JPH0859781A - Rigid polyurethane foam - Google Patents

Abstract

PURPOSE: To produce the rigid polyurethane foam giving a resin premix good in storage stability and useful for heat-insulating structures, etc., from a specific polyol, a specific foaming agent, a specific organic polyisocyanate, water, a specific catalyst. etc. CONSTITUTION: This rigid polyurethane foam is produced from (A) an organic polyisocyanate such as toluene diisocyanate, (B) a polyol containing ether units of the formula:-(CR<1> R<2> -CR<3> R<4> -O-)- (R<1> -R<4> are H, hydrocarbon; the total number of carbon atoms contained in the R<1> -R<4> is >=2), (C) water, (D) a catalyst, (E) a foaming agent such as a hydrocarbon compound, e.g. cyclopentane. (F) a foam stabilizer such as an organic silicon surfactant, and (G) other auxiliaries.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rigid polyurethane foam, which is expected to be suitably used as a heat insulating material or a heat insulating structural material for refrigerators, freezers, heat insulating panels, ships or vehicles.

[0002]

2. Description of the Related Art Rigid polyurethane foam generally has a closed cell structure and contains gas of chlorofluorocarbons, carbon dioxide gas and the like in the cells. Because of its excellent heat insulation performance, low-temperature dimensional stability, and workability, it is widely used as a heat insulating material for refrigerators, freezers, building materials, etc., or as a lightweight structural material.

[0003]

In recent years, chlorofluorocarbons have been regulated to protect the ozone layer of the earth. Chlorofluorocarbons are so stable in the atmosphere that they reach the ozone layer in the sky, where they are decomposed by the action of ultraviolet rays and the like, and it is thought that the decomposition products destroy the ozone layer. . This regulation target also includes R-11 (trichlorofluoromethane) which has been used as a foaming agent for rigid polyurethane foams. Therefore, development of a technique using a foaming agent that does not destroy the ozone layer is under study.

To solve the above problems, hydrocarbon compounds such as n-pentane, isopentane and cyclopentane have been proposed as one of the alternative blowing agents for R-11. For example, JP-A-2-91132 discloses R-11 and a hydrocarbon compound, that is, ethane, propane, n-butane, isobutane, n-pentane, isopentane, neopentane, n-.
Hexane, isohexane, n-heptane, isoheptane,
It teaches that a rigid polyurethane foam excellent in filling property, low temperature dimensional stability, compressive strength and the like can be obtained by using in combination with cyclopentane, cyclohexane, cycloheptane or the like, or by using these hydrocarbon compounds alone.
Further, JP-A-3-152160 discloses cyclopentane,
It teaches that a rigid polyurethane foam having a low thermal conductivity can be obtained by using cyclohexane or the like. However, the above-mentioned hydrocarbon compounds and the like have a drawback that they are difficult to dissolve in the polyols used for the production of ordinary rigid polyurethane foams. for that reason,
The storage stability as a resin premix deteriorates, the types of polyols that can be used are limited, and various performances of rigid polyurethane foam, such as filling properties, low temperature / moist heat / high temperature dimensional stability, compressive strength, thermal conductivity, etc. I couldn't get enough out of it and wasn't satisfied.

[0005]

DISCLOSURE OF THE INVENTION The inventors of the present invention have earnestly studied a polyol which satisfies various physical properties of rigid polyurethane foam and is excellent in storage stability as a resin premix using a hydrocarbon compound as a foaming agent. As a result, the present invention has been achieved.

That is, the present invention is the following (1) to (3). (1) In a rigid polyurethane foam produced from an organic polyisocyanate, a polyol, water, a catalyst, a foaming agent, a foam stabilizer, and other auxiliaries, a hydrocarbon compound is used as a foaming agent, and a polyol 100 is used as a polyol. A rigid polyurethane foam comprising a polyol containing 5% by weight or more of an ether unit represented by Formula 1 in parts by weight. ^{- (CR 1 R 2 -CR 3} R 4 -O) - in Formula 1 (wherein, R ¹ to R ⁴ are each hydrogen or hydrocarbon, R ¹
The total number of carbon atoms contained in R ⁴ is 2 or more. (2) R ^{1 to} R ^{4 in} Formula 1 are each hydrogen or hydrocarbon, and R 1
The rigid polyurethane foam according to (1), wherein a polyol containing 5% by weight or more of an ether unit in which the total number of carbon atoms contained in ^{1 to} R ⁴ is 2 is used. (3) The rigid polyurethane foam according to (1) or (2), wherein the hydrocarbon compound used as the foaming agent is cyclopentane.

