JP2011190438A - Polyisocyanate composition for rigid polyurethane foam for cyclopentane foaming and manufacturing method of rigid polyurethane foam using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rigid polyurethane foam for a thick heat-insulating material for a cyclopentane foaming having an excellent curability, capable of demolding in a short time, and having a good heat conductivity and to provide a manufacturing method thereof. <P>SOLUTION: The polyisocyanate composition for the rigid polyurethane foam for the cyclopentane foaming contains an isocyanate group-containing prepolymer (A) consisting of a polymeric MDI (a1), a low molecular weight polyol (a2) having a side chain alkyl group wherein total carbons is ≥4 and having a molecular weight of ≤200 and a foam stabilizer (a3) wherein addition of (a2) to (A) is 3-10 mass%. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention relates to a polyisocyanate composition for rigid polyurethane foam for foaming cyclopentane. Specifically, it is a rigid polyurethane that is compatible with the foaming system using cyclopentane and / or water that is friendly to the global environment, has excellent storage stability and curing properties, can be molded in a short time, and has good heat conduction characteristics. The present invention relates to a polyisocyanate composition for a rigid polyurethane foam for foaming cyclopentane capable of obtaining a foam and a method for producing a rigid polyurethane foam using the same.

Rigid polyurethane foam is useful as a heat insulating material, and has excellent moldability and processability. From heat insulation of electric refrigerators to insulation of buildings, low-temperature warehouses, storage tanks, freezing ship piping, etc. Used in a wide range of fields. Its thermal conductivity has been improved year by year,
It has reached 0.0215 W / mK (see Non-Patent Document 1) at the product level, and is said to have the highest heat insulating performance as a heat insulating material used near room temperature. However, against the background of the recent increase in energy saving, there is an increasing demand for further lowering the thermal conductivity of the heat insulating material.

Conventionally, in order to produce such a rigid polyurethane foam, a foaming process is performed by mixing and reacting a component A mainly composed of a polyol, a catalyst, a foaming agent and a foam stabilizer and a component B mainly composed of an organic isocyanate. A one-shot method is generally used in which a foam is formed by proceeding in parallel with a curing process. In the production of such a rigid polyurethane foam, conventionally, as a foaming agent, mainly trichloromonofluoromethane (hereinafter R-
However, conventional chlorofluorocarbons represented by R-11 are chemically stable and are known to diffuse to the stratosphere and destroy the ozone layer. Recently, it has been banned as a cause of destruction of the global environment.

Therefore, in recent years, diligent research has been conducted on such foaming agents as an alternative to Freon.
For example, hydrochlorofluorocarbon (hereinafter abbreviated as HCFC) 1,1-dichloro-1-fluoroethane (hereinafter abbreviated as HCFC-141b) and methylene chloride are listed as candidates for R-11. It has been.

However, since the HCFC mentioned above still contains chlorine atoms in the molecule, it has less influence on the ozone layer than R-11, but it still has the property of destroying the ozone layer, so it is also produced and used. Has been decided to cancel. Therefore, from the viewpoint of protecting the global environment, the use of a foaming agent that does not affect the destruction of the ozone layer has been newly proposed. In some applications, hydrocarbons that do not contain any chlorine atoms and do not risk the destruction of the ozone layer. For example, cyclopentane is introduced and applied.

However, cyclopentane is optimal as a foaming agent friendly to the global environment, but has some problems. In particular, since the thermal conductivity of the gas of cyclopentane itself is high, the heat insulation performance of the rigid polyurethane foam simply using cyclopentane is the same as that of conventional HCFC-
It is inferior to the one using 141b, and therefore, improvement of the heat insulating property is demanded.

In order to improve the thermal conductivity of the cyclopentane foamed foam, it has been proposed to reduce the compatibility between the foam raw material and cyclopentane, thereby miniaturizing the cell. Patent Document 1 includes (1) an organic polyisocyanate composed of an aromatic polyisocyanate, (2) a polyol composed of a polyether polyol and / or a polyester polyol, (3) a foaming agent,
(4) A method for producing a rigid polyurethane foam from a foam stabilizer, a catalyst and other auxiliary agents, wherein the foaming agent (3) is cyclopentane and water, and the polyol (2) is in phase with cyclopentane. A method for producing a rigid polyurethane foam, which is a polyether polyol and / or polyester polyol having low solubility, characterized in that cyclopentane is mixed and dispersed in a polyol premix comprising components (2) to (4). Yes.

