JPH09132628A - Rigid polyurethane foam and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a rigid polyurethane foam having a low thermal conductivity while improving the storage stability of a resin premix by reacting a specified polyol with an organic polyisocyanate in the presence of a specified blowing agent. SOLUTION: An organic polyisocyanate (A) (e.g. toluene diisocyanate), a polyol (B) containing 70wt.% or above esterpolyol having an average functionality of 2-4 and a hydroxyl value of 300-600mgKOH/g, a blowing agent (C) essentially consisting of water and cyclopentadiene, a catalyst (D) (e.g. trimethylaminoethylpiperazine), a foam stabilizer (E) and other adjuvants (F) (e.g. stabilizer) are prepared. Component B is used in such an amount that a mixture of components B, C, D, E and F forms an emulsion, The respective components are reacted with each other to form a rigid polyurethane foam. The obtained foam is useful as a heat insulation material for refrigerators, vehicles, etc.

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. . CFC-11 (trichlorofluoromethane), which has been used as a foaming agent for rigid polyurethane foams, has been included in this regulation target. Therefore, development of a technique using a foaming agent that does not destroy the ozone layer has been studied.

In order to solve the above problems, CFC-11
As one of the alternative blowing agents, hydrocarbons such as n-pentane, isopentane, and cyclopentane having an ozone depletion potential of 0 have been proposed. For example, JP-A-2-91132
No. is CFC-11 and hydrocarbons, that is, ethane, propane, n-butane, isobutane, n-pentane, isopentane, neopentane, n-hexane, isohexane, n-heptane, isoheptane, cyclopentane, cyclohexane, cycloheptane, etc. It teaches that a rigid polyurethane foam having excellent filling properties, low-temperature dimensional stability, compressive strength and the like can be obtained by using together with or using these hydrocarbons alone. Further, JP-A-3-152160 discloses
It teaches that a rigid polyurethane foam having a low thermal conductivity can be obtained by using cyclopentane, cyclohexane or the like. However, the rigid polyurethane foam using the above hydrocarbons as a foaming agent,
There is a disadvantage that the thermal conductivity is not lower than that of the conventional rigid polyurethane foam using CFC-11.

On the other hand, it is known in the prior art that CFC-11 is used 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 uses a polyether polyol and a polyester polyol having an aromatic amine as an initiator,
By using 8 to 50 parts by weight of the polyol component of the polyester polyol, it is possible to significantly reduce the thermal conductivity, and JP-A-2-180916 discloses that the average number of functional groups is 2.2 to 3.6 and the hydroxyl value is 200 to. 550mgKOH
By using 10 to 60 parts by weight of the aromatic polyester polyol of 10 g / g of the polyol component, it is possible to achieve improvement in resin strength and productivity while maintaining low thermal conductivity, and JP-A-2-245014 discloses that Average number of functional groups 2.2-3.6, hydroxyl value 200-550 mgKOH /
The use of 15 to 45 parts by weight of the aromatic polyester polyol (g) in a proportion of 15 to 45 parts by weight of the polyol component in combination with a specific polyether polyol makes it possible to obtain a rigid polyurethane foam having a balanced physical property.
-195718 has a hydroxyl value of 200 to 800 mg KO
H / g polyester polyol is used as the polyol component 1
It teaches that a rigid polyurethane foam having excellent thermal conductivity and adhesiveness to various materials can be obtained by using 0 to 70 parts by weight.

Further, the above-mentioned polyester polyol is produced by condensation of a dicarboxylic acid or its diester with a polyhydric alcohol, but JP-A-63-6013 and the references cited therein have different production methods. And teaches how to use it. That is, ethylene oxide and / or propylene oxide is added to a half ester and / or half amide produced by the reaction of a cyclic dicarboxylic acid anhydride and a polyhydric alcohol in the presence of a trifunctional or higher functional polyether polyol having a tertiary amino group. The ester polyol obtained by adding the above has a viscosity lower than that of the above-mentioned condensed polyester polyol having a corresponding hydroxyl value, and has less unesterified free polyol, and therefore has a unique molecular weight distribution, and is It has been proved that they have good compatibility with each other and are advantageous for producing a flame-resistant polyisocyanate addition product. However, all of these techniques use CFC-11 as a blowing agent or reduce the amount of CFC-11 used by using a relatively large amount of water, and use hydrocarbon as an essential component. No investigation was made on the foaming agent, and its effect was not clear.

