the reaction is carried out while adding the remaining polyurethane powder.

For this example the glycol-depolymerization reaction was completed in about 1.5 hours. The reaction time can be shortened slightly depending on the injection speed of the polyurethane powder, the reaction time is further shortened if the particle diameter of the polyurethane powder is reduced.

The recycled polyol thus produced had an OH value of 510 mg KOH / g.

Example 2

The same procedure as in Example 1 was carried out, except that potassium acetic acid was used instead of sodium hydroxide as a catalyst. The reaction was completed in about 3.5 hours. The regenerated polyol thus produced had an OH value of 512 mg KOH / g.

Example 3

The same procedure as in Example 1 was carried out using sodium acetic acid instead of sodium hydroxide as a catalyst. The reaction was completed in about 2.5 hours. The regenerated polyol thus produced had an OH value of 514 mg KOH / g.

Example 4

In the same manner as in Example 1, zinc acetic acid was used instead of sodium hydroxide as a catalyst. The reaction was completed in about 6 hours. The regenerated polyol thus produced had an OH value of 505 mg KOH / g.

Example 5

The same procedure as in Example 1 was conducted except that lead acetic acid was used instead of sodium hydroxide as a catalyst. The reaction was completed in about 3 hours. The recycled polyol thus produced had an OH value of 508 mg KOH / g.

Example 6

In the same manner as in Example 1, potassium hydroxide was used instead of sodium hydroxide as a catalyst. The reaction was completed in about 2.5 hours. The regenerated polyol thus produced had an OH value of 513 mg KOH / g.

Example 7

Into a reactor equipped with a cooler, 300 g of waste polyurethane foam powder having an average diameter of less than about 80 μm, 100 g of diethylene glycol, 3.0 g of p-toluene sulfonic acid and 1.0 g of sodium hydroxide were respectively introduced and the inside of the reactor was converted to nitrogen (D Ethylene glycol / PUR = 25/75 (w / w)). And while stirring the reaction, the reaction temperature was raised to 150 ℃, and reacted for 4 hours. The reaction was then removed through solid 200mesh screen to produce solid polyol. The regenerated polyol thus produced had an OH value of 542 mg KOH / g.

Example 8

Into a reactor equipped with a cooler, 320 g of waste polyurethane foam powder, 80 g of ethylene glycol, and 4.0 g of sodium acetate were added, and the remaining reaction conditions were reacted in the same manner as in Example 7 (ethylene glycol / PUR = 20). / 80 (w / w)). The recycled polyol thus produced had a OH value of 497 mg KOH / g.

Example 9

300 g of waste polyurethane foam powder, 100 g of ethylene glycol, and 4.0 g of zinc acetate instead of sodium acetate were added to a reactor equipped with a cooler, and the remaining reaction conditions were reacted in the same manner as in Example 7 (ethylene glycol / PUR = 25/75 (w / w)). The recycled polyol thus produced had an OH value of 475 mg KOH / g.

Example 10

As in Example 9, propylene glycol was used instead of ethylene glycol, and reacted with 4.0 g of magnesium acetate instead of zinc acetate (propylene glycol / PUR = 25/75 (w / w)). The regenerated polyol thus produced had an OH value of 598 mg KOH / g.

Example 11

The polyols prepared by Examples 7, 8, 9 and 10 were named Polyol 1, Polyol 2, Polyol 3, and Polyol 4, respectively, to prepare rigid polyurethane foams according to the formulation shown in Table 1 below. In Table 1, the unit of each sample is weight%.

Prescription for the Preparation of Rigid Foams sample A (comparative) B (invention) C (invention) D (invention) E (invention) F (invention) G (invention) H (invention) I (comparative) J (invention) K (invention) Polyol 3005 ^* 100 90 80 70 90 80 90 80 60 80 70 Polyol 1 (Example 7) 0 10 20 30 0 0 0 0 0 0 0 Polyol 2 (Example 8) 0 0 0 0 10 20 0 10 0 0 0 Polyol 3 (Example 9) 0 0 0 0 0 0 10 10 40 0 0 Polyol 4 (Example 10) 0 0 0 0 0 0 0 0 0 20 30 Catalyst ^** 2.4 2.4 2.4 2.4 2.4 2.4 2.4 2.4 2.4 2.4 2.4 Surfactant ^*** 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 H ₂ O 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 Cyclopentane 13.5 13.5 13.5 13.5 13.5 13.5 13.5 13.5 13.5 13.5 13.5 Mixing ratio (polyol / isocyanate = 100 /) 123 123 125 126 121 125 124 126 127 131 135 Response index 112 112 112 112 112 112 112 112 112 112 112

*) Polyol 3005: OH value = 120mg KOH / g (Korea Polyol CP-1106)

** Catalyst: tertiary amine catalyst

*** Surfactant: Polysiloxane Based Surfactant

Isocyanate: Hanwha-BASF Urethane LTD. M20S.

