JP2001354743A - Production method for rigid polyurethane foam - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a rigid polyurethane foam which is produced by using a non-ozone layer depleting blowing agent, has an improved heat conductivity, and does not exhibit shrinkage at a normal temperature inspect of the low density. SOLUTION: This rigid polyurethane foam is produced by using a polyol prepared by the aniline-initiated addition polymerization of an alkylene oxide and by using a blowing agent comprising carbon dioxide, a hydrocarbon or the like. Thus obtained foam has cells with very small diameters and has been markedly improved in wet heat resistance which is regarded as a method for accelerated testing of normal-temperature dimensional change.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a blowing agent containing carbon dioxide gas.
The present invention relates to a method for producing a rigid polyurethane foam using a hydrocarbon or a hydrofluorocarbon.

[0002]

2. Description of the Related Art A rigid polyurethane foam obtained by mixing a polyisocyanate, a polyol, a catalyst, a foam stabilizer, other auxiliaries, and a foaming agent can be used as a structural material having a self-adhesive force, and has a high moldability. Widely used as an excellent heat insulating material. However, chlorofluorocarbons such as trichlorofluoromethane (CFC-11), which has been used in large quantities as a foaming agent for rigid polyurethane foams, have already been discontinued due to the destruction of the ozone layer, and are currently mainly used. 1,
1-dichloro-1-fluoroethane (HCFC-141
Hydrochlorofluorocarbons such as b) are similarly regulated. It is carbon dioxide, hydrocarbon, or hydrofluorocarbon that can be used in the future in terms of environmental characteristics without destruction of the ozone layer, but any of them is chlorofluorocarbon or hydrochlorofluorocarbon. Has disadvantages.

Rigid polyurethane foams are required to have various foam properties such as moldability, strength, and foam fluidity, in addition to thermal conductivity and dimensional stability at room temperature.
In addition, low cost is required due to the large amount of use.

[0004] In rigid polyurethane foams, the choice of polyol has a great influence on them, and is important in foam performance. Numerous compounds such as sucrose and toluenediamine are generally used as initiators used in polyols of rigid polyurethane foams.However, when a carbon dioxide gas, hydrocarbon, or hydrofluorocarbon is used as a blowing agent, the rigid polyurethane foam When the density of the molded product is in a practical and low density range,
With these polyols, a rigid polyurethane foam for a heat insulating material that sufficiently satisfies the required performance required for practical use, such as a small cell diameter, sufficiently good heat insulating properties, and excellent dimensional change at room temperature, has not been obtained.

[0005]

Carbon dioxide or a hydrocarbon such as isobutane, n-pentane, cyclopentane, isopentane, n-hexane, cyclohexane, isohexane and heptane;
1,1,3,3-pentafluoropropane (HFC-2
45fa), and rigid polyurethane foams foamed with hydrofluorocarbons such as 1,1,1,2-tetrafluoroethane (HFC-134a) have a higher thermal conductivity of steam than foams foamed with chlorofluorocarbons and the like. It is known that the heat insulation property is deteriorated due to the high temperature.

When the bubble diameter is sufficiently small, the thermal conductivity is determined by the thermal conductivity of the vapor in the bubble, the thermal conductivity of the solid layer composed of the bubble skeleton and the bubble film constituting the bubble, and the heat conductivity from the bubble film to the bubble film. It is expressed by the sum of the thermal conductivity due to radiation, and it is known that the thermal conductivity due to radiation becomes smaller as the bubble diameter becomes smaller. Therefore, for rigid polyurethane foams, in the use of heat insulating materials, studies have been conducted to reduce the cell diameter in order to reduce the thermal conductivity.

Further, rigid polyurethane foam foamed with carbon dioxide gas and hydrocarbons generated from the reaction between water and polyisocyanate has a dimensional change at room temperature at a lower density level than foam foamed with CFC-11. It is known that the ratio increases and the dimensional stability deteriorates. If such a foam is left at room temperature, it gradually shrinks over a long period of time, and may eventually result in abnormal appearance of the product. It is known that the cause is correlated with the fact that carbon dioxide gas in the foam of the foam easily permeates through the polyurethane resin membrane and is easily released to the outside. Therefore, 100% water foaming using only carbon dioxide as a foaming agent is particularly remarkable.