Generally, in the production of rigid polyurethane foam, a resin premix obtained by mixing a polyol, a foaming agent, a catalyst, a foam stabilizer and other auxiliaries is reacted with an organic polyisocyanate. Conventionally, CFC-11
When used, CFC-11 had a high solubility in the polyol, so the resin premix became transparent, the components of the resin premix did not separate, and the storage stability was good. However, when a hydrocarbon such as cyclopentane is used as a foaming agent, its solubility in polyol is extremely inferior to that of CFC-11, so that a transparent resin premix having good storage stability can be obtained. The types and compositions of polyols were significantly limited. Hydrocarbons such as cyclopentane have extremely low solubility in polyester polyols that can reduce the thermal conductivity of rigid foams, so the resin premix becomes emulsified and the components of the resin premix separate in an extremely short time. That is, a resin premix of a hydrocarbon foam having a low thermal conductivity has a problem of poor storage stability.

[0008]

The present inventors have found that rigid polyurethane foams produced by using a blowing agent containing water and cyclopentane as essential components satisfy various physical properties and, in particular, have thermal conductivity. The present invention has been achieved as a result of intensive studies to improve the storage stability of a resin premix when an ester polyol is used in order to reduce the same as a rigid polyurethane foam using CFC-11.

That is, the present invention provides the following (1) and (2)
It is. (1) Organic polyisocyanate, polyol, foaming agent,
In a rigid polyurethane foam produced from a catalyst, a foam stabilizer, and other auxiliaries, a foaming agent containing water and cyclopentane as essential components is used as a foaming agent, and a polyol having an average functional group number of 2.0 to 4. 0, using a polyol containing 70 wt% or more of an ester polyol having a hydroxyl value of 300 to 600 mgKOH / g in a state where a mixture of a polyol, a foaming agent, a catalyst, a foam stabilizer, and other auxiliaries becomes an emulsion. A rigid polyurethane foam characterized by being manufactured. (2) Organic polyisocyanate, polyol, foaming agent,
In a method for producing a rigid polyurethane foam from a catalyst, a foam stabilizer, and other auxiliary agents, a foaming agent containing water and cyclopentane as essential components is used as a foaming agent,
As a polyol, a polyol containing 70 wt% or more of an ester polyol having an average number of functional groups of 2.0 to 4.0 and a hydroxyl value of 300 to 600 mgKOH / g is used as a polyol, a foaming agent, a catalyst, a foam stabilizer, and other auxiliary agents. A method for producing a rigid polyurethane foam, which comprises using the mixture as an emulsion.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, water and cyclopentane are used as essential components as a foaming agent. As a hydrocarbon other than cyclopentane that can be used as a blowing agent, n-
In the production of saturated hydrocarbons such as pentane, isopentane, neopentane, methylcyclopentane, n-hexane, isohexane, cyclohexane, n-heptane, isoheptane, cycloheptane, benzene, cyclopentene and other unsaturated hydrocarbons, usually cyclopentane , And hydrocarbons contained as impurities. A hydrocarbon selected from the above hydrocarbons may be used in combination. The amount of water used as a foaming agent is preferably 0.001 to 10 parts by weight, and more preferably 0.5 to 5 parts by weight, based on 100 parts by weight of the polyol. The amount of cyclopentane and the above hydrocarbon used as a blowing agent is suitably 5 to 30 parts by weight, and more suitably 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, Examples thereof include trimethylolpropane, pentaerythritol, diglycerin, sorbitol, sucrose, triethanolamine, diethanolamine, monoethanolamine and the like and their alkylene oxide adducts, which can be used alone or in any combination. Examples of the polyvalent active hydrogen compound and the alkylene oxide added to the carboxylic acid include ethylene oxide and propylene oxide, which can be used alone or in any combination.

