JPH06192372A - 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 and/or a urea group-containing polyoxyalkylene polyol, prepared by adding a 2-4C alkylene oxide to the urea group-containing polyol such as ethyleneurea as an initiator and having 87-500 hydroxyl equiv., (C) a component containing an active hydrogen compound having >=2 active hydrogens at a weight ratio satisfying the formula 0<= components (C)/[(B) + (C)]<0.8, (D) a catalyst, (E) a foam stabilizer, (F) a foaming agent and (G) a composition containing other raw materials and then expanding and curing the 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 comprises a polyisocyanate compound having at least two isocyanate groups as a main raw material, and at least two.
Produced by mixing active hydrogen compounds having individual active hydrogen-containing groups with auxiliary raw materials such as foaming agents, catalysts, foam stabilizers and other additives, and foaming and curing, building materials, lightweight structural materials, heat insulation for heat insulation It is used in various industrial fields such as wood. 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.

That is, the present invention provides (a) a component (a) 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 the hydroxyl group equivalent obtained by adding a C _{2 to} C ₄ alkylene oxide to the urea group-containing polyol as an initiator is 87 to 50.
0 urea group-containing polyoxyalkylene polyol (b),

[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)) < 0.8 (2) Rigid polyurethane foam obtained by mixing a composition containing (2) (d) catalyst, (e) foam stabilizer, (f) foaming agent, and (g) other raw material and then foam-curing the mixture. Regarding

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.

The urea group-containing polyoxyalkylene polyol used as the component (b) in the present invention is, specifically, ethylene urea (imidazolidone) to which an alkylene oxide such as ethylene oxide, propylene oxide or butylene oxide is added. There is a polyol having a hydroxyl equivalent of 87 to 500 obtained as a result. 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.

Component (c) used in the present invention means a component containing an active hydrogen compound having at least two active hydrogen-containing groups means an active group 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 (d) 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 (e) 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.

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 physical properties that the cells are fine and the thermal conductivity is good.

[0014]

EXAMPLES The present invention will be described in detail with reference to examples. Raw material used: ethylene urea; a reagent manufactured by Tokyo Kasei Co., Ltd. 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. 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 1 258 g of ethylene urea and 3.0 g of dimethylpalmitylamine as a catalyst were placed in a 2-liter autoclave with stirring.
Propylene oxide (hereinafter abbreviated as PO) was charged at 100 to 110 ° C. to carry out an addition reaction to synthesize polyol-1. After the removal of PO, the reaction amount of PO was 894 g according to the weight measurement of the product. As a result of analyzing the reaction product, the hydroxyl value was 309 mg-KOH / g, and the viscosity was 1440 centipoise.

Example 2 258 g of ethylene urea was placed in a 2 liter autoclave and charged with PO at 100 to 110 ° C. with stirring to carry out an addition reaction until the PO partial pressure does not decrease (until PO does not react) and polyol- 2 was synthesized. After the removal of PO, the reaction weight of PO was only 405 g by weighing the product.
As a result of analyzing the reaction product, the hydroxyl value was 507 mg-KOH / g.
Met. Comparing Example 1 and Example-2, it can be seen that dimethylpalmitylamine is effective as a reaction catalyst for PO.

Example 3 PO was reacted under the same conditions as in Example 1 except that dimethylstearylamine was used instead of dimethylpalmitylamine in Example 1. As a result of analyzing the reaction product, the hydroxyl value was 311 mg-KOH / g, and the viscosity was 1445 centipoise. Comparing Example-3 and Example-2, it is found that dimethylpalmitylamine is effective as a reaction catalyst for PO.

Example 4 PO was reacted under the same conditions as in Example 1 except that dimethyllaurylamine was used in place of dimethylpalmitylamine in Example 1. As a result of analyzing the reaction product,
The hydroxyl value was 313 mg-KOH / g, and the viscosity was 1450 centipoise. Comparing Example 4 and Example 2, it can be seen that dimethyllaurylamine is effective as a reaction catalyst for PO.

Examples 5 to 8 Polyol resin raw materials were mixed at 1 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 1 and 2 The same foaming test as in Example 7 was carried out 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.

[0022]

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 (3)

[Claims] 1. A component (a) comprising a (a) polyisocyanate compound having at least two isocyanate groups,
(b) Urea group-containing polyoxyalkylene polyol component having a hydroxyl equivalent of 87 to 500, which is obtained by adding ethylene urea of the following structural formula (1) (1) as an initiator and adding a C _{2 to} C ₄ alkylene oxide thereto. (B), (c) A 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 )) <0.8 (2) Obtained by mixing a composition containing a catalyst, (e) a foam stabilizer, (f) a foaming agent, and (g) other raw materials, followed by foaming and curing. Rigid polyurethane foam. 2. A component containing (a) a polyisocyanate compound having at least two isocyanate groups, (b) an ethyleneurea represented by the following structural formula (1) (Chemical Formula 2) as an initiator, and C ₂ -C A urea group-containing polyoxyalkylene polyol having a hydroxyl equivalent of 87 to 500 obtained by adding an alkylene oxide of ₄ ; (c) A 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 )) <0.8 (2) (d) Catalyst, (e) Foam stabilizer, (f) Foaming agent, and (g) A composition containing a raw material is mixed and then foamed and cured to obtain a hard polyurethane. Method of manufacturing foam. 3. A urea group having a hydroxyl equivalent of 87 to 500, which is obtained by using the urea group-containing polyoxyalkylene polyol of the component (b) in claim 1 as an initiator and adding a C _{2 to} C ₄ alkylene oxide thereto. A method for producing a urea group-containing polyoxyalkylene polyol by using a tertiary amine having a structure of the following formula (3) as a catalyst for adding an alkylene oxide when producing the contained polyoxyalkylene polyol. (However, in the formula (3), R represents an alkyl group or an alkenyl group having 10 to 18 carbon atoms.)