JP4051684B2 - Method for producing rigid polyurethane foam - Google Patents

Description

The present invention relates to a method for producing a rigid polyurethane foam using carbon dioxide, hydrocarbon, or hydrofluorocarbon as a foaming agent.

Rigid polyurethane foam obtained by mixing polyisocyanates, polyols, catalysts, foam stabilizers, other auxiliaries, and foaming agents can be used as a structural material with self-adhesive properties and has excellent moldability As widely used. However, chlorofluorocarbons such as trichlorofluoromethane (CFC-11), which has been used in large quantities as foaming agents for rigid polyurethane foams, have already been discontinued in order to destroy the ozone layer and are currently mainly used. Hydrochlorofluorocarbons such as 1,1-dichloro-1-fluoroethane (HCFC-141b) are also regulated. Carbon dioxide, hydrocarbons, or hydrofluorocarbons that can be used in the future without destroying the ozone layer are considered to be usable in the future, but all of them are different from chlorofluorocarbons or hydrochlorofluorocarbons. Has drawbacks.

Rigid polyurethane foam is required to have various foam performances such as moldability, strength, and foam flowability in addition to thermal conductivity and dimensional stability at room temperature. It has been demanded.

In rigid polyurethane foams, the choice of polyol has a significant impact on these and is important for foam performance. As initiators used for rigid polyurethane foam polyols, many compounds such as sucrose and toluenediamine are generally used. When carbon dioxide, hydrocarbon, or hydrofluorocarbon is used as a foaming agent, When the density of the molded product is in a practical and low density range, these polyols have sufficient performance required for practical use, such as small bubble size, good heat insulation and excellent dimensional change at room temperature. No satisfactory rigid polyurethane foam for thermal insulation has been obtained.
JP 56-163117 A

Carbon dioxide or hydrocarbons such as isobutane, n-pentane, cyclopentane, isopentane, n-hexane, cyclohexane, isohexane, and heptane, or 1,1,1,3,3-pentafluoropropane (HFC-245fa) And rigid polyurethane foams foamed with hydrofluorocarbons such as 1,1,1,2-tetrafluoroethane (HFC-134a) have a higher thermal conductivity of the steam than foams foamed with chlorofluorocarbons, etc. Therefore, it is known that the heat insulation properties deteriorate.

When the bubble diameter is sufficiently small, the thermal conductivity is the thermal conductivity of the vapor in the bubble, the thermal conductivity of the solid layer part consisting of the bubble skeleton and bubble film constituting the bubble, and the heat due to radiation from the bubble film to the bubble film. It is known that the thermal conductivity due to radiation is smaller as the bubble diameter is smaller. Therefore, in rigid polyurethane foams, studies have been conducted to reduce the bubble diameter for the purpose of reducing the thermal conductivity in the use of heat insulating materials.

In addition, carbon dioxide produced from the reaction between water and polyisocyanate, and rigid polyurethane foam foamed with hydrocarbon have a larger dimensional change rate at room temperature at a lower density level than foam foamed with CFC-11. It is known that the dimensional stability becomes worse. If such a foam is left at room temperature, it gradually shrinks over a long period of time, which may ultimately cause an abnormal appearance of the product. The cause of this is known to correlate with the fact that carbon dioxide in the foam bubbles easily permeates the polyurethane resin film and is thus easily released to the outside. Accordingly, 100% water foaming using only carbon dioxide as the foaming agent is particularly prone to this tendency.

Hydrocarbons such as cyclopentane and hydrofluorocarbons such as HFC-245fa are easily separated because they are poorly soluble in polyols and cannot be mixed much during premixing compared to CFC-11, HCFC-141b, and the like. In order to further reduce the density in such a system, it is necessary to use a relatively large amount of water. However, if water is increased, carbon dioxide generated by the reaction between water and polyisocyanate increases. Shrinkage is likely to occur at room temperature. The present invention provides a method for reducing the cell diameter of rigid polyurethane foam to improve heat insulation, and a method for solving the problem of dimensional stability at room temperature.

