JPH072969A - Method for manufacturing rigid polyurethane foam - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a rigid polyurethane foam having excellent low-temperature dimensional stability when a hydrogen atom-containing halogenated hydrocarbon or water is used as a foaming agent. A method for producing a rigid polyurethane foam using, as a polyol, an active hydrogen compound or a monoepoxy alcohol adduct of an alkylene oxide adduct thereof.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing rigid polyurethane foam. More specifically, it relates to a rigid polyurethane foam having excellent dimensional stability.

[0002]

2. Description of the Related Art Rigid polyurethane foam uses trichloromonofluoromethane (CFC-11) as a foaming agent and therefore has excellent heat insulating properties and is widely used as a heat insulating material for refrigerators, freezers, buildings and the like. . In recent years, in order to protect the earth's ozone layer, regulations on halogenated hydrocarbon blowing agents that do not contain hydrogen atoms have begun. CFC-11 is included in this regulation target, and the foaming agent for rigid urethane foam is shifting to hydrogen atom-containing halogen hydrocarbons or water having a small ozone depletion potential. However, since these newly used foaming agents have hydrogen atoms in the molecule, the dissolution and swelling in the generated urethane resin component is
It is said to be higher than the current CFC-11. Therefore, it is considered that the obtained foam has low strength, and particularly has poor dimensional stability and tends to shrink.

On the other hand, an example in which an alkylene oxide adduct of an aromatic ring-containing aliphatic diamine is used as a polyol which is difficult to shrink when foamed with a hydrogen atom-containing halogen hydrocarbon-based foaming agent (JP-A-4-148827). Proposed, but not sufficiently effective. That is, such an alkylene oxide adduct has a reduced viscosity with an increase in the number of moles of alkylene oxide added, and the workability during the production of polyurethane foam is easy, but if alkylene oxide is added excessively, it becomes a urethane foam. In this case, the dimensional stability is not improved. Conversely, if the number of moles of alkylene oxide added is reduced,
Because it becomes a solid or very viscous liquid even at room temperature,
It becomes practically difficult to use as a polyol component. In particular, this tendency becomes more remarkable as the number of parts of water used as the foaming agent increases. As described above, when a hydrogen atom-containing halogenated hydrocarbon or water is used as a foaming agent, no polyol has been found that can obtain the same dimensional stability as when using conventional CFC-11.

[0004]

The object of the present invention is to use a hydrogen atom-containing halogenated hydrocarbon or water as a blowing agent,
In manufacturing a rigid polyurethane foam, the present invention provides a method of manufacturing a rigid polyurethane foam having dimensional stability equivalent to that of the case of using conventional CFC-11.

[0005]

Means for Solving the Invention As a result of repeated studies on a method for producing a rigid polyurethane foam having low viscosity, good workability and excellent dimensional stability, as a raw material for the rigid polyurethane foam, the present inventors have found that The present invention was found to solve the above-mentioned problems by using a polyol having the structure of and reached the present invention.

That is, in the present invention, when a rigid polyurethane foam is produced by reacting a polyol and a polyisocyanate in the presence of a blowing agent, at least the active hydrogen compound (a) and / or the alkylene oxide of (a) is used as the polyol. A method for producing a rigid polyurethane foam, which comprises using the monoepoxy alcohol adduct (A) of the adduct (b) and using a halogen atom-containing halogenated hydrocarbon and / or water as the blowing agent; At least the (A) as a polyol
The method for producing a rigid polyurethane foam is characterized by using the alkylene oxide adduct (B).

The monoepoxy alcohol adduct (A) which is an essential component as the polyol (I) of the present invention is a compound obtained by adding a monoepoxy alcohol to the active hydrogen compound (a), and / or the active hydrogen compound (a). Is a compound obtained by adding a monoepoxy alcohol to the alkylene oxide adduct (b). Examples of the active hydrogen compound (a) include polyhydric alcohols, aliphatic amines, aromatic amines and bisphenols.

Specific examples of the polyhydric alcohol include 1
The hydroxyl group in the molecule is usually 2 to 8 alcohols such as ethylene glycol, diethylene glycol, propylene glycol, 1,4-butanediol, glycerin, trimethylolpropane, pentaerythritol, methyl glycoside, diglycerin, sorbitol, Examples include glucose and sucrose. Preferred are diethylene glycol, glycerin, pentaerythritol, sorbitol, and sucrose.

