JPH10182784A - Production of rigid polyurethane foam - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce the subject foam excellent in fluidity, heat insulation, mold realize and low-temperature dimensional stability by reacting an organic polyisocyanate with a resin premix composed of a specific polyol, a specified foaming agent, a catalyst, a foam stabilizer and other auxiliaries. SOLUTION: (A) An organic polyisocyanate such as toluene diisocyanate or diphenylmethane diisocyanate is mixed and reacted with a resin premix composed of (B) (i) a polyether polyol having 60-100mol% sucrose concentration in an initiator, 6.0-8.0 average functionality and 280-600mgKOH/g hydroxyl value in an amount of 5-50 pts.wt. based on 100 pts.wt. polyol component and (ii) an aromatic polyol having 2.0-2.9 average functionality and 280-600mgKOH/g hydroxyl value in an amount of >=20 pts.wt. based on 100 pts.wt. polyol component as the polyol component, (C) 1,1-dichloro-1-fluoroethane as a foaming agent, (D) a catalyst, (E) a foam stabilizer and (F) other auxiliaries to afford the objective polyurethane foam.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing a rigid polyurethane foam. More specifically, 1,1-dichloro-1-fluoroethane (hereinafter referred to as H
CFC-141b) as an essential component, and by using a specific polyol, has excellent fluidity, heat insulation performance, and mold releasability, and also has excellent low-temperature dimensions that can meet industrial demands for low density. This is a method for producing a rigid polyurethane foam having stability.

[0002]

2. Description of the Related Art Rigid polyurethane foams are widely used as heat insulating materials for refrigerators, freezer warehouses, building materials and the like and for spraying applications because of their excellent heat insulating performance, dimensional stability and workability. Conventionally, trichlorofluoromethane having a low thermal conductivity and a suitable boiling point as a foaming agent for a rigid polyurethane foam (hereinafter, referred to as trichlorofluoromethane)
This is a major reason that CFC-11) was used. However, chlorofluorocarbons (hereinafter, referred to as
The theory is that CFCs) contain chlorine atoms in their molecules and are extremely stable molecules, so they reach the ozone layer by diffusion effects and react with ozone to destroy the ozone layer of the earth. Already at the end of 1995, the use of CFCs has been completely abolished. At present, as a foaming agent for rigid polyurethane foam, hydrochlorofluorocarbons (hereinafter, referred to as HCFCs) which are substitutes thereof are used.
The use of HCFC-141b, which has a low thermal conductivity among C types, has become mainstream.

[0003]

Generally, a rigid polyurethane foam for heat insulation has a closed cell structure in which a foaming agent is sealed in a cell. Therefore, when a foaming agent having a boiling point equal to or higher than normal temperature (25 ° C. or higher) is used, the pressure in the cell decreases due to liquefaction of the foaming agent sealed in the cell at normal temperature or low temperature. This phenomenon is due to the inherent vapor pressure of the blowing agent, and as a result, the rigid polyurethane foam shrinks. That is, these temperatures are higher than normal
The most difficult problem in practical use of a foaming technique using a foaming agent having a boiling point of (° C or higher) is to avoid shrinkage of the rigid polyurethane foam at room temperature or lower, particularly at low temperatures, that is, to maintain good low-temperature dimensional stability. is there.

HCFC-141b (boiling point, 32.4 ° C.)
A foaming technique using as a foaming agent is disclosed in, for example,
Although good compressive strength, dimensional stability and low thermal conductivity are realized by using an aromatic amine-based polyol described in No. 281545 or a polyester polyol described in JP-A-3-86735, Compared with the conventional foaming technique using CFC-11 (boiling point, 23.6 ° C.) as a foaming agent, the above-mentioned problems have been avoided by increasing the set density or the overfilling rate and accompanyingly improving the strength of the cell structure. Was. On the other hand, there is an industrial demand for lowering the density of the rigid polyurethane foam as a problem leading to a reduction in production cost. In order to meet this demand without deteriorating the industrial application value, it is essential to establish a method for producing a rigid polyurethane foam having a lower density than the current state and excellent low-temperature shrinkage dimensional stability.

