JPH07179562A - Production of rigid polyurethane foam - Google Patents

Abstract

PURPOSE:To produce a rigid polyurethane foam low in fuming properties and excellent in dimensional stability without requirement of a chlorofluoromethane foaming agent by using an isocyanate composition composed of an organic polyisocyanate and a specific modified isocyanurate. CONSTITUTION:This foam is produced by using an isocyanurate composition composed of (A) 100 pts.wt. organic polyisocyanate (generally toluene diisocyanate and/or diphenylmethane diisocyanate) and (B) 0.001 to 5 pts.wt. modified isocyanurate which is a phenyl isocyanate derivative of the formula (R1 and R2 are each a halogen, H or a <=10C hydrocarbon) as an organic polyisocyanurate constituting a modified isocyanurate. In addition, the component (B) can be synthesized, e.g. by reacting phenyl isocyanate in the presence of an isocyanuration catalyst.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing rigid polyurethane foam. Specifically, it reduces the amount of specific freon used as a foaming agent, that is, chlorofluorocarbons, or substitutes it and has good strength and dimensional stability.
Moreover, the present invention relates to a method for producing a rigid polyurethane foam having low flammability or smoke emission.

[0002]

2. Description of the Related Art Rigid polyurethane foam is widely used as a heat insulating material for refrigerators, frozen warehouses, building materials, etc. and as a spraying application because it has excellent heat insulating performance, dimensional stability and workability. Polymethylene polyphenylene polyisocyanate (hereinafter referred to as "Polymeric MDI") and Polymeric M are used as organic polyisocyanates when producing a rigid polyurethane foam.
A modified product of DI was used, and 1,1,1-trichlorofluoromethane (hereinafter referred to as CFC-11) was used as a foaming agent.

In recent years, regulation of chlorofluorocarbons has been implemented to protect the earth's ozone layer. This regulation target also includes CFC-11 used as a foaming agent for rigid polyurethane foam. In general insulation, CFC-11 is 7-14% by weight in the foam.
A foaming technique for reducing the content of CFC-11 (hereinafter referred to as a CFC-11 reduction formula) or a foaming technique using only water as a foaming agent (hereinafter referred to as a complete water foaming formula). , Or 1,1-dichloro-1-fluoroethane (hereinafter referred to as HCFC-141b), 2,2-dichloro-1,1,1-trifluoro, which are considered to be foaming agents replacing CFC-11. Ethane (hereinafter HCFC-
The development of a foaming technology using 123) (hereinafter referred to as an alternative CFC prescription) has become an important issue for the protection of the earth's ozone layer.

However, in the case of the CFC-11 reduced formulation and the completely water-foamed formulation, the strength and dimensional stability, particularly the dimensional stability at high temperature and humidity at high temperature are deteriorated as compared with the conventional rigid polyurethane foam, and the liquid flow of the urethane undiluted solution. As a result, it was necessary to increase the product density. In addition, since CFC-11 used conventionally is a non-flammable gas, the hard polyurethane foam using this as a foaming agent has generally good flammability and smoke generation properties. But CF
In the case of the C-11 reduced prescription and the complete water foaming prescription, the amount of the non-combustible gas CFC-11 used decreases, and thus the flammability tends to deteriorate. In the case of the alternative CFC formula, the dimensional stability, particularly the low temperature dimensional stability, deteriorates, and the demolding performance also tends to deteriorate. In the case of alternative CFC prescription, 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. Rigid foams using these combustible gases as CFC substitutes have the property of being easier to burn than rigid polyurethane foams using CFC-11. Therefore, the amount of smoke emitted during combustion was also increased, and a rigid polyurethane foam that was satisfactory in all cases could not be obtained.

[0005]

A method for producing a rigid polyurethane foam having good dimensional stability, flame retardancy, and low smoke emission in a CFC-11 reduced formulation, a complete water formulation, and an alternative CFC formulation is developed. To do so was an important issue to reduce the amount of chlorofluorocarbons used.

[0006]

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

That is, in the present invention, at least 1 part of the organic polyisocyanate constituting the modified isocyanurate is a phenyl isocyanate derivative represented by the formula (Formula 2) per 100 parts by weight of the organic polyisocyanate. A method for producing a rigid polyurethane foam, which comprises using an isocyanate composition containing 0.001 to 50 parts by weight, preferably 5 to 20 parts by weight of a modified isocyanurate.

[Chemical 2] In the formula, R ₁ and R ₂ are a halogen atom, a hydrogen atom, and 10 carbon atoms.
It is a monovalent group selected from the following hydrocarbon groups. Here, the halogen atom is, for example, Cl or Br. Examples of the hydrocarbon group having 10 or less carbon atoms include a methyl group, an ethyl group and a methoxy group.

When an isocyanurate modified product is produced by a known method using only a bifunctional or higher functional monomer,
The trifunctional isocyanurate modified product once produced further reacted as an isocyanurate modified monomer, and a kind of gelled product was produced. When these modified isocyanurates were added to the organic polyisocyanate, the viscosity was remarkably increased, and it was difficult to obtain a practical isocyanate composition. However, when modified with an organic polyisocyanate in which at least one part of the phenyl isocyanate derivative is added, the formation of a gelled product is suppressed, and even if the obtained modified isocyanurate is added to the organic polyisocyanate. It was found that a practical isocyanate composition capable of suppressing an increase in viscosity can be obtained.