In the present invention, when 100 parts by weight or more of the above-mentioned ester polyols are used per 100 parts by weight of the polyol, and 70 parts by weight or more of them are used, the polyol, the foaming agent, the catalyst, the foam stabilizer, and other auxiliary agents. The mixture (resin premix) is an emulsion having good storage stability. If 70 parts by weight or more of the ester polyol is not used, the components are separated at 40 ° C. within 1 day even if the resin premix is turbid. As a polyol other than the ester polyol used in the present invention, a hydroxyl value of 300 to 60, which is usually used for producing a rigid polyurethane foam, is used.
Mention may be made of 0 mg KOH / g polyether polyol. 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.

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. The equivalent ratio of the organic polyisocyanate and the active hydrogen capable of reacting with the organic polyisocyanate in the mixture of the polyol, the foaming agent, the catalyst, the foam stabilizer and the auxiliary is:
NCO / H (active hydrogen) = 0.60 to 5.00 is particularly preferable.

Examples of the catalyst include trimethylaminoethylpiperazine, triethylamine, tripropylamine, N-methylmorpholine, N-ethylmorpholine, triethylenediamine, N, N, N ', N'-tetramethylhexamethylenediamine, Amine-based urethane-forming catalysts such as bis (2-dimethylaminoethyl) ether, N, N-dimethylcyclohexylamine, and carboxylic acid salts such as potassium octanoate can be used. These catalysts can be used alone or as a mixture, and the amount thereof used is 0.0001 parts by weight or more and 1 with respect to 100 parts by weight of the compound having active hydrogen.
An amount of 0.0 parts by weight or less is suitable.

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.

[0017]

The present invention will be described below with reference to examples. The raw materials used in Examples and Comparative Examples are as follows. Isocyanate A: Polymeric MDI (NCO% = 31.3) urethane modified with polyether polyetherpolyol A is an isocyanate having NCO% = 3 0.9. Polyether polyol A: Polyether polyol having a hydroxyl value of 470 mgK OH / g obtained by adding propylene oxide to sorbitol / glycerin (weight ratio 94/6). Polyether polyol B: 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. Polyether polyol C: sucrose / glycerin / 4,4′-diaminodiphenylmethane (weight ratio 20/40/20) added with propylene oxide / ethylene oxide (weight ratio 80/20) Ether polyol. Foam stabilizer: Nippon Unicar Co., Ltd. product SZ-1627 Catalyst: Active Material Chemical Co., Ltd. product Minico TMHD (Tetramethylhexamethylenediamine) Foaming agent: Cyclopentane Tokyo Kasei Co., Ltd. Reagent special grade> 99% Cyclopentane 75% product Aldrich Purity> 75% (compositions other than cyclopentane are the main components of saturated hydrocarbons having 5 to 6 carbon atoms) CFC-11 (Freon 11B) Mitsui DuPont Fluorochemical Co., Ltd.

Reference Example 1 Synthesis of ester polyol A 6.69 kg of phthalic anhydride, 2.03 kg of glycerin, 2.08 kg of 1,2-butanediol and 6
7.5 g of dimethyl palmitylamine was charged into a 30 L reaction tank, and the reaction tank was replaced with nitrogen, and then 3 kg / cm ^2.
It was pressurized with nitrogen until the temperature was raised. 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 reaction was completed, the residual propylene oxide was distilled off under reduced pressure, and the mixture was filtered to obtain an acid value of 0.
mgKOH / g, hydroxyl value 412 mgKOH / g, viscosity 35000 cps. (25 ° C) ester polyol A
I got

Examples 1 to 3 and Comparative Examples 1 to 5 The polyols, water, foam stabilizers, foaming agents and catalysts shown in Table 1 were mixed in predetermined amounts, and mixed with a mixer (rotation speed 680 rpm) for 10 times.
The resin premix was adjusted by stirring for 1 minute and kept at 25 ° C. A predetermined amount of isocyanate A adjusted to 20 ° C. was added to this, and the mixture was mixed at high speed for 5 seconds and adjusted to 40 ° C. in advance in an aluminum mold (space volume: thickness 20 mm × width 30
110 g was injected into 0 mm × length 450 mm), and after 5 minutes, the mold was removed. The equivalent ratio of isocyanate A to total active hydrogen was NCO / H = 1.10. Table 1 shows the state of the obtained resin premix, the density of the rigid polyurethane foam, and the thermal conductivity. Table 1 also shows the storage stability of the resin premix.