In order to improve the thermal conductivity of cyclopentane foamed foam, polymeric MDI
A polyisocyanate composition for rigid polyurethane foam for foaming cyclopentane, characterized in that is modified with only a short-chain polyol (Patent Document 2). Furthermore, a method for producing a rigid polyurethane foam with a thick cyclopentane foam for a thick article, which uses a foam stabilizer in an isocyanate group-terminated prepolymer and has excellent curing properties and can be molded in a short time has been proposed (
Patent Document 3). However, Patent Document 2 provides a rigid polyurethane foam having excellent thermal conductivity by using a specific low molecular polyol, and Patent Document 3 discloses a curing system as a whole system of an isocyanate composition and a polyol component. An excellent rigid polyurethane foam is provided. Therefore, it has not been possible to provide a rigid polyurethane foam excellent in thermal conductivity and curing properties.

JP 2000-128951 A JP 2008-260843 A JP 2009-179752 A

Uwa Thermal Engineering Co., Ltd. website, product information, cyclopentane February 1, 2006 Search URL: http://www.uwa-ud.co.jp/cyclopentane.htm

The present invention relates to a polymer for rigid polyurethane foam for foaming cyclopentane, which is environmentally friendly, has excellent storage stability and curing properties, can be molded in a short time, and can obtain a rigid polyurethane foam having good heat conduction properties. An object of the present invention is to provide an isocyanate composition and a method for producing a rigid polyurethane foam using the same.

That is, this invention is shown by the following (1)-(4).
(1 consisting of polymeric MDI (a1), a low molecular polyol (a2) having a side chain alkyl group and having 4 or more carbon atoms in the side chain and a molecular weight of 200 or less, and a foam stabilizer (a3) Contains an isocyanate group-containing prepolymer (A), and the added amount of (a2) is 3 with respect to (A).
A polyisocyanate composition for rigid polyurethane foam for foaming cyclopentane, characterized in that the content is from 10 to 10% by mass.
(2) The polyisocyanate composition for rigid polyurethane foam for foaming cyclopentane as described in (1) above, wherein the foam stabilizer (a3) contains a hydroxyl group.
(3) Hard to react and foam the isocyanate group-containing prepolymer (A) according to (1) or (2) above and the polyol (B) in the presence of the catalyst (C) and cyclopentane (D1) A method for producing polyurethane foam.
(4) The catalyst (C) contains a urethanization catalyst (c1) and a trimerization catalyst (c2), and the foaming agent uses cyclopentane (D1) and water (D2) in combination. The manufacturing method of the rigid polyurethane foam of Claim 3.

According to the present invention, a polyisocyanate composition for rigid polyurethane foam for foaming cyclopentane, which is friendly to the global environment, has excellent storage stability and curing properties, can be molded in a short time, and has good heat conduction properties, and uses the same. It was possible to provide the manufacturing method that was available.

The polyisocyanate composition for rigid polyurethane foam for foaming cyclopentane of the present invention comprises polymeric MDI (a1), a low molecular weight molecule having a side chain alkyl group and a total of 4 or more carbon atoms in the side chain and a molecular weight of 200 or less. It contains an isocyanate group-containing prepolymer (A) comprising a polyol (a2) and a foam stabilizer (a3).

This polymeric MDI means a mixture of organic isocyanate compounds with different degrees of condensation obtained by converting an amino group to an isocyanate group by phosgenation of a condensation mixture (polyamine) obtained by the condensation reaction of aniline and formalin. The composition of the finally obtained polymeric MDI can be changed by changing the raw material composition ratio and reaction conditions during the condensation. The polymeric MDI used in the present invention has different numbers of reaction liquids after conversion to isocyanate groups, or removal of the solvent from the reaction liquids, or bottoms obtained by distilling and separating part of the MDI, reaction conditions and separation conditions, etc. It may be a mixture of seeds. In addition, some isocyanate groups are biuret, allophanate, carbodiimide, oxazolidone, amide,
It may be modified to imide or the like.

The average number of functional groups of polymeric MDI is 2.3 or more, and preferably the number of functional groups is 2.3.
~ 3.1. The isocyanate content is 28 to 33% by weight, preferably 28.5.
~ 32.5% by mass. The viscosity (25 ° C.) is preferably 50 to 500 mPa · s, particularly preferably 100 to 300 mPa · s.