[0008] Hydrocarbons such as cyclopentane and hydrofluorocarbons such as HFC-245fa have poor solubility in polyols and are therefore easily separated, and are more frequently mixed in premixes than CFC-11 or HCFC-141b. Can not. In order to further reduce the density in such a system, it is necessary to use a relatively large amount of water in combination, but when the amount of water is increased, the amount of carbon dioxide gas generated by the reaction between water and the polyisocyanate increases. Shrinkage easily occurs at room temperature. The present invention provides a method for improving the heat insulating property by reducing the cell diameter of a rigid polyurethane foam, and a method for solving the problem of dimensional stability at room temperature.

[0009]

Means for Solving the Problems The inventors of the present invention have found that, among polyols using aniline as the main initiator, 1.0 to 5.7 moles of ethylene oxide is preferable for 1 mole of aniline. Is subjected to addition polymerization in the range of 1.5 to 4.5 mol, and
Addition polymerization is performed in an amount of 5.4 mol, desirably in the range of 0.3 to 3.8 mol, and a hydroxyl value of 250 to 550 mgKOH /
g, desirably 300 to 500 mgKOH / g in an amount of 20 to 100 parts by weight, desirably 30 to 70 parts by weight of 100 parts by weight of the polyol in the formulation of the rigid polyurethane foam.
It has been found that by using it in the range of parts by weight, a foam having a very fine cell diameter and good dimensional stability can be obtained.

In the case where aniline-based polyol is subjected to addition polymerization of ethylene oxide in an amount of 1.0 mol or less with respect to 1 mol of aniline, the dimensional stability of the obtained rigid polyurethane foam is not sufficiently good, and 5.7 mol or more. Even in the case of addition polymerization, the dimensional stability of the obtained rigid polyurethane foam is not sufficiently good. Further, when the hydroxyl value is 550 mgKOH / g or more, the flyability (fragility) of the obtained rigid polyurethane foam deteriorates, and when the hydroxyl value is 250 mgKOH / g or less, the obtained rigid polyurethane foam has dimensional stability. The property is not sufficiently good. Since the hydroxyl value and the number of moles of ethylene oxide added are limited, the number of moles of propylene oxide added is also limited to the range of 0 to 5.4 moles.

When the aniline-based polyol thus obtained is used to obtain a rigid polyurethane foam, when the rigid polyurethane foam is formulated, the aniline-based polyol is added in an amount of 20 parts by weight based on 100 parts by weight of the polyol. When used below, since the cells of the obtained rigid polyurethane foam are not sufficiently fine and the thermal conductivity is not good, the aniline-based polyol must be used in an amount of at least 20 parts by weight to solve this problem. There is

Further, the present inventors have found that a foam using the aniline-based polyol has a dimensional stability under a wet heat condition of 50 ° C. and 95% RH which is considered to be a test for accelerating shrinkage at room temperature. It was found to be better than a foam using. When a polyester polyol or the like, which is commercially available as a polyol for rigid polyurethane foam and is used, is used, the cells become finer, but when the amount of the foaming agent is increased and the density is decreased, the temperature is increased to 50 ° C. and 95% RH. The dimensional stability under wet heat conditions deteriorates, and shrinkage occurs at a density of 37 kg / m ³ . On the other hand, a foam using an aniline-based polyol has no shrinkage even at a density of 35 kg / m ³ , and has a possibility of lowering the density, which leads to lower costs.

Since dimensional change at room temperature requires time until a tendency appears, an accelerated test is required. Regarding the accelerated test of dimensional change at room temperature, there is no method specified in Japanese Industrial Standards and others, and it seems that each company is different. However, the inventors of the present invention have found that the dimensional change rate under the condition of 50 ° C. and 95% RH wet heat is used. Is used as an accelerated test. Rigid polyurethane foam, which tends to undergo dimensional change at room temperature, shows a clear shrinkage after about 100 days when a foam having an overpack ratio of 100% is left at room temperature, but the same foam is heated at 50 ° C and 95%.
When left under RH wet heat conditions, the same tendency of shrinkage is exhibited after about 2 weeks. Similar shrinkage may occur under 100 ° C. dry conditions, but in many cases the tendency is different,
The inventors of the present invention determine the dimensional change characteristics of each formulation at room temperature by measuring the heat and humidity resistance.

Among the raw materials used in the present invention, it is desirable to use polymeric MDI as the polyisocyanate.
There is no problem in using a polyisocyanate partially substituted with a prepolymer such as tolylene diisocyanate (TDI) or diphenylmethane diisocyanate (MDI).

