JP2002293868A - Rigid polyurethane foam and production method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an communicating-foam based polyurethane foam, extremely lightweight, little in ratio of restoring while having the communicating-foam, excellent in thermal-insulating property and safety, and easy in treating. SOLUTION: The communicating-foam based polyurethane foam is produced by reacting a polyol composition and a polyisocyanate, wherein the density of foam is 2 kg/m<3> or above and 20 kg/m<3> or below. The above polyol composition is composed of (A) a poly(oxyalkylene)polyether polyol having a number- average molecular weight of 2,000-9,000 and (B) the poly(oxyalkylene)polyether polyol having the number-average molecular weight of 250-750.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an open-celled rigid polyurethane foam. More specifically, the present invention relates to an open-cell rigid polyurethane foam for heat insulation of a building wall or the like.

[0002]

BACKGROUND OF THE INVENTION Conventionally, as a heat insulating material for buildings,
Glass wool, rock wool, etc. are used,
The heat insulating properties of glass wool and the like provided by the air contained between the fibers are not always sufficient. Further, it is not easy to fill the entire space between the inner and outer walls with glass wool or the like, and there is also a problem that the work requires considerable labor.

On the other hand, rigid polyurethane foams have excellent heat insulating properties, and are therefore widely used as heat insulating materials and structural materials for buildings, refrigerators and the like. Conventionally, rigid polyurethane foam has been used as a heat insulating material used for walls of buildings and the like. In particular, at a construction site, a method of spraying a rigid polyurethane foam on the inner surface of an outer wall to form a heat insulating layer is simpler and easier to operate, and its use as a substitute for glass wool or the like is progressing. I have.

[0004] However, in such spraying work at a construction site, in order to improve work efficiency,
It has been required to have excellent properties such as heat insulation and safety, and to further reduce the weight of the spray material.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a rigid polyurethane foam which is extremely lightweight, has excellent heat insulating properties and safety, and a method for producing the same.

[0006]

SUMMARY OF THE INVENTION The present inventors have made intensive studies to solve the above problems, and formed a rigid polyurethane foam using a polyol composition comprising a specific high molecular weight polyol and a specific low molecular weight polyol. As a result, an extremely low-density (light weight) rigid polyurethane foam was obtained. In addition, it has been found that this rigid polyurethane foam has an extremely low restoration rate despite being of the open-cell type. Furthermore, this rigid polyurethane foam was found to be excellent in heat insulation and safety,
The present invention has been completed. That is, the open-celled rigid polyurethane foam according to the present invention has the following features.

The open-celled rigid polyurethane foam according to the present invention has (A) a number average molecular weight of 2,000 to 9000.
A rigid polyurethane foam produced by reacting a polyoxyalkylene polyether polyol which is a polyoxyalkylene polyether polyol having a number average molecular weight of from 250 to 750 with a polyol composition, and a polyisocyanate. The core density of the foam is 2 kg / m ³ or more and 20 kg / m ³ or less.

[0008] In the polyol composition, the polyoxyalkylene polyether polyol (A) is contained in an amount of 60 to 95.
It is preferable that the polyoxyalkylene polyether polyol (B) is contained in a proportion of 5 to 40 mass% (however, (A) + (B) = 100 mass%). The open-cell type rigid polyurethane foam preferably has a compressive strength of 5 kPa or more and 50 kPa or less.

The open-cell type rigid polyurethane foam preferably has a closed cell ratio of 30% or less. The method for producing an open-celled rigid polyurethane foam according to the present invention is a method for producing a rigid polyurethane foam obtained from at least a polyol composition, a polyisocyanate, and a foaming agent, wherein the polyol composition comprises:
(A) 60 to 95% by mass of a polyoxyalkylene polyether polyol having a number average molecular weight of 2,000 to 9000, and (B) 5 to 40 of a polyoxyalkylene polyether polyol having a number average molecular weight of 250 to 750.
% ((A) + (B) = 100% by mass), and the rigid polyurethane foam obtained has a density of 2%.
It is not less than kg / m ^{3 and not} more than 20 kg / m ³ .

The polyoxyalkylene polyether polyol (A) has a number average molecular weight of 2,000 to 400.
At least one polyoxyalkylene polyether polyol (a) having a number average molecular weight of 4,000 or more and less than 6,000, and a number average molecular weight of 600 or less;
It is preferably a polyoxyalkylene polyether polyol in which at least one kind of polyoxyalkylene polyether polyol (c) of 0 to 9000 is mixed.

