JPH06192371A - Rigid polyurethane foam and its production - Google Patents

Abstract

PURPOSE:To obtain the subject foam, having a fine cell structure, improved in thermal conductivity and useful as building materials, etc., by mixing a polyisocyanate compound with a specific polyol component, a prescribed amount of an active hydrogen compound, a catalyst, a foam stabilizer, a foaming agent, etc., then expanding and curing the resultant mixture. CONSTITUTION:The objective foam is obtained by mixing (i) a component containing a polyisocyanate compound having >=2 isocyanate groups such as 4,4'-diphenylmethane diisocyanate with (ii) a urea group-containing polyol of the formula [A and B are 2-3C alkylene; (m) and (n) are 0-2; (m+n) is 2-4] and/or a urea group-containing polyoxyalkylene polyol component, prepared by adding a 2-4C alkylene oxide to the urea group-containing polyol as an initiator and having 50-500 hydroxyl equiv., (iii) an active hydrogen compound having >=2 active hydrogen atoms at a weight ratio satisfying the formula 0<= components (iii)/[(ii) + (iii)]<1.0, (iv) a catalyst, (v) a foam stabilizer, (vi) a foaming agent, etc., and then expanding and curing resultant mixture.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rigid polyurethane foam which can be used as a building material, a structural material, a heat insulating material or other uses. More specifically, the present invention relates to a rigid polyurethane foam in which the cells of the foam are miniaturized and the thermal conductivity is improved.

[0002]

2. Description of the Related Art Generally, a rigid polyurethane foam is composed of a polyisocyanate compound having at least two isocyanate groups as a main raw material, an active hydrogen compound having at least two active hydrogen-containing groups, and an auxiliary raw material. It is produced by mixing a foaming agent, a catalyst, a foam stabilizer and other additives and foaming and curing, and is used in various industrial fields such as building materials, lightweight structural materials, and heat insulating materials for keeping cold. Rigid polyurethane foam is a cross-linkable polymer formed by reacting a polyisocyanate with an active hydrogen compound such as a polyol in the presence of a foaming agent, and the foam is formed by innumerable cells. The polymer skeleton is composed of a urethane structure and a crosslinked structure formed by a reaction between a polyfunctional polyol having a relatively small molecular weight and a polyfunctional polyisocyanate compound. In many cases, since water is used as a part of the blowing agent, a large amount of urea bond generated by the reaction of water with an isocyanate is also contained. Further, in addition to the urethane-forming catalyst, an isocyanurate-forming catalyst may be used in some cases, and at this time, a large amount of isocyanurate bond is also contained.

[0003]

In rigid polyurethane foams, the size and shape of the cells are factors that have a great influence on the physical properties of the foams. Especially in applications such as heat insulating materials, in order to keep the thermal conductivity low, the cells must be Finer is more preferable. The cells can be made finer to some extent by using a silicone foam stabilizer having a strong foam-regulating ability, but this alone has a limit and it is necessary to improve the polyol itself which is a basic raw material. However, conventional polyols obtained by addition-polymerizing propylene oxide or ethylene oxide to an initiator aliphatic polyol, aliphatic amine, aromatic amine or phenol compound are fine cells and have good (low) thermal conductivity. Was insufficient to obtain. Therefore, in order to miniaturize the cells of the rigid foam and reduce the thermal conductivity, it was necessary to invent a new polyol that replaces the conventional polyol.

[0004]

As a result of intensive studies, the present inventors have found that a polyol having a urea bond in the skeleton of the polyol has an effect of making cells finer and lowering thermal conductivity. The invention was completed.

That is, the present invention provides (a) a component containing a polyisocyanate compound having at least two isocyanate groups, (b) a urea group-containing polyol represented by the following structural formula (1), and / or A urea group-containing polyoxyalkylene polyol having a hydroxyl equivalent of 50 to 500, which is obtained by adding a C _{2 to} C ₄ alkylene oxide to the urea group-containing polyol as an initiator,

[0006]

[Chemical 3] (However, in the formula (1), A and B represent a C _{2 to} C ₃ alkylene group, m and n independently represent 0, 1 or 2, and m + n = 2, 3 or 4.) (c ) Component (c) containing an active hydrogen compound having at least two active hydrogens in a weight ratio satisfying the following formula (2), 0 ≦ component (c) / (component (b) + component (c)) <1.0 (2) A composition containing (d) a catalyst, (e) a foam stabilizer, (f) a foaming agent, and (g) other raw materials, if necessary, is mixed and then foamed and cured. Rigid polyurethane foam.

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-toluene diisocyanate (hereinafter referred to as 2,4-TDI), 2,6 -Toluene diisocyanate (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.

Specific examples of the urea group-containing polyol used as the component (b) in the present invention include N, N'-bis (3-hydroxypropyl) urea and N, N, N'-tris (3 -
Hydroxypropyl) urea, N, N, N ', N'-tetrakis (3-hydroxyisopropyl) urea, more preferably
N, N'-bis (2-hydroxyethyl) urea, N, N, N'-tris (2-hydroxyethyl) urea, N, N, N ', N'-tetrakis (2-hydroxyethyl) urea, N , N'-bis (2-hydroxyisopropyl) urea, N, N, N'-tris (2-hydroxyisopropyl) urea, N, N, N ', N'-tetrakis (2-hydroxyisopropyl) urea, etc. As the urea-containing polyoxyalkylene polyol, there is a polyol having a hydroxyl group equivalent of 50 to 500 obtained by adding an alkylene oxide such as ethylene oxide, propylene oxide or butylene oxide to the above compound. If the hydroxyl group equivalent exceeds 500, the solubility with the polyol used in combination will become poor and the physical properties (particularly strength) of the foam will deteriorate when it is applied to a rigid foam, which is not preferable.

The component (c) used in the present invention, a component containing an active hydrogen compound having at least two active hydrogen-containing groups means an OH group, a primary amino group, a secondary amino group and an SH group. Is a component containing a compound having at least two active 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 (d) used in the method of the present invention
， As the catalyst, those usually used in rigid polyurethane foams are used. Specifically, triethylenediamine, tetramethylpropanediamine,
Tertiary amines such as tetramethylhexanediamine, pentamethyldiethylenetriamine, bis (N, N-dimethylaminoethyl) ether, dibutyltin dilaurate,
Examples thereof include metal catalysts such as stannous octoate, and isocyanate trimerization catalysts (isocyanurate forming catalysts) such as potassium octylate, potassium acetate, tetraalkylammonium chloride, tetraalkylammonium bromide, and tetraalkylammonium iodide.

Component (e) used in the method of the present invention
As the foam stabilizer, a commonly used silicone derivative for rigid polyurethane foam (which is an alkylene oxide-modified polydimethylsiloxane and has 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.

Component (f) used in the method of the present invention
The foaming agent is a conventionally known foaming agent. Specific examples include trichlorofluoromethane, chlorodifluoromethane, dichlorotrifluoroethane, dichlorofluoroethane, trichlorotrifluoroethane, chlorodifluoroethane, methylene chloride, water, and carbon dioxide gas. Other than these, any one having a foaming effect can be used.

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. The rigid polyurethane foam obtained by the method of the present invention has fine cells and has good thermal conductivity.