As the polyol used in the present invention, the aniline-based polyol is used in an amount of 20 to 1 based on 100 parts by weight of the polyol in the formulation of the rigid polyurethane foam.
When used in an amount of 00 parts by weight, desirably 30 to 70 parts by weight, bubbles are made finer and dimensional stability is further improved. In addition, regarding other polyols used in combination with the aniline-based polyol, general sucrose,
A polyol such as toluenediamine can be used.

The blowing agents used in the present invention generally include hydrochlorofluorocarbons, which have relatively low thermal conductivity of steam and good heat insulating properties. Is not particularly required, and a general polyol can be used. However, these blowing agents will be regulated in the future and will no longer be usable in the near future.

Among the blowing agents, carbon dioxide or a hydrocarbon such as isobutane, n-pentane, cyclopentane, isopentane, n-hexane, cyclohexane, isohexane and heptane, or HFC-245fa, as specified in the present invention. And HFC-134
Any one or a combination of a plurality of hydrofluorocarbons such as a has a relatively high thermal conductivity of steam and poor heat insulation, so that the effect of the present invention in which bubbles are miniaturized is exhibited most.

As the urethane catalyst used in the present invention, a tertiary amine compound or the like used in a general rigid polyurethane foam can be used. Flame retardants and the like can be used.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION A polyol, an auxiliary agent, and a foaming agent can be mixed into a premix liquid by a well-known method such as an electric mixer or a static mixer. The obtained premix liquid can be mixed with the polyisocyanate using an existing foaming machine or mixer, whereby a rigid polyurethane foam can be produced. The present invention is not limited to the type of foaming machine or mixer for rigid polyurethane foams, and commercially available well-known ones can be used.

[0020]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the present invention is limited thereto.

Example 1 Table 1 shows Formulations 1 and 2 of Comparative Examples and Formulations 3 and 4 of Examples.
Is shown. Toho Chemical Co. polyol, water, Kao tertiary amine catalyst Kaorizer No. 1 (TMHDA) and a silicone foam stabilizer L-5420 manufactured by Nippon Unicar were charged into paper cups having an inner volume of 500 cm ³ , respectively, and mixed so as to be sufficiently uniform to obtain a premix liquid. The stock solution temperature of the premix solution was adjusted to 20 ° C, and the stock solution temperature was previously adjusted to 20 ° C.
200 was injected and stirred for 4 seconds at a rotation speed of 7,000 rpm by an electric mixer manufactured by Tokushu Kika Kogyo. 2.5 thickness with polyethylene release sheet attached in advance
The mixture was quickly charged into a 50 cm square aluminum vertical panel and foamed. After measuring the cream time and the gel time, the rigid polyurethane foam obtained 5 minutes later was taken out, and the density at an overpack ratio of 100% was measured. The next day after the foaming, three samples of 35 cm in length and 7 cm in width were cut out from the vertical panel, and the thickness at the start was measured at -30 ° C, 100 ° C, and 100 ° C, respectively, by using a dial caliper gauge LO-1 manufactured by Ozaki Seisakusho. It was left in an atmosphere of 50 ° C. and 95% RH, and the maximum dimensional change after 4 weeks was measured to calculate the maximum dimensional change rate.
On the day after foaming, the thermal conductivity was 20 mm from the vertical panel.
cm, a width of 20 cm, and a thickness of 1.5 cm were cut out and measured with an Auto Lambda HC-073 manufactured by Eiko Seiki.

Formulations 1 and 2 of the comparative examples and Formulations 3 and 4 of the examples shown in Table 1 all use the same type of raw material except for the polyol, and are the raw materials in the rigid polyurethane foam formulation. , Cyclopentane, and the foam stabilizer were made to have the same weight content in the formulation, and the catalyst weight was adjusted so that the gel time was in the range of 35 to 55 seconds. However, the weight of cyclopentane was increased only in Formulation 2 of Comparative Example. In the formulation of Comparative Example 1, Toho Kagaku Kogyo's toluenediamine-based polyol, Tohopolyol AR-2589 was used as the polyol, and in Formulas 3 and 4 of the Examples,
Two aniline-based polyols manufactured by Toho Chemical Industry are used. The same type of isocyanate is used, and the required weight is an isocyanate index of 1.1.
Calculated as 0. For each of these formulations, cream time, gel time, density, dimensional change, flyability (fragility), cell diameter, and thermal conductivity were measured.