The polyoxyalkylene polyether polyol (B) is preferably a polyol obtained using an amine compound as an initiator. The blowing agent,
Preferably it is water.

[0012]

DETAILED DESCRIPTION OF THE INVENTION The open-celled rigid polyurethane foam of the present invention has (A) a number average molecular weight of 2,000 to 2,000.
A polyurethane foam produced using a polyol composition comprising a polyoxyalkylene polyether polyol having a molecular weight of 9000 and (B) a polyoxyalkylene polyether polyol having a number average molecular weight of 250 to 750, and Density is 2 kg / m ³ or more and 20 kg / m ³
It is characterized as follows.

The polyol, isocyanate, foaming agent, urethanizing catalyst and other additives used in the open-cell rigid polyurethane foam according to the present invention will be described below. [Polyol composition] The polyol composition used in the present invention comprises (A) a polyoxyalkylene polyether polyol having a number average molecular weight of 2,000 to 9000;
And a polyoxyalkylene polyether polyol having a number average molecular weight of 250 to 750.

The polyoxyalkylene polyether polyol (A) contained in the polyol composition of the present invention,
(B) is an oligomer or polymer obtained from an active hydrogen compound and an alkylene oxide, and is usually obtained by ring-opening polymerization of an alkylene oxide using an active hydrogen compound as an initiator in the presence of a catalyst. The polyoxyalkylene polyether polyol may be generally called a polyether polyol or a polyoxyalkylene polyol.

<Polyoxyalkylene polyether poly
All (A)> (Active hydrogen compound) In the present invention, the active hydrogen compound used as an initiator in the production of the polyoxyalkylene polyether polyol (A) includes a known active hydrogen compound, and is not particularly limited. . Examples of such an active hydrogen compound include an active hydrogen compound having an active hydrogen atom on an oxygen atom and an active hydrogen compound having an active hydrogen atom on a nitrogen atom. (Active hydrogen compound having active hydrogen atom on oxygen atom)
Examples of the active hydrogen compound having an active hydrogen atom on an oxygen atom include aliphatic polyols, alicyclic polyols, and aromatic polyols.

The aliphatic polyols include ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,6-hexane glycol, Examples thereof include 1,4-cyclohexanediol, glycerin, diglycerin, trimethylolpropane, pentaerythritol, and sorbitol.

The alicyclic polyols include α-methyl glycoside, sucrose and the like. As aromatic polyols, bisphenol A, bisphenol F,
2,6-dihydroxynaphthalene and the like. (Active hydrogen compound having active hydrogen atom on nitrogen atom)
Examples of the active hydrogen compound having an active hydrogen atom on a nitrogen atom include amine compounds such as aliphatic amines, alicyclic amines, cyclic amines, aromatic amines, and alkanolamines.

Examples of the aliphatic amines and alicyclic amines include methylamine, ethylamine, n-propylamine, isopropylamine, n-butylamine, isobutylamine, sec-butylamine, tert-butylamine, ethylenediamine, tetramethylenediamine, Hexamethylenediamine, cyclohexylamine and the like can be mentioned. Examples of cyclic amines include piperazine.

Examples of the aromatic amines include toluenediamine, phenylenediamine, diaminodiphenylmethane and the like. Examples of the alkanolamines include monoethanolamine, diethanolamine, triethanolamine, and isopropanolamine. (Active hydrogen compound having an active hydrogen atom on a sulfur atom) An active hydrogen compound containing an SH group such as thioglycol is exemplified.

Among these active hydrogen compounds, in the polyoxyalkylene polyether polyol (A) used in the present invention, it is desirable to use glycerin, propylene glycol, and more preferably glycerin. (Alkylene oxide) As the alkylene oxide used in the production of the polyoxyalkylene polyether polyol (A) of the present invention, a known alkylene oxide can be used and is not particularly limited. Such alkylene oxides include ethylene oxide, propylene oxide, 1,2-butylene oxide, 2,2
Epoxy compounds such as 3-butylene oxide, styrene oxide, cyclohexene oxide, epichlorohydrin, epibromohydrin, methyl glycidyl ether, allyl glycidyl ether and phenyl glycidyl ether are exemplified.