Specific examples of the above aliphatic amines include monoethanolamine, diethanolamine, triethanolamine, ethylenediamine and diethylenetriamine. Preferred are triethanolamine and ethylenediamine.

Specific examples of the aromatic amine include 2,
4- and 2,6-diaminotoluene (TDA), crude TDA, 1,2-, 1,3- and 1,4-phenylenediamine, diethyltolylenediamine, 1,2-, 1,
3- and 1,4-xylylenediamine, 2,4'- and 4,4'-diaminodiphenylmethane (MDA),
Crude MDA, naphthylene-1,5-diamine, 3,3 '
-Dichloro-4,4'-diaminodiphenylmethane. Preferably, TDA, xylylenediamine,
It is MDA.

Specific examples of the bisphenols include:
For example, bisphenol A [2,2'-bis (4-hydroxyphenyl) propane], bisphenol F [2,
2'-bis (4-hydroxyphenyl) methane], bisphenol S [2,2'-bis (4-hydroxyphenyl) sulfone], 4,4'-dihydroxybiphenyl,
2,2'-bis (4-hydroxyphenyl) hexafluoropropane may be mentioned. Bisphenol A and bisphenol F are preferred.

As the active hydrogen compound (a) of the present invention,
In addition to the above-mentioned ones, oligomers having two or more hydroxyl groups can also be used, and examples thereof include polyester polyol, polycarbonate polyol, polycaprolactone polyol and the like. Specific examples of the above polyester polyols include condensed polyester polyols composed of polycarboxylic acids and polyols. Examples of the polycarboxylic acid include adipic acid, phthalic anhydride, terephthalic acid, trimellitic acid and pyromellitic acid. Preferred are phthalic anhydride and terephthalic acid. Examples of the polyol include those having 2 to 8 hydroxyl groups in one molecule described in the section of polyhydric alcohol. Preferred are 1,4-butanediol, ethylene glycol and diethylene glycol.
Specific examples of the polyester polyol include poly (1,
4-butanediol terephthalate) and poly (diethylene glycol) terephthalate. Preferred is poly (ethylene glycol) terephthalate.

The alkylene oxide adduct (b) of the active hydrogen compound (a) of the present invention is the above-mentioned (a) to which an alkylene oxide is added. As this alkylene oxide, ethylene oxide (hereinafter referred to as EO
Abbreviated), propylene oxide (hereinafter abbreviated as PO),
Butylene oxide, and combinations thereof (block and / or random addition). PO, EO, and a combination thereof are preferable. The number of moles of alkylene oxide added is usually 1 to 20 moles, and preferably 2 to 16 moles.

The monoepoxy alcohol adduct (A) which is an essential component as the polyol (I) of the present invention is a compound obtained by adding a monoepoxy alcohol to the active hydrogen compound (a), and / or the active hydrogen compound (a). Is a compound obtained by adding a monoepoxy alcohol to the alkylene oxide adduct (b). (A) or (b) of the present invention
Examples of monoepoxy alcohols to be added to glycidol, glycidol, 3,4 epoxy-1-butanol, 2,3 epoxy-1-butanol, monoglycidyl ether of diol synthesized from epichlorohydrin and diol (for example, ethylene glycol monoglycidyl ether). , Butanediol monoglycidyl ether, hexanediol monoglycidyl ether, etc.). Glycidol is preferred. The number of moles of the monoepoxy alcohols (A) added is usually 2 to 20 moles, and preferably 4 to 18 moles.

The number of functional groups of the monoepoxy alcohol adduct (A) of the present invention is usually 6 to 20, preferably 8 to 18. When the number of functional groups is less than 6, the crosslink density in the case of using a rigid urethane foam is not sufficient and the dimensional stability is insufficient. When the number of functional groups exceeds 20,
The viscosity of (A) rises sharply. Therefore, it becomes difficult to uniformly mix (A) with the hydrogen atom-containing halogenated hydrocarbon-based foaming agent, and the obtained rigid urethane foam has rough cells and becomes nonuniform. The hydroxyl value of the (A) is usually 2
00 to 1300, preferably 300 to 1200
Is. The molecular weight converted from the hydroxyl number of (A) is usually 300 to 1200.

