JPH09165427A - Rigid polyurethane foam and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a rigid polyurethane foam reduced in thermal conductivity by using an emulsion comprising water and cyclopentane as blowing agents, a polyol comprising a specified ester polyol, a catalyst, a foam stabilizer, other adjuvants and a storage stability improver. SOLUTION: One hundred (100) pts.wt. polyol having containing 70wt.% or above ester polyol having an average functionality of 2.0-4.0 and a hydroxyl value of 300-600mgKOH/g, a blowing agent comprising about 0.001-10 pts.wt. water and 5-30 pts.wt. hydrocarbon (e.g. cyclopentane), about 0.0001-10 pts.wt. tert. amine (e.g. triethylamine), about 0.1-10 pts.wt. foam stabilizer, a flame retardant and 1-10 pts.wt. storage stability improver (e.g. 9-12C linear saturated hydrocarbon) are fed in a reactor and mixed to form an emulsion. Next, an organic polyisocyanate (e.g. diphenylmethane diisocyanate) in such an amount that an equivalent ratio of isocyanato groups to active hydrogen atoms is in the range of 0.60-5.00 is added to the reactor and agitated at a high speed, and the resultant mixture is poured into e.g. an aluminum mold, foamed and cured to obtain a rigid polyurethane foam.

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 and a method for manufacturing the same, and is expected to be suitably used as a heat insulating material or heat insulating structural material for refrigerators, freezers, heat insulating panels, ships, vehicles and the like.

[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. CFC-11 (trichlorofluoromethane), which has been conventionally used as a foaming agent for rigid polyurethane foam due to its characteristics such as low thermal conductivity and nonflammability, is also included in this regulation. Therefore, development of a technique that does not destroy the ozone layer, that is, uses a foaming agent having an ozone depletion coefficient of 0 is under study.

In order to solve the above problems, hydrocarbons such as n-pentane, isopentane and cyclopentane having an ozone depletion potential of 0 have been proposed as an alternative blowing agent for CFC-11. For example, Japanese Patent Laid-Open No. 2-91132 discloses CF
C-11 and hydrocarbons, ie ethane, propane, n-
Butane, isobutane, n-pentane, isopentane, neopentane, n-hexane, isohexane, n-heptane, isoheptane, cyclopentane, cyclohexane, cycloheptane, etc., or by using these hydrocarbons alone, filling properties and low temperature dimensions It teaches that a rigid polyurethane foam having excellent stability and compressive strength can be obtained. Further, JP-A-3-152160 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-mentioned hydrocarbon or the like as a foaming agent has a higher thermal conductivity of the foaming agent itself than CFC-11.
There was a disadvantage that the thermal conductivity was not lower than that of the rigid polyurethane foam using No. 1.

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. Also, Japanese Patent Application Laid-Open No. 3-1
95718 has a hydroxyl value of 200 to 800 mg KOH /
10 g of the polyester polyol is used as the polyol component.
It teaches that 70 parts by weight can be used to obtain a rigid polyurethane foam having excellent thermal conductivity and adhesion to various materials. Further, the polyester polyol is produced by condensation of a dicarboxylic acid or its diester and a polyhydric alcohol, but JP-A-63-6013 and the references cited therein have different production methods.
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 the addition of the above has a unique molecular weight distribution because the viscosity is lower than that of the above-mentioned condensed polyester polyol having a corresponding hydroxyl value and the amount of free polyol not esterified is small.
It has been shown that it has good compatibility with isocyanate and is advantageous for the production of 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.

The rigid polyurethane foam is usually produced by reacting a resin premix obtained by mixing a polyol, a foaming agent, a catalyst, a foam stabilizer and other auxiliaries with an organic polyisocyanate. Conventionally, when CFC-11 was used as a foaming agent, CFC
Since the solubility of -11 in the polyol was high, the resin premix was transparent and had good storage stability.

However, when a hydrocarbon such as cyclopentane is used as a foaming agent, its solubility in polyol is CF.
In order to obtain a resin premix that is inferior to C-11 and is transparent and has excellent storage stability, the type and composition of the polyol were limited. In rigid polyurethane foams, polyester polyols that can have low thermal conductivity have extremely poor solubility with hydrocarbons such as cyclopentane, so the resin premix becomes an emulsion and the components of the resin premix separate in an extremely short time. . That is, a resin premix for obtaining a rigid polyurethane foam having a low thermal conductivity by using a hydrocarbon as a foaming agent becomes an emulsion and has a problem of poor storage stability.

[0008]

DISCLOSURE OF THE INVENTION The inventors of the present invention have satisfied various physical properties in a rigid polyurethane foam produced by using a blowing agent containing water and cyclopentane as essential components, and particularly have a high thermal conductivity. The present invention has been accomplished 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 CFC-11 to the same level as a rigid polyurethane foam.

That is, the present invention is as follows (1) to (3). (1) Organic polyisocyanate, polyol, foaming agent,
In a rigid polyurethane foam produced from a catalyst, a foam stabilizer, and other auxiliaries, water and cyclopentane are essential components as a foaming agent, a polyol has an average functional group number of 2.0 to 4.0, and a hydroxyl value of 300 to 600 mg.
A mixture containing 70 wt% or more of KOH / g ester polyol is used, and a mixture of the polyol, the foaming agent, the catalyst, the foam stabilizer and the other auxiliary agent becomes an emulsion, and as a storage stabilizer of the emulsion, 1 chain saturated hydrocarbon compound having 9 to 12 carbon atoms per 100 parts by weight of polyol
A rigid polyurethane foam characterized by being used in an amount of at least 10 parts by weight. (2) Polyol 100 is used as a storage stabilizer for emulsions.
The rigid polyurethane foam according to (1), characterized in that 1 part by weight or more and 5 parts by weight or less of a chain saturated hydrocarbon compound having 9 or more and 12 or less carbon atoms is used per part by weight. (3) Organic polyisocyanate, polyol, foaming agent,
In a method for producing a rigid polyurethane foam from a catalyst, a foam stabilizer, and other auxiliaries, water and cyclopentane are essential components as a foaming agent, a polyol has an average functional group number of 2.0 to 4.0, and a hydroxyl value of 300 to 600
Using a mixture containing 70% by weight or more of mgKOH / g ester polyol, a mixture of polyol, a foaming agent, a catalyst, a foam stabilizer and other auxiliaries becomes an emulsion, and as a storage stabilizer of the emulsion, A method for producing a rigid polyurethane foam, which comprises using 1 part by weight or more and less than 10 parts by weight of a chain saturated hydrocarbon compound having 9 or more and 12 or less carbon atoms per 100 parts by weight of a polyol.

[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
0.001 to 10 parts by weight is suitable for 100 parts by weight of the polyol, and 0.5 to 5 parts by weight is more suitable. The amount of the above hydrocarbon used as a foaming agent is suitably 5 to 30 parts by weight, 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 diester thereof and polyol such as ethylene glycol, propylene glycol, 1,4-butanediol, 1,2-butanediol and glycerin in the presence of a catalyst such as titanium alkoxide or Cyclic acid anhydrides such as aromatic polyester polyols and phthalic anhydride produced by reducing the acid value to 5 mgKOH / g by condensation in the absence of polyhydric compounds having two or more active hydrogens capable of reacting with isocyanate. Produced by adding alkylene oxide to a carboxylic acid produced by adding an active hydrogen compound, using a tertiary amine containing a long-chain hydrocarbon such as dimethylpalmitylamine as a catalyst until the acid value becomes 5 mgKOH / g or less. Ester polyols.

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.

The chain saturated hydrocarbon compound used as the storage stabilizer of the emulsion of the present invention includes n-nonane and n-
Linear saturated hydrocarbon compounds such as dodecane and branched saturated hydrocarbon compounds such as 2-methyloctane can be mentioned, and they can be used in any combination. Cyclic hydrocarbon compounds such as cyclododecane are less effective as storage stabilizers.
The hydrocarbon compound having 8 or less carbon atoms contributes as a foaming agent and is enclosed in the closed cells of the rigid polyurethane foam and has a lower thermal conductivity than that of cyclopentane, which deteriorates the thermal conductivity of the rigid polyurethane foam. Not preferable. Further, a hydrocarbon compound having 13 or more carbon atoms is not preferable because it causes cell roughness of the obtained rigid polyurethane foam and deteriorates the thermal conductivity.

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.

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

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.

[0021]

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% = 3
Isocyanate of NCO% = 30.9 in which 1.3) is urethane-modified with polyether polyether polyol A. Polyether polyol A: Polyether polyol having a hydroxyl value of 470 mgKOH / g obtained by adding propylene oxide to sorbitol / glycerin (weight ratio 94/6). Polyether polyol B: sucrose / glycerin / 4,
4'-diaminodiphenylmethane (weight ratio 20/40 /
20) with propylene oxide / ethylene oxide (weight ratio 80/20) added to give a hydroxyl value of 400 mg KOH /
g of polyether polyol. Storage stabilizer: NN (n-nonane) manufactured by Kanto Chemical Co., Inc.
Reagent Deer Special Grade ND (n-dodecane) Kanto Chemical Co., Ltd. Reagent Deer Special Grade Additive: CD (Cyclododecane) Kanto Chemical Co., Ltd. Reagent Purity> 99% NO (n-octane) Kanto Chemical Co., Ltd. Reagent Deer 1st grade NP (n-pentadecane) Kanto Chemical Co., Ltd. reagent Deer special grade 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 grade, purity> 99% CFC-11 (Freon 11B), Mitsui DuPont Fluorochemical Co., Ltd.