Of these alkylene oxide compounds, it is desirable to use ethylene oxide, propylene oxide, 1,2-butylene oxide or styrene oxide, more preferably ethylene oxide or propylene oxide. These compounds can be used alone or in combination of two or more.

When these compounds are used in combination, they preferably contain ethylene oxide, and the proportion of ethylene oxide in the alkylene oxide is preferably 5 to 70% by mass, more preferably 20 to 50% by mass. Desirably. (Catalyst) When producing the polyoxyalkylene polyether polyol (A) from the active hydrogen compound and the alkylene oxide, a catalyst can be usually used. Such a catalyst is not particularly limited, and a known catalyst can be used. As such a catalyst, an alkali metal catalyst can be used, and examples thereof include potassium hydroxide, sodium hydroxide, and cesium hydroxide.

(Polyoxyalkylene polyether poly)
Method for Producing All (A)) The polyoxyalkylene polyether polyol (A) used in the present invention is obtained by subjecting the alkylene oxide to ring-opening polymerization using the catalyst as required and the active hydrogen compound as an initiator. And can be produced by a conventional method. As a production method, for example, when an alkali metal catalyst is used, usually, the reaction temperature is about 60 to 160 ° C., and the pressure is 0.5 to 6 kg / cm.
^By appropriately setting the reaction time, reaction temperature, pressure and the like in 2G, a polyoxyalkylene polyether polyol having a desired molecular weight can be produced.

In the present invention, the thus obtained polyoxyalkylene polyether polyol (A)
Is a gel permeation chromatography (GP
The number average molecular weight measured in C) is 2000 to 9000,
Preferably 2500 to 8000, more preferably 30
It is desirable to be in the range of 00-6000. Such a polyoxyalkylene polyether polyol (A)
May be a mixture of a plurality of polyoxyalkylene polyether polyols having different (number average) molecular weight ranges.

When a plurality of polyoxyalkylene polyether polyols having different numbers average molecular weights are used, for example, the number average molecular weight is preferably 2
000 or more and less than 4000, more preferably 2500 to
3500 at least one polyoxyalkylene polyether polyol (a);
Less than 000, more preferably 4500 to 5500 at least one polyoxyalkylene polyether polyol (b), preferably 6000 or more and 9000 or less,
More preferably, it is a polyoxyalkylene polyether polyol obtained by mixing at least one of 6,500 to 8,000 polyoxyalkylene polyether polyols (c).

When such polyols (a) to (c) are mixed, the number average molecular weight of the mixed polyoxyalkylene polyether polyol (A) may be 2000 to 9000, and is not particularly limited. These mixing ratios, for example, preferably the polyol (a) is 5 to
60% by mass, the polyol (b) is 5 to 60% by mass, and the polyol (c) is 5 to 60% by mass (provided that (a) + (b)
+ (C) = 100% by mass), more preferably 10 to 50% by mass of the polyol (a) and 1% by mass of the polyol (b).
It is desirable that the proportion of the polyol (c) is 10 to 50% by mass (however, (a) + (b) + (c) = 100% by mass).

The polyoxyalkylene polyether polyol (A) thus obtained preferably has a hydroxyl value of 20 to 100 mgKOH / g, more preferably 30 to 100 mgKOH / g.
Desirably, it is 60 mgKOH / g. <Polyoxyalkylene polyether polyol (B)
> (Active hydrogen compound) The active hydrogen compound used as an initiator in the production of the polyoxyalkylene polyether polyol (B) having a number average molecular weight of 250 to 750 used in the present invention is the polyoxyalkylene polyether polyol described above. Active hydrogen compounds having an active hydrogen atom on an oxygen atom, active hydrogen compounds having an active hydrogen atom on a nitrogen atom, and active hydrogen compounds having an active hydrogen atom on a sulfur atom are the same as those described in (A). Can be

Among them, in the production of the polyoxyalkylene polyether polyol (B), it is preferable to use an active hydrogen compound having an active hydrogen atom on a nitrogen atom, that is, the above-mentioned amine compound. Among such amine compounds, preferably ethylenediamine,
It is desirable to use diethylenetriamine, more preferably ethylenediamine.

When an amine compound is used as an initiator in the production of the polyoxyalkylene polyether polyol (B), a rigid polyurethane foam having open cells and low restoring rate can be obtained. (Alkylene oxide) As the alkylene oxide used in the production of the polyoxyalkylene polyether polyol (B) used in the present invention, the same known alkylene oxide as the polyoxyalkylene polyether polyol (A) can be used. There is no particular limitation.