The present invention further provides, in place of the above (A),
It is also a method for producing a rigid urethane foam using a polyol (B) obtained by further adding an alkylene oxide to (A). When (B) is used as the polyol component (I), the viscosity is lowered and the compatibility with the hydrogen atom-containing halogenated hydrocarbon blowing agent is improved. The alkylene oxide added to the (B) may be the same as the alkylene oxide added to the active hydrogen compound (a), preferably PO, EO and a combination thereof.
The addition mole number of this alkylene oxide is usually 0 to 20 moles, and preferably 0 to 18 moles. If it exceeds 20 moles, the compatibility with the hydrogen atom-containing halogenated hydrocarbon-based foaming agent becomes too good, and the dimensional stability becomes insufficient. The molecular weight converted from the hydroxyl value of (B) is usually 200 to 1800.

As the polyol component of the present invention, not only the above-mentioned (A) alone, (B) alone but also a combination of (A) and (B), and a polyol which can be used in a usual rigid polyurethane foam, for example, the above-mentioned ones. Active hydrogen compound (a)
The active hydrogen compound, its alkylene oxide adduct, polybutadiene polyol, acrylic polyol, polymer polyol modified with an ethylenically unsaturated monomer and the like described in the item 1) may be used in combination. The total amount of (A), (B) or (A) and (B) in the polyol (I) is usually 5 to 100% by weight, preferably 10 to
It is 100% by weight. When the total amount of the (A), (B) or (A) and (B) is less than 5%, the crosslink density of the rigid urethane foam is not high and the dimensional stability is not sufficient.

As the polyisocyanate (II) used in the present invention, those conventionally used for rigid polyurethane foams can be used. Examples of such polyisocyanates include ordinary aromatic polyisocyanates, aliphatic polyisocyanates, alicyclic polyisocyanates, and modified products thereof (for example, carbodiimide group, allophanate group, urea group, buret group, isocyanurate group). , Oxazolidone groups), and isocyanate group-terminated prepolymers.

Specific examples of such aromatic polyisocyanates include 1,3- and 1,4-phenylene diisocyanates, 2,4- and / or 2,6-tolylene diisocyanate (TDI), crude TDI, Diphenylmethane-2,4'- and / or -4,4'-diisocyanate (MDI), polymethylene polyphenylisocyanate (crude MDI), naphthylene-1,5-diisocyanate, triphenylmethane-4,4 '. ，
4 ''-triisocyanate. Specific examples of the aliphatic isocyanate, isophorone diisocyanate,
1,6-hexamethylene diisocyanate, 4,4'-
These are dicyclohexylmethane diisocyanate, 1,4-cyclohexyl diisocyanate and 2,2,4-trimethylhexamethylene diisocyanate. Specific examples of the alicyclic polyisocyanate are xylylene diisocyanate and tetramethyl xylylene diisocyanate. Specific examples of the modified polyisocyanate include carbodiimide-modified MDI, sucrose-modified TDI, castor oil-modified MDI and the like. Of these, preferred are MDI, crude MDI, sucrose-modified TDI, and carbodiimide-modified MDI.

The ratio of the polyol component to the polyisocyanate component can be variously changed, but the equivalent ratio of the hydroxyl group of the polyol component to the isocyanate group of the polyisocyanate component is usually 1.0: 0.5 to 1.0: 1.
5, preferably 1.0: 0.9 to 1.0: 1.2. Further, when the equivalent ratio of the hydroxyl group and the isocyanate group is 1.0: 1.5 to 1.0: 50, a polyisocyanurate foam can be produced.

As the foaming agent (III) in the present invention,
A hydrogen atom-containing halogenated hydrocarbon-based blowing agent and / or water can be used. Generally, when a hydrogen atom-containing halogenated hydrocarbon-based foaming agent having a small ozone depletion coefficient is used, the obtained rigid polyurethane foam has poor dimensional stability and tends to shrink. The (A) in the present invention
By using and / or (B), a rigid polyurethane foam having excellent dimensional stability can be produced even when a hydrogen atom-containing halogenated hydrocarbon-based blowing agent is used. The hydrogen atom-containing halogenated hydrocarbon-based blowing agent used in the present invention is of HCFC type (for example, HCFC-123, HCFC-141b,
HCFC-22, HCFC-142b); HFC type (for example, HFC-134a, HFC-152a,
HFC-356). Preferably, HCFC
-141b, HFC-134a, HFC-356 and mixtures thereof. If necessary, water and low boiling point hydrocarbons may be used in combination with these hydrogen atom-containing halogenated hydrocarbon blowing agents. Further, water can be used alone without using a halogenated hydrocarbon-based foaming agent or low boiling point hydrocarbons. The low boiling point hydrocarbons are hydrocarbons having a boiling point of 0 to 50 ° C., and specific examples thereof include
Propane, butane, pentane and mixtures thereof.

