JP3265085B2 - Polyurethane recycling law - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention is based on high-molecular-weight polyols such as flexible polyurethane foams (cushion materials, car interior materials, etc.) and thermosetting and thermoplastic polyurethane elastomers (shoe soles, rolls, etc.). The present invention relates to a method of chemically treating polyurethane waste to regenerate it as a low-molecular-weight polyol.

[0002]

2. Description of the Related Art Recycling of synthetic polymers is becoming a major issue with the recent global environmental protection movement. Various methods for recycling polyurethane by chemical decomposition have long been reported. The best studied method is the glycolysis method, which decomposes by transesterification with a low molecular weight glycol. JP-B-53-34000 describes a method of regenerating a polyol after decomposing a flexible polyurethane foam with a low molecular weight glycol such as diethylene glycol. However, in this method, (a) the decomposition temperature is as high as 200 ° C. or higher, (b) the decomposition rate is not fast even at high temperatures, and (c) alkylene oxide is added to the remaining low molecular weight decomposition solution obtained by separating and extracting the high molecular weight polyol. When the low-molecular-weight regenerated polyol obtained as above is used as a raw material for a rigid foam, there are various problems such as a decrease in the physical properties of the foam due to a low average number of functional groups. JP A 51-16380 discloses, a method of decomposing a polyurethane in aqueous alkali such as potassium hydroxide is described, the method large amounts of K ₂ CO
It is not practical because it produces ₃ by-product.

[0003] Japanese Patent Publication No. 42-10634 describes a method in which a flexible polyurethane foam is decomposed with monoethanolamine, and then an aromatic amine and monoethanolamine are separated and recovered from the decomposition product by distillation. . However, it is very difficult to separate high boiling aromatic amines by distillation. In addition, the method of the patent describes that oxazolidone-2 and N-hydroxyethylimidazolidone produced in a large amount by the reaction of oxazolidone-2 and monoethanolamine are produced in large amounts. A method in which sodium hydroxide and monoethanolamine are used in combination in order to eliminate this by-product is described in JP-B-43-21079. This method uses oxazolidone-2
Is decomposed with sodium hydroxide to produce monoethanolamine and Na ₂ CO _3, and the monoethanolamine is not consumed. However, this method requires a large amount of Na
It is not practical because ₂ CO ₃ is by-produced.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a high-molecular-weight polyol by a method which is fast decomposing, does not produce extra by-products, is easy to add an alkylene oxide, and does not require a post-treatment step. A method for regenerating a low-molecular-weight polyol that can be reused as a urethane raw material from a polyurethane made from polyurethane, and a method for producing a polyurethane such as a polyurethane foam and a polyisocyanurate foam using the regenerated low-molecular-weight polyol. is there.

[0005]

Means for Solving the Problems The present inventors have conducted intensive studies to achieve the above object, and as a result, have found an excellent method for decomposing and regenerating polyurethane using a high molecular weight polyol as a raw material, and have completed the present invention. . That is, the present invention decomposes a polyurethane waste made from a high molecular weight polyol as a raw material in a monoalkanolamine having 2 to 3 carbon atoms, and converts a high molecular weight polyol having 6 to 16 carbon atoms from the obtained decomposition solution.
A method for regenerating a low-molecular-weight polyol by adding and removing alkylene oxide having 2 to 4 carbon atoms to the remaining low-molecular-weight decomposed product without a catalyst or with a tertiary amine catalyst, and the regenerated low-molecular-weight This is a method for producing a polyurethane such as a polyurethane foam and a polyisocyanurate foam using a polyol.

Hereinafter, the method of the present invention will be described in detail. The high molecular weight polyol defined in the present invention is a polyoxyalkylene polyol having a molecular weight of 700 or more and having 2 to 5 hydroxyl groups. When such a high molecular weight polyol is decomposed by the method of the present invention, it is separated without dissolving in an alkanolamine layer containing a low molecular weight decomposition product. Specific examples of the monoalkanolamine include 1-amino-2-ethanol, 1-amino-2-propanol, and 1-amino-3-propanol. Among them, 1-amino-2-ethanol (hereinafter referred to as monoethanolamine) which is inexpensive and easily available in large quantities is preferable. The amount of the alkanolamine required to decompose the polyurethane is theoretically at least twice the number of moles of the isocyanate groups constituting the polyurethane. The decomposition solution separates the decomposition solution into an upper layer formed by a high molecular weight polyol and a lower layer formed by a low molecular weight decomposed product and monoethanolamine. Below this, the decomposition is partially incomplete, but there is no practical problem as long as the decomposition product is liquid and uniform. The decomposition temperature is preferably 100 ° C. or higher, but particularly 140 ° C. to 16 ° C.
0 ° C. is preferred. Below this temperature the decomposition rate is slow,
At higher temperatures, vapors of the monoalkanolamine are scattered, causing safety and health problems. The decomposition time increases as the decomposition ratio (foam weight / alkanolamine weight) increases, but is usually 10 hours or less. In order to prevent coloring, the decomposition is preferably performed in a state where oxygen is blocked to some extent. If the decomposition ratio is high, the viscosity of the decomposition solution in the lower layer increases, but if the decomposition ratio is within the usual preferred range, it is not more than 30,000 centipoise (25 ° C.). The low molecular weight decomposition product thus obtained is a brown transparent liquid.
The resulting low molecular weight decomposed products are amines derived from polyurethane raw materials and ureadiols such as N, N'-bis (hydroxyethyl) urea. In addition, a small amount of cyclic urea monol such as N-hydroxyethylimidazolidone is by-produced. However, when the decomposition time is prolonged, the amount produced is increased. Ureadiol is a compound that has not been described in conventional literature or patents.

