JPH06345842A - Production of rigid polyurethane foam - Google Patents

Abstract

PURPOSE:To obtain a rigid polyurethane foam useful as a heat insulating material for refrigerator, etc., having excellent heat insulating performances without damaging excellent dimensional stability and compression strength, from an organic polyisocyanate, a catalyst, a foam stabilizer, a specific blowing agent and a polyol. CONSTITUTION:This urethane foam is obtained from (A) an organic polyisocyanate, (B) a polyol comprising 40-90wt.% based on the whole polyol components of an aromatic polyester polyol which is obtained by reacting phthalic acid (anhydride) with glycerol and ethylene glycol and has >=3 average number of functional groups and 300-600 hydroxyl number, (C) a blowing agent composed of 1,1-dichloro-1-fluoroethane or 2,2-dichloro-1,1,1-trifluoroethane and (D) auxiliaries such as catalyst and foam stabilizer. A polyol obtained by reacting 1mol phthalic acid (anhydride) with 1.0-1.5mol glycerol and 1.0-1.5mol ethylene glycol is preferable as the used component B.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing a rigid polyurethane foam. Specifically, 1,1-dichloro-1-fluoroethane (hereinafter, referred to as a foaming agent)
R-141b) and / or 2,2-dichloro-
The present invention relates to a method for producing a rigid polyurethane foam that uses 1,1,1-trifluoroethane (hereinafter, referred to as R-123) and has excellent heat insulation performance.

[0002]

2. Description of the Related Art Rigid polyurethane foam is widely used as a heat insulating material for refrigerators, frozen warehouses, building materials and the like because it has excellent heat insulating performance, dimensional stability and workability. This is because trichlorofluoromethane (hereinafter referred to as R-11), which has excellent heat insulating properties and filling properties, is used as a foaming agent when producing a rigid polyurethane foam. In recent years, regulations on chlorofluorocarbons have been implemented to protect the earth's ozone layer. R-11, which is used as a foaming agent for rigid polyurethane foam, is also included in this regulation. Therefore, there is an urgent need to develop a foaming agent for rigid polyurethane foam, which replaces R-11.
So-called hydrochlorofluorocarbons such as R-123 are considered as candidates for alternative blowing agents. However, when R-141b and R-123 are used as the foaming agent, compared with the conventional foam foamed using R-11,
There are problems such as 1) decrease in thermal conductivity, 2) decrease in foaming efficiency, 3) deterioration in physical properties of foam such as dimensional stability at low temperature and compressive strength, and a satisfactory rigid polyurethane foam cannot be obtained. In particular, when using rigid polyurethane foam for heat insulating materials in refrigerators, showcases, etc., R-11
R-141b, which is required to have the same degree of heat insulation performance as when used, and whose thermal conductivity peculiar to the foaming agent is inferior to that of R-11,
When 2-123 was used and the same raw material as the conventional one was used, a rigid polyurethane foam practically satisfactory could not be obtained such that the thermal conductivity of the rigid polyurethane foam was lowered and the low temperature dimensional stability was also deteriorated.

[0003]

