JP3081217B2 - Manufacturing method of rigid polyurethane foam - Google Patents

Description

The present invention relates to a method for producing a rigid polyurethane foam. More specifically, 1,1-dichloro-1-fluoroethane (HCFC-141b) or 1,1-dichloro-
The present invention relates to a method for producing a rigid polyurethane foam having excellent low-temperature dimensional stability, compressive strength and thermal conductivity using 2,2,2-trifluoroethane (HCPC-123).

[Conventional technology]

Rigid polyurethane foam is widely used as a heat insulating material for refrigerators, freezer warehouses, etc. because of its excellent heat insulation properties and low-temperature dimensional stability, but chlorofluorocarbons are used as foaming agents for conventional rigid polyurethane foam production. ing.

This is largely because the rigid polyurethane foam obtained by using chlorofluorocarbons in producing the rigid polyurethane foam has excellent heat insulating properties and other physical properties.

[Problems to be solved by the invention]

However, in recent years, regulations for chlorofluorocarbons have been started to protect the earth's ozone layer. This regulation includes trichlorofluoromethane, which has been used as a foaming agent for rigid polyurethane foams. Therefore, 1,1-dichloro-1-fluoroethane (HCFC-141b) or 1,1-dichloro-2, which is a hydrochlorofluorocarbon that has a shorter life in the atmosphere than the chlorofluorocarbon and does not adversely affect the ozone layer. 2,2
-Trifluoroethane (HCFC-123) has received attention as an alternative. However, when these new blowing agents are used, a) the thermal conductivity increases as compared with the case where conventional trichlorofluoromethane is used.

B) Foam properties such as low-temperature dimensional stability and compressive strength are significantly deteriorated.

However, it is difficult to obtain a satisfactory rigid polyurethane foam by the conventional method for producing a rigid polyurethane foam. Therefore, 1,1-dichloro-1-fluoroethane (HCFC-141b)
Alternatively, when 1,1-dichloro-2,2,2-trifluoroethane (HCFC-123) is used, the density is considerably increased in order to have the same low-temperature dimensional stability and foam properties such as compressive strength. There is a need. In addition, it was difficult to obtain a practically satisfactory foam such as the heat insulation property of the conventional product was deteriorated.

An object of the present invention is to use 1,1-dichloro-1-fluoroethane (HCFC-141b) or 1,1-dichloro-, which has a strong resin dissolving power, as a foaming agent in the production of a rigid polyurethane foam.
It is an object of the present invention to provide an excellent rigid polyurethane foam having physical properties that can be used more practically than conventional products even when 2,2,2-trifluoroethane (HCFC-123) is used.

[Means for solving the problem]

The present inventors have conducted intensive studies to achieve the above object, and have reached the present invention.

That is, the present invention relates to a method for producing a rigid polyurethane foam from an organic polyisocyanate and a polyol, a foaming agent, a catalyst, a surfactant and other auxiliaries, wherein the polyol has 3 to 8 hydroxyl groups in one molecule. Production of rigid polyurethane foam characterized by using polyoxyalkylene polyol (X) to which 0.125 to 1.0 mol of lactone and 1.0 to 3.0 mol of alkylene oxide are added per 1 mol of hydroxyl group of polyhydric alcohol or polyoxyalkylene polyol (y). About the law.

The polyhydric alcohol or polyoxyalkylene polyol (y) used in the present invention has 3 to 8 hydroxyl groups in one molecule, and the hydroxyl groups and the lactone react to form an ester bond, and further, the alkylene oxide Reacts to synthesize a polyoxyalkylene polyol (X) having an ester skeleton.

As the polyhydric alcohol used in the present invention, glycerin, trimethylolpropane, 1,2,6-hexanetriol, triethanolamine, pentaerythritol,
Tetramethylolcyclohexane, methylglucoside,
2,2,6,6-tetrakis (hydroxyl) cyclohexanol, sorbitol, mannitol, dulcyltol,
The polyoxyalkylene polyol (y) is obtained by adding an alkylene oxide to the above-mentioned alcohols, and these can be used alone or in combination of two or more.

As the lactone used in the present invention, β-propiolactone, γ-butyrolactone, δ-valerolactone, ε
-Caprolactone and the like.

Examples of the alkylene oxide used in the present invention include ethylene oxide, propylene oxide, butylene oxide and the like, and these may be used alone or in combination of two or more.