The inventors of the present invention mainly used aniline as a polyol in a method for producing a rigid polyurethane foam using one or a combination of carbon dioxide, hydrocarbon, or hydrofluorocarbon as a blowing agent. Of the polyol used as an agent, ethylene oxide is addition-polymerized in an amount of 1.0 to 5.7 mol, preferably 1.5 to 4.5 mol, and propylene oxide is 0 to 5. mol per mol of aniline. An aniline-based polyol synthesized by addition polymerization in a range of 4 mol, preferably 0.3 to 3.8 mol, and having a hydroxyl value in the range of 250 to 550 mgKOH / g, preferably 300 to 500 mgKOH / g, 20-100 weights of 100 parts by weight of polyol in the polyurethane foam formulation Parts, preferably by using a range of 30 to 70 parts by weight, bubble diameter becomes very fine, and a form having good dimensional stability it is obtained.

According to the present invention, a low-density, high-performance is produced in 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 that destroys the ozone layer. It becomes possible to obtain a rigid polyurethane foam. Rigid polyurethane foams according to the composition of the present invention are selected by selecting the 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 refining the foam bubbles, the heat insulation is improved. Furthermore, the dimensional stability at room temperature leading to a significant appearance deformation is greatly improved, and the foam fluidity becomes better and the density is lowered. As a result, an effect of cost reduction can be expected.

In the aniline-based polyol, when 1.0 mol or less of ethylene oxide is added to 1 mol of aniline, the dimensional stability of the obtained rigid polyurethane foam is not sufficiently good, and 5.7 mol or more is added and polymerized. Even in this case, the dimensional stability of the obtained rigid polyurethane foam is not sufficiently good. When the hydroxyl value is 550 mgKOH / g or more, the resulting rigid polyurethane foam has poor flyability (fragility). When the hydroxyl value is 250 mgKOH / g or less, the obtained rigid polyurethane foam is dimensionally stable. The properties are not good enough. Since the hydroxyl value and the number of added moles of ethylene oxide are limited, the number of added moles of propylene oxide is also limited to the range of 0 to 5.4 moles.

In addition, when using the aniline-based polyol thus obtained to obtain a rigid polyurethane foam, the aniline-based polyol is used in an amount of 20 parts by weight or less out of 100 parts by weight of the polyol in the formulation of the rigid polyurethane foam. In this case, since the air bubbles of the obtained rigid polyurethane foam are not sufficiently fine and the thermal conductivity is not low and good, it is necessary to always use 20 parts by weight or more of aniline-based polyol in order to solve this problem.

Furthermore, the inventors of the present invention use other polyols that have a dimensional stability under conditions of 50 ° C. and 95% RH wet heat, in which foams using the aniline-based polyols are considered to be an acceleration test for shrinkage at room temperature. It was found to be better than foam. It is marketed as a polyol for rigid polyurethane foam, and when the polyester polyol that is usually used is used, the bubbles become finer. However, if the amount of foaming agent is increased and the density is lowered, the temperature is reduced to 50 ° C. and 95% RH. The dimensional stability under wet heat conditions deteriorates and shrinks at a density of 37 kg / m ³ . On the other hand, the foam using the aniline-based polyol has no possibility of shrinkage even at a density of 35 kg / m ³ , and there is a possibility of lowering the density leading to cost reduction.

Since dimensional changes at room temperature require time until a tendency appears, an accelerated test is necessary. Regarding the accelerated test of dimensional change at room temperature, there are no methods defined by Japanese Industrial Standards and others, and it seems that each company is different. However, the inventors of the present invention have a dimensional change rate under conditions of 50 ° C. and 95% RH wet heat. Is used as an accelerated test. Rigid polyurethane foam, which tends to cause dimensional changes at room temperature, shows obvious shrinkage after about 100 days when a foam with an overpack rate of 100% is left at room temperature, but the same foam is left under conditions of 50 ° C and 95% RH wet heat. Then, a similar contraction tendency is exhibited after about 2 weeks. The same shrinkage may occur even under dry conditions at 100 ° C, but the tendency is different in many cases. Therefore, the inventors of the present invention determine the dimensional change characteristics of each prescription at room temperature by measuring the heat and moisture resistance. ing.