[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. n-Propanolamine; Tokyo Kasei Co. 1-amino-3-
Propanol (first-grade reagent) diethanolamine; DEA manufactured by Mitsui Toatsu Chemicals, Inc. Dimethyl palmitylamine; Farmin manufactured by Kao Corporation
DM-60. Dimethyl stearylamine; Farmin manufactured by Kao Corporation
DM-80. Dimethyllaurylamine; Farmin DM manufactured by Kao Corporation
-20. Diphenylurea; N, N'-diphenylurea (reagent first grade) manufactured by Tokyo Kasei Co., Ltd. Urea: Urea manufactured by Mitsui Toatsu Chemicals, Inc. Polyol A: A polyol having a hydroxyl value of 554 mg-KOH / g obtained by adding propylene oxide to glycerin. Polyol B: A polyol having a hydroxyl value of 300 mg-KOH / g, which is obtained by adding propylene oxide to glycerin. Silicone foam stabilizer: L-5420, 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 1 366 g (6.0 mol) of monoethanolamine and 424 g (6.0 mol) of diphenylurea were placed in a 1-liter flask and the temperature was raised to 150 ° C. with stirring and the reaction was continued for 2 hours. After adding excess BSA (N, O-bis (trimethylsilyl) acetamide) to a part of the product and heating at 120 ° C for 2 hours for silylation, the composition of the product was analyzed by heating gas chromatography. Ethanolamine was completely reacted to react with aniline and BHEU (N, N'-bis (2-
It was confirmed that hydroxyethyl) urea) was produced. The product was distilled under reduced pressure at 70 to 60 ° C. and 20 to 5 mmHg for a long time to separate it into aniline and BHEU. BHEU
As a result of further analyzing the minutes by temperature-rising gas chromatography, the purity was 85%. Hydroxyl value by phthalic anhydride-pyridine method is 770mg-KOH / g (BHEU theoretical value is 758
)Met.

Example 2 450 g (6.0 mol) of isopropanolamine and 424 g (6.0 mol) of diphenylurea were placed in a 1-liter flask and the temperature was raised to 150 ° C. with stirring and the reaction was continued for 2 hours. After a portion of the product was silylated by the same method as in Example-1, the composition was analyzed by temperature-programmed gas chromatography. As a result, diphenylurea and isopropanolamine were completely reacted and aniline and BHPU (N, N'- It was confirmed that bis (2-hydroxypropyl) urea) was produced. The product was distilled under reduced pressure at 70 to 60 ° C. and 20 to 3 mmHg for a long time to separate into aniline and BHPU. The BHPU content was further analyzed by temperature rising gas chromatography, and as a result, the purity was 88.
%Met. The hydroxyl value was 650 mg-KOH / g (theoretical value for BHPU was 637).

Example 3 120 g (2.0 mol) of urea and 420 g (4.0 mol) of diethanolamine were placed in a 1-liter flask and stirred at 150 ° C.
The temperature was raised to 60 ° C. and the reaction was carried out for 60 hours until the generation of ammonia gas stopped. After a part of the product was silylated by the same method as in Example 1, the composition of the product was analyzed by temperature rising gas chromatography. As a result, urea and diethanolamine were completely reacted and TH
It was confirmed that EU (N, N, N ', N'-tetrakis (2-hydroxyethyl) urea) (purity 90%) and a small amount of N-hydroxyethylimidazolidone were produced. The hydroxyl value is
It was 940 mg-KOH / g (theoretical value of THEU is 951).

Example 4 200 g of BHEU obtained in Example 1 and 2.0 g of dimethylpalmitylamine as a catalyst were placed in a 2-liter autoclave and propylene oxide (hereinafter abbreviated as PO) was added at 100 to 110 ° C. with stirring. The reaction was carried out to synthesize polyol-1. After the removal of PO, the reaction amount of PO was 513 g according to the weight measurement of the product. As a result of analyzing the reaction product, the hydroxyl value was 312 mg-KOH / g and the viscosity was 865 centipoise.

Comparative Example 1 100 g of BHEU obtained in Example 1 was placed in a 2-liter autoclave and charged with PO at 100-110 ° C. with stirring until the partial pressure of PO did not decrease (until PO stopped reacting). The reaction was carried out to synthesize a polyol. After the removal of PO, the weight of the product was measured and the reaction amount of PO was only 124 g.
Met. As a result of analyzing the reaction product, the hydroxyl value was 46.
It was 0 mg-KOH / g. Comparing Example 4 with Comparative Example 1, it is found that dimethylpalmitylamine is effective as a reaction catalyst for PO.