The decomposition product obtained by the method of the present invention is usually used as it is because it has a high active hydrogen value, contains a large amount of highly reactive amine, and contains a cyclic urea monool which reduces the foam properties. Cannot be used as a raw material for rigid polyurethane foams. Therefore,
It is necessary to add an alkylene oxide such as propylene oxide (hereinafter referred to as PO) to form a normal polyol. However, potassium hydroxide, which is a normal alkylene oxide addition catalyst, reacts with urea in the decomposition product to produce K. Cannot be used because it produces ₂ CO ₃ . However, surprisingly, an alkylene oxide is added to H of the CONH group of a ureadiol such as N, N'-bis (hydroxyethyl) urea or a cyclic ureamonool such as N-hydroxyethylimidazolidone even without a catalyst, Even more surprisingly, it has been found that more alkylene oxide is added when dimethylamine, which binds to an alkyl or alkenyl group having 10 to 18 carbon atoms, is used as a catalyst. Alkylene oxide is added to amines, which are other decomposition products, in the absence of a catalyst or a tertiary amine catalyst, but is no longer added to polyols of decomposition products. Is a polyol composition having a suitably uniform molecular weight. The addition reaction of the alkylene oxide is
It is carried out according to a general method for synthesizing a polyoxyalkylene polyol. The reaction temperature is from 80 to 140C, preferably from 100 to 130C.

Specific examples of the tertiary amine catalyst for the addition reaction of alkylene oxide include low-molecular-weight aliphatic amines such as triethylamine, triethylenediamine, pentamethyldiethylenetriamine and tetramethylpropanediamine, dimethylaniline, pyridine and imidazole. The most preferred catalyst is a long-chain aliphatic dimethyl such as an alkyl or alkenyl group having 10 to 18 carbon atoms such as dimethyl palmitylamine, dimethylstearylamine and dimethyllaurylamine. Amine. Unlike the low molecular weight tertiary amine catalyst, this long-chain aliphatic amine not only has a high catalytic effect of alkylene oxide addition, but also hardly acts as a urethanization catalyst when a polyol as an addition product is used as a raw material for urethane. There is an advantage. The above-mentioned catalyst is used by mixing it in an amount of 0.05 to 3.0% by weight with respect to the weight of the alkylene oxide addition final product to the decomposition product solution.
5 to 1.0% by weight.

The polyol obtained by the method of the present invention can be reused as a raw material for polyurethane such as polyurethane foam and polyisocyanurate foam.
As the method, any method conventionally used in the production of polyurethane can be applied. The simplest method is to use a mixture (premix resin) in which the regenerated polyol, catalyst, foam stabilizer, additive, foaming agent and the like are preliminarily mixed, and an organic polyisocyanate at 1000.
There is a method in which the mixture is vigorously stirred and mixed with a high-speed rotating lab stirrer of 90009000 rpm and foamed in a specific container. However, as an actual production method, there is a method in which the above-mentioned two liquids are subjected to collision mixing with a commercially available high-pressure foaming machine for urethane and injected into a mold. As a high-pressure foaming machine, for example, HK- manufactured by Maruka Kakoki Co., Ltd.
It is commercially available from many machine manufacturers such as 270.