However, the isocyanurate modified product obtained by these methods has a functional group number of 3 or less, and for example, a monofunctional isocyanurate modified product is partially produced, but in this case, the reaction is stopped in the process of polymer formation. Can cause. However, even if a trimer containing only phenyl isocyanate (functional group number 0) is added to an organic polyisocyanate, no deterioration in physical properties, particularly strength and dimensional stability, is observed, and a hard polyurethane having improved combustibility and smoke generation is obtained. I got a form.

When R ₁ and R ₂ shown in Formula 1 are a hydrogen atom and a methyl group, respectively, and when they are a hydrogen atom and an ethyl group, respectively, as compared with the case where both R ₁ and R ₂ are hydrogen atoms. The compatibility stability of the isocyanurate modified product in the organic polyisocyanate becomes better, and the content of the isocyanurate modified product can be increased.

As the organic polyisocyanate used in the present invention, all known ones can be used, but the most common ones are toluene diisocyanate (hereinafter abbreviated as TDI) and / or diphenylmethane diisocyanate (hereinafter MDI). Is abbreviated). TDI is a mixture of isomers, that is, 2,4-body 100% product, 2,4-body / 2,6-body = 8
A so-called crude TDI containing polyfunctional tar known as TDI-TRC manufactured by Mitsui Toatsu Chemicals, Inc., such as 0/20 and / or 65/35 (each by weight ratio), can also be used. The MDI is 4,
Polymeric MDI represented by the Cosmonate series manufactured by Mitsui Toatsu Chemicals, Inc., which contains polynuclear bodies of three or more nuclei, is preferably used in addition to a pure product having a 4'-form as a main component. Further, a prepolymer having an isocyanate group obtained from these organic polyisocyanate and the polyol described below at the molecular end can also be used. NCO / H (active hydrogen) = 0.7 to 5.0 (equivalent ratio) is suitable for the ratio of active hydrogen in the isocyanate composition and the resin liquid described later.

As the polyol used in the present invention, all known polyols can be used, but sucrose / glycerin /
A polyol having a hydroxyl value of 450 mgKOH / g, which is obtained by adding propylene oxide to a tolylenediamine mixture, is particularly preferable. Other than that, for example, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, trimethylolpropane, pentaerythritol, sorbitol, polyhydric alcohols such as sucrose, and aromatic amines such as tolylenediamine. There are polyether polyols having a hydroxyl value of 350 to 800 mg KOH / g, which are obtained by addition-polymerizing alkylene oxides in a single or mixed system of compounds and aliphatic amines such as ethylenediamine and triethanolamine. As the polyester polyol, all known ones can be used, but there are polyester diol, polyester triol and the like produced by the condensation reaction of the above polyhydric alcohol and a low molecular weight carboxylic acid such as adipic acid and phthalic acid. You may use together these polyether polyol and polyester polyol.

As the catalyst, for example, amine type urethane-forming catalysts such as trimethylaminoethylpiperazine, triethylamine, tripropylamine, N-methylmorpholine, N-ethylmorpholine, triethylenediamine, tetramethylhexamethylenediamine and the like are known. All catalysts can be used. Examples of the trimerization catalyst include quaternary ammonium hydroxides; hydroxides of alkaline earth metals, alkoxides and carboxylates such as potassium acetate, potassium octanoate and potassium 2-ethylhexanoate; Known catalysts such as non-basic metal carboxylates such as lead octoate can be used. These catalysts can be used alone or as a mixture, and the amount thereof is 0.0 to 100 parts by weight of the compound having active hydrogen.
01 to 10.0 parts by weight is suitable.

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

Other flame retardants, plasticizers, stabilizers, colorants and the like can be added as required. To carry out the present invention, a predetermined amount of a polyol, a foaming agent, a catalyst and a foam stabilizer is mixed to form a resin liquid. The resin solution and the organic polyisocyanate are mixed at a high ratio at a high speed and poured into a void or a mold. At this time, the liquid ratio of the organic polyisocyanate and the resin liquid is adjusted so that the equivalent ratio (NCO: H) of the organic polyisocyanate and the active hydrogen of the resin liquid is 0.7: 1 to 5: 1. .