Example 5 200 g of BHPU obtained in Example 2 and 2.0 g of dimethylstearylamine as a catalyst were placed in a 2-liter autoclave and PO was charged at 100 to 110 ° C. with stirring to carry out an addition reaction to synthesize polyol-2. did. After the removal of PO, the reaction amount of PO was 500 g according to the weight measurement of the product. As a result of analyzing the reaction product, the hydroxyl value was 278 mg-KOH / g.

Comparative Example 2 100 g of BHPU obtained in Example 2 was placed in a 2-liter autoclave and PO was charged at 100 to 110 ° C. with stirring to carry out an addition reaction until the PO partial pressure did not decrease to synthesize a polyol. After removing PO, P
The reaction amount of O was only 103 g. As a result of analyzing the reaction product, the hydroxyl value was 487 mg-KOH / g. Example 4
Comparison between Comparative Example 1 and Comparative Example 1 reveals that dimethylstearylamine is effective as a reaction catalyst for PO.

Example 6 200 g of THEU obtained in Example 3 and 2.0 g of dimethyllaurylamine as a catalyst were placed in a 2-liter autoclave and PO was charged at 100 to 110 ° C. with stirring to carry out an addition reaction to synthesize polyol-3. did. After the removal of PO, the reaction amount of PO was 231 g as determined by weighing the product. As a result of analyzing the reaction product, the hydroxyl value was 450 mg-KOH / g.

Comparative Example 3 100 g of THEU obtained in Example 3 was placed in a 2-liter autoclave and PO was charged at 100 to 110 ° C. with stirring to carry out an addition reaction until the PO partial pressure did not decrease to synthesize a polyol. After removing PO, P
The reaction amount of O was only 30 g. As a result of analyzing the reaction product, the hydroxyl value was 724 mg-KOH / g. Example 4
Comparing Comparative Example 1 with Comparative Example 1, dimethyllaurylamine was
It can be seen that it is effective as a reaction catalyst of O.

Examples 7 to 12 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 is a vertical aluminum panel (400 x 400 x 25mm)
It was quickly put into the inside of the container to foam polyurethane. After foaming and curing, one day after demolding, cutting was performed and the density, the cell state of the foam and the thermal conductivity were measured. The thermal conductivity used the Anacon model 88 measuring machine.

Comparative Examples 4 to 5 The same foaming test as in Example 7 was conducted using the commonly used polyols A and B shown in Table 1. First
As is clear from the table, the cell and thermal conductivity were poor.

[0027]

By using the urea group-containing polyol of the present invention, it is possible to obtain a polyurethane foam having a good cell and thermal conductivity.

Front page continued (72) Inventor Keiko Ishikawa 1190 Kasama-cho, Sakae-ku, Yokohama-shi, Kanagawa Mitsui Toatsu Chemical Co., Ltd.

Claims (7)