Polymeric MDI contains diphenylmethane diisocyanate (MDI) having two benzene rings and two isocyanate groups in one molecule, a so-called dinuclear component. The isomer constituting MDI is 2,2'-diphenylmethane diisocyanate (
Hereinafter, 2,2'-MDI is abbreviated), 2,4'-diphenylmethane diisocyanate (
Hereinafter, abbreviated as 2,4'-MDI), 4,4'-diphenylmethane diisocyanate (
Hereinafter, the four types are abbreviated as 4,4′-MDI). The isomer composition ratio of MDI is not particularly limited, but the 4,4′-MDI content is 70% by mass or more, preferably 90 to 99.9% by mass.
Is more preferable because the strength of the foam obtained is improved. Polymeric M
The MDI content of DI and the isomer composition ratio of MDI can be obtained from a calibration curve based on the area percentage of each peak obtained by GPC or gas chromatography (hereinafter abbreviated as GC).

The polymeric MDI used in the present invention is a binuclear substance (having two benzene rings in one molecule) in gel permeation chromatography (hereinafter abbreviated as GPC).
The peak area ratio of the components is 20 to 70%, preferably 25 to 65%. When the peak area ratio of the binuclear body exceeds 70%, the strength of the rigid polyurethane foam obtained is lowered and the brittle body tends to become brittle. On the other hand, when it is less than 20%, the viscosity of the resulting polyisocyanate increases, and the filling property into the mold tends to decrease.

In the present invention, if necessary, polyisocyanates other than the above-described polymeric MDI can also be used. Examples include MDI isocyanurate-modified products, uretonimine-modified products, allophanate-modified products, and the like. 2,4-tolylene diisocyanate, 2,6
-Tolylene diisocyanate, xylene-1,4-diisocyanate, xylene-1,3
An aromatic diisocyanate such as diisocyanate, tetramethylxylene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, an aliphatic diisocyanate such as tetramethylene diisocyanate, hexamethylene diisocyanate, 3-methyl-1,5-pentane diisocyanate, lysine diisocyanate; Examples include alicyclic diisocyanates such as isophorone diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated xylene diisocyanate, and hydrogenated diphenylmethane diisocyanate. In addition, these polymeric materials, urethanized products, ureaated products, allophanated products, biuretized products, carbodiimidized products, uretoniminate products, uretdioneized products, isocyanurated products, and the like, and a mixture of two or more of these may be mentioned.

The low molecular polyol (a2) used in the present invention is a low molecular polyol having a side chain alkyl group and having 4 or more carbon atoms in the side chain. Preferably, the total carbon number is 4 or more and 8 or less. The polymeric MDI (a1) is 3 to 1 with respect to the polyisocyanate composition (A).
By urethane modification with 0% by mass of the low molecular polyol (a2), a highly polar urethane group is imparted to the isocyanate. Thereby, the compatibility of isocyanate and cyclopentane is lowered, and cyclopentane is finely dispersed in the system. (A2
If the modification amount is less than the lower limit, the polyisocyanate composition (A) becomes turbid, causing a problem of separation of the liquid. In order to eliminate the turbidity, it is necessary to reduce the addition amount of the foam stabilizer. For this reason, thermal conductivity and curing properties are deteriorated. Moreover, since the viscosity of a polyisocyanate composition (A) will become high when it exceeds an upper limit, the problem that a moldability deteriorates will arise.

Since the thermal conductivity of the resulting foam is better as the cells are finer, the rigid polyurethane foam using the polyisocyanate composition of the present invention has a good thermal conductivity. In addition, a side chain alkyl group prevents aggregation between molecules at the time of manufacture of an isocyanate group containing prepolymer, and contributes to the storage stability of a polyisocyanate composition. In addition, when the number of carbon atoms of the side chain alkyl group is too small, there is a problem that turbidity is likely to occur in the isocyanate due to aggregation by the urethane group, and when the number of carbon atoms is too large, the dimensional stability of the resulting foam is deteriorated. appear. Further, when the number average molecular weight exceeds 200, there arises a problem that the dimensional stability of the obtained foam is deteriorated.

Examples of such a low molecular polyol (a2) include 2,2-diethyl-1,3-propanediol, 2,4-diethyl-1,5-pentanediol, 2,2-dimethylolheptane, and the like.