Among the raw materials used in the present invention, it is desirable to use polymeric MDI as the polyisocyanate, but some use polyisocyanate replaced with prepolymers such as tolylene diisocyanate (TDI) or diphenylmethane diisocyanate (MDI). There is no hindrance.

As the polyol used in the present invention, by using the aniline-based polyol in the range of 20 to 100 parts by weight, preferably 30 to 70 parts by weight, out of 100 parts by weight of the polyol in the formulation of the rigid polyurethane foam, Miniaturization further improves dimensional stability. In addition, regarding other polyols used in combination with aniline-based polyols, general polyols such as sucrose and toluenediamine can be used.

In general, hydrochlorofluorocarbons are included as blowing agents used in the present invention, and these have a relatively low thermal conductivity of vapor and good heat insulation properties, and therefore need special measures as in the present invention. However, general polyol can be used. However, these blowing agents will be regulated in the future and will not be usable in the near future.

Among the blowing agents, carbon dioxide gas or hydrocarbons such as isobutane, n-pentane, cyclopentane, isopentane, n-hexane, cyclohexane, isohexane, and heptane, or HFC-245fa, and HFC- Since one or a combination of a plurality of hydrofluorocarbons such as 134a has a relatively high thermal conductivity of vapor and poor heat insulation, the effect of the present invention that makes bubbles finer is most exerted.

The urethane catalyst used in the present invention can be a tertiary amine compound or the like used in general rigid polyurethane foams, and other ordinary foam stabilizers, flame retardants and the like which are generally marketed as other auxiliary agents. Can be used.

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

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto.

Example 1 Table 1 shows Formulations 1 and 2 of Comparative Examples and Formulations 3 and 4 of Examples. Toho Chemical Co., Ltd. polyol, water, Kao tertiary amine catalyzer No. 1 (TMHDA) and Nihon Unicar silicone foam stabilizer L-5420 were charged into a paper cup having an internal volume of 500 cm ³ , respectively, and mixed so as to be sufficiently uniform to obtain a premix solution. The stock solution temperature of the premix solution is adjusted to 20 ° C., and Mitsui Chemicals Cosmonate M-200 with the stock solution temperature adjusted to 20 ° C. is injected into the premix solution, and the rotational speed is 7,000 rpm by an electric mixer manufactured by Special Machine Industries. For 4 seconds. This mixture was quickly put into an aluminum vertical panel having a thickness of 2.5 cm and a 50 cm square to which a polyethylene release sheet had been attached in advance and foamed. After measuring the cream time and gel time, the rigid polyurethane foam obtained after 5 minutes was taken out, and the density when the overpack rate was 100% was measured. The next day after foaming, 3 samples of 35 cm length and 7 cm width were cut out from the vertical panel, and the starting thickness was measured with dial caliper gauge LO-1 manufactured by Ozaki Mfg. The sample 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. The thermal conductivity was measured the next day after foaming by cutting out a sample having a length of 20 cm, a width of 20 cm, and a thickness of 1.5 cm from the vertical panel, and measuring with an auto lambda HC-073 manufactured by Eihiro Seiki.

The formulations 1 and 2 of the comparative examples shown in Table 1 and the formulations 3 to 4 of the examples are the same in the types of raw materials other than the polyol, and are water and cyclopentane that are raw materials in the formulation of the rigid polyurethane foam. The weight content in the formulation was the same for the foam stabilizer 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 is increased only in the prescription 2 of the comparative example. In the formulation of Comparative Example 1, toluene diamine-based polyol and Toho Polyol AR-2589 manufactured by Toho Chemical Industry are used as the polyol, and in the formulations 3 to 4 of Examples, two aniline-based polyols manufactured by Toho Chemical Industry are used. . Further, the same type of isocyanate was used, and the required weight was calculated with an isocyanate index of 1.10. With respect to these formulations, cream time, gel time, density, dimensional change rate, fly ability (fragility), bubble diameter, and thermal conductivity were measured, respectively.