[0010]

Next, the present invention will be described in detail with reference to examples. Parts in the examples represent parts by weight. Raw materials used Polyol A; triol having a hydroxyl value of 56 mg-KOH / g obtained by adding propylene oxide to glycerin. Polyol B: a diol having a hydroxyl value of 37 mg-KOH / g obtained by adding propylene oxide and ethylene oxide to dipropylene glycol. Polyol C: Triol having a hydroxyl value of 540 mg-KOH / g obtained by adding propylene oxide to glycerin. DEG; diethylene glycol. AE-300: "AE-30" manufactured by Mitsui Toatsu Chemicals, Inc.
Tetrol having a hydroxyl value of 766 mg-KOH / g obtained by adding propylene oxide to ethylenediamine at 0 ". Isocyanate A: Aromatic diisocyanate “T-80 / 20” (Tolylene diisocyanate) manufactured by Mitsui Toatsu Chemicals, Inc. NCO% = 48.3. Isocyanate B: 80% by weight of an aromatic diisocyanate “MDI-PH” (diphenylmethane diisocyanate, NCO% = 31.3) manufactured by Mitsui Toatsu Chemicals and “M
DI-LK "(NCO% = 28.3 with carbodiimide-modified diphenylmethane diisocyanate) 20% by weight
Mixture. NCO% = 32.5. Isocyanate C: an aromatic polyisocyanate “M-200” (crude MDI) manufactured by Mitsui Toatsu Chemicals, Inc. NCO
% = 31.3. L-520: a polydimethylsiloxane derivative manufactured by Nippon Unicar Co., Ltd. Silicone foam stabilizer for flexible foam. L-5420: a polydimethylsiloxane derivative manufactured by Nippon Unicar Co., Ltd. Silicone foam stabilizer for rigid foam. Catalyst A: "L-1020" manufactured by Mitsui Toatsu Chemicals, Inc. Urethane catalyst. Catalyst B: dibutyltin dilaurate with "Stan BL" manufactured by Sankyoki Co., Ltd. Catalyst C: N, N, N'N'-tetramethylhexamethylenediamine with "Kaolyzer No-1" manufactured by Kao Corporation. CFC 11: Trichlorofluoromethane monoethanolamine manufactured by Mitsui DuPont Fluorochemicals, Inc .; “MEA” manufactured by Mitsui Toatsu Chemicals, Inc. DM-60; "Farmin DM-60" manufactured by Kao Corporation
Is a weak tertiary amine mainly composed of dimethyl palmitylamine.

Reference Example 1 Preparation of Flexible Polyurethane Foam A for Decomposition and Regeneration <Polyol Resin> Part Polyol A 200 Water 10 L-520 2 Catalyst A 0.6 Catalyst B 0.4 <Isocyanate> Part Isocyanate A 114 (NCO Index = 100) After thoroughly mixing the resin raw materials, the mixture was mixed with isocyanate by high-speed stirring, poured into a wooden case, and foam-cured to obtain Form A.

Reference Example 2 Preparation of Polyurethane Elastomer B for Decomposition / Regeneration <Polyol Resin> Part Polyol B 200 DEG 10 AE-300 12 DBTDL 0.002 <Isocyanate> Part Isocyanate B 62.6 (NCO Index = 100) Resin Raw Material Was thoroughly mixed, mixed with an isocyanate, poured into an iron housing, and cured to obtain an elastomer B.

Example 1 Decomposition of Flexible Polyurethane Foam A 150 parts of monoethanolamine was placed in a 1-liter separable flask equipped with a condenser, heated to 150 ° C., and 150 parts of foam A was continuously added thereto for 3 hours. After decomposing, high molecular weight polyol A in the upper layer was extracted and removed three times with heptane to obtain brown transparent low molecular weight decomposed product A.
A part of the decomposition product was silylated with BSA (N, O-bis (trimethylsilyl) acetamide) and analyzed by gas chromatography (GC) and GC-mass analysis. As a result, the main product was an aromatic compound derived from isocyanate. And N, N'-bis (hydroxyethyl) urea, and the by-product was found to be N-hydroxyethylimidazolidone. The decomposition product has a viscosity of 100
Total active hydrogen value by centipoise (25 ° C.), acetic anhydride-pyridine method is 1370 mg-KOH / g (theoretical value is 1349)
Met.

Example 2 Decomposition of Elastomer B 200 parts of monoethanolamine was placed in a 1-liter separable flask equipped with a condenser, heated to 150 ° C., and 284 parts of elastomer B were continuously added and decomposed for 3 hours. Thereafter, the high molecular weight polyol B in the upper layer was extracted and removed three times with heptane to obtain a brown transparent low molecular weight decomposition product B. The viscosity was 100 centipoise (25 ° C.), and the total active hydrogen value was 1290 (theoretical value was 1266).

Example 3 Addition of PO to Decomposition A (without catalyst) 200 parts of Decomposition A obtained in Example 1 were placed in a 2-liter autoclave, and PO was charged with stirring and 100 parts.
Reacted polyol A at -110 ° C. for 5 hours until the partial pressure drop of PO disappears (until PO stops reacting)
Compound 1 was synthesized. After removing PO, a pale yellow transparent liquid was obtained. As a result of the analysis, the hydroxyl value was 700 mg-KOH / g.