The conditions for measuring various physical properties are as follows. Density: Measure the core of rigid polyurethane foam. Thermal conductivity: manufactured by Hidehiro Seiki Co., Ltd. Auto Λ HC-072
Depending on the mold, an intermediate temperature of 25 ° C (low heating plate 10 ° C, high heating plate 4
Measured at 0 ° C. Resin premix condition: Visually observe the sample in a closed 100 ml glass bottle at 15 to 25 ° C. Storage stability: 80 g of resin premix immediately after being adjusted in a 100 ml glass bottle was sealed and stored in a constant temperature water bath at 20 ° C and 40 ° C, and the separation of components was visually observed.

Table 1 shows examples and comparative examples. The numbers in the examples represent parts by weight unless otherwise specified.

[0022]

[Table 1]

According to the comparison of Examples 1 to 3 and Comparative Examples 1 and 2, when cyclopentane was used as a blowing agent, the ester polyol described in the present invention was mixed with 70% of polyol.
It can be seen that the storage stability of the emulsified resin premix is remarkably improved when more than parts by weight are used. Comparative Examples 1 and 2 show that when the amount of the ester polyol described in the present invention used was less than 70 parts by weight, the resin premix separated the components within 1 day. Comparative Examples 3-5
According to the comparison, although only a conventional polyether polyol can be used to obtain a resin premix which is transparent and has excellent storage stability, the thermal conductivity of the rigid polyurethane foam produced from the resin premix is CFC-
It can be seen that the thermal conductivity of the rigid polyurethane foam in which the amount of 11 used is reduced is significantly inferior.

[0024]

Industrial Applicability According to the present invention, in a rigid polyurethane foam produced by using a blowing agent containing water and cyclopentane as essential components, the amount of CFC-11 used is reduced to the same level or more. The storage stability of the resin premix, which becomes an emulsion, could be greatly improved while showing a reduced thermal conductivity.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI technical display location C08G 101: 00) C08L 75:04 (72) Inventor Hiroshi Fujino 1190 Kasama-cho, Sakae-ku, Yokohama-shi, Kanagawa Mitsui Toatsu Chemical Co., Ltd. (72) Inventor Mitsugu Kita 1190 Kasama-cho, Sakae-ku, Yokohama-shi, Kanagawa Mitsui Toatsu Chemical Co., Ltd.

Claims (2)

[Claims] An organic polyisocyanate, a polyol,
In a rigid polyurethane foam produced from a foaming agent, a catalyst, a foam stabilizer, and other auxiliaries, a foaming agent containing water and cyclopentane as essential components is used as a foaming agent, and an average number of functional groups of 2.0 as a polyol. ~ 4.
0, using a polyol containing 70 wt% or more of an ester polyol having a hydroxyl value of 300 to 600 mgKOH / g in a state where a mixture of a polyol, a foaming agent, a catalyst, a foam stabilizer, and other auxiliaries becomes an emulsion. A rigid polyurethane foam characterized by being manufactured. 2. An organic polyisocyanate, a polyol,
1. A method for producing a rigid polyurethane foam from a foaming agent, a catalyst, a foam stabilizer, and other auxiliaries, wherein a foaming agent containing water and cyclopentane as essential components is used as the foaming agent, and an average number of functional groups of 2. 0-4.
0, using a polyol containing 70 wt% or more of an ester polyol having a hydroxyl value of 300 to 600 mgKOH / g in a state where a mixture of a polyol, a foaming agent, a catalyst, a foam stabilizer, and other auxiliary agents becomes an emulsion. A method for producing a rigid polyurethane foam, comprising: