JPH06192363A - Production of rigid polyurethane foam - Google Patents

Abstract

PURPOSE:To efficiently obtain the subject foam useful as a building material, etc., by using a polyisocyanate compound component with a component containing a specific active hydrogen compound, a catalyst, a foam stabilizer and a foaming agent. CONSTITUTION:This rigid polyurethane foam is obtained by using (A) a component of a polyisocyanate compound having 2 or more isocyanate groups such as 4,4'-diphenylmethane diisocyanate, (B) a component containing an active hydrogen compound having >=2 active hydrogen-containing groups, (C) a catalyst such as triethylenediamine, (D) a foam stabilizer such as polyoxyethylene octadecylamine, (E) a foaming agent such as trichlorofluoromethane and (F) a component of a decomposed solution prepared by decomposing a rigid polyurethane foam in a 2-3C monoalkanolamine so as to provide a ratio of the components (F)/[(B)+(F)]<=15wt.% based on the component (B).

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention is to decompose a waste material of a rigid polyurethane foam used for a building material, a structural material, a heat insulating material or other uses, and then mix this with a polyol and use it as a raw material of the rigid polyurethane foam. On how to do.

[0002]

2. Description of the Related Art In recent years, recycling of synthetic polymers has become a major issue as part of global environmental protection. Various methods have been conventionally known as a method for chemically decomposing a polyurethane resin and recycling it. The most well-studied method is the glycolysis method using low molecular weight glycol. JP-B-53-34000 discloses that a rigid polyurethane foam is decomposed by using a low molecular weight glycol such as diethylene glycol as a decomposing agent, and the foam is decomposed, and a phase containing a high molecular weight polyol and a carbamate intermediate and A method for separating the amine-containing phase is described. This method has a problem that the decomposition temperature is as high as 200 ° C. or more and that the urethanation catalyst is deactivated because the acid value is high when the phase containing the carbamate intermediate and the amine is used as it is as a raw material for the rigid polyurethane foam. There is. In addition, the carbamate intermediate has a problem that when potassium hydroxide, which is used as an addition catalyst for usual alkylene oxides, is added, the carbamate intermediate is decomposed to form a carbonate and the catalyst is deactivated. A method of adding an alkylene oxide such as propylene oxide without a catalyst in order to reduce the acid value is also described, but the product obtained by this method contains a large amount of a bifunctional compound derived from glycol as a decomposer. Therefore, when used as a raw material for rigid polyurethane foam, there is a problem that the mechanical strength of the foam becomes poor.

Japanese Unexamined Patent Publication (Kokai) No. 51-16380 describes a method of decomposing polyurethane in alkaline water such as potassium hydroxide. In this method, the urethane bond reacts with potassium hydroxide in the same number of moles. Consumed and a large amount of K ₂ C
There is a problem that O ₃ is produced as a by-product. JP-A-51-39610 describes a method of heating polyurethane in a polyol together with a Lewis acid and adding an amine to the product. This method has a problem that the reaction tank is corroded by a trace amount of water in the Lewis acid and polyurethane or polyol. Also, the decomposition efficiency is not high. Cellular Polymer Vol. 6, pp. 27-41 (1988) describes a method of decomposing polyurethane for shoe soles by transesterification with low molecular weight glycol using potassium acetate as a decomposition catalyst. Potassium acetate, which is a catalyst for trimerization (isocyanurate formation) of isocyanate, is present in the decomposition liquid, and low molecular weight glycol adversely affects the physical properties of the foam, which is not preferable.

JP-B-42-10634 describes a method of decomposing a polyurethane foam using an amine compound such as an alkanolamine as a decomposing agent, and then separating and recovering the amine compound and the polyol. The main products obtained by this method are described to be polyols, amines and N-hydroxyethylimidazolidone and oxazolidone-2 in equivalent amounts (large amounts). However, since the latter two compounds have only one OH group, it was considered that a decomposition product containing a large amount of such a compound cannot be used as a polyol.

[0005]

In the conventional method, it was not possible to obtain a polyol having a normal hydroxyl value by decomposing a rigid polyurethane foam and then adding alkylene oxide side. However, it is an important subject to recover the waste material of rigid polyurethane foam and reuse it by some method.

[0006]

Means for Solving the Problems As a result of earnest studies, the present inventors have found that after decomposing a rigid polyurethane foam with a monoalkanolamine, it can be directly mixed with a polyol to be used as a raw material for the rigid polyurethane foam. I found out. That is, the present invention is the following (a) ~
the component (e), (a) a polyisocyanate compound component (a) having at least two isocyanate groups, (b) a component (b) containing an active hydrogen compound having at least two active hydrogen-containing groups, When a rigid polyurethane foam is produced using (c) a catalyst, (d) a foam stabilizer, and (e) a foaming agent, (f) the rigid polyurethane foam has 2 to 3 carbon atoms.
The decomposed solution component (f) obtained by decomposing it in the monoalkanolamine of
(Component (b) + Component (f)) ≦ 15% by weight The present invention relates to a method for producing a rigid polyurethane foam, which is used in a range.

The method of the present invention will be described in detail below. As the polyisocyanate compound having at least two isocyanate groups in the component (a) used in the method of the present invention, those conventionally used in rigid polyurethane foams are used. Specifically, 4,4'-
Diphenylmethane diisocyanate (hereinafter referred to as 4,4'-MDI), 2,4'-diphenylmethane diisocyanate (hereinafter referred to as 2,4'-MDI), 2,4-diisocyanate toluene (hereinafter referred to as 2,4-TDI), 2,6 -Diisocyanate toluene (hereinafter referred to as 2,6-TDI), and their dimers, 3
Also included are crude TDI, crude MDI, which are polymers or multimers, or mixtures thereof, as well as mixtures thereof. Further, an isocyanate prepolymer, which is a reaction product of an active hydrogen compound that reacts with an isocyanate such as a polyol, an amine, or a mercaptan, and the above isocyanate are also included.

Component (b) used in the present invention means a component containing an active hydrogen compound having at least two active hydrogen-containing groups, and the components such as OH group, primary amino group, secondary amino group and SH group. It is a component containing a compound having at least two hydrogen-containing groups. Specifically, it is usually a low molecular weight compound having two or more hydroxyl groups in the molecule and having a hydroxyl value of 200 to 600 mg-KOH / g. Such compounds are, for example,
It is obtained by adding an alkylene oxide to a low molecular weight active hydrogen compound which is an initiator. More specifically, for example, ethylene glycol, glycerin, trimethylolpropane, pentaerythritol, α-methyl glycoside, sorbitol, saccharose, and other low molecular weight polyols (called initiator), or ethylenediamine, diethylenetriamine, piperazine, 4,4'-diaminodiphenylmethane (4,4'-MDA), 2,4'-diaminodiphenylmethane (2,4'-MDA), 2,4-diaminotoluene (2,4-TD
A) Polyether polyols obtained by adding alkylene oxides such as propylene oxide, ethylene oxide and butylene oxide to amine compounds (initiators) such as A, and 2,6-diaminotoluene (2,6-TDA). Alternatively, a low molecular weight or high molecular weight polyol having a hydroxyl value outside the above range can also be used by mixing an amount not too much. Specifically, as the low molecular weight polyol, there are initiators of the above polyols, and as the high molecular weight polyol, a high molecular weight polyether obtained by addition-polymerizing propylene oxide, ethylene oxide or butylene oxide to the above initiator. There is a polyol. Furthermore, the amine compound of the above-mentioned initiator and the compound having a high molecular weight primary or secondary amino group can be mixed with the above-mentioned polyol and used. In addition, any polyol that can be used in the production of urethane resin can be basically used. Specifically, there are polyester polyols obtained by esterification of dicarboxylic acids such as phthalic anhydride and adipic acid with low molecular weight glycols, and polytetramethylene ether glycols obtained by ring-opening polymerization of tetrahydrofuran. Further, as the SH group-containing active hydrogen compound, specifically, thioglycol,
Alternatively, there is mercaptan obtained by esterification of β-mercaptopropionic acid and pentaerythritol.

Component (c) used in the method of the present invention
As the catalyst, those conventionally used in rigid polyurethane foams are used. Specifically, tertiary amines such as triethylenediamine, tetramethylpropanediamine, tetramethylhexanediamine, pentamethyldiethylenetriamine, bis (N, N-dimethylaminoethyl) ether, dibutyltin dilaurate, stannas octoate, etc. Examples include metal catalysts, potassium octylate, potassium acetate, tetraalkylammonium chloride, tetraalkylammonium bromide, tetraalkylammonium iodide, and other isocyanate trimerization catalysts (isocyanurate-forming catalysts).

Component (d) used in the method of the present invention
As the foam stabilizer, a commonly used silicone derivative for rigid polyurethane foam (alkylene oxide-modified polydimethylsiloxane having an alkoxy group or an active OH group at the end) is used. Further, so-called nonionic surfactants such as polyoxyethylene octadecylamine, polyoxyethylene beef tallow alkylamine, and long-chain fatty acid alkylol amide can also be used as the foam stabilizer. The component (e) blowing agent used in the method of the present invention is a conventionally known blowing agent. Specifically, for example, trichlorofluoromethane, chlorodifluoromethane, dichlorotrifluoroethane,
Dichlorofluoroethane, trichlorotrifluoroethane, chlorodifluoroethane, methylene chloride,
There are water and carbon dioxide. Other than these, any one having a foaming effect can be used.

Component (f) used in the method of the present invention
Specific examples of the monoalkanolamine used for the production of 1-amino-2-ethanol and 1-amino
-2-propanol and 1-amino-3-propanol.
Of these, 1-amino-2-ethanol, which is inexpensive and easily available in large quantities, is preferable. The foam weight relative to the weight of the decomposer (hereinafter referred to as "decomposition ratio") can theoretically be up to the 2nd position with ordinary rigid polyurethane foam, and this range is preferable. That is, all the urethane bonds and urea bonds are decomposed in the presence of monoalkanolamine in an amount twice as much as the isocyanate used in producing the rigid polyurethane foam to be decomposed. However, in some cases, there is no problem even if the decomposition ratio is increased to 3 for example. In this case, the decomposition with the monoalkanolamine is partially insufficient, but the product is uniform and there is no problem in terms of actual performance. The decomposition temperature is 100
C. or higher is preferable, but 140 to 160.degree. C. is particularly preferable. If the temperature is lower than this, the decomposition rate is slow, and if the temperature is raised to higher than this, the vapor of the monoalkanolamine scatters, causing various problems. The decomposition product thus obtained is a brown liquid. The viscosity of this liquid is
It depends on the decomposition ratio, but it is 30,000 centipoise (25 ° C.) or less if the decomposition ratio is within a normal preferable range.

The product obtained by decomposing with a monoalkanolamine, that is, the component (f) is a polyol derived from a polyol which is a raw material of a rigid polyurethane foam,
It has been found that amines derived from polyisocyanate and N, N'-bis (hydroxyethyl) urea derived from monoalkanolamine (hereinafter abbreviated as BHEU) are the main components. The production of BHEU was not described in the conventional literatures and patents, and it was described that the main product was HEIM (N-hydroxyethylimidazolidone) having only one OH group. However, it was surprisingly found by the present inventors that the decomposition liquid obtained by decomposition with such a monoalkanolamine can be mixed as it is with a polyol and used as a raw material for a rigid polyurethane foam. The decomposition product obtained by decomposing by the method of the present invention, that is, the component (f) is used by mixing up to 15% by weight with respect to the component (b). If it is used in excess of 15% by weight, the reactivity will be high, resulting in foam failure during the foaming process.

As the method for producing the rigid polyurethane foam of the present invention, all the methods conventionally used in the production of rigid foam can be applied. The simplest method is to use a mixture of the above-mentioned polyol, catalyst, foam stabilizer, shrinkage-preventing agent and foaming agent (premix resin) and an organic polyisocyanate in an amount of 1000-90.
There is a method in which strong stirring and mixing is performed with a high-speed rotating lab stirrer at 00 rpm and foaming is performed in a specific container. However, an actual production method is a method in which the above two liquids are collision-mixed with a commercially available high-pressure foaming machine for urethane and then injected into a mold. Examples of the high-pressure foaming machine include HK-270 manufactured by Maruka Kakoki Co., Ltd.
There are many machines on the market. Further, foaming with a spray device is also possible. The rigid polyurethane foam obtained by the method of the present invention becomes a good foam when the mixing amount is 15% by weight or less. In addition, it suggests that it is suitable for spray foam because the use of such a decomposition liquid accelerates foam hardening.

[0014]

EXAMPLES The present invention will be described in detail with reference to examples. Raw material used Monoethanolamine; ME manufactured by Mitsui Toatsu Chemicals, Inc.
A. 2-propanolamine; 1-amino-3 manufactured by Tokyo Kasei Co., Ltd.
-Propanol (first-grade reagent) polyol A; the hydroxyl value obtained by adding propylene oxide to glycerin is
450 mg-KOH / g polyol. Silicone foam stabilizer: L-5340, a polydimethylsiloxane derivative manufactured by Nippon Unicar Co., Ltd. Catalyst A; Kao No. Kalyzer No-1 with N, N, N ', N'-
Tetramethylhexamethylenediamine. Freon 11; trichlorofluoromethane manufactured by DuPont Mitsui Fluorochemicals. Cosmonate M-200; polyisocyanate manufactured by Mitsui Toatsu Chemicals, Inc. and crude MDI. All NCO 31.0%. The results of Examples and Comparative Examples are summarized in Table 1.

[0015]

[Table 1]

Example 1 Preparation of Rigid Polyurethane Foam A rigid polyurethane foam for decomposition was obtained by foaming with the following raw material composition. <Polyol resin> Polyol A 100 Water 3.5 L-5340 1.5 Catalyst A 1.5 Freon 11 20 <Isocyanate> M-200 176 (NCO index = 1
10) After thoroughly mixing the resin raw materials, the mixture was mixed with isocyanate by high-speed stirring, and the mixture was poured into a wooden box and foam-cured to obtain foam A.

Example 2 Decomposition of Rigid Polyurethane Foam After 1000 g of monoethanolamine was placed in a 3-liter separable flask equipped with a condenser and heated to 150 ° C.,
A strip of 1000 g of Form A was continuously placed and decomposed for 3 hours. The decomposition product was brown. Decomposition products are BSA
After silylation with (N, O-bis (trimethylsilyl) acetamide) it was analyzed by gas chromatography (GC) and GC-mass analysis. As a result, the main products are amines corresponding to M-200, polyols A and B.
It was HEU and the by-product was found to be HEIM. The viscosity of the decomposition product is 1700 centipoise (25
C.), pH = 11.0, and the total active hydrogen value by the acetic anhydride-pyridine method was 927 mg-KOH / g (theoretical value was 924). This decomposition liquid is referred to as decomposition liquid-A.

Example 3 Decomposition of Rigid Polyurethane Foam 1000 g of monoethanolamine was placed in a 3 liter separable flask equipped with a condenser and heated to 150 ° C.,
A strip of 1400 g of Form A was continuously placed and decomposed for 5 hours. The decomposition products were analyzed in the same manner as in Example 1. The decomposition product is brown and has a viscosity of 7,000 centipoise (25
℃), the total active hydrogen number is 809 mg-KOH / g (theoretical value is 77
It was 3). This decomposition liquid is referred to as decomposition liquid-B.

Example 4 Decomposition of Rigid Polyurethane Foam 1000 g of monoethanolamine was placed in a 3-liter separable flask equipped with a condenser and heated to 150 ° C.,
A strip of 2000 g of Form A was continuously placed and decomposed for 10.7 hours. The decomposition product was blackish brown. As a result of analysis in the same manner as in Example 1, the viscosity of the decomposition product was 20000.
Centipoise (25 ° C.), pH = 10.6, total active hydrogen number was 645 mg-KOH / g (theoretical value was 615). This decomposition liquid is referred to as decomposition liquid-C.

Example 5 Decomposition of Rigid Polyurethane Foam 1000 g of isopropanolamine was placed in a 3-liter separable flask equipped with a condenser and heated to 150 ° C., and 1130 g of foam A was continuously put therein to decompose for 5 hours. The decomposition product was blackish brown. As a result of analysis in the same manner as in Example 1, the decomposition product had a viscosity of 7,000 centipoise (25 ° C.), pH = 10.4, and a total active hydrogen value of 800 mg-KOH / g. This decomposition liquid is referred to as decomposition liquid-D.

Examples 6 to 13 and Comparative Example 1 1 polyol resin raw material was used in the composition ratio shown in Table 1.
After mixing in a polypropylene cup of liter so as not to entrap air, add Isocyanate M-200 so that the index becomes 105, and mix with high speed rotation stirrer at high speed for about 5 seconds at 5000 ~ 7000 rpm.
This mixture was quickly placed in a wooden box (200 x 200 x 200 mm) to foam polyurethane. The cream time (CT), gel time (GT) and tack free time (TFT) in the foam-hardening process were measured. The cells were foamed and cured, and the cells were cut one day after the mold was removed, and the cell state, internal crack state and flyability of the foam were measured. As a result, as shown in Table 1, good foams could be obtained when up to 15 parts of each decomposition solution was added. If it exceeds 15 parts, the reaction becomes faster, resulting in cell roughening, internal cracks and poor flyability. Comparative Example 1
It can be seen that foam hardening is faster in all of the examples.

[0022]

When the decomposition product of the rigid polyurethane foam waste obtained by the method of the present invention is mixed with a polyol and used as a raw material for the rigid polyurethane foam, a good foam is obtained.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Keiko Ishikawa 1190 Kasama-cho, Sakae-ku, Yokohama-shi, Kanagawa Mitsui Toatsu Chemical Co., Ltd.

Claims (1)

[Claims] 1. The following components (a) to (e), (a) a polyisocyanate compound component (a) having at least two isocyanate groups, and (b) active hydrogen having at least two active hydrogen-containing groups. A component-containing component (b), (c) a catalyst,
(f) When a rigid polyurethane foam was produced using a foam stabilizer and (e) a foaming agent, (f) the rigid polyurethane foam was obtained by decomposing it in a monoalkanolamine having 2 to 3 carbon atoms. Decomposition solution component (f),
For (b), component (f) / (component (b) + component (f)) ≤ 1
A method for producing a rigid polyurethane foam, which is used in an amount of 5% by weight.