Examples of the foam stabilizer (a3) used in the present invention include known silicone surfactants such as L-5340, L-5420, L-5421, L-manufactured by Toray Dow Corning.
5740, L-580, SZ-1142, SZ-1642, SZ-1605, SZ-16
49, SZ-1675, SH-190, SH-192, SH-193, SF-2945F
SF-2940F, SF-2936F, SF-2938F, SRX-294A, F-305, F-341, F-343, F-374, F-345, F-348 made by Shin-Etsu Chemical Co., Ltd.
B-8404, B-8407, B-8465, B-8444, manufactured by Goldschmidt
Examples thereof include one or a mixture of two or more of B-8467, B-8433, B-8466, B-8870, B-8450, and the like. Among these, a foam stabilizer containing a hydroxyl group is preferable in terms of excellent thermal conductivity and curing properties. The amount of the foam stabilizer (a3) used is preferably 0.3 to 1.4% by mass based on the total weight of the polyisocyanate composition because of storage stability of the liquid.

The isocyanate group-containing prepolymer (A) used in the present invention has the above-mentioned polymeric MDI (a1) and a side chain alkyl group, the total number of carbons in the side chain is 4 or more, and the molecular weight is 200.
It is obtained by reacting the following low molecular polyol (a2) at 40 to 100 ° C. to synthesize an isocyanate group-containing prepolymer and adding or reacting the foam stabilizer (a3). The isocyanate content of the polyisocyanate (A) thus obtained is 28 to 31% by mass.
Is preferable, and 29-30.5 mass% is especially preferable.

In addition to the isocyanate group-containing prepolymer (A), the polyisocyanate composition of the present invention includes an antioxidant, an ultraviolet absorber, a flame retardant, a plasticizer, a pigment / dye, an antibacterial agent, as necessary.
It is also possible to add various additives and auxiliaries such as antifungal agents.

The specific procedure of the method for producing the rigid polyurethane foam of the present invention is as follows: a polyisocyanate composition containing the aforementioned isocyanate group-terminated prepolymer (A), and the aforementioned polyol (B), catalyst (C), foaming In the presence of the agent (D), the foaming agent (E), and other additives, etc., they are mixed, foamed and cured using an apparatus described later.

There is no restriction | limiting in particular as a polyol (B), The thing used for well-known urethane industry can be used, For example, polyester polyol, polyether polyol, polycarbonate polyol, etc. are mentioned. In consideration of foam strength and the like, a low molecular polyol, a low molecular polyamine, a low molecular amino alcohol, or the like can be used in combination.

The catalyst (C) used in the present invention is characterized by containing a urethanization catalyst (C1) and a trimerization catalyst (C2). As the urethanization catalyst (C1), N-methylimidazole,
Metal complexes such as trimethylaminoethylpiperazine, tripropylamine, tetramethylhexamethylenediamine, triethylenediamine, triethylamine, N-methylmorpholine, dimethylcyclohexylamine, dibutyltin diacetate, dibutyltin dilaurate, and acetylacetone metal salts Etc. Examples of the trimerization catalyst (C2) include 2,4,6-tris (dimethylaminomethyl) phenol, triazines such as 1,3,5-tris (dimethylaminopropyl) hexahydro-s-triazine, 2,4-bis (Dimethylaminomethyl) phenol, potassium 2-ethylhexanoate, sodium 2-ethylhexanoate, potassium acetate, sodium acetate, amine compounds such as 2-ethylaziridine and the like, tertiary amine carboxylates, etc. Examples include quaternary ammonium compounds, diazabicycloundecene, lead compounds such as lead naphthenate and lead octylate, alcoholate compounds such as sodium methoxide, phenolate compounds such as potassium phenoxide, and the like. These (C1) and (C2) can be used alone or in combination of two or more. The amount of the total catalyst (C) used is suitably from 0.01 to 15% by mass based on the polyol for reasons such as filling into the mold.

As the blowing agent, cyclopentane (D1) or (D1) and water (D2) are used in combination.
When the foaming agent is cyclopentane only, the resulting foam tends to shrink. The amount of the blowing agent used is 0.1 to 30% by mass of cyclopentane and 0.1 to 3% by mass of water based on the polyol.
It is.

Furthermore, for example, carbonate compounds such as ethylene carbonate and propylene carbonate can be used as a cocatalyst for promoting the reaction.

In the present invention, other additives can be used. Examples of the additives include plasticizers, fillers, colorants, flame retardants, organic or inorganic fillers, antioxidants, ultraviolet absorbers, plasticizers, pigments / dyes, antibacterial agents / antifungal agents, and the like. . In the present invention, it is preferable to use a flame retardant.
Examples of the flame retardant include phosphate esters such as triethyl phosphate and tris (β-chloropropyl) phosphate, and phosphate compounds such as phosphite esters such as ethyl phosphite and diethyl phosphite.

The rigid polyurethane foam obtained by the present invention has chemical bonds such as urethane bonds and urea bonds. Moreover, depending on manufacturing conditions, an isocyanurate group can be generated at the time of foaming. The isocyanurate group is generated by trimerizing an isocyanate group with a catalyst, and can improve mechanical strength, heat resistance, and the like.

Isocyanate index (total isocyanate groups / total active hydrogen groups × 100)
Is 50 to 800, preferably 80 to 300.

In producing the rigid polyurethane foam, any apparatus can be used as long as the raw material liquids can be mixed uniformly. For example, small mixer, low pressure or high pressure foaming machine for injection foaming, low pressure or high pressure foaming machine for slab foaming, low pressure or high pressure foaming machine for continuous line, spraying work For example, a spray foaming machine can be used.

EXAMPLES Hereinafter, although an Example demonstrates this invention in more detail, this invention is not limited to these. In Examples and Comparative Examples, “%” indicates “mass%”.

[Synthesis of polyisocyanate for rigid polyurethane foam]
<Synthesis Example 1>
In a reactor equipped with a stirrer, a cooling tube, a nitrogen introduction tube, and a thermometer, P-MDI (1) was 985.9.
kg was charged and heated to 40 ° C. with stirring. Next, 5 kg of DMH was added and reacted at 80 ° C. for 4 hours with stirring, then 1.8 kg of L-6900 and B-8466 of 7.
Charge 3kg, mix uniformly, polyisocyanate NCO- for rigid polyurethane foam
1 was obtained. The NCO content of NCO-1 was 30.1%.

Synthesis Examples 2-6
In the same manner as in Synthesis Example 1, polyisocyanate compositions NCO-2 to 6 for rigid polyurethane foam were obtained with the raw materials and preparation ratios shown in Table 1. For NCO-5 and NCO-7, the prepolymer became cloudy due to compatibility problems.

Synthesis Examples 1-7, in Table 1, MR-200: Polymeric MDI manufactured by Nippon Polyurethane Industry
Trade name, Millionate (registered trademark) MR-200
Isocyanate content = 31.1%
MDI content = 40%
Isomer content other than 4,4′-MDI in MDI = 0.1%
Viscosity at 25 ° C. = 130 mPa · s
* Also in Table 2, DMH: 3,3-dimethylol heptane DEPD: 2,4-diethyl-1,5-pentanediol 1,4BD: 1,4-butanediol SUR-1: Silicone foam stabilizer, product Name "L-6900 (made by Momentive)"
SUR-2: Silicone foam stabilizer, trade name “B8466 (manufactured by Evonik)”

[Formulation of polyol premix]
By mixing at a mass blending ratio shown in Table 2, polyol premixes OH-1 to OH-2 were obtained.

In the above blending example, polyol-1: polyether polyol obtained by adding propylene oxide with sucrose as an initiator, polyether polyol mainly composed of polyol, nominal hydroxyl value = 390
Polyol-2: Polyether polyol mainly composed of polyether polyol obtained by addition of propylene oxide using sorbitol as an initiator, nominal functional group number = 5.0, nominal hydroxyl value = 460
Polyol-3: Polyether polyol using toluenediamine as an initiator, nominal hydroxyl value = 460
CAT-1: Tetramethylethylenediamine, trade name “TOYOCAT-TE (manufactured by Tosoh)”
CAT-2: Tris (dimethylaminopropyl) hexahydro-s-triazine, trade name “TOYOCAT-TRC (manufactured by Tosoh)”
CAT-3: Pentamethyldiethylenetriamine, trade name “TOYOCAT-DT
(Tosoh)

<Molding polyurethane foam>
In a combination of NCO-1 and OH-1 (Example 1), the isocyanate is 45 ° C. ±
After adjusting the polyol to 1 ° C. and 20 ° C. ± 1 ° C., it was blended in a 2.0-liter polyethylene beaker with an isocyanate index of 120, stirred and mixed for several seconds with a stirring mixer at a rotational speed of 5000 rpm, and kept at 45 ° C. in advance. Mold foaming was performed in a 500 × 500 × 100 mm aluminum mold, and the resulting foam was checked for cure properties and the like. The pack rate was 165%. The results are shown in Table 3.