The polyoxyalkylene polyol (X) used in the present invention contains 0.125 to 1.0 mol of lactone and 0.125 mol of alkylene oxide per mol of hydroxyl group of polyhydric alcohol or polyoxyalkylene polyol (y) having 3 to 8 hydroxyl groups in one molecule. From 1.0 to 1 mole of hydroxyl group
3.0 mol was added. If the number of hydroxyl groups per molecule of the polyhydric alcohol or polyoxyalkylene polyol (y) is less than 3, the polyurethane foam tends to be weak when formed. On the other hand, if the number of hydroxyl groups per molecule exceeds 8, the number of ester bonds per molecule increases, and therefore, the viscosity of the polyoxyalkylene polyol (X) increases, and the workability during foaming deteriorates.

When less than 0.125 mol of lactone is reacted per 1 mol of hydroxyl group of polyhydric alcohol or polyoxyalkylene polyol (y), the solubility resistance to hydrochlorofluorocarbon is lost. On the other hand, when it exceeds 1.0 mol, unreacted lactone remains. Therefore, the physical properties of the rigid polyurethane foam obtained by reacting with the organic polyisocyanate are deteriorated.

When less than 1.0 mole of alkylene oxide is reacted per mole of hydroxyl group of the polyhydric alcohol or polyoxyalkylene polyol (y), a desired rigid polyurethane foam can be obtained because of poor mixing and dispersibility with an organic polyisocyanate. Absent. On the other hand, if it exceeds 3.0 moles, the solubility resistance to hydrochlorofluorocarbon is lost.

In the present invention, a catalyst used for adding a lactone and an alkylene oxide to a hydroxyl group of a polyhydric alcohol or a polyoxyalkylene polyol (y) is represented by the following general formula (I) or (II) as an amine system. It is an amine compound.

NR ₁ R ₁ R ₂ (I) R ₁ R ₂ N (CH ₂ ) _n NR ₁ R ₂ (II) (wherein R ₁ is a hydrogen atom, an alkyl group having 1 to 6 carbon atoms,
It represents a —CH ₂ CH ₂ OH group or a —CH ₂ CH (CH ₃ ) OH group. R ₂ represents an alkyl group having 1 to 6 carbon atoms, a —CH ₂ CH ₂ OH group or a —CH ₂ CH (C
H ₃ ) represents an OH group. Alternatively, n represents an integer of 1 to 6. Examples of the amine compound include dibutylamine,
Ethylenediamine, tetramethylenediamine, monoethanolamine, diethanolamine, triethanolamine, isopropanolamine, triethylamine, tri-n-propylamine, di-n-propylamine, n
-Propylamine, n-amylamine, N, N-dimethylethanolamine, isobutylamine, isoamylamine, methyldiethylamine and the like.

Examples of the alkali hydroxide catalyst include lithium hydroxide, sodium hydroxide, potassium hydroxide, magnesium hydroxide, calcium hydroxide, barium hydroxide and the like. Each of the above catalysts can be used alone or in combination of two or more. The amount of these catalysts used is the above-mentioned polyhydric alcohol or polyoxyalkylene polyol (y)
0.1 to 2.0 per 100 parts by weight (parts indicate parts by weight)
Department.

The organic polyisocyanate used in the present invention is a conventionally known organic polyisocyanate, and is not particularly limited. Aromatic, aliphatic, alicyclic polyisocyanates and modified products thereof, for example, diphenylmethane diisocyanate, crude diphenylmethane diisocyanate Isocyanate, tolylene diisocyanate, crude tolylene diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated tolylene diisocyanate, triphenylmethylene triisocyanate , Tolylene triisocyanate, modified (carbodiimide, etc.) diphenylmethane diisocyanate and the like, and mixtures thereof, and excess amounts of these organic polyisocyanates and polyols (eg, low molecular polyols and / Or polymeric polyol) and NCO base end prepolymer (NCO group content eg 5-35% obtained by reacting a), and the like.

These organic polyisocyanates are used alone or in combination of two or more. The amount of use is such that the equivalent ratio between the NCO group and the active hydrogen in the resin solution is 0.8 to 5.0.

