KR20090089269A - Method for seperating and recovering polyol from decomposing polyurethane - Google Patents

Abstract

A method for seperating and recovering polyol from waste polyurethane is provided to obtain polyol of high purity with an efficient method regardless of the kind of waste polyurethane. A method for seperating and recovering polyol from waste polyurethane comprises the steps of: (a) heating and stirring the waste polyurethane crushed material in a reactor; (b) inputting water, solvent, ethanol and surfactant in the heated vessel, heating and stirring the materials, spraying to the heated crushed material-containing reactor, heating the product to 230 ‹C, when the temperature of content reached 230 ‹C, reacting the materials for 2~3 hours at 230 ‹C under 2 pressure; (c) discharging the gas within the reactor and decompressing the material while cooling it to 20 ‹C or less; and inducing phase separation by mass separation to obtain an upper transparent polyol layer and a lower polyol mixture layer.

Description

Method for separating and recovering polyol from polyurethane waste {METHOD FOR SEPERATING AND RECOVERING POLYOL FROM DECOMPOSING POLYURETHANE}

The present invention relates to a method for recovering a polyol from a polyurethane waste, and more particularly, to a technique for efficiently separating and recovering a polyol from a polyurethane waste containing a foreign material by depolymerization with glycol. .

Generally, polyurethane is widely used in many parts of daily life because of its excellent physical properties, and such polyurethane is widely used in various rubbers, paints, adhesives, fibers, building materials, and insulation foams. This is the highest usage. However, due to the physical properties of the polyurethane foam is very difficult to regenerate, the treatment of these wastes is a big problem.

In addition, the above-mentioned polyurethanes are classified into thermosetting polyurethanes and thermoplastic polyurethanes. Thermoplastic polyurethanes are easily recycled or recycled in various ways because they are easily recycled or recycled. However, in the case of thermosetting polyurethanes, the utilization of regeneration is very low. It is true.

In particular, the reduction of solid waste to product systems of the same or similar use through proper disposal is called closed loop recycling, and the method of recycling in this way is a physical recycling process that involves simple reprocessing after washing and grinding. It can be divided into chemical recycling including chemical reactions such as recycling and depolymerization.

Finely crushed waste polyurethane is used as a filler in injection or extrusion molding products or as an enhancer for polyurethane-based adhesives, or physically recycled, which is crushed and compressed as a rebonded foam, is limited in its use. to be. Chemical recycling methods for depolymerizing polyurethane using various solvents include hydrolysis with water, glycolysis with various glycols, and aminolysis with amines.

The hydrolysis method of chemical regeneration method has been studied a lot, but it is disadvantageous in terms of economical low conversion rate, and the regeneration polyol is prepared by depolymerization of polyurethane using a glycol depolymerization reaction, these regeneration polyol Attention has been paid to the reaction of diisocyanates with diisocyanates and recycled into polyurethane foam production materials.

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. 4,110,266 describes the conversion of polyurethane foams to polyols by reacting them with ammonia or amines to decompose them, and decomposing the products containing a mixture of polyols, ureas and amines in an autoclave at an elevated temperature of 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.

However, there is no commercial use of the above-mentioned U.S. patents as the results will be completely different depending on the method of the underwater reaction and the pressure and temperature of the solvent and the minor differences.

In addition, Korean Patent No. 0627209 depolymerizes waste polyurethane foam powder using glycol and depolymerization catalyst, removes amine through esterification by adding anhydrous compound, and then separates impurities using a filter to remove regenerated polyol. A method for preparing the same is disclosed, and Korean Laid-Open Patent Publication No. 1998-032323 discloses a recycled polyol by depolymerizing waste hard polyurethane foam powder with glycol and Lewis acid catalyst, inorganic acetate, or alkali catalyst as depolymerization catalyst. Later, it is disclosed that after mounting and purifying the filter of 50 to 250 mesh and using it for the production of polyurethane foam.

However, the above inventions by depolymerization of polyurethane with glycol are for improving the conversion efficiency from waste polyurethane to polyol or removing amines from recycled polyol, and the waste polyurethane by the above methods. Even when depolymerized to prepare a regenerated polyol, it is still necessary to further process such as filtering or fractional distillation to separate and obtain pure polyol from the depolymerization mixture. In addition, the above methods are generally economically disadvantageous due to a long reaction time, the use of a catalyst, an additional process of separation purification, and the like.

Recognizing this problem, the present inventors have studied the method for separating pure polyols from depolymerization mixtures in a simple, efficient and economical manner after converting waste polyurethanes to polyols by glycol depolymerization. The present invention has been completed.

