JPH09136936A - Rigid polyurethane foam - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rigid polyurethane foam which has excellent heat insulating properties and good dimensional stability without use of a regulated foaming agent, i.e., trichlorofluoromethane (CFC-11), according to an alternative chlorofluorocarbon formulation. SOLUTION: This rigid polyurethane foam is prepd. from an org. polyisocyanate, a polyol, a foaming agent, a catalyst, a foam stabilizer, and other assistants. The foaming agent is a hydrofluorocarbon, and the polyol is the one containing not less than 20 pts.wt. ester polyol having an average functionality of 2.0 to 4.0 and a hydroxyl value of 300 to 600mg KOH/g.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a rigid polyurethane foam. More specifically, the present invention relates to a rigid polyurethane foam exhibiting excellent strength and dimensional stability without using specific freon (ie, chlorofluorocarbon) or hydrochlorofluorocarbon as a foaming agent and having excellent heat insulation performance.

[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. Due to its excellent heat insulation performance, low-temperature dimensional stability, workability, etc., it is widely used as a heat insulation material for refrigerators, freezers, building materials, etc. and as a spray application. This uses chlorofluorocarbons or hydrochlorofluorocarbons represented by 1,1,1-trichlorofluoromethane (hereinafter referred to as (CFC-11)) as a foaming agent when producing a rigid polyurethane foam. That is the main reason.

[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 chlorine radicals generated will destroy the ozone layer. became. CFC-11, which has been used as a foaming agent for rigid polyurethane foam up to now, is also included in this regulation target. Therefore, development of a technique using a foaming agent that does not destroy the ozone layer is under study.

In order to solve the above problem, 1,1,1,2-tetrafluoroethane having an ozone depletion potential of 0 (hereinafter referred to as HFC-) is used as one of the alternative blowing agents for CFC-11.
134a), 1,1,1,3,3-pentafluoropropane (hereinafter referred to as HFC-245fa), 1,
1,2,2,3-pentafluoropropane (hereinafter HFC
Hydrofluorocarbons such as 1,1,1,2,2-pentafluoroethane (hereinafter referred to as HFC-125) have been proposed. However,
The rigid polyurethane foam using the above hydrofluorocarbons as a foaming agent has a disadvantage that the heat insulation performance, that is, the thermal conductivity is deteriorated as compared with the conventional rigid polyurethane foam using CFC-11.

On the other hand, it is known in the prior art using CFC-11 as a foaming agent that the thermal conductivity of rigid polyurethane foam can be reduced by using polyester polyol. For example, JP-A-56
No. 163117, a polyether polyol having an aromatic amine as an initiator and a polyester polyol are used in combination, and the polyester polyol is used as a polyol component of 8-5.
It teaches that the thermal conductivity can be significantly reduced by using 0 parts by weight. In addition, JP-A-2-18091
No. 6 has an average number of functional groups of 2.2 to 3.6 and a hydroxyl value of 200.
It teaches that by using 10 to 60 parts by weight of a polyol component of an aromatic polyester polyol of ˜550 mgKOH / g, improvement in resin strength and productivity can be achieved while maintaining low thermal conductivity. Further, Japanese Patent Application Laid-Open
No. -245014, by using an aromatic polyester polyol having an average number of functional groups of 2.2 to 3.6 and a hydroxyl value of 200 to 550 mgKOH / g in an amount of 15 to 45 parts by weight of a polyol component, and combining it with a specific polyether polyol, It teaches that a rigid polyurethane foam having a balanced physical property can be obtained.

Further, JP-A-3-195718 discloses a hard polyurethane excellent in thermal conductivity and adhesion to various materials by using 10 to 70 parts by weight of a polyol component of a polyester polyol having a hydroxyl value of 200 to 800 mgKOH / g. It teaches that a foam can be obtained. Further, the above-mentioned polyester polyol is produced by condensation of a dicarboxylic acid or its diester and a polyhydric alcohol, but JP-A-63-6013 and the literature cited therein have different production methods, Teaches how to use. That is, the half ester and // produced by the reaction between the cyclic dicarboxylic acid anhydride and the polyhydric alcohol
Alternatively, an ester polyol obtained by adding ethylene oxide and / or propylene oxide to a half amide in the presence of a trifunctional or higher-functional polyether polyol having a tertiary amino group is more suitable than the above condensed polyester polyol having a corresponding hydroxyl value. Also has a unique molecular weight distribution due to its low viscosity and a small amount of unesterified free polyol, and has good compatibility with isocyanates, which is advantageous for the production of flame-resistant polyisocyanate addition products. Has been revealed.