Reference Example 1 Synthesis of ester polyol A 6.69 kg phthalic anhydride, 2.03 kg glycerin, 2.08 kg 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 6 The polyols, water, foam stabilizers, foaming agents and catalysts shown in Table 1 were adjusted in predetermined amounts and kept at 20 ° C. A predetermined amount of isocyanate A adjusted to 20 ° C. was added to this, and mixed for 5 seconds at high speed, and an aluminum mold (thickness 20
mm x width 300 mm x length 450 mm) 110 g
It was injected and demolded 5 minutes later. The equivalent ratio of isocyanate A to total active hydrogen was NCO / H = 1.10. Various physical properties such as thermal conductivity of the obtained rigid polyurethane foam are shown in Table 1. Table 1 also shows the storage stability of the resin premixes of Examples and Comparative Examples.

[0024]

[Table 1] The conditions for measuring the physical properties of the rigid polyurethane foam are as follows. 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. Density Measure the core of rigid polyurethane foam. Cell condition Visual evaluation. 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.

According to the comparison of Examples 1 to 3 and Comparative Example 1, when cyclopentane was used as a foaming agent, the ester polyol described in the present invention was emulsified by using 70 parts by weight or more of the polyol. It can be seen that the storage stability is remarkably improved when 1 part by weight or more of the chain saturated hydrocarbon compound is used as the storage stabilizer in the resin premix. From Comparative Example 2, it is understood that the chain saturated hydrocarbon compound has a higher storage stability effect than the cyclic saturated hydrocarbon compound. From Comparative Example 3, it can be seen that the thermal conductivity of the obtained rigid polyurethane foam deteriorates when the chain saturated hydrocarbon compound is used in an amount of 10 parts by weight or more. Comparative Example 4 shows that the chain saturated hydrocarbon compound having 8 or less carbon atoms acts as a foaming agent due to a decrease in density and a deterioration in thermal conductivity. Further, Comparative Example 5 shows that the chain saturated hydrocarbon compound having 13 or more carbon atoms causes cell roughening and deteriorates the thermal conductivity. From the comparison between Examples 1 to 3 and Comparative Example 6, the rigid polyurethane foam of the present invention has a CF
It can be seen that the thermal conductivity could be reduced as much as the conventional rigid polyurethane foam in which the amount of C-11 used was reduced.

[0026]

Industrial Applicability According to the present invention, various physical properties of a rigid polyurethane foam produced by using a blowing agent containing water and cyclopentane as essential components are satisfied, and thermal conductivity is CFC.
It was possible to significantly improve the storage stability of the emulsified resin premix while reducing it to the level of rigid polyurethane foam using -11.

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

Claims (3)

[Claims] An organic polyisocyanate, a polyol,
In a rigid polyurethane foam produced from a foaming agent, a catalyst, a foam stabilizer, and other auxiliaries, water and cyclopentane are essential components as a foaming agent, an average number of functional groups is 2.0 to 4.0, and a hydroxyl value is a polyol. 300-6
70% by weight of ester polyol of 00 mg KOH / g
A mixture of polyol, a foaming agent, a catalyst, a foam stabilizer and other auxiliaries is used as an emulsion containing the above, and as a storage stabilizer of the emulsion, a carbon number is 9 per 100 parts by weight of the polyol. A rigid polyurethane foam characterized by using 1 to 10 parts by weight of a chain saturated hydrocarbon compound of 12 to 12 parts by weight. 2. As a storage stabilizer for an emulsion, 1 to 5 parts by weight of a chain saturated hydrocarbon compound having 9 to 12 carbon atoms is used per 100 parts by weight of a polyol. The rigid polyurethane foam according to claim 1, which is characterized in that 3. An organic polyisocyanate, a polyol,
In a method for producing a rigid polyurethane foam from a foaming agent, a catalyst, a foam stabilizer, and other auxiliaries, water and cyclopentane are essential components as a foaming agent, and a polyol has an average functional group of 2.0 to 4.0 and a hydroxyl group. Value 300
To 600 mgKOH / g of ester polyol containing 70% by weight or more, a polyol, a foaming agent, a catalyst,
A mixture of a foam stabilizer and other auxiliaries becomes an emulsion, and as a storage stabilizer of the emulsion, one chain saturated hydrocarbon compound having 9 or more and 12 or less carbon atoms is used per 100 parts by weight of the polyol. A method for producing a rigid polyurethane foam, characterized by using at least 10 parts by weight.