Accordingly, the present inventors have recognized this problem, and have continued to study a method for separating pure polyols from depolymerization mixtures in a simple, efficient and economical way after converting waste polyurethanes to polyols by glycol depolymerization. As a result, the present invention has been completed, and an object of the present invention is to provide a method for efficiently separating and recovering a polyol from a polyurethane waste containing foreign matter.

This object can be achieved by the method of the present invention.

The method for separating and recovering a polyol from the polyurethane waste according to the present invention comprises the steps of: (a) pulverizing various waste polyurethanes into suitable sizes, and then adding the pulverized product to a reactor and stirring while heating to 200 ^° C .; (b) 5 to 10% of water, 1% of solvent (DMF) + BBP, 2% of ethanol, and 1% of surfactant based on 100 parts by weight of the waste polyurethane crushed product were placed in a preheated heating container and heated to 150 ^° C. and stirred for a pulverized product is when after a spray to the reactor is heated stirred and heated to 230 ^o C, the temperature of the contents reached 230 ^o C in the glycol 3-10% parts by weight of the reactor and between 2 ~ 3 230 ^o C , The reaction was stirred under an atmosphere of 2 atm, but in a completely closed pressure in a nitrogen atmosphere (speed of the stirrer 80 ~ 120 RPM); (c) opening the gas discharge valve of the reactor to discharge the gas and putting the contents into a container equipped with a decompression device to reduce the pressure while cooling to a final -1 atmosphere and a temperature below 20 ^o C for 20 hours; And (d) layer separation occurs by mass separation, whereby an upper transparent polyol layer and a lower mixed polyol layer are distinguished. The two polyols are disadvantageously obtained in different containers.

In the separation and recovery method of the present invention, in the step (a), the waste polyurethane powder preferably has a particle size of 100 mm or less. If the particle size of the powder exceeds 100 mm, the reaction time may be long.

The catalyst is preferably a water-soluble alcohol such as methanol or ethanol, and the amount thereof is not limited, but it is preferable to use 2 to 8 parts by weight.

The solvent mixture is preferably added 0.5 to 5 parts by weight, more preferably 1 to 3 parts by weight with respect to 100 parts by weight of the waste polyurethane powder, the composition is 1: dimethylformamide (DMF) and benzyl butyl phthalate (BBP) 1: 0.5 to 1 mixed may be used. When the amount of the solvent mixture is less than 0.5 parts by weight, the reaction does not occur well, and when it exceeds 5 parts by weight, there is a problem that a reverse reaction occurs.

Since the mixture of DMF and BBP is not mixed with the affinity with water, the affinity between the alcohol and water is increased through the surfactant. At this time, if the affinity with water is low or the ratio with water does not match, the phenomenon of igniting when the solvent is heated to high temperature and put into the heated waste polyurethane pulverized product or ejected in the form of vaporized gas through pressure regulating device The phenomenon occurs that the proportion of the solvent is lowered to generate a problem in the reaction formula.

Therefore, in order to solve this problem, after mixing DMF (dimethylformamide) and BBP (benzyl butyl phthalate) at room temperature in a 1: 1 ratio, dilute water and alcohol diluted with a surfactant, and stir well, and then put them in a solvent heating furnace. The heated solvent mixture thus produced has a high affinity with water, which does not ignite even when directly applied to the fire, and prevents it from evaporating at a high temperature to the pressure regulator.

The reason for heating and adding the solvent is to increase the affinity with water for various foreign substances added to the waste polyurethane when precipitated in the temperature reduction reaction chamber after dissolution to obtain a highly purified polyol. According to this result, it is possible to obtain a purified polyol up to 70-90%.

Since the gas discharged in the step (c) includes various organic solvents used in the polyurethane reaction or the depolymerization reaction, the discharged gas can be liquefied again by using a cooling device and reused.

The present invention is modified by a method of preparing a recycled polyol by glycol-glycolysis of a polyurethane which is conventionally carried out using a catalyst such as waste polyurethane powder, glycol, metal acetate, etc. to continuously separate and obtain a recycled polyol. As a simple and high efficiency method, glycol, a specific catalyst and a solvent mixture are added to the waste polyurethane powder for depolymerization to liquefy, and the liquid mixture of the high temperature produced by the depolymerization reaction is sealed as it is without cooling to room temperature. It is characterized in that the polyol can be easily separated and obtained by a reduced pressure cooling reaction which is gradually cooled at.

The waste polyurethane powder contains foreign substances such as dyes and other resin additives. Therefore, since the depolymerization reaction product by glycolysis by glycol is mixed with other components in addition to the polyol, pure polyol is separated and obtained from the reaction product. In order to do this, filtering (separate) or fractional distillation or the like is required. However, in the case of the present invention, it is possible to easily obtain and separate a polyol using spontaneous delamination without such an additional process.