However, all of these techniques use CFC-11 as a blowing agent, or use a relatively large amount of water to reduce the amount of CFC-11 used. The effect was not clear.

[0008]

Means for Solving the Problems As a result of intensive studies for achieving the above object, the present inventors have found that if an ester polyol is used as a polyol component, a rigid polyurethane foam using hydrofluorocarbon as a foaming agent is also used. The present invention has been completed based on the finding that various physical properties can be satisfied and that the thermal conductivity can be particularly reduced to the level of a rigid polyurethane foam using CFC-11.

That is, the present invention is a rigid polyurethane foam produced from an organic polyisocyanate, a polyol, a foaming agent, a catalyst, a foam stabilizer, and other auxiliaries, wherein the foaming agent is a hydrofluorocarbon and 100 parts by weight of the polyol. In which the average number of functional groups is 2.0 to 4.0,
A rigid polyurethane foam comprising 20 parts by weight or more of an ester polyol having a hydroxyl value of 300 to 600 mgKOH / g.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION As the foaming agent used in the present invention, hydrofluorocarbons (HFCs) can be used, but especially HFC-134a, HFC-245fa, HFC
-245ca, HFC-236ea, HFC-125 or mixtures thereof are preferred. The amount of the hydrofluorocarbon used as the foaming agent is appropriately 5 to 50 parts by weight based on 100 parts by weight of the polyol.
Parts by weight are more suitable. The amount of water used as a foaming agent is 0.
001 to 10 parts by weight is suitable, and 0.5 to 5 parts by weight is more suitable. The amount of the hydrofluorocarbon used as a foaming agent is preferably 5 to 50 parts by weight, more preferably 10 to 25 parts by weight, based on 100 parts by weight of the polyol.

The ester polyol used in the present invention is usually 3 in a rigid polyurethane foam.
The following are mentioned which have a hydroxyl value of 00-600 mgKOH / g. Dicarboxylic acid such as phthalic acid and / or its diester and ethylene glycol, propylene glycol, 1,4-butanediol, 1,2-butanediol, glycerin or other polyol in the presence or absence of a catalyst such as titanium alkoxide. In addition, a polyvalent active hydrogen compound having two or more active hydrogens capable of reacting with an isocyanate in a cyclic acid anhydride such as an aromatic polyester polyol or phthalic anhydride produced by reducing the acid value to 5 mgKOH / g by condensation. Ester polyol produced by adding an alkylene oxide to a carboxylic acid produced by adding a carboxylic acid to an acid value of 5 mgKOH / g or less with a tertiary amine containing a long-chain hydrocarbon such as dimethylpalmitylamine as a catalyst. Etc.

As the polyvalent active hydrogen compound, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1,2-butanediol, 1,4-butanediol, 1,6-hexane glycol, glycerin, Trimethylolpropane, pentaerythritol, diglycerin, sorbitol, sucrose, triethanolamine, diethanolamine, monoethanolamine and the like can be mentioned, and they can be used alone or in any combination.
Examples of the alkylene oxide added to the carboxylic acid include ethylene oxide and propylene oxide, which can be used alone or in any combination.

As the polyol other than the ester polyol used in the present invention, a hydroxyl value of 300 to 600 mg KO, which is usually used for producing rigid polyurethane foam, is used.
H / g polyether polyol may be mentioned. As the initiator of the polyether polyol, dipropylene glycol, glycerin, trimethylolpropane, monoethanolamine, diethanolamine, triethanolamine, pentaerythritol, ethylenediamine,
2,4- and 2,6-diaminotoluene, 4,4'-
Diaminodiphenylmethane, sorbitol, sucrose and the like can be mentioned, and they can be used in any combination. Examples of the alkylene oxide to be added include ethylene oxide and propylene oxide, which can be used in any combination. Regarding the ratio of the ester polyol to the polyether polyol, 20-80 parts by weight of the ester polyol is suitable for 100 parts by weight of the polyol, but 40-70 parts by weight is more suitable.