When comparing these performances, the formulation using the toluenediamine-based polyol of Comparative Example 1 has a thermal conductivity of 0.0220 W / m ° C., whereas the aniline-based examples of Example 3 and Example 4 In the prescription using the polyol, the thermal conductivity is improved to 0.0204 to 0.0206 W / m ° C., and at the same time, the bubble diameter is 350 μm in the prescription of Comparative Example 1, while the examples 3 and It can be seen that the prescription of Example 4 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 by about 10% compared to the formulation of Comparative Example 1. When comparing the performance of the formulation of Comparative Example 1 and the formulation of Comparative Example 2, since the density of the formulation of Comparative Example 2 was low, the dimensional change rate under an atmosphere of -30 ° C. and 50 ° C. and 95% relative humidity, Remarkably large and dimensional stability is deteriorated.

In contrast, in the formulations of Example 3 and Example 4, the density was about 10% lower than that of Comparative Example 1, respectively, but at −30 ° C., both were −0.8%. In the case of 95% at 50 ° C., it is 0.4% to −1.0%, which shows that the prescription of Comparative Example 2 is improved as compared with −12.5% and −10.3%.

Example 2 Table 2 shows the formulation 5 of the comparative example and the formulations 6 to 8 of the examples. The method for producing the rigid polyurethane foam and the method for measuring the foam performance are the same as in Example 1.

In Comparative Example 5 shown in Table 2, and in Examples 6 to 8, the same raw materials other than polyol were used, and water, cyclopentane, and raw materials in the rigid polyurethane foam formulation were used. The foam stabilizer was 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. In the formulation of Comparative Example 5, sucrose polyol manufactured by Toho Chemical Industry, Toho Polyol O-850, polyester polyol for rigid polyurethane foam manufactured by Toho Rika Industry Co., Ltd., and phantol PL-305 are used in a weight ratio of 1: 1. In Formulas 6 to 8 of Examples, the weight ratios of Toho Polyol O-850 and Toho Chemical Industry's aniline polyol AB-250 were changed. Further, the same type of isocyanate was used, and the required weight was calculated with an isocyanate index of 1.10. With respect to these formulations, cream time, gel time, density, dimensional change rate, fly ability (fragility), bubble diameter, and thermal conductivity were measured, respectively.

Comparing these performances, in the prescription combining the sucrose-based polyol of Comparative Example 5 and the conventionally used polyester polyol, the bubble diameter is as small as 200 μm and the thermal conductivity is as low as 0.0204 W / m ° C. Although it is good, the dimensional change rate under the atmosphere of 50 ° C. and 95% relative humidity is greatly contracted to −7.8%, whereas the sucrose polyol and the aniline polyol of Examples 6 to 8 were combined. In any of the formulations, the bubble diameter is sufficiently small and the thermal conductivity is low and good, and the dimensional change rate in the atmosphere of 50 ° C. and 95% relative humidity is as small as −1.5 to 0.4% and good.

Here, when the content and performance of the aniline-based polyol are compared, the cell diameter, thermal conductivity, and dimensional change rate in the atmosphere of 50 ° C. and 95% relative humidity are all the values of the aniline-based polyol of Example 8. It can be seen that 50 parts of the formulation, 30 parts of the aniline-based polyol of Example 7 and 20 parts of the aniline-based polyol of Example 6 and the order of decreasing aniline-based polyol are worse. From the difference in the degree, the lower limit of the amount of aniline-based polyol used is 20 parts in 100 parts by weight of polyol, and is desirably 30 parts or more.

Example 3 Table 3 shows formulations 9 to 11 in Examples using aniline-based polyols. The method for producing the rigid polyurethane foam and the method for measuring the foam performance are the same as in Example 1.