Similarly to Example 1, rigid polyurethane foams were molded for Examples 2 to 3 and Comparative Examples 1 to 4, and the curing properties and the like were confirmed. The results are shown in Table 3.

<Appearance>
Store in a glass bottle under an atmosphere of 20 ° C., and after about 24 hours, visually check the condition.
Clear: There is no turbidity and you can see the other side
Turbidity: Separation where the liquid is turbid and the other side is not visible: Precipitation is present at the bottom of the liquid

<Cure property test>
(1) The foam is injected into a horizontal mold of 500 × 500 × 100 mmt so that the packing rate is 165.
(2) Demold after a predetermined time.
(3) After demolding, the foam is cut in the middle and divided into four equal parts.
(4) The thickness of the cut surface is measured.
(5) The smaller the thickness of the cut surface, the better the demoldability.

<Thermal conductivity test>
Using a thermal conductivity measuring device HC-074 (Auto Λ) manufactured by Eihiro Seiki Co., Ltd., JIS A
Measurement was performed according to 1412.
The smaller the measured value, the better the thermal conductivity.
Heat transfer amount = area to conduct heat (m ² ) ÷ thickness of object (m) × thermal conductivity (W / mK) × temperature difference. The smaller the measured value of thermal conductivity, the smaller the heat transfer amount. , Less energy loss.

When a foam is produced using a polyisocyanate composition that does not use the low-molecular polyol (a2), the thermal conductivity is greatly deteriorated (Example 1, Comparative Example 1). Also,
Even when the low molecular polyol (a2) is used, when a foam stabilizer is added to the polyol premix, not only the turbidity is generated in the polyol premix (OH-2)
As a result, the thermal conductivity and the curing property are deteriorated (Example 1, Comparative Example 3).

When the amount of the low-molecular polyol (a2) added is less than the lower limit, the polyisocyanate composition is turbid due to the cohesive force of the foam stabilizer, and the thermal conductivity and curing properties are further deteriorated. (Example 1, comparative example 2).

When the carbon number of the side chain of the low molecular polyol is less than 4, turbidity occurs because the cohesive force of the low molecular polyol is too strong in the polyisocyanate composition, and this turbidity precipitates.
Since the liquid was separated and a good rigid polyurethane foam could not be obtained, it was not possible to evaluate the thermal conductivity and the curing property.

The polyisocyanate composition for rigid polyurethane foam and the rigid polyurethane foam obtained by the present invention are optimal as thick heat insulating materials, but in addition, board, panel, refrigerator, firewood, door, shutter, sash, concrete It can be applied to various types of heat insulating materials such as residential houses, bathtubs, cryogenic tank equipment, refrigerated warehouses, pipe covers, plywood sprays, condensation prevention, and slabs.

Claims (4)

An isocyanate group comprising a polymeric MDI (a1), a low molecular polyol (a2) having a side chain alkyl group and having a total number of carbon atoms of 4 or more and a molecular weight of 200 or less, and a foam stabilizer (a3) Containing prepolymer (A), and the added amount of (a2) is 3 to 1 with respect to (A)
A polyisocyanate composition for rigid polyurethane foam for foaming cyclopentane, characterized by being 0% by mass. The polyisocyanate composition for rigid polyurethane foam for cyclopentane foaming according to claim 1, wherein the foam stabilizer (a3) contains a hydroxyl group. The polyisocyanate composition containing the isocyanate group-containing prepolymer (A) according to claim 1 or 2 and the polyol (B) are reacted and foamed in the presence of a catalyst (C) and cyclopentane (D1). Manufacturing method of rigid polyurethane foam. The catalyst (C) contains a urethanization catalyst (c1) and a trimerization catalyst (c2),
The blowing agent uses cyclopentane (D1) and water (D2) in combination.
A method for producing a rigid polyurethane foam according to 1.