Of these alkylene oxide compounds, it is desirable to use ethylene oxide, propylene oxide, 1,2-butylene oxide or styrene oxide, and more preferably ethylene oxide or propylene oxide. These compounds can be used alone or in combination of two or more.

When these compounds are used in combination, it is preferable to contain ethylene oxide, and the ratio of ethylene oxide in the alkylene oxide is preferably 5%.
It is desirable that the content be 70 to 70% by mass, more preferably 20 to 50% by mass. (Catalyst) When producing the polyoxyalkylene polyether polyol (B) from the active hydrogen compound and the alkylene oxide, a usual catalyst can be used as in the case of the polyoxyalkylene polyether polyol (A). The catalyst is not particularly limited, and an alkali metal catalyst can be used, and examples thereof include potassium hydroxide, sodium hydroxide, and cesium hydroxide. When an amine compound is used as the initiator, KOH is preferably used.

(Polyoxyalkylene polyether poly
Production method of all (B)) The polyoxyalkylene polyether polyol (B) used in the present invention can be produced in the same manner as the production method of the polyoxyalkylene polyether polyol (A). The alkylene oxide can be produced by ring-opening polymerization using the above-mentioned catalyst and the above-mentioned active hydrogen compound as an initiator by a conventional method.

As a production method, for example, when an alkali metal catalyst is used, the reaction temperature is usually 60 to 160.
A polyoxyalkylene polyether polyol having a desired molecular weight range can be produced by appropriately setting the reaction time, the reaction temperature, the pressure, and the like at about ° C and a pressure of 0.5 to 6 kg / cm ² G. In the present invention, the polyoxyalkylene polyether polyol (B) thus obtained has a number average molecular weight of 25 measured by gel permeation chromatography (GPC).
It is desirably in the range of 0 to 750, preferably 300 to 700, more preferably 400 to 600.

When the (number average) molecular weight of the polyoxyalkylene polyether polyol (B) is in the above range, a rigid polyurethane foam having a low density and excellent heat insulating properties can be obtained. Such a polyoxyalkylene polyether polyol (B) may be a mixture of a plurality of polyoxyalkylene polyether polyols having different number average molecular weights.

The polyoxyalkylene polyether polyol (A) thus obtained preferably has a hydroxyl value of 300 to 700 mgKOH / g, more preferably 40 to 700 mgKOH / g.
Desirably, it is 0 to 600 mgKOH / g. (Polyol composition) The polyol composition used in the present invention comprises a polyoxyalkylene polyether polyol (A) having the number average molecular weight of 2,000 to 9000, and a polyoxyalkylene polyether having the number average molecular weight of 250 to 750. And polyol (B).

In such a polyol composition, the polyoxyalkylene polyether polyol (A) contains 60 to 9
5% by mass of the polyoxyalkylene polyether polyol (B) is a ratio of 5 to 40% by mass, preferably,
The content of the polyoxyalkylene polyether polyol (A) is 70 to 85% by mass and the content of the polyoxyalkylene polyether polyol (B) is 15 to 30% by mass. More preferably, the polyoxyalkylene polyether polyol (A) is 75 to 80% by mass of the polyoxyalkylene polyether polyol (B) is 20 to 25% by mass
Is desirable. (However, (A) +
(B) = 100% by mass) When the polyoxyalkylene polyether polyol (A) and the polyoxyalkylene polyether polyol (B) are in the above ratio in the polyol composition, the obtained rigid polyurethane foam has a low density. (Light weight), a small restoration rate, and excellent heat insulation.

(Other polyols) The polyol composition used in the present invention is in a range not to impair the effects of the present invention.
If necessary, other polyols different from the specific polyoxyalkylene polyether polyols (A) and (B) can be contained. Other polyols are not particularly limited as long as they are different from the polyoxyalkylene polyether polyols (A) and (B). Such polyols include, for example, ethylene glycol and propylene glycol.
Trihydric alcohols such as glycerin and trimethylolpropane; tetrahydric alcohols such as pentaerythritol and diglycerin; polyoxyalkylene polyols; and polyester polyols.

These other polyols can be used alone or in combination of two or more. In the present invention, the hydroxyl value of such a polyol is preferably 20 mgKOH / g to 700 mgKOH / g, and more preferably 30 mgKOH / g to 600 mgKOH / g.