[0005]

Means for Solving the Problems The present inventors have conducted intensive studies to achieve the above object, and as a result, have found that HC
Even when FC-141b was used as an essential component, the sucrose concentration in the initiator was 6% as the polyol component.
0-100 mol% and the average number of functional groups is 6.0-8.
0, a polyether polyol having a hydroxyl value of 380 to 480 mg KOH / g, 5 to 50 parts by weight per 100 parts by weight of the polyol component, and an average number of functional groups of 2.0 to
2.9, by using an aromatic polyol having a hydroxyl value of 280 to 600 mg KOH / g in an amount of 20 parts by weight or more per 100 parts by weight of a polyol component,
The present inventors have found that it is possible to produce a rigid polyurethane foam excellent in remarkably low-temperature dimensional stability while maintaining the demolding property and the heat insulation performance, and completed the present invention which can meet the demand for industrial low density. Reached.

That is, the present invention relates to a method for producing a rigid polyurethane foam by mixing and reacting an organic polyisocyanate with a resin premix comprising a polyol, a foaming agent, a catalyst, a foam stabilizer and other auxiliaries. , (1) a compound having HCFC-141b as an essential component as a foaming agent, and (2) a polyol component,
The sucrose concentration in the initiator is 60 to 100 mol%, the average number of functional groups is 6.0 to 8.0, and the hydroxyl value is 380 to 380.
480 mgKOH / g of a polyether polyol is used in an amount of 5 to 50 parts by weight per 100 parts by weight of a polyol component, the average number of functional groups is 2.0 to 2.9, and the hydroxyl value is 280 to 60.
A method for producing a rigid polyurethane foam, characterized in that 0 mgKOH / g of an aromatic polyol is used in an amount of 20 parts by weight or more per 100 parts by weight of a polyol component.

JP-A-3-86718 discloses that HCFC-141b is used as a foaming agent and the average number of functional groups is from 4.6 to 4.6.
8.0, a polyol having a hydroxyl value of 300 to 800 mgKOH / g and a polyol having an average functional group of 3.0 to 4.5 and a hydroxyl value of 300 to 800 mgKOH / g are used to improve the low-temperature dimensional stability of the rigid polyurethane foam. It discloses that it can be improved. However, the present invention
The sucrose concentration in the initiator is 60 to 100 mol%, the average number of functional groups is 6.0 to 8.0, and the hydroxyl value is 380 to 480 m.
gKOH / g polyol and average number of functional groups is 2.0
It has been found that the combined use of an aromatic polyol having a hydroxyl value of from 2.9 to 2.9 and a hydroxyl value of from 280 to 600 mgKOH / g can improve the low-temperature dimensional stability while maintaining more excellent physical properties.

[0008]

DETAILED DESCRIPTION OF THE INVENTION The blowing agent used in the present invention is 1,1.
-Dichloro-1-fluoroethane as an essential component. Other components that may be included include HFC
-134a, HCFC-142b, HCFC-22, etc., and 1,1-dichloro-1 which is an essential component
-Other blowing agents may be used as long as they do not inhibit the effect of fluoroethane. Further, it is preferable to use water as an auxiliary foaming agent. Usually, the amount of water used is preferably 0.5 to 2.5 parts by weight based on 100 parts by weight of the polyol component. If the amount of water used is less than 0.5 parts by weight, the fluidity is reduced,
Exceeding the weight part is not preferred because the brittleness, adhesiveness and thermal conductivity of the surface of the rigid polyurethane foam decrease. The amount of the foaming agent used depends on the set temperature and the amount of water used as the auxiliary foaming agent.
0 to 40 parts by weight, preferably 24 to 35 parts by weight.