The ether unit of the formula 1 of the present invention is obtained by ring-opening addition of an alkylene oxide to a polyol having two or more active hydrogens capable of reacting with an organic polyisocyanate. The catalyst used for ring-opening addition may be an acidic catalyst such as BF ₃ .Et ₂ O or a basic catalyst such as an alkali metal hydroxide. Specific examples of the alkylene oxide which gives the ether unit of the formula 1 include 1,2-butylene oxide and 2,3-
There are butylene oxide, isobutylene oxide, styrene oxide, 1,2-epoxyalkane having 5 or more carbon atoms, and the like, with butylene oxide being preferred. These compounds can be used alone or in combination of two or more. The polyol containing ether units of formula 1 is
It may contain less than 90% by weight of ether units of oxypropylene and / or oxyethylene.

In the present invention, as the polyol, a polyol containing an ether unit of the formula 1 is an essential component, and if necessary, less than 90% by weight of the polyol, and 2 or more active hydrogens capable of reacting with the organic polyisocyanate. Propylene oxide obtained by adding alkylene oxide such as propylene oxide and ethylene oxide to the initiator having, polyester polyol obtained by dehydration condensation of polycarboxylic acid or carboxylic acid half ester and low molecular weight polyol, obtained by polymerizing caprolactone The average hydroxyl value of the polyester polyols to be used is 300 to 600 m
It can be used in a weight ratio of gKOH / g. If the ether unit of the formula 1 is not more than 10% by weight in the polyol used, a resin premix having excellent storage stability cannot be obtained. As the initiator of the polyether polyol, dipropylene glycol, glycerin, trimethylolpropane, monoethanolamine, diethanolamine,
Examples thereof include triethanolamine, pentaerythritol, ethylenediamine, 2,4- and 2,6-diaminotoluene, 4,4′-diaminodiphenylmethane, sorbitol, sucrose and the like.

The hydrocarbon compound used as the blowing agent is
There are cyclopentane, n-pentane, isopentane, etc.,
These compounds may be used alone or in combination of two or more. An appropriate amount of water is 0.001 to 10 parts by weight with respect to 100 parts by weight of the polyol, and
More suitable is 5 to 5 parts by weight.

In the present invention, all known organic polyisocyanates can be used. The most common are toluene diisocyanate (TDI) and diphenylmethane diisocyanate (MDI). TDI
Is a mixture of isomers, that is, 100% 2,4-isomer,
2,4-body / 2,6-body = 80 / 20,65 / 35 (weight ratio), etc., as well as the product name Mitsui Cosmonate T
So-called crude TDI containing polyfunctional tars known as RC etc. can also be used. Also, for the MDI,
So-called polymeric M such as Mitsui Cosmonate M-200 containing polyhedra with three or more nuclides in addition to pure products containing 4,4'-diphenylmethane diisocyanate as a main component.
DI can be used.

Organic polyisocyanate and polyol,
The equivalent ratio of the active hydrogen capable of reacting with the organic polyisocyanate in the mixture of water, the catalyst, the foaming agent, the foam stabilizer and the other auxiliary agent is NCO / H (active hydrogen) = 0.60 or more.
A value of 00 or less is particularly suitable.

As the catalyst, for example, amine-based urethane-forming catalysts such as trimethylaminoethylpiperazine, triethylamine, tripropylamine, N-methylmorpholine, N-ethylmorpholine, triethylenediamine, tetramethylhexamethylenediamine, etc. can be used. . These catalysts can be used alone or as a mixture, and the amount of the catalyst used is the amount of the compound 100 having active hydrogen.
Appropriately 0.0001 parts by weight or more and 10.0 parts by weight or less with respect to parts by weight.

As the foam stabilizer, a conventionally known organosilicon surfactant is used. For example, L-5420, L-5340, SZ-1645, SZ- manufactured by Nippon Unicar Co., Ltd.
1627, SZ-1923, Shin-Etsu Chemical Co., Ltd. F-343, F-345, F-347, F-348, F
-350S or the like is suitable. The amount of these foam stabilizers used is
It is 0.1 part by weight or more and 10 parts by weight or less based on 100 parts by weight of the total of the compound having active hydrogen and the organic polyisocyanate. In addition, flame retardants, plasticizers, stabilizers, colorants and the like can be added as required.