Example 12

When preparing rigid polyurethane foams by the formulation of Example 11, cream time, gel time, and free rise density were determined to determine the reactivity of the diisocyanate with each polyol mixture. The measurement results of the density are shown in Table 2 below.

Prescription A B C D E F G H I J K Cream Time (sec.) 11 9 9 8 8 7 8 7 ND 9 7 Gel time (sec.) 58 57 50 40 45 40 47 29 ND 36 30 Free climbing density (g / l) 30.2 30.2 31.2 33.7 30.4 31.6 30.2 31.0 ND 31.7 36.3

* ND: reaction cannot proceed too fast or no foam is formed

In Table 2, cream time, gel time and free rising density are indexes indicating the reactivity of diisocyanate and polyol during PUR preparation, which means that the reaction proceeds rapidly when the cream time and gel time are short. If the reaction proceeds rapidly, the gelation proceeds quickly, causing the surface of the PUR to harden too early, resulting in a free rise density and a final foam density.

Cream time also means the time when the reactants turn creamy color when PUR is foamed, and gel time means the time when the PUR surface hardens and sticks to gel.

Therefore, it can be seen from the results of Table 2 that when the content of the regenerated polyol exceeds 30% by weight, the progression proceeds rapidly so that no foam is formed. On the other hand, when the content of the recycled polyol is less than 10% by weight, the economical advantages of using the recycled polyol are insignificant.

Example 13

A rigid polyurethane foam was prepared according to Formula A of Example 11, wherein the mixture of recycled polyols and pure polyols (polyol 3005) of Examples 7-10 had a content of 0 weight percent, 10 weight percent, Polyurethane foams were prepared by varying 20 weight percent, or 30 weight percent, and thermal conductivity was measured according to ASTM C 177.

FIG. 2 shows the initial thermal conductivity and FIG. 3 shows the thermal conductivity after aging. As can be seen in Figure 2, the recycled polyols 1 to 4 all have a higher thermal conductivity as the mixing ratio of the regenerated polyols increases for the pure polyols. It can be seen that at 30% by weight, the thermal insulation property is improved by about 10% compared to that produced only with pure polyol (that is, 0% content of recycled polyol).

Polyurethane foams also generally increase their thermal insulation properties as they age. As can be seen in FIG. 3, the thermal insulation properties of the formulations (-■-) and (-○-) in which the regenerated polyols are mixed, rather than the formulations made only of pure polyols (… ○…), are thermal conductivity values K regardless of the aging time. It can be seen that the low factor results in improved thermal insulation properties. In addition, the prescription (-■-) and (-○-) is a case in which the recycled polyol 2 is mixed at a ratio of 10% by weight or 20% by weight, respectively, and as the mixing ratio of the regenerated polyol increases, the thermal insulation property increases. . In particular, the increase in thermal insulation properties increases with time, and after 14 days of aging, the thermal insulation properties are improved by about 13% in the case of the formulation (-○-) having 20% of the recycled polyol content than the foam made of the pure polyol. It became.

Example 14

Polyurethane foams undergo deformation of their form over time after foam molding. Therefore, the dimensional stability according to the change over time is one of the important requirements, according to ASTM D 794 and ASTM D 2126, the dimensional stability at low temperature (-20 ℃) and high temperature (70 ℃), respectively.

That is, a polyurethane foam was prepared according to Formula K of Table 1 using the regenerated polyols of Examples 9 and 10, which were subjected to high temperature dimensional stability for 24 hours under conditions of 70 ° C. and 95% relative humidity (FIG. 4). And low temperature dimensional stability at -20 ° C. for 24 hours (FIG. 5).

The results are shown in FIGS. 4 and 5. As can be seen in FIGS. 4 and 5, the dimensional stability at 70 ° C. of the polyurethane foams prepared according to the process of the invention is slightly improved compared to the polyurethane foams prepared using pure polyols alone, but at -20 ° C. It can be seen that greatly improved. This demonstrates that it is very advantageous to use the rigid polyurethane foams produced in the process of the invention in the manufacture of products (eg freezers, etc.) used in low temperature environments.