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

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.

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, as 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. In addition, an organic polyisocyanate obtained by partially modifying the above-mentioned organic polyisocyanate by means of urethanization, trimerization, carbodiimidation, amidation or the like can also be used.

To carry out the present invention, a predetermined amount of a polyol, a foaming agent, a catalyst and a foam stabilizer is mixed to prepare a resin solution. The resin solution and the organic polyisocyanate are mixed at a high speed at a fixed ratio, and injected into a cavity or a mold. At this time, the liquid ratio between the organic polyisocyanate and the resin liquid is adjusted so that the equivalent ratio (NCO: OH) between the organic polyisocyanate and the active hydrogen of the resin liquid becomes 0.7: 1 to 5: 1. .

[0018]

EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to the following examples unless it exceeds the gist. The results of Examples and Comparative Examples are summarized in Table-1. ~ 3. Shown in The numbers in the table represent parts by weight unless otherwise specified. The raw materials used in Examples and Comparative Examples are as follows. Isocyanate A: Polymeric MDI (NCO% = 3
NCO% obtained by urethane-modifying 1.3) with polyol 1 =
30.9 isocyanate.

Ester polyol A: 6.69 kg phthalic anhydride, 2.03 kg glycerin, 2.08 kg
1,2-butanediol and 67.5 g of dimethylpalmitylamine were charged into a reaction vessel having an internal volume of 30 L, the reaction vessel was replaced with nitrogen, and the pressure was raised to 3 kg / cm ^{2 with} nitrogen to raise the temperature. After reacting at 100 ° C. for 1 hour, the reactor was returned to normal pressure and 4.19 kg of propylene oxide was charged. The mixture was stirred for 5 hours while maintaining the temperature at 100 ° C., heated to 120 ° C., and further reacted for 5 hours until no decrease in internal pressure was observed. After the completion of the reaction, the residual propylene oxide was distilled off under reduced pressure and filtered to obtain an acid value of 0 mgKOH / g, a hydroxyl value of 412 mgKOH / g and a viscosity of 35000 cps.
(25 ° C.) ester polyol A was obtained.

Ester polyol B: 1330 g of phthalic anhydride, 1390 g of glycerin and 780 g of ethylene glycol were placed in a 5 L flask equipped with a partial condenser and a condenser for condensate, and 120
The reaction was carried out at a temperature of 1 hour. 220 while flowing nitrogen gas
The temperature was raised to ℃ and dehydration reaction was performed for 9 hours. Acid value 0.48mg
KOH / g, hydroxyl value 520 mg KOH / g, viscosity 24
000 cps. (25 ° C.) ester polyol B was obtained.

Polyol 1: Polyether polyol having a hydroxyl value of 470 mgKOH / g obtained by adding propylene oxide to sorbitol / glycerin (weight ratio 94/6). Polyol 2: Polyether polyol having a hydroxyl value of 450 mgKOH / g obtained by adding propylene oxide / ethylene oxide (weight ratio 80/20) to 2,4-diaminotoluene. Polyol 3: sucrose / glycerin / 4,4′-diaminodiphenylmethane (weight ratio 20/40/20) to propylene oxide / ethylene oxide (weight ratio 80/2
0) added polyether polyol having a hydroxyl value of 400 mg KOH / g.