Various improvements have been made to rigid polyurethane foams for the purpose of improving heat insulation performance. For example, in JP-A-56-163117, an aromatic amine polyol and a polyester polyol are used in combination to improve the thermal conductivity which was conventionally 0.0150 to 0.0160 kcal / mhr ° C to 0.0130 to 0.0140 kcal / mhr ° C. In addition, in JP-A-2-180916, by using an aromatic polyester polyol having an average functional group number of 2.2 to 3.6 and a hydroxyl value of 200 to 550 in an amount of 10 to 60% by weight of the polyol component, In addition to improving the thermal conductivity of
It is described that the resin strength was also improved. However, all of these technologies use R-11, which is currently subject to CFC regulation as a blowing agent, or use a relatively large amount of water to reduce the amount of R-11 used, so-called saving. A new R-141, a CFC technology
b, not suitable for R-123. We have
Previously, the inventors invented a method in which even when the foaming agents R-141b and R-123 are used, a dimensional change rate and a compressive strength almost equal to those when the conventional R-11 is used can be obtained. These are as described in JP-A-1-287125 and JP-A-3-86735, but this method is not always satisfactory in terms of heat insulation performance as compared with the case of using R-11. Was not.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to solve the above-mentioned problems, and as a result, by using a special polyol component in the production of a rigid polyurethane foam, R-as a foaming agent. 141b and /
Alternatively, even when R-123 was used, a method for producing a hard polyurethane foam having excellent heat insulating properties and good physical properties was found, and the present invention was accomplished. That is, the present invention is a method for producing a rigid polyurethane foam from an organic polyisocyanate, a polyol, a foaming agent, a catalyst, a foam stabilizer and other auxiliary agents, the foaming agent is R-141b and / or R-123, And 40 ~ of the polyol component
In a method for producing a rigid polyurethane foam, 90% by weight is a polyester polyol having an average number of functional groups of 3 or more and a hydroxyl value of 300 to 600, which is obtained by reacting o-phthalic acid or phthalic anhydride with glycerin and ethylene glycol. is there. Instead of the conventionally used R-11,
When using R-123 and / or R-141b,
According to the present invention, a rigid polyurethane foam having excellent heat insulation performance is manufactured for the first time.

The aromatic polyester polyol used in the present invention has a hydroxyl value of 300 to 600, preferably 350 to 550, and more preferably 400 to 550, and the number of parts used is 40 to 90% by weight, preferably 60 to 60% by weight of the polyol component. 80% by weight. If the number of parts used is less than 40% by weight, the thermal conductivity of the resulting rigid polyurethane foam will decrease, resulting in 90% by weight.
If it exceeds, the compatibility with HCFC deteriorates and separation occurs.

In the present invention, the polyols that can be used in combination with the aromatic polyester polyol are all polyols that are usually used as urethane raw materials. Polyols normally used as urethane raw materials are, for example,
Propylene oxide or ethylene oxide added to polyhydric alcohols such as ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, dipropylene glycol, trimethylolpropane, pentaerythritol, sorbitol and sucrose. Aromatic tolylenediamine, aliphatic ethylenediamine to which propylene oxide and ethylene oxide are added, and the like, and polyester polyols include aliphatic polyester polyols and the like.

The organic polyisocyanate used in the present invention is an organic compound having two or more isocyanate groups in one molecule, and is an aliphatic or aromatic polyisocyanate compound, and further these compounds. Includes modified products of. Examples of the aromatic polyisocyanate include various grades such as tolylene diisocyanate, diphenylmethane diisocyanate, and polymethylene polyphenyl isocyanate, and examples of the aliphatic polyisocyanate include hexamethylene diisocyanate and isophorone. There are diisocyanates and the like, and modified products thereof include carbodiimide modified products and prepolymer modified products. Preferred organic polyisocyanates in the present invention are aromatic polyisocyanates or modified products of aromatic polyisocyanates, particularly preferably diphenylmethane diisocyanate, polymethylene polyphenyl isocyanate and modified products thereof.

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 as a mixture, and the amount thereof used is 100 parts by weight of the compound having active hydrogen.
0.001 to 10.0 parts by weight 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, F-343, F- manufactured by Shin-Etsu Chemical Co., Ltd.
347, F-350S, F-345, F-348, etc. are suitable. The appropriate amount of these foam stabilizers is 0.1 to 10.0 parts by weight based on 100 parts by weight of the compound having active hydrogen. Other flame retardants, plasticizers, stabilizers, colorants and the like can be added as required.

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

[0011]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. Parts in the examples represent parts by weight.