In the present invention, the polyol composition may contain a polyester polyol comprising an aliphatic polybasic acid, an aromatic polybasic acid or an anhydride thereof and a polyhydric alcohol. Can be used. Examples of the aliphatic polybasic acid and its anhydride include oxalic acid, malonic acid, adipic acid, succinic acid, succinic anhydride and the like.

Examples of the aromatic polybasic acid and its anhydride include terephthalic acid, isophthalic acid, phthalic anhydride, trimellitic anhydride, pyromellitic anhydride and the like. As the polyvalent alcohol, for example,
In the case of octafunctional, ethylene glycol, propylene glycol, butanediol, propanediol, diethyleneglycol, trimethylpentanedole, glycerin, pentanedole, sorbitol, and sucrose
And the like. Further, an alkylene oxide adduct of alcohol different from the polyoxyalkylene polyether polyol can also be used.

[ Polyisocyanate] The polyisocyanate used in the present invention is a compound having at least two isocyanate groups. The polyisocyanate used in the present invention is not particularly limited as long as it can be used for producing a rigid polyurethane foam. Such polyisocyanates include, for example, 4,4 ′
-Diphenylmethane diisocyanate (4,4'-MD
I), 2,4'-diphenylmethane diisocyanate (2,4'-MDI), 2,4-toluene diisocyanate (2,4-TDI), 2,6-toluene diisocyanate (2,6-TDI) and the like. . Moreover, these dimers, trimers or multimers can also be used. Further, crude TDI, crude MDI, or a mixture thereof, which is a mixture of the above-mentioned monomer, dimer, trimer or multimer can also be used.

An isocyanate prepolymer which is a reaction product of the above polyisocyanate and an active hydrogen compound can also be used. [Blowing agent] Any blowing agent other than Freon can be used in the present invention.

A plurality of foaming agents can be used in combination, and either a physical foaming agent or a chemical foaming agent can be used.
Among them, in the present invention, it is desirable to use water, carbon dioxide gas, and more preferably water. As the water as the foaming agent, ion-exchanged water and distilled water can usually be used, and industrial water can also be used as it is.

The amount of water is preferably from 10 to 50 parts by mass, more preferably from 15 to 35 parts by mass, particularly preferably from 20 to 30 parts by mass, per 100 parts by mass of the polyol composition. . [Urethanization catalyst] Examples of the urethanization catalyst that can be used in the present invention include amines, quaternary ammonium compounds, alkali metal salts, and the like usually used for urethane foaming.
Any catalyst such as a tin compound, a phenolate compound, a metal halide, or a metal complex compound can be used without any particular limitation.

The amines include, for example, trimethylaminoethylpiperazine, triethylamine, tripropylamine, N-methylmorpholine, N-ethylmorpholine, triethylenediamine, tetramethylhexamethylenediamine, dimethylcyclohexylamine, diazobicycloundecene , 1,3,5-tris (dimethylaminopropyl) hexahydro-s-triazine and the like.

As the aziridine, for example, 2-ethylaziridine and the like can be mentioned. Examples of the quaternary ammonium compound include carboxylic acid salts of tertiary amines. Examples of the alkali metal salts include potassium octylate, sodium acetate and the like.

Examples of the lead compound include lead naphthenate, lead octylate and the like. Examples of the tin compound include dibutyltin diacetate and dibutyltin dilaurate. Examples of the alcoholate compound include sodium methoxide, sodium ethoxide and the like.

As the phenolate compound, for example,
Potassium phenoxide, lithium phenoxide, sodium phenoxide and the like can be mentioned. Examples of the metal halide include iron chloride, zinc chloride, zinc bromide, tin chloride and the like. Examples of the metal complex compound include a metal complex compound such as a metal salt of acetylacetone.

These catalysts can be used alone or in combination of two or more. It is desirable to use the catalyst in an amount of preferably 0.001 to 15.0 parts by mass, more preferably 3 to 10 parts by mass, based on 100 parts by mass of the polyol composition. [Foam stabilizer ] As the foam stabilizer that can be used in the present invention,
A conventionally known surfactant of a silicon-containing compound may be used.

Examples of such a silicon-containing compound include silicone derivatives (alkylene oxide-modified polydimethylsiloxane having a terminal alkoxy group or active OH group). Also, so-called nonionic surfactants such as polyoxyethylene octadecylamine and long-chain fatty acid alkylol amide can be used.