The amount of the hydrogen atom-containing halogenated hydrocarbon blowing agent used is usually 0 to 100 parts by weight of the polyol component.
50 parts by weight, preferably 0 to 45 parts by weight. The amount of water used is usually 100 parts by weight of polyol,
It is 0.1 to 10 parts by weight, and preferably 0.5 to 8 parts by weight. The amount of low boiling hydrocarbons used is usually 0 to 30.
Parts by weight, preferably 0 to 20 parts by weight.

In the present invention, a catalyst usually used for polyurethane reaction, for example, an amine-based catalyst (triethylenediamine, N-ethylmorpholine, diethylethanolamine, 1,8-diazabicyclo (5.4.0) undecene-7, etc.) , Metal catalysts (stannous octylate, dibutyltin dilaurate, lead octylate, etc.) can be used. The amount of the catalyst is usually 0.001 to 5% by weight based on the weight of the reaction mixture.

Further, if necessary, a foam stabilizer and a coloring agent (dye,
Additives such as pigments), plasticizers, fillers, flame retardants, antiaging agents and antioxidants can also be used.

The manufacturing method in the present invention is as follows. First, a predetermined amount of a polyol component, a foaming agent, a foam stabilizer, a catalyst, other additives and the like are mixed, and a polyurethane foaming machine is used to rapidly and continuously mix the polyisocyanate component at a constant ratio. The obtained mixed liquid is poured into a mold. After curing, the mold is removed to obtain a rigid polyurethane foam.

The rigid polyurethane foam obtained by the present invention has good heat insulating properties and particularly excellent dimensional stability, and therefore can be widely used as a heat insulating material for refrigerators, freezers, buildings and the like.

[0027]

EXAMPLES The present invention will be further described below with reference to examples, but the present invention is not limited thereto. Parts in the examples are parts by weight, and the molecular weight is the molecular weight in terms of hydroxyl number. (Production Example of Polyol) [Production Example 1] 182 parts of sorbitol and 1 part of potassium hydroxide were charged into an autoclave, and after purging with nitrogen, 444 parts of glycidol were gradually injected at 110 ° C. After press-fitting glycidol, addition polymerization was carried out at the same temperature for 2 hours to obtain 12 functional groups
Thus, a polyol (A-1) having a molecular weight of 626 was obtained. [Production Example 2] PO was further added to the polyol (A-1) at 870.
By partial addition polymerization, a polyol (B-1) having a functional group number of 12 and a molecular weight of 1496 was obtained. [Production Example 3] 182 parts of sorbitol were subjected to addition polymerization of 505 parts of PO, and 4 parts of glycidol were added in the same manner as in Production Example 1.
44 parts of addition polymerization was performed to obtain a polyol (A-2) having 12 functional groups and a molecular weight of 1131. [Production Example 4] In the same manner as in Production Example 2, the polyol (A-
Further, 365 parts of PO were added to 2) to obtain a polyol (B-2) having 12 functional groups and a molecular weight of 1496. [Production Example 5] 1184 parts of glycidol was added to 106 parts of diethylene glycol, and 1276 parts of PO was added to obtain a polyol (B-3) having 18 functional groups and a molecular weight of 2566. [Production Example 6] 592 parts of glycidol were addition-polymerized with 106 parts of diethylene glycol, and 682 parts of EO were additionally polymerized to obtain a polyol (B-4) having 10 functional groups and a molecular weight of 1380. [Production Example 7] Glycidol 2 in 60 parts of ethylenediamine
By addition-polymerizing 96 parts, a polyol (A-3) having 8 functional groups and a molecular weight of 356 was obtained. [Production Example 8] PO was further added to the polyol (A-3) 232
By partial addition polymerization, a polyol (B-5) having 8 functional groups and a molecular weight of 588 was obtained.