Example 4 PO addition to decomposition product A (weak amine catalyst) 200 parts of decomposition product A obtained in Example 1 and 5 parts of DM-6
0 into a 2-liter autoclave while stirring.
O is charged and subjected to an addition reaction at 100 to 110 ° C. and reacted for 5 hours until the partial pressure of PO is not reduced.
A2 was synthesized. After PO removal, the reaction product was analyzed, and as a result, the hydroxyl value was 490 mg-KOH / g.

Example 5 PO addition to decomposed product B (weak amine catalyst) 200 parts of decomposed product B obtained in Example 2 and 5 parts of DM-6
0 into a 2-liter autoclave while stirring.
O was charged and reacted at 100 to 110 ° C. for 5 hours until there was no decrease in the partial pressure of PO, followed by removing PO to obtain a pale yellow transparent liquid (regenerated polyol-B1). Hydroxyl value is 520mg-K
OH / g.

Example 6 Preparation of Rigid Foam and Formability and Physical Properties of Foam A polyol resin raw material was placed in a 1-liter polypropylene cup at the composition ratio shown below and mixed so as not to entrap air. The mixture was added so that the index became 105, and the mixture was rapidly stirred and mixed at 5,000 to 7000 rpm for about 5 seconds with a high-speed rotating lab stirrer. This mixture was quickly placed in a wooden box (200 × 200 × 200 mm) to foam polyurethane. . During the foaming and curing process, cream time (CT), gel time (GT) and tack free time (TFT) were measured. After foaming and curing, the mold was removed, cut one day later, and the density, cell state of the foam, flyability, dimensional stability, compressive strength, and thermal conductivity were examined. The thermal conductivity used was Anacon Model 88. <Polyol resin> part Regenerated polyol A2 100 L-5420 2.0 Catalyst C 2.5 Freon 11 40 <Isocyanate> part Isocyanate A 123 (NCO index = 105) CT is 10 seconds, GT is 40 seconds, TFT is 49 seconds Met. The foam density is 30 g / cm ³ , the desired flyability is good, the cells are fine and good, the closed cell ratio is 87
%, Compressive strength length 2.2, width 0.8 kg / cm ² , thermal conductivity 140 (Kcal / m ° CH), 70 ° C, dimensional stability 95
% Humidity (24 hours elapsed), vertical 0.1%, horizontal 1.2
%, Vertical 0.1% at 70 ° C (24 hours), horizontal 0.2%, vertical 0.1% at -30 ° C (24 hours),
Horizontal-good at 0.6%.

Comparative Example 1 Comparison with Example 6 Instead of the regenerated polyol A2 of Example 6, polyol C was used.
Was performed under the same conditions as in Example 6 except that was used.
CT was 10 seconds, GT was 51 seconds, and TFT was 60 seconds. The foam density is 29 g / cm ³ , the desired flyability is good, the cells are fine and good, the closed cell ratio is 86
%, Compressive strength length 2.1, width 0.6 kg / cm ² , thermal conductivity 142 (Kcal / m ° CH), 70 ° C, dimensional stability 95
% Humidity (24 hours), vertical 0.3%, horizontal 1.4
%, 70% (elapsed for 24 hours) -0.1% for vertical, 0.2% for horizontal, -30 ° C (elapsed for 24 hours), 0.3% for vertical,
Horizontal-0.7%. As is clear from the comparison between Example 6 and Comparative Example 1, when a low-molecular-weight polyol obtained by decomposing and regenerating polyurethane waste by the method of the present invention is used as a raw material for rigid urethane foam, the same as ordinary polyols is obtained. It can be seen that the sample has normal moldability and physical properties.
Of course, it can be applied to polyurethane other than rigid urethane foam.

[0020]

According to the method of the present invention, a normal low molecular weight polyol can be obtained from polyurethane waste, and this regenerated polyol can be used as a raw material for polyurethane such as polyurethane foam and polyisocyanurate foam.

Claims (3)

(57) [Claims] 1. A polyurethane waste produced from a high molecular weight polyol as a raw material is decomposed in a monoalkanolamine having 2 to 3 carbon atoms. A method in which a low molecular weight polyol is regenerated by extracting and removing with hydrogen and adding an alkylene oxide having 2 to 4 carbon atoms to the remaining low molecular weight decomposition product without a catalyst or with a tertiary amine catalyst. 2. The method according to claim 1, wherein the tertiary amine catalyst has the following structure. Embedded image (Wherein, R represents an alkyl group or alkenyl group having 10 to 18 carbon atoms) 3. A method for producing a polyurethane using the low molecular weight polyol regenerated by the method according to claim 1.