As such silicon-containing compounds, for example, SZ-1127, SZ-1142, SZ-160
5, SZ-1642, SZ-1649, SZ-165
5, L-580, L-5740, L-5420, L-5
421 etc. (trade name, manufactured by Nippon Unicar Co., Ltd.), SF-2
935F, SF-2938F, SF-2940F, SF
-2945F, SF-2908, SRX-294A, S
H-190, SH-192, SH-193, etc. (manufactured by Dow Corning Silicone Toray Co., Ltd.), F-327, F
-345, F-305, etc. (trade name, Shin-Etsu Chemical Co., Ltd.)
) Can be used.

[Other Additives] In the rigid polyurethane foam according to the present invention, various additives can be added according to applications and purposes. Examples of such additives include a flame retardant, an antioxidant, a coloring agent, and a viscosity reducing agent. [Production Method of Rigid Polyurethane Foam] The open-celled rigid polyurethane foam of the present invention comprises the above-mentioned specific polyol composition, polyisocyanate, foaming agent, and, if necessary, a urethanizing catalyst, a foam stabilizer, and the like. It can be manufactured from additives and the like.

The foaming method is not particularly limited, and it is possible to employ a method in which the foaming is carried out in a mold having a shape or a shape similar to a known molded product. It is preferable that the polyol composition and the polyisocyanate are mixed immediately before foaming. Mixing of other components as necessary, a combination of the mixture as appropriate,
The order of mixing, the storage time after mixing, etc. can be determined.

The other components are generally mixed with a polyol composition or a polyisocyanate in advance, if necessary.
The stored amount may be used appropriately. In the present invention, among such mixed components, a polyol composition, a foaming agent, and a foam stabilizer, a urethane-forming catalyst, other additives, a cross-linking agent, and the like used as necessary are previously mixed as a resin premix. Preferably, the resin premix is reacted with a polyisocyanate.

The viscosity of such a resin premix is 2,500 mPa from the viewpoint of the mixing property in a foaming machine and the moldability of a foam.
S / 25 ° C or lower is preferable, and 1000 mPa · s / 25 ° C or lower is more preferable. The method of mixing the polyol composition and the polyisocyanate or the method of mixing the resin premix and the polyisocyanate is not particularly limited, and any of known dynamic mixing, static mixing, and the like may be used. Also, both may be used in combination.

As a mixing method by dynamic mixing, there is a mixing method using a stirring blade or the like. Examples of the mixing method by static mixing include a method of mixing in a machine head mixing chamber of a foaming machine, and a method of mixing in a liquid feed pipe using a static mixer or the like. Mixing performed immediately before foaming or mixing of a gaseous component and a liquid component such as a physical foaming agent is preferably performed using static mixing, and mixing between storable components is preferably performed using dynamic mixing.

The mixing temperature and pressure can be arbitrarily set depending on the quality of the intended open-cell type rigid polyurethane foam, the type and composition of the raw materials, and the like. You can also. As a specific production temperature and the like, each starting component is stirred and mixed at a liquid temperature of 15 to 80 ° C., preferably 20 to 30 ° C., and the temperature can be controlled under normal pressure or high pressure as required, such as a closed mold. To obtain a rigid polyurethane foam.

The NCO index (NCO / OH) is not particularly limited, but is preferably 0.8 or less.
More preferably, it is 0.5 or less. When the NCO index is 0.8 or less, it is preferable to use water in an amount of 15 to 35 parts by mass based on 100 parts by mass of the polyol composition. When the NCO index is 0.8 or more, CO ₂ may be used in combination.

[Rigid Polyurethane Foam] The open-cell rigid polyurethane foam obtained by the present invention preferably has a closed cell ratio of 30% or less, more preferably 20%.
A rigid polyurethane foam having an open cell of 10% or less, particularly preferably 10% or less. Such an open-cell rigid polyurethane foam has a foam density (core density) of 2 kg / m ³ or more and 20 kg / m ³ or less, preferably 6 to 15 kg / m ^3.
kg / m ^3, further preferably a 7~10kg / m ^3.