Formulations 9 to 11 of the examples shown in Table 3 all use aniline-based polyols manufactured by Toho Chemical Industry, and the other types of raw materials are the same. The pentane and the foam stabilizer had 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. In the prescriptions 9 to 11 of the examples, those in which the hydroxyl value of aniline-based polyol or the weight ratio of ethylene oxide and propylene oxide was changed were synthesized and used. Further, the same type of isocyanate was used, and the required weight was calculated with an isocyanate index of 1.10. With respect to these formulations, cream time, gel time, density, dimensional change rate, fly ability (fragility), bubble diameter, and thermal conductivity were measured, respectively.

When comparing these performances, 2.1 mol of ethylene oxide of Example 9 and 0.3 mol of propylene oxide were subjected to addition polymerization, and an aniline-based polyol, Toho polyol AB-204 having a hydroxyl value of 550 mgKOH / g was obtained. In the formulation used, 2 mol of ethylene oxide of Example 8 and 1.2 mol of propylene oxide were subjected to addition polymerization, and the performance of the formulation using an aniline polyol and toho polyol AB-250 having a hydroxyl value of 450 mgKOH / g was compared. However, the bubble diameter, thermal conductivity, and dimensional change rate under a humidity atmosphere of 50 ° C. and 95% are all good, but there is fly abilities and brittleness. The upper limit of the hydroxyl value of 550 mgKOH / g is desirably 500 mgKOH / g. It is considered to be.

In addition, in the prescription using aniline-based polyol, Toho polyol AB-450 having a hydroxyl value of 250 mgKOH / g by addition polymerization of 5.7 mol of ethylene oxide and 1.8 mol of propylene oxide in Example 10, Example 8 was used. Compared to the performance of the formulation, the fly abilities are better than the performance of the formulation of Example 9, but all of the bubble diameter, thermal conductivity, and dimensional change rate in a humidity atmosphere of 50 ° C. and 95% Good, but a little worse. This situation is the same as that of Example 11 in which 1.0 mol of ethylene oxide and 5.4 mol of propylene oxide are addition-polymerized and a hydroxyl value of 250 mgKOH / g is used, and an aniline polyol, Toho polyol AB-449 is used. . From this, it is considered that the lower limit of the hydroxyl value is 250 mgKOH / g, and desirably 300 mgKOH / g.

Furthermore, in the prescription using the aniline-based polyol and the toho polyol AB-451 in which 6.2 mol addition polymerization of only propylene oxide without using the ethylene oxide of Comparative Example 12 and having a hydroxyl value of 250 mgKOH / g is used, Is equally good, but the cell diameter, thermal conductivity, and dimensional change rate under the atmosphere of 50 ° C. and 95% relative humidity are all considerably worse than those of the comparative example 5 using the conventionally used polyester polyol. It is getting worse. From this, the lower limit of the number of moles of ethylene oxide added is 1.0 mole, desirably 1.5 moles, and the upper limit is 5.7 moles, desirably 4.5 moles. Conceivable.

Since the hydroxyl number and the number of added moles of ethylene oxide are limited, the number of added moles of propylene oxide is naturally limited to the range of 0 to 5.4 moles, desirably 0.3 to 3.8 moles.

Claims (1)

In the method for producing a rigid polyurethane foam using, as a blowing agent, any one of carbon dioxide, hydrocarbon, or hydrofluorocarbon, or a combination thereof , ethylene oxide is added in an amount of 1.0 to 5.5 with respect to 1 mol of aniline. An aniline-based polyol synthesized by addition polymerization of 7 mol of propylene oxide in the range of 0 to 5.4 mol and having a hydroxyl value in the range of 250 to 550 mgKOH / g was used in a rigid polyurethane foam formulation with 100 parts by weight of polyol. Of these, the method for producing a rigid polyurethane foam is characterized by being used in the range of 20 to 100 parts by weight.