In the present invention, a polyether polyol used as one of the polyol components (the polyether polyol and the aromatic polyol used in the present invention; the same applies hereinafter) has a sucrose concentration in the initiator of 60 to 100 m.
ol%, the average number of functional groups is 6.0 to 8.0, and the hydroxyl value is 380 to 480 mgKOH / g, preferably 400 to 4
It is of 60 mg KOH / g. Usually, the viscosity of these polyol components at 25 ° C. is 170,000 cp.
s or less. Sucrose concentration in the initiator is 60mo
If it is less than 1%, the low-temperature dimensional stability is not sufficiently improved.
When the average number of functional groups is less than 6.0, it is difficult to keep the sucrose concentration in the initiator at 60 mol% or more due to the composition of the polyether polyol. The hydroxyl value is 480mgK
If it exceeds OH / g, the viscosity increases, which is not preferable. On the other hand, if it is less than 380 mgKOH / g, the low-temperature dimensional stability decreases due to a decrease in strength due to an increase in the distance between crosslinking points due to an increase in the number of moles of alkylene oxide added. Also,
The amount of the polyether polyol to be used is 5 to 50 parts by weight, preferably 10 to 40 parts by weight, per 100 parts by weight of the polyol component. If the amount is less than 5 parts by weight, the effect is not remarkably seen, and if it exceeds 50 parts by weight, the viscosity increases and the fluidity decreases, which is not preferable.

The aromatic polyol which is one of the polyol components used in the present invention has an average number of functional groups of 2.0.
2.9, and a hydroxyl value of 280-600 mgKOH / g. If the average number of functional groups exceeds 2.9, the fluidity decreases, which is not preferable. On the other hand, if it is less than 2.0, the strength is undesirably reduced. The amount of the aromatic polyol used is
It is at least 20 parts by weight, preferably 30 to 60 parts by weight, per 100 parts by weight of the polyol component. By using the aromatic polyol in an amount of 20 parts by weight or more together with the polyether polyol, good fluidity can be obtained, and a reduction in thermal conductivity due to miniaturization of cells of the obtained rigid urethane foam can be achieved. . There is no particular upper limit on the amount used, but it is determined based on the obtained effects and costs.

As the aromatic polyol, for example, phthalic anhydride can be used in the form of glycerin, trimethylolpropane, ethylene glycol, propylene glycol,
Low molecular weight triols such as 2-butanediol and 1,4-butanediol, ester polyols obtained by polymerizing alkylene oxides with half-esterified diols, or low molecular weight carboxylic acids such as adipic acid and phthalic acid Examples include polyester polyols produced by a condensation reaction with a polyhydric alcohol, and polyether polyols obtained by addition-polymerizing an alkylene oxide to an aromatic hydroxy compound such as bisphenol A.

Other polyols may be used in combination with the polyol components of the polyether polyol and the aromatic polyol used in the present invention. As the polyol that can be used in combination, all known polyols can be used. For example,
Polyhydric alcohols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, trimethylolpropane, trimethylolethane, glycerin, pentaerythritol, alphamethylglucoside, sorbitol, and sucrose, ethylenediamine, A hydroxyl value of 350 to 800 mg obtained by addition-polymerizing an alkylene oxide to a single or mixed system of aliphatic amines such as ethanolamine and isopropanolamine.
KOH / g polyether polyol and the like.

As the catalyst, for example, amine urethanes such as trimethylaminoethylpiperazine, triethylamine, tripropylamine, N-methylmorpholine, N-ethylmorpholine, triethylenediamine, tetramethylhexamethylenediamine, pentamethyldiethylenetriamine, etc. All known catalysts such as catalysts can be used. The amount of use is 0.001 to 10.3 based on 100 parts by weight of the total compound having active hydrogen used in the present invention.
0 parts by weight.

As the foam stabilizer, a conventionally known organic silicon-based surfactant is used. For example, L-5420 and L-5421 manufactured by Nippon Unicar Co., Ltd., SH-193 manufactured by Dow Corning Toray Silicone Co., Ltd., and F-5 manufactured by Shin-Etsu Chemical Co., Ltd.
-327, F-345, F-305 and the like are suitable. These foam stabilizers are used in an amount of 0.1 to 100 parts by weight of the total of the compound having active hydrogen and the organic polyisocyanate.
To 10 parts by weight. In addition, a flame retardant, a plasticizer, a stabilizer, a colorant, and the like can be added as needed.