The open-cell type rigid polyurethane foam preferably has a number average molecular weight of 2,000 to 900 relative to the skeleton derived from all polyoxyalkylene polyether polyols in the foam.
The skeleton derived from the polyoxyalkylene polyether polyol (A) having 0 is 60 to 95% by mass, and the skeleton derived from the polyoxyalkylene polyether polyol (B) having the number average molecular weight of 250 to 750 is 5
The skeleton derived from the polyoxyalkylene polyether polyol (A) is more preferably 70 to 85% by mass, and the skeleton derived from the polyoxyalkylene polyether polyol (B) is 15 to 40% by mass. ~
At 30% by mass, particularly preferably, the skeleton derived from the polyoxyalkylene polyether polyol (A) is
75 to 80% by mass, the skeleton derived from the polyoxyalkylene polyether polyol (B) is 20 to 25.
It is desirable to be contained in a ratio of mass%. (However,
(A) + (B) = 100% by mass) Such an open-cell type rigid polyurethane foam according to the present invention is preferable because it has a small recovery ratio while having open cells.

The dimensional change in wet heat of the open-cell type rigid polyurethane foam according to the present invention is preferably -3% to 3%.
%, More preferably -2 to 2%, particularly preferably -1.
It is desirably in the range of １1%. The compressive strength of the open-cell type rigid polyurethane foam according to the present invention is preferably 5 kPa or more and 50 kPa or less, more preferably 7 to 50 kPa.
kPa, particularly preferably 10 to 30 kPa.

The open cell type rigid polyurethane foam according to the present invention has a thermal conductivity of 20 mW / mK to 35 mW / m.
It is preferably K. Such open-celled rigid polyurethane foam is very low-density and lightweight, so that the polyurethane foam can be efficiently sprayed on site and handled easily. Also, it has excellent heat insulation performance. Furthermore, since it has a small restoration rate while having open cells, it can be used as a structural material for buildings, and is also useful as a substitute for glass wool and rock wool as a heat insulating material used for walls and the like. is there. In addition, since water is used as a foaming agent, it is excellent in terms of safety and response to environmental problems.

(Method for Measuring Physical Properties) In the present invention, various physical properties were evaluated by the following methods. <Density of foam> The total density was measured by the method described in JIS K-6400. The total density refers to "apparent density" defined by JIS standards. In the present invention, the total density was measured using a rectangular foam sample having a skin skin. The core density was measured by removing the skin and preparing a rectangular solid foam sample. <Heat and heat dimensional change> After the elapse of 24 hours, the core portion of the obtained rigid polyurethane foam was 80 × 80 with a slitter.
The foam was cut into a piece having a size of × 20 mm, and the cut foam was allowed to stand in an oven set at 70 ° C. and a humidity of 95% RH for 48 hours to measure a wet heat dimensional change rate. <Compressive strength> The compressive strength was measured according to the method of a compression test of a foamed plastic hard material described in JIS K7220. <Closed cell rate> The closed cell rate of the present invention was measured by a measurement method usually used for a rigid polyurethane foam. That is, using the “pneumatic apparent volume measuring device”, the AST
It was determined as an apparent volume ratio (%) measured by the method described in MD-2856. <Thermal conductivity> The thermal conductivity is a value measured according to JIS A-1412 using a model TCA-8 of Anacon as a measuring device.

[0064]

The open-celled rigid polyurethane foam according to the present invention is extremely lightweight (ultra-low density), has excellent heat insulating properties and safety, and is easy to handle. Also,
It is a novel rigid polyurethane foam having a small recovery rate while having open cells. Such a rigid polyurethane foam can be used as an alternative heat insulator to glass wool and rock wool used as a heat insulator for construction.

[0065]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples. In the examples, parts mean parts by mass unless otherwise specified. (Raw materials used) Polyol A : 450 mg of hydroxyl value obtained by adding ethylene oxide and propylene oxide to ethylene diamine
KOH / g polyether polyol.

Number average molecular weight 499. Polyol B : a polyether polyol having a hydroxyl value of 56 mgKOH / g obtained by adding ethylene oxide and propylene oxide to glycerin. Number average molecular weight 2705. Polyol C : a polyether polyol having a hydroxyl value of 34 mgKOH / g obtained by adding ethylene oxide and propylene oxide to glycerin.