[0023]

[Table 1]

Comparing these performances, the formulation using the toluenediamine-based polyol of Comparative Example 1 had a thermal conductivity of 0.0220 W / m ° C., whereas Examples 3 and 4 had a thermal conductivity of 0.0220 W / m ° C. In the formulation using the aniline-based polyol, the thermal conductivity is 0.0204 to 0.0206 W /
m.degree. C. and at the same time, the bubble diameter was 350 .mu.m in the formulation of Comparative Example 1, whereas Examples 3 and 4
It can be seen that the prescription is as small as 200 to 210 μm. In addition, the formulation of Comparative Example 2 increased the weight of cyclopentane and reduced the density of the formulation of Comparative Example 1 by about 10%. Comparing the performances of the formulation of Comparative Example 1 and the formulation of Comparative Example 2, the density of the formulation of Comparative Example 2 was lower than that of -3.
The dimensional change rate in an atmosphere of 0 ° C. and 50 ° C. and a relative humidity of 95% is extremely large, and the dimensional stability is deteriorated.

On the other hand, in the formulations of Examples 3 and 4, the density was about 10% higher than that of Comparative Example 1.
Despite the low density, at -30 ° C, all were -0.8%, and at 50 ° C, 95%, 0.4% to -1.0%.
%, Which is -12.5%, -1 of the formulation of Comparative Example 2.
It turns out that it is improving compared with 0.3%.

Example 2 Table 2 shows Formulation 5 of Comparative Example and Formulations 6 to 8 of Examples. The method for producing the rigid polyurethane foam and the method for measuring the foam performance are the same as those in Example 1.

Formulation 5 of the comparative example and Formulations 6 to 8 of the examples shown in Table 2 were all of the same type of raw material other than the polyol, and were water, cyclo- The weight content in the formulation was the same for pentane and the foam stabilizer, and the catalyst weight was adjusted so that the gel time was in the range of 35 to 55 seconds. In the formulation of Comparative Example 5, a sucrose-based polyol manufactured by Toho Chemical Industry, Toho Polyol O-850, and a polyester polyol for rigid polyurethane foam manufactured by Toho Rika Kogyo Co., Ltd., Phanthol PL-305 were used in a weight ratio of 1: 1 as the polyol polyol. Then, in Formulations 6 to 8 of the examples, the weight ratio of Toho polyol O-850 and the aniline-based polyol AB-250 manufactured by Toho Chemical Industry was used while being changed. The same type of isocyanate was used, and the required weight was calculated with an isocyanate index of 1.10. For each of these formulas, cream time,
Gel time, density, dimensional change, flyability (fragility), cell size, and thermal conductivity were measured.

[0028]

[Table 2]

When these performances are compared, Comparative Example 5
In a formulation in which a sucrose-based polyol and a conventionally used polyester polyol are combined, the cell diameter is 200
μm and a low thermal conductivity of 0.0204 W / m ° C., which is good. However, the dimensional change rate in a 50 ° C. 95% relative humidity atmosphere is greatly shrunk to −7.8%. In the formulations in which the sucrose-based polyol and the aniline-based polyol of Examples 6 to 8 were combined, the bubble diameter was sufficiently small, the thermal conductivity was low and good, and the dimensional change rate in a humidity atmosphere at 50 ° C and 95% was- 1.5% to 0.4%, which is small and good.

Here, when the content of the aniline-based polyol is compared with the performance, the cell diameter, the thermal conductivity, and the
In each of the dimensional change rates under a humidity of 95 ° C. and a relative humidity of 95%, the formulation of the aniline-based polyol of Example 8 was 50 parts, the formulation of the aniline-based polyol of Example 7 was 30 parts, and the content of the aniline-based polyol of Example 6 was 20 parts. It can be seen that the order of the formulation and the amount of the aniline-based polyol became worse in order of decreasing amount. From the difference between these levels, the lower limit of the amount of the aniline-based polyol used is considered to be 20 parts, preferably 30 parts or more, per 100 parts by weight of the polyol.

Example 3 Table 3 shows the formulation 9 of the example using an aniline-based polyol.
To 11 are shown. A method for producing a rigid polyurethane foam,
The method for measuring the foam performance is the same as in Example 1.

Formulations 9 to 11 in the examples shown in Table 3 use aniline-based polyols manufactured by Toho Chemical Industries,
The same kind of other raw materials are used, and the raw materials in the formulation of the rigid polyurethane foam, water, cyclopentane, and the foam stabilizer, have the same weight content in the formulation, and the catalyst weight has a gel time of 35 to 55 seconds. Adjusted to be within range. In Formulations 9 to 11 of the examples, those obtained by changing the hydroxyl value of the aniline-based polyol or the weight ratio of ethylene oxide to propylene oxide were synthesized and used. The same type of isocyanate was used, and the required weight was calculated with an isocyanate index of 1.10. For each of these formulations, cream time, gel time, density, dimensional change, flyability (fragility), cell diameter, and thermal conductivity were measured.