In the method of the present invention, a resin premix is prepared by adding the above-mentioned polyol component, a foaming agent, a foam stabilizer, and other flame retardants, plasticizers, stabilizers, coloring agents and the like as necessary. React with polyisocyanate. As the organic polyisocyanate used in the present invention, all known organic polyisocyanates can be used, but the most common one is toluene diisocyanate (hereinafter referred to as TDI).
And / or diphenylmethane diisocyanate (hereinafter referred to as MDI). TDI is 2,4-body 100
% Product or a mixture of isomers, that is, 2,4-form / 2,6-
A so-called so-called "TDI-TRC" manufactured by Mitsui Toatsu Chemicals, Inc., which contains a multifunctional tar, including those having a body ratio of 80/20 or 65/35 (each by weight) or other mixing ratios. Crude TDI can also be used. Also,
As MDI, Mitsui Toatsu Chemical Co., Ltd., which contains a polynuclear body of three or more nuclei in addition to a pure product having a 4,4′-isomer as a main component
Polymeric MD represented by Cosmonate series
I is preferably used. In addition, a prepolymer having an isocyanate group at the molecular terminal obtained from the organic polyisocyanate and a polyol described below can also be used as a part or all of the isocyanate composition.

The ratio between the NCO groups in the organic polyisocyanate and the active hydrogen in the resin premix is NCO / OH
(Active hydrogen) = 0.7 to 5.0 (equivalent ratio) is particularly preferred. Therefore, in order to carry out the present invention, the organic polyisocyanate and the resin premix are required to have an equivalent ratio (NCO: OH) of the organic polyisocyanate to the active hydrogen of the resin premix in the range of 0.7: 1 to 5: 1. The mixture is mixed at a high speed with a desired liquid ratio, and injected into a cavity or a mold. A rigid urethane foam can be obtained by a conventional foam molding method.

[0017]

The present invention will be described below in detail with reference to examples and comparative examples. However, the present invention is not limited to the following examples. In Examples and Comparative Examples,
The raw materials used are as follows. Polyether polyol A: sucrose / glycerin (weight ratio 60/40) to which propylene oxide is added and polymerized has a hydroxyl value of 450 mgKOH / g, and a viscosity of 6,000 cps (2
5 ° C.) polyether polyol. Average number of functional groups 4.4
4. Concentration of sucrose in the initiator: 28.8 mol% Polyether polyol B: synthesized in Reference Example 1. Polyether polyol C: synthesized in Reference Example 2. Polyether polyol D: synthesized in Reference Example 3. Aromatic polyol A: Addition of propylene oxide / ethylene oxide to m-tolylenediamine / triethanolamine (weight ratio 70/30), hydroxyl value 400
A polyether polyol having a mgKOH / g viscosity of 10,000 cps (25 ° C.). Aromatic polyol B: hydroxyl value obtained by addition polymerization of propylene oxide / ethylene oxide to bisphenol A 2
80 mg KOH / g, viscosity 100,000 cps (25
C) polyether polyol. Aromatic polyol C: synthesized in Reference Example 4. Organic polyisocyanate: Cosmonate M-200 manufactured by Mitsui Toatsu Chemicals, Inc. Polymeric MDI NCO% 31.3% Foam stabilizer: SZ-1653 manufactured by Nippon Unicar Co., Ltd. Catalyst A: Kao Riser No. manufactured by Kao Corporation . Catalyst B: Kao Riser No. 3 manufactured by Kao Corporation 1 (tetramethylhexamethylenediamine) Blowing agent A: HCFC-141 manufactured by Central Glass Co., Ltd.
b (1,1-dichloro-1-fluoroethane) Blowing agent B: Freon-11A (trichlorofluoroethane) manufactured by Mitsui Dupont Fluorochemicals Co., Ltd.

