JPH107760A - Method for producing rigid polyurethane foam - Google Patents

Abstract

(57) Abstract: An isocyanurate comprising a diisocyanate derivative in which at least a part of an organic polyisocyanate constituting a modified isocyanurate is based on 100 parts by weight of an organic polyisocyanate. By using an isocyanate composition to which 1 to 50 parts by weight of the modified product is added, a rigid polyurethane foam having good dimensional stability and low smoke emission can be obtained. [Effect] Complete water foaming formulation, HCFC-14 alternative foaming agent
By using the formulation using 1b or the like, a rigid polyurethane foam having low smoke emission and excellent dimensional stability can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing a rigid polyurethane foam. More specifically, the production of rigid polyurethane foams having good strength and dimensional stability after reducing or replacing specific fluorocarbons, ie, chlorofluorocarbons, as a foaming agent, and having low flammability or smoke emission. It is about the method.

[0002]

2. Description of the Related Art Rigid polyurethane foam is widely used as a heat insulating material for refrigerators, freezer warehouses, building materials and the like and for spraying applications because of its excellent heat insulating performance, dimensional stability and workability. When producing a rigid polyurethane foam, polymethylene polyphenylene polyisocyanate (hereinafter referred to as polymeric MDI) and polymeric M are used as organic polyisocyanates.
A modified product of DI was used, and 1,1,1-trichlorofluoromethane (hereinafter referred to as CFC-11) was used as a blowing agent.

In recent years, chlorofluorocarbons have been regulated to protect the earth's ozone layer. This regulation includes CFC-11 used as a foaming agent for rigid polyurethane foam. In general thermal insulation, CFC-11 is 7-14% by weight in the foam.
And a foaming technique for reducing the content of CFC-11 (hereinafter referred to as a reduced formulation of CFC-11) or a foaming technique using only water as a foaming agent (hereinafter referred to as a complete water foaming formulation). ), Or 1,1 dichloro-1-fluoroethane (hereinafter referred to as HCFC-141b), 2,2 dichloro-1,1,1-trifluoroethane (hereinafter HCFC-l), which is considered to be a foaming agent replacing CFC-11.
Development of a foaming technique (hereinafter, referred to as an alternative CFC formulation) using a carbon dioxide (hereinafter referred to as 123) is an important issue for protection of the ozone layer on the earth.

[0004] However, in the case of the reduced formulation of CFC-11 and the completely water-foamed formulation, the strength and dimensional stability, especially the dimensional stability at high temperature and wet heat, are deteriorated as compared with the conventional rigid polyurethane foam, and the liquid flow of urethane stock solution , Resulting in a need to increase product density. Further, since CFC-11 conventionally used is a non-flammable gas, the flame retardancy and smoke generating properties of a rigid polyurethane foam using this as a foaming agent were generally good. But CF
In the case of the C-11 reduction prescription and the complete water foaming prescription, the flame retardancy tends to deteriorate because the amount of the nonflammable gas CFC-11 used decreases.

[0005] In the case of an alternative CFC formulation, the dimensional stability, particularly the dimensional stability at low temperature, tends to deteriorate, and the demolding performance tends to deteriorate. In the case of alternative chlorofluorocarbon formulation, HCFC-14
1b, 1-chloro-1,1-difluoroethane (hereinafter H
CFC-142b), 1,1-difluoroethane (hereinafter referred to as HFC-152a) and the like are combustible gases.

[0006] Rigid foams using these flammable gases as a substitute for chlorofluorocarbon have the property of being more easily burned than rigid polyurethane foams using CFC-11. Therefore, the amount of smoke generated during combustion also increased, and a rigid polyurethane foam satisfying all of them could not be obtained.

[0007]

SUMMARY OF THE INVENTION A method for producing a rigid polyurethane foam having good dimensional stability, excellent flame retardancy, and low smoke emission in a reduced formulation of CFC-11, a complete water formulation, and an alternative fluorocarbon formulation has been developed. Doing so was an important issue in reducing the use of chlorofluorocarbons.

[0008]

Means for Solving the Problems As a result of extensive studies to achieve the above object, the present inventors have used an isocyanate composition to which an isocyanurate-modified isocyanate derivative is added as an isocyanate composition. If so, it is possible to produce a rigid polyurethane foam having good dimensional stability and excellent flame retardancy and low smoke generation even in a reduced formulation of CFC-11, a complete water formulation, and an alternative fluorocarbon formulation. The knowledge was obtained, and the present invention was completed.

That is, the present invention relates to (1) 100 parts by weight of an organic polyisocyanate, wherein at least a part of the organic polyisocyanate constituting the modified isocyanurate is a diisocyanate represented by the following general formula (1): A method for producing a rigid polyurethane foam, characterized by using an isocyanate composition obtained by adding 1 to 50 parts by weight of a modified isocyanurate comprising a derivative [Chemical Formula 2];

[0010]

Embedded image (In the formula, R is a monovalent group selected from a halogen atom, a hydrogen atom, and a hydrocarbon group having 20 or less carbon atoms.) (2) In the general formula (1), R represents a hydrogen atom, a methyl group, or an ethyl group. (1) The method for producing a rigid polyurethane foam according to (1), which is a mixture of one or more of the bases.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The method of the present invention will be described below in detail. In the isocyanate composition of the present invention, at least one part of the organic polyisocyanate constituting the isocyanurate-modified product is a diisocyanate derivative represented by the following general formula (1) based on 100 parts by weight of the organic polyisocyanate. Isocyanate composition containing 1 to 50 parts by weight, preferably 5 to 30 parts by weight of the modified isocyanurate. The diisocyanate derivative [formula 3] used in the present invention has a structure represented by the following general formula (1).

[0012]

Embedded image In the formula, R is a monovalent group selected from a halogen atom, a hydrogen atom, and a hydrocarbon group having 20 or less carbon atoms. Here, the halogen atom is, for example, Cl or Br. Examples of the hydrocarbon group having 20 or less carbon atoms include a methyl group, an ethyl group, and a methoxy group.

When a modified isocyanurate is produced by a known method using only a difunctional or higher functional monomer,
The once formed trifunctional isocyanurate-modified product was further reacted as an isocyanurate-modified monomer to form a kind of gel. When these modified isocyanurates were added to organic polyisocyanate, the viscosity was significantly increased, and it was difficult to obtain a practical isocyanate composition. The present inventors have analyzed the isocyanurate modification reaction of the diisocyanate derivative in detail, and as a result, the isocyanurate reaction first produces a trimer, the concentration of which is relatively high, and the concentration of the diisocyanate derivative of the raw material. It was found that if the content did not decrease, no further reaction proceeded and no gel was formed. It has also been found that trifunctional isocyanurate compounds are difficult to dissolve in aliphatic or alicyclic hydrocarbon solvents such as pentane, hexane and cyclohexane. By utilizing these properties, the formation of a gelled substance is suppressed even when modified with a diisocyanate derivative, and the increase in viscosity can be suppressed even when the modified isocyanurate obtained is added to an organic polyisocyanate. It was found that a practical isocyanate composition was obtained.

Conventionally, there has been proposed a method of using a phenyl isocyanate derivative as an isocyanate composition for a rigid polyurethane foam containing a modified isocyanurate (JP-A-7-179562), but the isocyanate obtained by these methods has been proposed. The nullate-modified product has three or less functional groups. For example, a monofunctional isocyanurate-modified product is partially produced. In this case, the reaction may be stopped in the course of polymer production.

However, when a trimer consisting of diisocyanate alone is added to the organic polyisocyanate, physical properties, particularly strength and dimensional stability, are improved, and a rigid polyurethane foam having improved flammability and smoke-generating properties is obtained. be able to. When R represented by the general formula (1) is a methyl group or an ethyl group, the compatibility and stability of the modified isocyanurate in the organic polyisocyanate are lower than when the hydrogen is a hydrogen atom. Thus, the content of the modified isocyanurate can be increased.

As the organic polyisocyanate raw material used in the present invention, all known organic polyisocyanate materials can be used, but the most common one is toluene diisocyanate (hereinafter referred to as TDI).
) And / or diphenylmethane diisocyanate (hereinafter abbreviated as MDI). TDI is a mixture of isomers, that is, 100% 2,4-isomer, 2,4-isomer / 2,6-isomer.
Body = 80/20 and / or 65/35 (each by weight), TDI-Mitsui Toatsu Chemical Co., Ltd.
So-called crude TDI containing a multifunctional tar known as TRC can also be used. As MDI, a polymeric MDI represented by Cosmonate series manufactured by Mitsui Toatsu Chemicals Co., Ltd., which contains a polynuclear substance having three or more nuclei in addition to a pure product having a 4,4′-isomer as a main component. Is preferably used.