When these performances are compared, Example 9
Was subjected to addition polymerization of 2.1 mol of ethylene oxide and 0.3 mol of propylene oxide to give a hydroxyl value of 550 mg KO.
In the formulation using the aniline-based polyol and Toho polyol AB-204 in H / g, 2 mol of ethylene oxide and 1.2 mol of propylene oxide of Example 8 were used.
An aniline-based polyol having a hydroxyl value of 450 mgKOH / g by molar addition polymerization, Toho polyol AB-25
Compared with the performance of the formulation using 0, the bubble diameter, the thermal conductivity, and the dimensional change rate in a 50 ° C, 95% -related humidity atmosphere are all good with little difference, but there is flyability and fragility occurs. Therefore, the upper limit of the hydroxyl value of the aniline polyol is 550 mgKOH / g,
Desirably, it is believed to be 500 mg KOH / g.

Further, in the formulation of Example 10, 5.7 moles of ethylene oxide and 1.8 moles of propylene oxide were subjected to addition polymerization to obtain a hydroxyl value of 250 mgKOH / g using an aniline-based polyol and tohopolyol AB-450. Compared to the performance of the formulation of Example 8, the flyability is better than the performance of the formulation of Example 9, but the bubble diameter, thermal conductivity, and dimensional change rate in a humidity atmosphere at 50 ° C. and 95% are related. Both are good but slightly worse. This situation is the same as that in Example 11 in which 1.0 mol of ethylene oxide and 5.4 mol of propylene oxide were added and polymerized to obtain a hydroxyl value of 250 mgKOH / g, and a aniline-based polyol, Tohopolyol AB-449, was used. . From this, the lower limit of the hydroxyl value is 250 mgKOH / g, preferably 300 mgKOH / g.
It is believed to be mgKOH / g.

Further, in Example 12, the aniline-based polyol having a hydroxyl value of 250 mgKOH / g and a tohopolyol AB-451 prepared by addition-polymerizing only 6.2 mol of propylene oxide without using ethylene oxide: The flyability is similarly good, but the cell diameter, thermal conductivity, and dimensional change under a humidity atmosphere of 50 ° C. and 95% are considerably poor, and the conventionally used polyester polyol of Comparative Example 5 is used. Is worse than the prescription. From this, it is considered that the lower limit of the number of moles of added ethylene oxide is 1.0 mole, preferably 1.5 moles, and the upper limit is 5.7 moles, preferably 4.5 moles. Conceivable.

Since the hydroxyl value and the number of moles of ethylene oxide added are limited, the number of moles of propylene oxide added is also 0 to 5.4 moles, preferably 0.3 to 3 moles.
Limited to the range of 8 moles.

[0037]

[Table 3]

[0038]

According to the present invention, there is provided a method for producing a rigid polyurethane foam using carbon dioxide, hydrocarbon or hydrofluorocarbon as a blowing agent without using a hydrochlorofluorocarbon-based blowing agent which is a substance that destroys the ozone layer. A low-density, high-performance rigid polyurethane foam can be obtained. The rigid polyurethane foam according to the composition of the present invention is compared with a rigid polyurethane foam using a conventional polyol by selecting an appropriate type of alkylene oxide and using an appropriate amount of an aniline-based polyol to which an appropriate amount is added. ,
Since the thermal conductivity can be lowered by reducing the size of the foam cells, the heat insulating property is improved. Furthermore, the dimensional stability at room temperature, which leads to significant appearance deformation, is greatly improved, and the foam fluidity becomes better, resulting in lower density, and as a result, the effect of lowering costs can be expected.

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Claims (2)

[Claims] 1. An ethylene oxide and 1.0 to 5.7 mol of ethylene oxide and 0 to propylene oxide are added to 1 mol of aniline.
The addition polymerization is carried out in the range of ~ 5.4 mol, and the hydroxyl value is 250
An aniline-based polyol synthesized so as to be in a range of from 550 mgKOH / g to 20 to 10 parts by weight of the polyol 100 parts by weight in the formulation of the rigid polyurethane foam.
A method for producing a rigid polyurethane foam, which is used in a range of 0 parts by weight. 2. The method for producing a rigid polyurethane foam according to claim 1, wherein one or a combination of a plurality of carbon dioxide, hydrocarbon, and hydrofluorocarbon is used as a foaming agent. .