Reference Example 1 Synthesis of Polyether Polyol B 301 g of sucrose, 624 g of the above polyether polyol A and 6.75 g of dimethyl palmitylamine were charged into a 2 L reaction tank, and the reaction tank was purged with nitrogen. Thereafter, stirring and heating were started, and the internal pressure of the reaction vessel was increased to 4.0 k at 100 ° C.
The reaction was carried out by gradually charging 303 g of propylene oxide so as to keep g / cm ² or less. After charging propylene oxide for 2 hours, the temperature was raised to 110 ° C., and the mixture was stirred for 3 hours until no decrease in internal pressure was observed. After the reaction,
Residual propylene oxide is removed under reduced pressure and water 1
23 g were added. After stirring at 100 ° C. for 1 hour to confirm dissolution of unreacted sucrose, dehydration was performed under reduced pressure. Subsequently, 273 g of propylene oxide was charged. After completion of the reaction, the remaining propylene oxide was removed, and further filtered (exposed filtration) to give a pale yellow clear hydroxyl value of 452 mgK.
OH / g of polyether polyol B was obtained. Average number of functional groups 6.00, sucrose concentration in initiator 60.0 mo
1%.

Reference Example 2 Synthesis of polyether polyol C 358 g of sucrose, 437 g of polyether polyol (sorbitol / glycerin = 94/6% by weight, propylene oxide was added thereto, and the hydroxyl value was 470 mgKOH /
g, average number of functional groups = 5.63) and 6.75 g of dimethyl palmitylamine were charged into a 2 L reaction vessel,
After purging the reactor with nitrogen, stirring and heating were started, and 583 g of propylene oxide was gradually charged at 100 ° C. so that the internal pressure of the reactor was kept at 4.0 kg / cm ² or less, and the reaction was carried out. Was. After charging propylene oxide in 2 hours, 110
C., and stirred for 3 hours until no decrease in internal pressure was observed. After the completion of the reaction, residual propylene oxide was removed under reduced pressure, and 150 g of water was added. 1 at 100 ° C
After stirring for an hour and confirming dissolution of unreacted sucrose, dehydration was performed under reduced pressure. Subsequently, 122 g of propylene oxide was charged, and after completion of the reaction, the remaining propylene oxide was removed, followed by filtration (exposed filtration) to obtain a light yellow clear polyether polyol C having a hydroxyl value of 455 mgKOH / g. Average number of functional groups: 7.09, sucrose concentration in initiator: 60.0 mol%.

Reference Example 3 Synthesis of Polyether Polyol D 514 g of sucrose and 6.75 g of dimethyl palmitylamine were charged into a 2 L reaction vessel, and the reaction vessel was purged with nitrogen, followed by stirring and heating. Then, 863 g of propylene oxide was gradually charged at 100 ° C. so that the internal pressure of the reaction vessel was maintained at 4.0 kg / cm ² or less, and the reaction was carried out. 6
After charging propylene oxide for an hour, the temperature was raised to 110 ° C,
The mixture was stirred for 3 hours until no decrease in internal pressure was observed. After the reaction was completed, residual propylene oxide was removed under reduced pressure, and 275 g of water was added. Stir at 100 ° C for 1 hour,
After confirming dissolution of unreacted sucrose, dehydration was performed under reduced pressure. Subsequently, 122 g of propylene oxide was charged. After the completion of the reaction, the remaining propylene oxide was removed, followed by filtration (exposed filtration) to obtain a light yellow clear polyether polyol D having a hydroxyl value of 456 mgKOH / g. Average number of functional groups 8.00, sucrose concentration in initiator 100.0 mol%

Reference Example 4 Synthesis of aromatic polyol C 6.69 kg of phthalic anhydride, 2.03 kg of glycerin, 2.08 kg of 1,4-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.
The temperature was increased by pressurizing with nitrogen. 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 temperature was maintained at 100 ° C. and stirred for 5 hours.
The temperature was raised to 20 ° C., and the reaction was continued for another 5 hours until no decrease in internal pressure was observed. After completion of the reaction, the remaining propylene oxide was distilled off under reduced pressure and filtered to obtain an acid value of 0 mgKOH / g.
Hydroxyl value 412mgKOH / g, viscosity 35,000cp
s (25 ° C.) of aromatic polyol C was obtained.