Further, a prepolymer having an isocyanate group at the molecular terminal obtained from these organic polyisocyanate and a polyol described later can also be used. The ratio of active hydrogen in the isocyanate composition and the resin solution described below is NCO /
H (active hydrogen) = 0.7 to 5.0 (equivalent ratio) is particularly preferred. As the polyol used in the present invention, any known polyol can be used, and a polyol having a hydroxyl value of 450 mgKOH / g obtained by adding propylene oxide to a sucrose / glycerin / tolylenediamine mixture is particularly preferable.

In addition, for example, ethylene glycol,
Polyethylene alcohol such as diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, trimethylolpropane, pentaerythritol, sorbitol, sucrose, aromatic amines such as tolylenediamine, ethylenediamine, triethanolamine, etc. And polyether polyols having a hydroxyl value of 350 to 800 mg KOH / g obtained by addition polymerization of an alkylene oxide to a single or mixed aliphatic amine. As the polyester polyol, any known polyester polyol can be used, and examples thereof include polyester diols and polyester triols formed by a condensation reaction of the above polyhydric alcohol with a low molecular weight carboxylic acid such as adipic acid and phthalic acid. These polyether polyols and polyester polyols may be used in combination.

Examples of the catalyst include known urethanization catalysts such as trimethylaminoethylpiperazine, triethylamine, tripropylamine, N-methylmorpholine, N-ethylmorpholine, triethylenediamine and tetramethylhexamethylenediamine. All catalysts can be used.

Examples of the trimerization catalyst include quaternary ammonium hydroxides; hydroxides, alkoxides and carboxylate salts of alkaline earth metals such as potassium acetate, potassium octoate and 2-ethylhexane. A known catalyst such as potassium acid; a carboxylate of a non-basic metal such as lead octanoate can be used. These catalysts
They can be used alone or as a mixture, and the amount is 0.01 to 1 part by weight per 100 parts by weight of the compound having active hydrogen.
0.0 parts by weight is suitable.

As the foam stabilizer, a conventionally known organic silicon-based surfactant is used. For example, L-5420 and L-5421 manufactured by Nippon Unicar Co., Ltd., SH-193 manufactured by Dow Corning Toray Silicone Co., Ltd., and F-5 manufactured by Shin-Etsu Chemical Co., Ltd.
-327, F-345, F-305, etc. are suitable.
The amount of use of these foam stabilizers is 0.1 to 0.1 parts per 100 parts in total of the compound having active hydrogen and the organic polyisocyanate.
10 parts.

In addition, carbonates such as ethylene carbonate and propylene carbonate, carboxylate esters such as methyl formate and methyl acetate, flame retardants, stabilizers, plasticizers, coloring agents and the like may be used as required. It can also be added to a naat composition or a polyol composition.

In practicing the present invention, a predetermined amount of a polyol, a foaming agent, a catalyst and a foam stabilizer is mixed to form a resin solution. The resin solution and the organic polyisocyanate are mixed at a high speed at a fixed ratio, and injected into a cavity or a mold. At this time, the liquid ratio between the organic polyisocyanate and the resin liquid is adjusted such that the equivalent ratio (NCO: H) of the organic polyisocyanate to the active hydrogen of the resin liquid becomes 0.7: 1 to 5: 1. .

[0024]

The present invention will be described in more detail with reference to the following Examples and Comparative Examples, but it should not be construed that the invention is limited thereto. . In the examples and comparative examples, the raw materials used are described below. Isocyanate-A. : Cosmonate M-200 manufactured by Mitsui Toatsu Chemical Co., Ltd. Crude diphenylmethane diisocyanate NCO%: 31.3 Isocyanate-B. : Cosmonate T-100 2,4-toluene diisocyanate (manufactured by Mitsui Toatsu Chemicals, Inc.) NCO%: 48.3 Polyol-1: APP-240C Hydroxyl value: 240 mgKOH / g Foam stabilizer: Nippon Unicar Co., Ltd. -5420 Amine catalyst: Polycat-42 foaming agent (Freon) R-141b: 1,1-dichloro-1-fluoroethane manufactured by Air Products

<Modified Isocyanurate-A> 800 parts by weight of cyclohexane was added to 1000 parts by weight of isocyanato B in a nitrogen stream, dissolved at room temperature, and cooled to 10 ° C. 20 parts by weight of a 10% Polycat41 (amine catalyst; manufactured by Air Products) cyclohexane solution was added, and then the temperature was raised to 40 ° C. to carry out a reaction. 40-4
After reacting at 5 ° C. for 1 hour, the reaction was stopped by adding 2.5 g of 10% orthophosphoric acid in cyclohexane and cooled to 20 ° C.