[Claims] 1. A component (b) which comprises (a) a polyisocyanate compound having at least two isocyanate groups,
(b) Urea group-containing polyol represented by the following structural formula (1) (Chemical Formula 1) and / or hydroxyl group equivalent obtained by adding C _{2 to} C ₄ alkylene oxide to the urea group-containing polyol as an initiator A polyoxyalkylene polyol component (b) having a urea group of 50 to 500, embedded image (However, in the formula (1), A and B represent a C _{2 to} C ₃ alkylene group, m and n independently represent 0, 1 or 2, and m + n = 2, 3 or 4.) (c ) Component (c) containing an active hydrogen compound having at least two active hydrogens in a weight ratio satisfying the following formula (2), 0 ≦ component (c) / (component (b) + component (c)) <1.0 (2) A composition containing (d) a catalyst, (e) a foam stabilizer, (f) a foaming agent, and (g) other raw materials, if necessary, is mixed and foamed and cured. The resulting rigid polyurethane foam. 2. (a) A component (a) containing a polyisocyanate compound having at least two isocyanate groups,
(b) Urea group-containing polyol represented by the following structural formula (1) (Chemical Formula 2) and / or hydroxyl group equivalent obtained by adding C _{2 to} C ₄ alkylene oxide to the urea group-containing polyol as an initiator A urea group-containing polyoxyalkylene polyol component (b) of 50 to 500, embedded image (However, in the formula (1), A and B represent a C _{2 to} C ₃ alkylene group, m and n independently represent 0, 1 or 2, and m + n = 2, 3 or 4.) (c ) Component (c) containing an active hydrogen compound having at least two active hydrogens in a weight ratio satisfying the following formula (2), 0 ≦ component (c) / (component (b) + component (c)) <1.0 (2) A composition containing (d) a catalyst, (e) a foam stabilizer, (f) a foaming agent, and (g) other raw materials, if necessary, is mixed and foamed and cured. Method for producing rigid polyurethane foam. 3. The hydroxyl group equivalent obtained by adding a C ₂ -C ₄ alkylene oxide to the urea group-containing polyol of the component (b) of claim 1 as an initiator,
When a urea group-containing polyoxyalkylene polyol of 500 is produced, a urea group-containing polyoxyalkylene polyol is prepared by using a tertiary amine having a structure of the following formula (3) as a catalyst for adding alkylene oxide. Method of manufacturing. (However, in the formula (3), R represents an alkyl group or an alkenyl group having 10 to 18 carbon atoms.) 4. The urea group-containing polyol of component (b) comprises
N, N'-bis (2-hydroxyethyl) urea, N, N, N'-tris (2-hydroxyethyl) urea, N, N, N ', N'-tetrakis (2-hydroxyethyl) urea, N , N'-bis (2-hydroxypropyl) urea, N, N, N'-tris (2-hydroxypropyl) urea or N, N, N ', N'-tetrakis (2-
A method according to claim 1, characterized in that it is hydroxypropyl) urea. 5. The urea group-containing polyoxyalkylene polyol of component (b) is N, N'-bis (2-hydroxyethyl) urea, N, N, N'-tris (2-hydroxyethyl) urea, N , N, N ', N'-Tetrakis (2-hydroxyethyl) urea, N, N'-bis (2-hydroxypropyl) urea, N,
N, N'-tris (2-hydroxypropyl) urea or N,
Urea group-containing polyoxyalkylene polyol obtained by adding N, N ', N'-tetrakis (2-hydroxypropyl) urea as an initiator and adding an alkylene oxide selected from ethylene oxide, propylene oxide and butylene oxide The method of claim 1, wherein the method is: 6. The urea group-containing polyol of component (b) comprises
N, N'-bis (2-hydroxyethyl) urea, N, N, N'-tris (2-hydroxyethyl) urea, N, N, N ', N'-tetrakis (2-hydroxyethyl) urea, N , N'-bis (2-hydroxypropyl) urea, N, N, N'-tris (2-hydroxypropyl) urea or N, N, N ', N'-tetrakis (2-
3. The method according to claim 2, which is hydroxypropyl) urea. 7. The urea group-containing polypolyol of component (b) is N, N′-bis (2-hydroxyethyl) urea, N, N,
N'-tris (2-hydroxyethyl) urea, N, N, N ', N'-
Tetrakis (2-hydroxyethyl) urea, N, N'-bis (2-hydroxypropyl) urea, N, N, N'-tris (2-
Urea obtained by using (hydroxypropyl) urea or N, N, N ', N'-tetrakis (2-hydroxypropyl) urea as an initiator and adding an alkylene oxide selected from ethylene oxide, propylene oxide and butylene oxide to the initiator. The method according to claim 2, which is a group-containing polyoxyalkylene polyol.