Examples 1 to 5 and Comparative Examples 1 to 6 Table 1 (Examples 1 to 5) and Table 2 (Comparative Examples 1 to 6)
A predetermined amount of a resin premix having the composition shown in Table 2 was blended, and high-speed mixing with an organic polyisocyanate was carried out to foam. The conditions are shown below. Foaming liquid temperature; organic polyisocyanate / resin premix = 20 (° C) / 20 (° C). A predetermined amount of a foaming liquid was poured into a vertical aluminum panel (size: 400 × 400 × 35 mm in thickness) which had been adjusted to 45 ° C. in advance, and was released after 8 minutes. The dimensional stability was evaluated using a free foaming box (size: 250 × 250 × 250).
mm) and 24 hours in a constant temperature room at 23 ° C and 65% humidity.
The core portion of the rigid polyurethane foam left for a time was cut out, and the dimensions and density were measured. After foaming, the mixture was allowed to stand in an atmosphere of -30 ° C for 24 hours, and quantified by a dimensional change rate%. The fluidity was evaluated by measuring the foam length and the foam weight after molding with the above aluminum vertical panel, and quantifying the length per unit weight (mm / g). 23 ℃ after foaming
The thermal conductivity of the foam left in a constant temperature room of 65% humidity for 24 hours was measured as follows. Sample size: 200 × 200 × 25 mm Measuring equipment: Auto-λ HC-072 (intermediate temperature: 25 ° C.) manufactured by Eiko Seiki Co., Ltd. The evaluation of the releasability was made by aluminum horizontal mold (size 330 × 330) which was adjusted to 45 ° C. in advance. × 80 mm in thickness) and a predetermined amount of the foaming liquid was injected, and the mold was removed after 5 minutes. Immediately after the mold was released, the thickness was measured with a dial gauge to measure the state of the foam swelling. The evaluation was based on how many millimeters the original thickness of 80 mm swelled.

[0023]

[Table 1]

[0024]

[Table 2]

[0025]

According to the present invention, HCFC is used as a foaming agent.
When -141b is used, it is possible to obtain a rigid polyurethane foam having excellent low-temperature dimensional stability while maintaining good fluidity, heat insulation performance, and demoldability.
This can meet the demand for industrial low density.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Satoru Akimoto 1190 Kasama-cho, Sakae-ku, Yokohama-shi, Kanagawa Prefecture Inside Mitsui Toatsu Chemical Co., Ltd. (72) Inventor Toshikazu Nakajima 1190 Kasama-cho, Sakae-ku, Yokohama-shi, Kanagawa Mitsui Toatsu Chemical (72) Inventor Hiroshi Fujino 1190 Kasama-cho, Sakae-ku, Yokohama-shi, Kanagawa Mitsui Toatsu Chemical Co., Ltd.

Claims (1)

[Claims] 1. A method for producing a rigid polyurethane foam by mixing and reacting an organic polyisocyanate and a resin premix comprising a polyol, a foaming agent, a catalyst, a foam stabilizer and other auxiliaries, As a foaming agent, 1,1-dichloro-1-fluoroethane is used as an essential component. (2) As a polyol component, the sucrose concentration in the initiator is 60 to 100 mol% and the average number of functional groups is 6.0 to 6.0.
8.0 and a hydroxyl value of 380 to 480 mgKOH /
g of the polyether polyol as the polyol component 10.
5 to 50 parts by weight per 0 parts by weight, the average number of functional groups is 2.0 to 2.9, and the hydroxyl value is 280 to 600 mgKOH.
/ G of an aromatic polyol having a polyol component of 100
A method for producing a rigid polyurethane foam, comprising using 20 parts by weight or more per part by weight.