[0014]

The present invention will be described below with reference to examples. The raw materials used in Examples and Comparative Examples are as follows. Cosmonate M-200: Mitsui Toatsu Chemical Co., Ltd. product Polymeric MDI NCO% 31.3 Polyol A: Sorbitol / glycerin (weight ratio 94
A polyether polyol having a hydroxyl value of 470 mgKOH / g obtained by adding 1,2-butylene oxide to / 6). Polyol B: sorbitol / glycerin (weight ratio 94
/ 6) with 1,2-epoxydodecane / propylene oxide (10/90) added to give a hydroxyl value of 470 mgKOH
/ G of polyether polyol. Polyol C: sorbitol / glycerin (weight ratio 94
/ 6) with 1,2-butylene oxide / ethylene oxide (85/15) added to give a hydroxyl value of 470 mgKOH /
g of polyether polyol. Polyol D: sorbitol / glycerin (weight ratio 94
/ 6) propylene oxide added hydroxyl value 470
mg KOH / g polyether polyol. Polyol E: sorbitol / glycerin (weight ratio 94
/ 6) to propylene oxide / ethylene oxide (85
/ 15) -added polyether polyol having a hydroxyl value of 470 mgKOH / g. Foam stabilizer: Nippon Unicar Co., Ltd. product SZ-1627 Catalyst: Active Material Chemical Co., Ltd. product Minico TMHD (Tetramethylhexamethylenediamine) Foaming agent: Cyclopentane, isopentane, n-pentane Tokyo Kasei Co., Ltd. reagent special grade

The polyols shown in Tables 1 and 2 and water as a foaming main agent, a foam stabilizer, a foaming agent, and a catalyst were adjusted to predetermined amounts, and 20
It was kept at ℃. A predetermined amount of organic polyisocyanate (Cosmonate M-200) adjusted to 20 ° C. was added to this, and mixed for 5 seconds at high speed, and an aluminum mold (thickness 20 mm × width 300 mm × length) previously adjusted to 40 ° C. 450 m
m) was injected with 110 g, and the mold was removed after 5 minutes. The equivalent ratio of organic polyisocyanate to total active hydrogen is NCO / H =
It was set to 1.10. Tables 1 and 2 show various characteristic values of the obtained rigid polyurethane foam and stability with time of the resin premix.

The various characteristic values of the rigid polyurethane foam and the conditions for measuring the stability of the resin premix with time are as follows. Density The density of the core of rigid polyurethane foam. Thermal conductivity Measured at an intermediate temperature of 25 ° C (low heating plate 10 ° C, high heating plate 40 ° C) using an Auto Λ HC-072 type manufactured by Eiko Seiki Co., Ltd. Resin premix stability over time After adjusting the resin, leave it in a closed container for 1 day and then visually observe. ◯: Uniformly transparent Δ: Opaque and separated into 3 layers ×: Completely separated into 2 layers Low temperature dimensional stability The foam sample was left in a constant temperature bath at −30 ° C. for 6 hours or more, and the volume change rate was measured. Compressive strength Measures the compressive strength in the direction perpendicular to the foaming direction of the foam.

[0017]

[Table 1]

[0018]

[Table 2]

Table 1 shows examples and Table 2 shows comparative examples.
Comparative examples in Table 2 show that when a hydrocarbon compound such as cyclopentane, isopentane or n-pentane is used as a foaming agent,
It shows that the stability of the resin premix of the polyol obtained by adding propylene oxide and / or ethylene oxide as the polyol with time is not good. From Table 1, when a polyether polyol obtained by adding butylene oxide, 1,2-epoxydodecane, etc. as a polyol is used, a resin premix having better stability over time than that in Table 2 is obtained, and polyurethane is obtained. It can be seen that the physical properties of the foam are also good.

[0020]

INDUSTRIAL APPLICABILITY The present invention provides a resin premix having good storage stability when using a hydrocarbon compound as a foaming agent, and achieves various physical properties of the rigid polyurethane foam produced thereby. To do.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical indication location C08L 75:04 (72) Inventor Izugawa 2-1, Tango-dori, Minami-ku, Aichi Prefecture Mitsui Toatsu Chemical Co., Ltd.

Claims (3)

[Claims] 1. An organic polyisocyanate, a polyol,
In a rigid polyurethane foam produced from water, a catalyst, a foaming agent, a foam stabilizer, and other auxiliaries, a hydrocarbon compound is used as the foaming agent, and as the polyol, an ether represented by the formula 1 in 100 parts by weight of the polyol. A rigid polyurethane foam comprising a polyol containing 5% by weight or more of a unit. ^{- (CR 1 R 2 -CR 3} R 4 -O) - in Formula 1 (wherein, R ¹ to R ⁴ are each hydrogen or hydrocarbon, R ¹
The total number of carbon atoms contained in R ⁴ is 2 or more. ) 2. A polyol containing 5 wt% or more of ether units in which R ^{1 to} R ^{4 in} formula 1 are each hydrogen or hydrocarbon and the total number of carbon atoms contained in R ^{1 to} R ⁴ is 2. The rigid polyurethane foam according to claim 1, which is characterized in that 3. The rigid polyurethane foam according to claim 1, wherein the hydrocarbon compound used as the foaming agent is cyclopentane.