The raw materials used in the examples are as follows. Organic polyisocyanate A: a product of Mitsui Toatsu Chemicals, Inc.
Polymeric MDI total NCO 31.3%. Aromatic polyester polyol A: phthalic anhydride 148g
And 62 g of ethylene glycol and 92 g of glycerin were produced by reacting at 200 to 230 ° C. while stirring in a flask. Hydroxyl value 540, viscosity 30000 CPS / 25 ℃. Aromatic polyester polyol B: phthalic anhydride 148g
And 93 g of ethylene glycol and 92 g of glycerin were reacted by stirring at 200 to 230 ° C in a flask. Hydroxyl value 550, viscosity 24000 CPS / 25 ℃. Aromatic polyester polyol C: phthalic anhydride 148g
And 186 g of ethylene glycol and 92 g of glycerin were stirred in a flask and reacted at 200 to 230 ° C. Hydroxyl value 540, viscosity 20000 CPS / 25 ℃. Polyether polyol A: a polyether polyol having a hydroxyl value of 450 mg KOH / g obtained by adding propylene oxide to a mixture of sucrose / glycerin / tolylenediamine. Polyether polyol B: Hydroxyl value 450 obtained by adding propylene oxide to a mixture of sorbitol / glycerin
mgKOH / g polyether polyol. Foam stabilizer: L-5420 manufactured by Nippon Unicar Co., Ltd. Catalyst: tetramethylhexamethylenediamine. Blowing agent: R-141b.

Examples 1 to 6 A predetermined amount of the polyol, the foaming agent, the foam stabilizer and the catalyst shown in Table 1 were mixed in advance, a predetermined amount of the organic polyisocyanate was added thereto, and the mixture was mixed at a high speed for 8 seconds, and immediately. The foaming liquid was poured into a free foaming box (size: 250 × 250 × 250 mm wooden box). Further, a predetermined amount of the foaming liquid was poured into an aluminum vertical panel (size: inner size 400 × 400 × 30 thickness mm) adjusted to 45 ° C. in advance, and the foam was demolded after 6 minutes. Various characteristic values of the obtained rigid polyurethane foam are shown in Tables 1 and 2. The measurement conditions for various physical properties of the rigid polyurethane foam are as follows. Free density: 100 x 100 x 100 tmm The density of the core part of the foam obtained by free foaming. Thermal conductivity: 200 × 200 × 20mm, (by Auto-λ EKO) Dimensional stability: 95 × 95 × 95mm, -30 ℃ × 24 hours

Comparative Examples 1 to 4 Rigid polyurethane foams having the formulations shown in Table 2 were obtained in the same manner as in Examples. Table 2 shows various characteristic values of the obtained rigid polyurethane foam.

[0015]

[Table 1]

[0016]

[Table 2]

[0017]

EFFECT OF THE INVENTION Alternative blowing agents for R-11 R-141b, R
The rigid polyurethane foam obtained by the formulation using -123 is inferior in the heat insulation performance (heat conductivity) of the rigid polyurethane foam as compared with the rigid polyurethane foam obtained by the formulation using the conventional R-11 in a large amount. It was However, according to the present invention, by using a special aromatic polyester polyol as the polyol component, the thermal conductivity is almost the same as that of the rigid polyurethane foam obtained from the conventional formulation using a large amount of R-11. A rigid polyurethane foam having excellent heat insulation performance was obtained.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical display location C08L 75:04 (72) Inventor Toshikazu Nakajima 1190 Kasama-cho, Sakae-ku, Yokohama-shi, Kanagawa Mitsui Toatsu Chemical Co., Ltd. In-house (72) Inventor Yuji Uchida 1190 Kasama-cho, Sakae-ku, Yokohama-shi, Kanagawa Mitsui Toatsu Chemical Co., Ltd.

Claims (2)

[Claims] 1. An organic polyisocyanate, a polyol,
A method for producing a rigid polyurethane foam from a foaming agent, a catalyst, a foam stabilizer and other auxiliaries, wherein the foaming agent comprises 1,
1-dichloro-1-fluoroethane and / or 2,2,
-Dichloro-1,1,1-trifluoroethane,
Moreover, 40 to 90% by weight of the polyol component is an average number of functional groups of 3 or more obtained by reacting o-phthalic acid or phthalic anhydride with glycerin and ethylene glycol, and a hydroxyl value of 300 to 6
A process for producing a rigid polyurethane foam, which is 00 aromatic polyester polyol. 2. The aromatic polyester polyol is glycerin based on 1 mol of o-phthalic acid or phthalic anhydride.
The method for producing a rigid polyurethane foam according to claim 1, which is an aromatic polyester polyol obtained by reacting 1.0 to 1.5 mol and 1.0 to 1.5 mol of ethylene glycol.