The spontaneous layer separation phenomenon in the present invention is caused by the unique additive mixing and reaction conditions according to the present invention.

The presence of water and surfactants introduced into the reactor makes the organic solvent water soluble, thereby dissolving the surrounding foreign substances such as amines, curing agents, and pigments in water, thereby attracting and attracting foreign substances to the water molecules. As the decompression temperature decreases, the water molecules themselves combine with the surrounding water molecules, thereby increasing the size of the water molecules. The combination of such water molecules with foreign substances such as amines, curing agents, and pigments is larger than the polyols and thus precipitates downward, thereby separating pure polyols and mixed polyols by mass differences. In this layer separation, the role of water is important, so that the separation of water due to adsorption and precipitation of foreign substances may occur sufficiently even with the addition of 10% water and the water contained in the alcohol used as a catalyst. If you are in a clean state or if you are using ultra-high purity alcohol, you may want to increase your water input.

Layer separation may occur even when the temperature and the content of the catalyst and the environment do not match, but in order to obtain at least 70% or more of the transparent polyol, the same conditions as the present invention should be satisfied.

In addition, the ratio of the input material such as a catalyst is very small compared to other inventions and the reaction time is also only 1/10 of other inventions. Therefore, there is a difference between other inventions in terms of economics and workability.

The amount of water to be added to the catalyst does not interfere with the reaction even with sufficient supply. However, when the amount of water is increased, the use of the mixed polyol obtained is limited. desirable.

According to the step (d), 60 to 90% of the transparent polyol layer and 10 to 40% of the mixed polyol layer are obtained. The obtained transparent polyol is a dye and a foreign material removed and can be used for the same purpose as a pure polyol. Mixed polyols may be used in the manufacture of adhesives or polyurethane foams.

And (e) reacting the polyol obtained in the above step with a diisocyanate to form a polyurethane foam.

According to the present invention, regardless of the type of waste polyurethane, it is possible to separate and obtain a high purity polyol in a simple and efficient manner, and the polyurethane foam prepared using the obtained polyol is excellent in strength, dimensional stability, and the like. It shows physical properties.

In addition, the present invention relates to the recycling of waste polyurethane based on economical efficiency, which can be used regardless of the type of waste polyurethane (thermosetting and thermoplastic), and does not require powder-crushed waste polyurethane, cooling Through sealing, the temperature of the barrel decreases and the pressure drops to increase the rate of layer separation, the polyol obtained in the upper layer is very clean, and the impurities that settle in the lower layer are solidified, so that the polyol of the upper layer is removed without special equipment. It can be separated.

Hereinafter, the present invention will be described in detail with reference to Examples and Test Examples, but the present invention is not limited to the following examples.

In order to find the optimum depolymerization reaction conditions, repeated experiments were carried out while changing the preheating temperature of the reactor and the addition amounts of glycol, solubilizer and catalyst.

Preparation of Recycled Polyols

<Example 1>

50 kg of waste polyurethane powder ground to a size of about 20 mm was put in a reactor heated to a temperature of 230 ° C. and stirred for 1 hour while raising the reactor temperature to 250 ° C. After diluting 1 kg of a solvent mixture of DMF (dimethylformamide) and BBP (benzyl butyl phthalate) 1: 1 with 2 kg of ethanol, and putting it into the reactor, 2 kg of ethylene glycol (EG) was introduced into the reactor for 1 hour at a pressure of 2 kgf. The reaction mixture was stirred to obtain a liquid mixture.

<Example 2>

50 kg of waste polyurethane powder ground to a size of about 30 mm was put in a reactor heated to a temperature of 220 ° C. and stirred for 2 hours while raising the reactor temperature to 250 ° C. After diluting 500 g of a solvent mixture mixed with DMF and BBP 1: 0.5 with 1 kg of methanol and adding it to a reactor, 5 kg of ethylene glycol (EG) was added to the reactor and stirred for 30 minutes at a pressure of 2 kgf to obtain a liquid mixture. .

Comparative Example 1

50 kg of the waste polyurethane powder ground to a size of about 20 mm was put in a reactor heated to a temperature of 150 ° C. and stirred for 1 hour while raising the reactor temperature to 180 ° C. 250 g of a solvent mixture in which DMF and BBP were mixed 1: 1 was diluted with 500 g of ethanol, and then introduced into a reactor, and 1.5 kg of ethylene glycol (EG) was added to the reactor, followed by stirring for 1 hour at a pressure of 2 kgf.

Comparative Example 2

50 kg of waste polyurethane powder ground to a size of about 20 mm was put in a reactor heated to a temperature of 230 ° C. and stirred for 1 hour while raising the reactor temperature to 250 ° C. 5 Kg of a solvent mixture mixed with DMF and BBP in a 1: 1 ratio was diluted in 5 kg of ethanol and added to a reactor, and 10 kg of ethylene glycol (EG) was added to the reactor and reacted with stirring at a pressure of 3 kgf for 3 hours.