Examples of the foaming catalyst for obtaining the rigid polyurethane foam usable in the present invention include, for example, amine urethanization catalysts (triethylamine, tripropylamine, triisopropanolamine, tributylamine, trioctylamine, hexadecyldimethylamine, N- Methylmorpholine, N-ethylmorpholine, N-octadecylmorpholine, monoethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, N, N-dimethylethanolamine, diethylenetriamine, N, N, N ', N'-tetramethyl Ethylenediamine, N, N, N ', N'-tetramethylpropylenediamine,
N, N, N ', N'-tetramethylbutanediamine, N, N, N',
N'-tetramethyl-1,3-butanediamine, N, N, N ',
N'-tetramethylhexamethylenediamine, bis [2
-(N, N-dimethylamino) ethyl] ether, N, N-dimethylbenzylamine, N, N-dimethylcyclohexylamine, N, N, N ', N ", N" -pentamethyldiethylenetriamine, triethylenediamine, triethylenediamine Formate and other salts of ethylenediamine, oxyalkylene adducts of amino groups of primary and secondary amines, azacyclic compounds such as N, N-dialkylpiperazines, various N, N ', N "-trialkyl Aminoalkylhexahydrotriazines (β-aminocarbonyl catalyst of JP-B-52-0443517, JP-B-53
-014279 β-aminonitrile catalyst, etc.), organometallic urethanization catalyst, (tin acetate, tin octylate, tin oleate, tin laurate, dibutyltin diacetate, dibutyltin dilaurate, dibutyltin dichloride, lead octanoate) , Lead naphthenate, nickel naphthenate, cobalt naphthenate, etc.).

These catalysts are used alone or as a mixture, and the amount of use is 0.0001 to 10.0 parts with respect to 100 parts of the compound having active hydrogen.

The foam stabilizer in the present invention is a conventionally known organosilicon-based surfactant, for example, L-52 manufactured by Nippon Unicar Co., Ltd.
0, L-540, L-5340, L-5410, L-5420, L-571
0, L-5720, etc., manufactured by Toray Silicone
-190, SH-192, SH-193, SH-194, SH-195, etc., and F-305, F-306, F-31 manufactured by Shin-Etsu Silicone Co., Ltd.
7, F-341 and F-345, and TFA-4200 by Toshiba Silicone Co., Ltd.

The amount of the foam stabilizer used is 0.1 to 20 parts based on 100 parts of the total of the compound having active hydrogen and the organic polyisocyanate.

Examples of the flame retardant include tris (2-chloroethyl) phosphate, tris (dichloropropyl) phosphate, tris (dibromopropyl) phosphate, CR-505 and CR-507 manufactured by Daihachi Chemical Co., and Akzo Japan Co., Ltd.
Fyrol-6 or the like can be used.

In addition, a plasticizer, a filler, a stabilizer, a colorant, and the like can be added as needed.

In order to industrially carry out the present invention, 1,1-dichloro-1-fluoroethane (HCFC-141b) or an auxiliary such as a polyoxyalkylene polyol, a catalyst, a foam stabilizer and other flame retardants and a blowing agent are used. A predetermined amount of 1,1-dichloro-2,2,2-trifluoroethane (HCFC-123) is mixed to prepare a resin solution.

Using a polyurethane foaming machine, the resin liquid and the organic polyisocyanate are rapidly mixed continuously at a constant ratio.

The obtained rigid polyurethane foam stock solution is injected into a void or a mold. At this time, the flow ratio between the resin solution and the organic polyisocyanate is adjusted so that the equivalent ratio between the organic polyisocyanate and the active hydrogen-containing polyol compound becomes 0.8 to 5.0.

After injection, the foam is hardened within a few minutes to obtain a rigid polyurethane foam.

The rigid polyurethane foam obtained in the present invention can be used as a heat insulating material or a structural material for electric refrigerators, heat insulating panels, ships or vehicles, and the like.

〔Example〕

Hereinafter, the present invention will be described specifically with reference to examples. The raw materials used in the examples are as follows.

Hereinafter, the polyol means a polyoxyalkylene polyol.

The hydroxyl value (OH value) and viscosity were measured according to JIS K15
Followed 57.

Polyol A: (Mn) 150, (f) 3.0 polyoxyalkylene polyol (b) 281 g (1.87 mol) and γ-butyrolactone
483 g (5.61 mol) was charged into an autoclave 2 and the temperature was raised to 120 ° C. after purging with nitrogen. 2.1 g of triethylamine and 2.1 g of potassium hydroxide were added and mixed, and 652 g (11.23 mol) of propylene oxide were gradually charged. After reacting for 3 hours, propylene oxide in the system was removed, then neutralized with acetic acid, and further filtered under reduced pressure. OH value 231mgK
1401 g of polyoxyalkylene polyol (A) having an OH / g and a viscosity of 18500 cp / 25 ° C. was obtained.

Polyol B: 526 g (3.53 mol) of triethanolamine and 304 g (3.53 mol) of γ-butyrolactone were charged into an autoclave 2 and purged with nitrogen, followed by heating to 120 ° C. 4.4 g of triethylamine was added and mixed, and 614 g of propylene oxide was further added.
(10.57 mol) was gradually charged. After reacting for 3 hours, propylene oxide in the system was removed. OH value 421mgK
1431 g of polyoxyalkylene polyol (B) having an OH / g and a viscosity of 18,100 cp / 25 ° C. was obtained.