[0016]

EXAMPLES The present invention will be specifically described below with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

The raw materials used in Examples and Comparative Examples are described below. Isocyanate-A: Mitsui Toatsu Chemicals Co., Cosmonate M-200, crude diphenylmethane diisocyanate,
NCO%: 31.3 Isocyanate-B: Mitsui Toatsu Chemical Co., Cosmonate T-1002,4-toluene diisocyanate, NC
O%: 48.3 Phenyl isocyanate: manufactured by Kanto Chemical Co., Inc., NCO%: 3
2.1 p-Methylphenyl isocyanate: manufactured by Kanto Chemical Co., Inc., N
CO%: 21.5 Polyol-1: APP-240C Hydroxyl value: 240 m
gKOH / g polyol-2: polyether polyol obtained by adding propylene oxide to ethylenediamine hydroxyl value: 450
mgKOH / g Foam stabilizer: Nippon Unicar L-5420 Catalyst: Air Products Polycat-42 Foaming agent (CFC) R-141b: 1, 1-dichloro-1
-Fluoroethane

<Production of Isocyanurate Modified Product-A> To 100 parts by weight of phenyl isocyanate, 1.0 part by weight of an isocyanurate-forming catalyst Polycat 42 was added with stirring under a nitrogen stream at room temperature. The obtained crude crystals were recrystallized with a benzene solvent.

<Production of Modified Isocyanurate-B> Phenyl isocyanate 3 to 100 parts by weight (0.575 mol) of isocyanate-B dissolved in an oven.
7.7 parts by weight (0.288 mol) was added and the isocyanurate-forming catalyst Polycat 4 was added at room temperature under a nitrogen stream.
1.0 parts by weight of 2 was added with stirring. The obtained crude crystals were recrystallized with a benzene solvent. NCO%: 17.4 <Production of Isocyanurate Modified Product-C> p-Ethylphenylisocyanate 38. with respect to 100 parts by weight (0.575 mol) of isocyanate-B dissolved in an oven.
3 parts by weight (0.288 mol) was added, and 1.0 part by weight of the nurate forming catalyst, Polycat 42, was added with stirring under a nitrogen stream at room temperature. The obtained crude crystals were recrystallized with a benzene solvent. NCO%: 16.9

Isocyanate-C: Isocyanate-A
10 parts by weight of isocyanurate modified product-A well pulverized in a mortar was added to 100 parts by weight, and 8 was added under a nitrogen stream.
It melt | dissolved at 0 degreeC with stirring for 2 hours. After cooling, it was discharged and designated as isocyanate-C. NCO%: 28.1 (viscosity 215
CPS.25 ℃)

Isocyanate-D: Isocyanate-A
To 100 parts by weight, 10 parts by weight of the isocyanurate modified product-B well ground in a mortar under a nitrogen stream was added, and the mixture was stirred and dissolved at 80 ° C. for 2 hours under a nitrogen stream. After cooling, it was discharged and designated as isocyanate-D. NCO%: 29.8
(Viscosity 238CPS.25 ℃)

Isocyanate-E: Isocyanate-A
10 parts by weight of isocyanurate modified product-C well ground in a mortar with respect to 100 parts by weight of nitrogen was added, and the mixture was stirred and dissolved at 80 ° C. for 2 hours in a stream of nitrogen, cooled, and then discharged. And NCO%: 29.5
(Viscosity 203 CPS.25 ℃)

Examples 1 to 6 and Comparative Examples 1 to 2 A predetermined amount of resin solution having the composition shown in Table 1 was compounded and the temperature was adjusted to 25.
After the temperature was maintained at ℃, a predetermined amount of the isocyanate composition was added thereto, and the mixture was mixed at high speed for 5 seconds, and immediately the aluminum plate (23 to 2
(5 ° C.) and foamed. After foaming, 23 ℃, humidity 65
%, Various physical property values of the foam left to stand in a thermostatic chamber for 24 hours were measured. Low temperature dimensional stability is 24h in -30 ℃ atmosphere
After standing still, the dimensional change was measured. JIS smoke test
According to A1321.

[0024]

[Table 1]

[0025]

EFFECT OF THE INVENTION CFC-11 reduced formulation, completely water-foaming formulation, or alternative CFC formulation, for example HCFC-141b.
The rigid polyurethane foam obtained by the formulation using the above-mentioned etc. is remarkably inferior in dimensional stability and smoke emission property of the rigid polyurethane foam as compared with the rigid polyurethane foam obtained by the conventional formulation using a large amount of CFC-11. Was there. However, with respect to 100 parts by weight of the organic polyisocyanate, 1 to 30 parts of the isocyanurate modified product in which at least a part of the organic polyisocyanate constituting the isocyanurate modified product is a phenyl isocyanate derivative is used.
By using the isocyanate composition added in parts by weight, a rigid polyurethane foam having good dimensional stability and low smoke emission can be obtained.

Claims (2)

[Claims] 1. An isocyanurate in which at least a part of the organic polyisocyanate constituting the modified isocyanurate is a phenyl isocyanate derivative represented by the formula (1) per 100 parts by weight of the organic polyisocyanate. A method for producing a rigid polyurethane foam, which comprises using an isocyanate composition obtained by adding 0.001 to 50 parts by weight of a modified product. [Chemical 1] (In the formula, R ₁ and R ₂ are a halogen atom, a hydrogen atom, and a carbon number 1
It is a monovalent group selected from hydrocarbon groups of 0 or less. ) 2. In the formula 1, R ₁ and R ₂ are both a hydrogen atom, a hydrogen atom and a methyl group, a hydrogen atom and an ethyl group, and are one kind or a mixture of two or more kinds. 1. The method for producing a rigid polyurethane foam according to 1.