Confirmation of reaction product

The liquid mixture obtained in Examples 1 and 2 showed the color of the waste polyurethane powder injected, and the strength of the reaction mixture using mDI (methylene diphenyl diisocyanate) and TDI (toluene diisocyanate) was used. It was confirmed that the polyurethane foam showing, the liquid mixture contains a polyol.

However, in the case of Comparative Example 1, the injected materials were entangled in the reactor and the liquid mixture itself was not produced. In the case of Comparative Example 2, a liquid mixture was produced, but the reaction test was carried out using MDI (methylene diphenyl diisocyanate) and TDI (toluene diisocyanate), but the reaction did not produce satisfactory polyurethane foam.

Isolation of Pure Polyols

The polyol was separated from the liquid mixture produced in Examples 1 and 2, and a reaction product by a conventional catalyst glycol depolymerization reaction was used as a comparative example.

<Example 3>

600 g of the high temperature liquid mixture produced in Example 1 was taken and placed in a closed reactor, and placed under reduced pressure and reduced temperature environment which was gradually cooled at room temperature for 24 hours.

<Example 4>

600 g of the hot liquid mixture produced in Example 2 was taken and placed in a closed reactor, and placed under a reduced pressure and reduced temperature environment which was gradually cooled at room temperature for 24 hours.

Comparative Example 3

A four-necked flask was equipped with a reflux condenser, thermometer, mechanical stirrer, and dropping device, and a heating mantle with temperature control was installed. 600 g of waste polyurethane foam pulverized to a constant size was added, 400 g of diethylene glycol and 6.0 g of zinc acetic acid were added, and the temperature was controlled by gradually adjusting the initial temperature to 130 ° C. Under nitrogen atmosphere, the reaction temperature was raised to 200 ° C. by 10 ° C. per hour, and stirring was continued for 4 hours until the pulverized waste polyurethane was dissolved. High pressure vacuum reaction for 2 hours to obtain a regenerated polyol. A small amount of the produced regenerated polyol was taken into a closed reactor and cooled slowly for 24 hours.

Confirmation of separation

In the case of Examples 3 and 4, the separation of the waste polyurethane powder into an almost transparent transparent upper polyol layer (80%) and a mixed polyol layer (20%) at the bottom where the pigments and foreign substances were mixed The phenomenon appeared.

However, in Comparative Example 3, even after 24 hours, no delamination occurred.

As a result of the component analysis, the upper transparent polyol showed a purity close to that of the pure polyol, and the mixed polyol was confirmed to be a mixture of dyes and foreign substances.

The present invention relates to the efficient recycling of polyurethane waste, and according to the present invention, by efficiently recycling the polyurethane waste, which has been difficult to recycle in the past, the amount of waste can be reduced, As it can be applied to the field, the industrial use value is high in the economic aspect in the high oil price era.

1 is a process chart showing a method for separating and recovering a polyol from polyurethane waste according to an embodiment of the present invention and a method for preparing a polyurethane foam using the same.

Claims (3)

A method for separating and recovering polyol from polyurethane waste, comprising the following steps. (a) pulverizing various waste polyurethanes into suitable sizes, and then putting the pulverized product into a reactor and stirring with heating to 200 ^° C .; (b) based on 100 parts by weight of the waste polyurethane pulverized product Water 5-10%, the solvent (DMF) + BBP 1%, Ethanol 2%, surface active agent into a 1% based on the heating vessel prepared was sprayed into the reactor, which is heated and stirred for a pulverized product by heating to 150 ^o C 230 ^o When the temperature of the contents reached 230 ^o C by heating and stirring the mixture, 3 to 10% by weight of glycol was added to the reactor and stirred for 2 to 3 hours under an environment of 230 ^o C and 2 atmospheres, but completely enclosed in a nitrogen atmosphere. Process in state (speed of stirrer 80-120 RPM); (c) opening the gas discharge valve of the reactor to discharge the gas and putting the contents into a container equipped with a decompression device to reduce the pressure while cooling to a final -1 atmosphere and a temperature below 20 ^o C for 20 hours; (d) A layer separation phenomenon occurs by mass separation, whereby an upper transparent polyol layer and a lower mixed polyol layer are distinguished, and the two polyols are disadvantageously obtained in different containers. 2. The process of claim 1 wherein the catalyst is methanol or ethanol. 2. The method of claim 1, wherein the solvent mixture is a mixture of dimethylformamide (DMF) and benzyl butyl phthalate (BBP) in a ratio of 1: 0.5 to 1.

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