The reaction mass is decanted, and the obtained viscous semi-crystalline substance is transferred to a beaker and dried at room temperature under reduced pressure.
798 parts by weight (79.8% yield) of isocyanurate-modified 2,4-toluene diisocyanate were obtained.
(NCO%; 24.3%)

<Isocyanate-C> Isocyanate-
A isocyanurate-modified product-A based on 100 parts by weight of A
10 parts by weight were added and dissolved by stirring at 80 ° C. for 2 hours under a nitrogen stream. After cooling, the mixture was discharged and used as isocyanate-C. NCO%: 30.6% (viscosity: 345 CPS / 25 ° C.) <Isocyanate-D> Isocyanurate-modified product-A under nitrogen flow with respect to 100 parts by weight of isocyanate-A,
20 parts by weight were added and dissolved by stirring at 80 ° C. for 2 hours under a nitrogen stream. After cooling, the mixture was discharged and used as isocyanate-D. NCO%: 29.9% (viscosity: 1300 CPS / 25 ° C.) <Isocyanate-E> Isocyanurate-modified product-A, based on 100 parts by weight of isocyanate-A, under a nitrogen stream.
30 parts by weight were added and dissolved by stirring at 80 ° C. for 2 hours under a nitrogen stream. After cooling, the mixture was discharged and used as isocyanate-E. NCO%: 29.2% (viscosity 6900 CPS / 25 ° C)

Example After a predetermined amount of a resin solution having the composition shown in Table 1 was mixed and maintained at a temperature of 25 ° C., a predetermined amount of an isocyanate composition was added thereto, followed by high-speed mixing for 5 seconds. Poured onto plate (23-25 ° C) and allowed to foam.
(Examples 1 to 6)

[Comparative Example] For comparison, Table 1 also shows foaming examples using isocyanates containing no modified isocyanurate. (Comparative Examples 1 and 2) 23 after foaming
Various physical property values of the foam left for 24 hours in a constant temperature room at 65 ° C. and a humidity of 65% were measured. As for the low-temperature dimensional stability, a dimensional change was measured after standing at −30 ° C. for 24 hours.

The smoke test was conducted according to JIS-A1321. As is clear from the present Examples and Comparative Examples, the use of the isocyanate composition containing the modified isocyanurate shown in the present invention significantly improved the compressive strength, dimensional stability and smoke emission of polyurethane foam. You.

[0031]

[Table 1]

[0032]

EFFECTS OF THE INVENTION A reduced formula of CFC-11, a completely water foaming formula, or an alternative fluorocarbon formula, for example, HCFC-141b
The rigid polyurethane foam obtained from the formulation using the same or the like is significantly inferior in the dimensional stability and the smoke generating property of the rigid polyurethane foam as compared with the rigid polyurethane foam obtained from the conventional formulation using a large amount of CFC-11. I was However, by using an isocyanate composition in which 1 to 50 parts by weight of a modified isocyanurate derivative comprising a diisocyanate derivative having a specific structure is added to 100 parts by weight of an organic polyisocyanate, good dimensional stability is obtained. Thus, a rigid polyurethane foam having improved physical properties and low smoke emission can be obtained.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Shiro Honma 1190 Kasama-cho, Sakae-ku, Yokohama-shi, Kanagawa Mitsui Toatsu Chemicals Co., Ltd.

Claims (2)

[Claims] An organic polyisocyanate constituting at least a part of an isocyanurate-modified product is a diisocyanate derivative represented by the following general formula (1) based on 100 parts by weight of an organic polyisocyanate. A method for producing a rigid polyurethane foam, comprising using an isocyanate composition obtained by adding 1 to 50 parts by weight of a modified isocyanurate. Embedded image (In the formula, R is a monovalent group selected from a halogen atom, a hydrogen atom, and a hydrocarbon group having 20 or less carbon atoms.) 2. The rigid polyurethane foam according to claim 1, wherein in the general formula (1), R is a hydrogen atom, a methyl group or an ethyl group, or a mixture of two or more thereof. Method.