Polyol C Polyoxyalkylene polyol having a hydroxyl value of 450 mgKOH / g and a viscosity of 480 cp / 25 ° C. obtained by adding propylene oxide to glycerol.

Polyol D Polyoxyalkylene polyol having a hydroxyl value of 450 mgKOH / g and a viscosity of 8500 cp / 25 ° C. obtained by adding propylene oxide to a mixture of sucrose and glycerol.

MDI-CR: crude diphenylmethane diisocyanate manufactured by Mitsui Toatsu Chemicals, Inc. NCO = 31.0% L-5420: Nippon Unicar Co., Ltd. foam stabilizer.

TMHD: Catalyst manufactured by Kokusai Chemical Co., Ltd. (Tetramethylhexamethylenediamine) Blowing agent: F-11A; Trichlorofluoromethane manufactured by DuPont-Mitsui Fluorochemicals Co., Ltd.

 HCFC-141b; 1,1-dichloro-1-fluoroethane.

HCFC-123; 1,1-dichloro-2,2,2-trifluoroethane Examples 1 and 2 and Comparative Examples 1 and 2 are shown in Tables 1 and 2. As a laboratory method for producing a rigid polyurethane foam, a resin solution having the composition shown in Tables 1 and 2 was prepared, and this was mixed with a predetermined amount of MDI-CR as an organic polyisocyanate at 5000 rpm at 5000 rpm. The mixture was rapidly mixed for 2 seconds, immediately poured into a vertical wooden box having a size of 200 × 200 × 200 mm, and freely foamed. After the injection, the foam was cured in a few minutes to obtain a rigid polyurethane foam. The resulting rigid polyurethane foam was measured for dimensional stability at low temperature, that is, dimensional change and compressive strength when stored at -30 ° C for 24 hours.

Further, the mixed solution was injected and foamed in a vertical cavity having a size of 300 × 300 × thickness of 35 mm. One day after foaming, the mixture was cut into 200 × 200 × 25 mm, and the thermal conductivity was measured.

 The physical properties were measured according to the following test methods.

Foam density: JIS-A-9514 Compressive strength: JIS-A-9514 Low-temperature dimensional stability: JIS-A-9514 Thermal conductivity: JIS-A-1412 [Effects of the Invention] As can be seen from the comparative examples in Table 2, in the conventional formulation, 1,1-dichloro-1-fluoroethane (HCFC-1) was used as a foaming agent.
41b) Compression strength and low-temperature dimensional stability when using 1,1-dichloro-2,2,2-trifluoroethane (HCFC-123) compared to when using trichlorofluoromethane (F-11A) Poor properties and high thermal conductivity.

However, as shown in Table 1, in the production method of the present invention, compressive strength, low-temperature dimensional stability and thermal conductivity similar to those using conventional trichlorofluoromethane (F-11A) were obtained.

Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) C08G 18/48 C08J 9/14

Claims (3)

(57) [Claims] 1. A method for producing a rigid polyurethane foam from an organic polyisocyanate and a polyol, a foaming agent, a catalyst, a surfactant and other auxiliaries, wherein the polyol has 3 to 8 hydroxyl groups per molecule. 0.125 to 1.0 mol of a lactone and 1.0 to 3.0 mol of an alkylene oxide per 1 mol of a hydroxyl group of the polyhydric alcohol or polyoxyalkylene polyol (y) having the amine catalyst represented by the general formula (I) or (II) and / or water A method for producing a rigid polyurethane foam, comprising using a polyoxyalkylene polyol (X) added by reacting with an alkali oxide catalyst. NR ₁ R ₁ R ₂ (I) R ₁ R ₂ N (CH ₂ ) _n NR ₁ R ₂ (II) (wherein R ₁ is a hydrogen atom, an alkyl group having 1 to 6 carbon atoms,
—CH ₂ CH ₂ OH or —CH ₂ CH (CH ₃ ) OH; R ₂ represents an alkyl group having 1 to 6 carbon atoms, —CH ₂ CH ₂ OH group, or —CH ₂ CH (C
H ₃ ) represents an OH group. N represents an integer of 1 to 6. ) 2. The method according to claim 1, wherein the foaming agent is 1,1-dichloro-1-fluoroethane (HCFC-141b) or 1,1-dichloro-2,2,2-trifluoroethane (HCFC-123). )). 3. An organic polyisocyanate and a polyol
The method for producing a rigid polyurethane foam according to claim 1, wherein the NCO / OH (equivalent ratio) is 0.8 to 5.0.