(Production Method for Rigid Polyurethane Foam) Example 1 10 parts of polyol (A-1), 90 parts of polyol (C-1) having a molecular weight of 561 obtained by adding 425 parts of PO to erythritol 136 parts, and silicone SH- 193
(Tore Silicone Co., Ltd. foam stabilizer) 1.5 parts, U-Cat
1000 (San Apro Co. amine catalyst) 2.0 parts, HC
FC-141b (40 parts) was pre-blended, and Millionate MR-200 (Nippon Polyurethane crude MDI) 1 was added to the mixture.
Add 78 parts and add homodisper (stirrer made by special machine) 3
After stirring at 000 rpm for 10 seconds, open mold [23
X 23 x 10 (height) cm]. After completely curing, the mold was removed to obtain a rigid polyurethane foam. Examples 2 to 12 According to the method of Example 1, rigid polyurethane foams were produced according to the blending amounts shown in Table 1.

[0029]

[Table 1]

Comparative Examples 1 to 5 Comparative Example 1 was prepared by using the polyol (C-1) used in Example 1 alone. In addition, the polyol (A-
A polyol (C-2) having a molecular weight of 626 obtained by adding the same amount of PO instead of glycidol of 1) is used as a polyol (C-2), and a polyol having a molecular weight of 356 obtained by adding PO instead of glycidol of polyol (A-3) is used as a polyol (C-2). C-3). m-xylylenediamine (136 parts) was polymerized with 425 parts of PO to give a polymer having a molecular weight of 561 (C-
4). In the same manner as in Example 1, rigid polyurethane foams were prepared according to the blending amounts shown in Table 2.

[0031]

[Table 2]

(Evaluation method of dimensional change rate) After 1 day, 10c
A m-square test sample was cut out, and the dimension [L1 (cm)] in each of length, width and height was measured. This sample is 23
After leaving it in a constant temperature bath at ℃ for 60 days, measure again [L2 (cm)]
Was measured, and the rate of dimensional change in each of length, width, and height was calculated by the following formula. Dimensional change rate (%) = (L1−L2) × 100 / L1 The maximum value among the dimensional change rates in the vertical, horizontal and height directions was defined as the maximum dimensional change rate. The maximum dimensional change rate of the rigid urethane foams obtained in Examples 1 to 12 is shown in Table 3, and the maximum dimensional change rate of the hard urethane foams obtained in Comparative Examples 1 to 5 is shown in Table 4.
Shown in.

[0033]

[Table 3]

[0034]

[Table 4]

The maximum dimensional change rate of Examples 1 to 12 is 3 to 8.
% Is clearly smaller than the maximum dimensional change rates of 11 to 21% in Comparative Examples 1 to 5, and the dimensional stability is good.

[0036]

According to the present invention, a polyol having a low viscosity, good workability, and excellent dimensional stability can be obtained as a raw material for a rigid polyurethane foam. Therefore, it is extremely useful for applications such as refrigerators, freezers, and heat insulating materials for construction.

Continuation of front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical display location C08L 75:04 (72) Inventor Yasushi Kumagai 1-11, Hitotsubashi-honcho, Higashiyama-ku, Kyoto 1 Sanyo Chemical Industry Co., Ltd.

Claims (5)

[Claims] 1. When a rigid polyurethane foam is produced by reacting a polyol (I) with a polyisocyanate (II) in the presence of a foaming agent (III), at least an active hydrogen compound (a) is used as the polyol (I). And / or (a) alkylene oxide adduct (b)
1. A method for producing a rigid polyurethane foam, which comprises using the monoepoxy alcohol adduct (A) of 1. and a hydrogen atom-containing halogenated hydrocarbon and / or water as a foaming agent (III). 2. The method according to claim 1, wherein at least the polyol (I) is used in the production of a rigid polyurethane foam by reacting the polyol (I) with the polyisocyanate (II) in the presence of a foaming agent (III). Hardness characterized by using a polyol (B) obtained by further adding an alkylene oxide to a monoepoxy alcohol adduct (A) and using a halogen atom-containing halogenated hydrocarbon and / or water as a foaming agent (III). Polyurethane foam manufacturing method. 3. The monoepoxy alcohol adduct (A)
The method for producing a rigid polyurethane foam according to claim 1 or 2, wherein the number of functional groups is 6 to 20. 4. The method for producing a rigid polyurethane foam according to claim 1, wherein the monoepoxy alcohol added to the adduct (A) is glycidol. 5. The method for producing a rigid polyurethane foam according to claim 1, wherein the content of the (A) and / or the (B) in the polyol (I) is 5 to 100% by weight. .