Number average molecular weight 4125. Polyol D : hydroxyl value 3 obtained by adding ethylene oxide and propylene oxide to dipropylene glycol
7.5 mg KOH / g polyether polyol. Number average molecular weight 2850. Flame retardant A : Trischloropropyl phosphate (TCPP)
(Phirol PCF (trade name, Akzo Kashima Co., Ltd.
Foaming agent : L5740S (manufactured by Nippon Yunika Co., Ltd.) Catalyst : bis (2-dimethylaminoethyl) ether (MI
NICOTMDA) Water isocyanate : Cosmonate M-200 (manufactured by Mitsui Chemicals, Inc.)

[0068]

Example 1 An isocyanate was added to a mixture of a polyol, a flame retardant, a foam stabilizer, a catalyst, and water at a ratio shown in Table 1 so as to have an index shown in Table 1, and the liquid temperature was 20 ° C
Approximately 5 at 6000 rpm using a high-speed rotating lab stirrer
For 20 seconds, and the obtained mixture is 20 cm × 20 cm × 20
Quickly poured into a cm wooden box and allowed to foam. 15 minutes after the injection, the obtained polyurethane foam was taken out to obtain a rigid polyurethane foam.

The obtained rigid polyurethane foam was mixed with 20
After a lapse of time, the foam was cut into 100 × 100 × 100 mm with a slitter and the core density inside the foam was measured. In addition, the wet heat dimensional stability, the closed cell ratio, and the thermal conductivity were measured. Table 1 shows the results.

[0070]

[Table 1]

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Makoto Maruyama 1190 Kasama-cho, Sakae-ku, Yokohama-shi, Kanagawa Prefecture Inside (72) Inventor Masaaki Shibata 1190 Kasama-cho, Sakae-ku, Yokohama-shi, Kanagawa Mitsui Chemicals Inc. F term (reference) 4J034 BA07 DB04 DC50 DG02 DG03 DG04 DG05 DG06 HC12 HC64 HC67 HC71 KA01 KB03 KC02 KC17 KD02 KD04 KD12 NA03 NA08 QA05 QB01 QC01 QD03 RA10 RA15

Claims (8)

[Claims] (A) a number average molecular weight of 2,000 to 900
A rigid polyurethane foam produced by reacting a polyoxyalkylene polyether polyol having a molecular weight of 0 and (B) a polyoxyalkylene polyether polyol having a number average molecular weight of 250 to 750 with a polyisocyanate. An open-cell rigid polyurethane foam, wherein the rigid polyurethane foam has a core density of 2 kg / m ³ or more and 20 kg / m ³ or less. 2. The polyol composition, wherein the polyoxyalkylene polyether polyol (A) contains 60 to 9
5% by mass, and the polyoxyalkylene polyether polyol (B) is contained at a ratio of 5 to 40% by mass (however, (A) + (B) = 100% by mass). The open-celled rigid polyurethane foam according to claim 1. 3. The open-celled rigid polyurethane foam according to claim 1, wherein the open-celled rigid polyurethane foam has a compressive strength of 5 kPa or more and 50 kPa or less. 4. The open-cell rigid polyurethane foam according to claim 1, wherein the open-cell type rigid polyurethane foam has a closed cell ratio of 30% or less. 5. A method for producing a rigid polyurethane foam obtained from at least a polyol composition, a polyisocyanate, and a blowing agent, wherein the polyol composition has (A) a number average molecular weight of 2,000 to 9000. Polyoxyalkylene polyether polyol
95 mass% and (B) a polyoxyalkylene polyether polyol having a number average molecular weight of 250 to 750
-40% by mass (however, (A) + (B) = 100% by mass), wherein the density of the obtained rigid polyurethane foam is 2 kg / m ³ or more and 20 kg / m ³ or less. Method for producing rigid polyurethane foam. 6. The polyoxyalkylene polyether polyol (A) has a number average molecular weight of at least one of 2,000 to less than 4,000.
(a) and at least one polyoxyalkylene polyether polyol having a number average molecular weight of 4,000 or more and less than 6000
(b) and at least one polyoxyalkylene polyether polyol having a number average molecular weight of 6000 or more and 9000 or less
6. The process for producing an open-cell rigid polyurethane foam according to claim 5, wherein the polyoxyalkylene polyether polyol is a mixture of (c) and (c). 7. The open-cell rigid polyurethane foam according to claim 5, wherein the polyoxyalkylene polyether polyol (B) is a polyol obtained by using an amine compound as an initiator. Production method. 8. The method for producing an open-celled rigid polyurethane foam according to claim 5, wherein the foaming agent is water.