Foam stabilizer: Nippon Unicar Co., Ltd. product SZ-1627 Catalyst: Active Material Chemical Co., Ltd. product Minico TMHD (Tetramethylhexamethylenediamine) Foaming agent: CFC-11 (Trichloromonofluoromethane) HCFC-141b ( 1,1-dichloro-1-fluoroethane) HFC-134a (1,1,1,2-tetrafluoroethane) HFC-245fa (1,1,1,3,3-pentafluoropropane) HFC-245ca (1 , 1,2,2,3-Pentafluoropropane) HFC-236ea (1,1,1,2,3,3-hexafluoropropane)

Examples 1 to 8 and Comparative Examples 1 to 12 Table-1. ~ 3. A predetermined amount of the polyol, water, foam stabilizer, foaming agent, and catalyst shown in (4) was adjusted and kept at 20 ° C. (Examples 1 and 2 and Comparative Examples 1 and 2 are 0 ° C.) To this, a predetermined amount of isocyanate A adjusted to 20 ° C. is added, followed by high speed mixing for 2 seconds, and immediately a free foaming box (size 250 ×).
(250 × 250 mm) and foamed. 23 ° C after foaming
Various physical property values of the foam left for 24 hours in a thermostatic chamber with a humidity of 65% were measured. The equivalent ratio of isocyanate A to total active hydrogen was NCO / H = 1.10.

The conditions for measuring the physical properties of the rigid polyurethane foam are as follows. Free Density: The density of the core of the foam obtained by free foaming into a 250 × 250 × 250 mm box. Compressive strength: Measured according to JIS A9514. High-temperature dimensional stability: After standing still in an atmosphere of 70 ° C. for 24 hours, the dimensional change rate was measured. Low temperature dimensional stability: After standing still for 24 hours in an atmosphere of −30 ° C., the dimensional change rate% was measured. Wet heat dimensional stability: 70 ° C. 95% relative humidity after being left standing in an atmosphere of 95% relative humidity for 24 hours, and then measured the dimensional change rate%. Thermal conductivity: An intermediate temperature of 25 ° C. (low heat The plate was measured at 10 ° C. and the hot plate 40 ° C.).

From Examples 1 to 8 and Comparative Examples 1 to 8, when the ester polyol described in the present invention was used, compared with the system using the conventional polyol, even when hydrofluorocarbon was used as the blowing agent, the heat It can be seen that the conductivity is significantly reduced. Examples 1 to 8
From Comparative Examples 9 to 12, the rigid polyurethane foam of the present invention was formulated with a reduced amount of CFC-11 or hydrochlorofluorocarbon (HCFC-141b).
It can be seen that the thermal conductivity could be reduced to the same level as or higher than that of the conventional rigid polyurethane foam using as a foaming agent.

[0026]

[Table 1]

[0027]

[Table 2]

[0028]

[Table 3]

[0029]

EFFECTS OF THE INVENTION The rigid polyurethane foam obtained from the alternative CFC formula is remarkably inferior in heat insulation performance and dimensional stability as compared with the rigid polyurethane foam obtained from the conventional recipe using CFC-11. However, by using the ester polyol described in the present invention as the polyol component, a rigid polyurethane foam having excellent heat insulation performance and good dimensional stability was obtained even when hydrofluorocarbon was used as the foaming agent.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shinsuke Matsumoto 1190 Kasama-cho, Sakae-ku, Yokohama-shi, Kanagawa Mitsui Toatsu Chemical Co., Ltd. (72) Hiroshi Fujino 1190 Kasama-cho, Sakae-ku, Yokohama-shi, Kanagawa Mitsui Toatsu Chemical Within the corporation

Claims (3)

[Claims] 1. A rigid polyurethane foam produced from an organic polyisocyanate, a polyol, a foaming agent, a catalyst, a foam stabilizer, and other auxiliaries, wherein the foaming agent is a hydrofluorocarbon, and the polyol has an average functionality of 2 0.0 to 4.0, hydroxyl value 300 to 600 mg KOH
A rigid polyurethane foam characterized in that it is a polyol containing 20% by weight or more of an ester polyol of 10 g / g. 2. A blowing agent is 1,1,1,2-tetrafluoroethane, 1,1,1,3,3-pentafluoropropane, 1,1,2,2,3-pentafluoropropane,
1,1,1,2,3,3-hexafluoropropane,
The rigid polyurethane foam according to claim 1, which is 1,1,1,2,2-pentafluoroethane or a mixture of two or more thereof. 3. The viscosity of the ester polyol is 40,000.
The rigid polyurethane foam according to claim 1, which has a CPS. (25 ° C) or lower.