Example 15

The cell structures of the polyurethane foams prepared from Formulas A to D of Table 1 were magnified 20 times with a scanning microscope to take electron micrographs (FIGS. 6A-6D). The result is a denser cell structure of the formulation in which regenerated polyols are mixed in amounts of 10% (FIG. 6B), 20% (FIG. 6C), and 30% (FIG. 6D), respectively, compared to Formula A (FIG. 6A) made only of pure polyols. To demonstrate that the thermal insulation properties are improved.

According to the method of the present invention, an efficient method for recycling and using waste polyurethane foam is provided. In other words, by depolymerizing the waste polyurethane foam to produce a recycled polyol, and then blended with the net polyol in a specific ratio to produce a rigid polyurethane foam with improved thermal insulation properties and dimensional stability, the aspect of regeneration of the waste polyurethane foam and insulation Satisfactory results can be obtained both in terms of production of rigid polyurethane foams with improved properties and dimensional stability.

Claims (8)

The following steps (1) to (3): (1) grinding the waste polyurethane foam to obtain a powder; (2) adding 15 to 100 parts by weight of glycol and 0.01 to 10 parts by weight of catalyst with respect to 100 parts by weight of the waste polyurethane foam powder obtained in (1) to a reactor with a cooler; And (3) reacting for 30 minutes to 15 hours at a reaction temperature of 120 ° C to 300 ° C under a nitrogen atmosphere to produce regenerated polyols; The catalyst of step (2) comprises a Lewis acid catalyst such as zinc chloride, iron chloride, aluminum chloride, mercury chloride; Carboxylic acids such as acetic acid, formic acid, propionic acid, butyric acid and benzoic acid; Inorganic acetates such as magnesium acetic acid, lead acetic acid, calcium acetic acid, potassium acetic acid, zinc acetic acid, sodium acetic acid, phosphoric acetic acid and the like; And one or two or more mixtures selected from the group consisting of alkali catalysts such as sodium carbonate, sodium bicarbonate, potassium hydroxide or sodium hydroxide, to obtain a recycled polyol by glycol-depolymerizing a polyurethane foam. 2. The process of claim 1 wherein the catalyst is sodium hydroxide, potassium hydroxide, sodium acetic acid, lead acetic acid, phosphorous acetic acid or zinc acetic acid. The method of claim 2 wherein the catalyst is sodium hydroxide. The following steps (1) to (6): (1) grinding the waste polyurethane foam to obtain a powder; (2) adding 15 to 100 parts by weight of glycol and 0.01 to 10 parts by weight of catalyst with respect to 100 parts by weight of the waste polyurethane foam powder obtained in (1) to a reactor with a cooler; (3) reacting for 30 minutes to 15 hours at a reaction temperature of 120 ° C to 300 ° C under a nitrogen atmosphere to produce regenerated polyols; (4) removing impurities contained in the recycled polyol; (5) mixing the impurity-removing regenerated polyol obtained in step (4) in an amount of 10-30% by weight based on the total weight of the mixture of the pure polyol and the regenerated polyol to obtain a mixed polyol; And (6) reacting the mixed polyol of step (5) with diisocyanate to obtain a polyurethane foam The catalyst of step (2) comprises a Lewis acid catalyst such as zinc chloride, iron chloride, aluminum chloride, mercury chloride; Carboxylic acids such as acetic acid, formic acid, propionic acid, butyric acid and benzoic acid; Inorganic acetates such as magnesium acetic acid, lead acetic acid, calcium acetic acid, potassium acetic acid, zinc acetic acid, sodium acetic acid, phosphoric acetic acid and the like; And one or two or more mixtures selected from the group consisting of alkali catalysts such as sodium carbonate, sodium bicarbonate, calcium hydroxide, potassium hydroxide or sodium hydroxide and the like. 5. The process of claim 4, wherein the catalyst is sodium hydroxide, potassium hydroxide, sodium acetic acid, lead acetic acid, phosphorous acetic acid or zinc acetic acid. 6. The method of claim 5 wherein the catalyst is sodium hydroxide. 5. Process according to claim 4, characterized in that the mixing ratio of the recycled polyol in step (5) is in the range of 10-25 wt%, based on the total weight of the mixture of the pure polyol and the recycled polyol. 5. Process according to claim 4, characterized in that the polyurethane foam obtained in step (6) is a rigid polyurethane foam.