JPH03258824A - Preparation of rigid polyurethane foam - Google Patents

Abstract

PURPOSE:To prepare the subject foam having a fine cell structure and having excellent insulating characteristics, low temperature dimensional stability, etc., by reacting a specific organic polyisocyanate with a polyol in the presence of a specific foaming agent, a catalyst, etc. CONSTITUTION:(A) An organic polyisocyanate component comprising (i) the prepolymer of polymethylene polyphenylisocyanate with an hydroxyl group- containing compound and (ii) the prepolymer of tolyleneisocyanate with the hydroxyl group-containing compound is reacted with (B) a polyol component comprising (iii) a polyetherpolyol prepared from tolylenediamine and/or methylglycoside as initiators, (iv) a polyetherpolyol prepared from trimethylpropane as an initiator and (v) a low mol.wt. diol in a iii : iv weight ratio of 1:0.25-4 and in a (iii+iv): weight ratio of 1:0.02-0.5 in the presence of a foaming agent substituted with trichloromonofluoromethane, a catalyst and a foam stabilizer to provide the objective foam.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a method for manufacturing rigid polyurethane foam.

More specifically, as a blowing agent, a substitute for trichloromonofluoromethane (hereinafter referred to as R-11), preferably 1
, 1-dichloro-2,2,2-trifluoroethane (hereinafter referred to as HCFC-123) and 1,1-dichloro-1
-Fluoroethane (hereinafter referred to as HCFC-141b)
The present invention relates to a method for producing a rigid polyurethane foam that has a fine cell structure, has excellent heat insulation properties, and has excellent low-temperature dimensional stability and compressive strength.

Conventional Technologies and Issues Rigid polyurethane foam is a good heat insulating material and has excellent moldability and processability, so it is used for insulation in electric refrigerators, buildings, and low-temperature warehouses.

It is used in a wide range of fields, including insulation for storage tanks, refrigerated ships, piping, etc. To produce such rigid polyurethane foam, a polyol, a catalyst.

Foam stabilizer 1 A one-shot method in which component A, which is mainly composed of a foaming agent, and component B, which is mainly composed of isocyanate, are mixed and reacted, and the foaming process and curing process proceed in parallel to form a foam. Generally used.

The blowing agent used in the production of such polyurethane foam is mainly R-11, and since water reacts with incyanate to generate carbon dioxide, it is used in combination with R-11 as a chemical blowing agent. Often. However, since CFC gas conventionally used as a blowing agent is chemically stable, it diffuses into the stratosphere and destroys the ozone layer existing in the stratosphere. As a result, ultraviolet rays emitted from the sun are not absorbed by the ozone layer and reach the earth's surface, increasing the incidence of skin cancer, which has become a serious environmental problem in recent years.

For this reason, regulations on the use of fluorocarbon gas have been strictly enforced since 1989, and R-11 for polyurethane has also been subject to regulations.

Therefore, various studies have been conducted on foaming agents that can replace fluorocarbon gas, such as HCFC-123,
141b and the like have been proposed as substitutes for R-11. However, these HCFC-1 as blowing agents
Compared to the foam using R-11, the foam using 23,141b (1) has poorer physical properties such as low-temperature dimensional stability and compressive strength at the same density, and (2) has a thermal insulation property of 10 to 15. X 10-'kcal/
There are problems such as deterioration of mh'C and (3) slow initial reactivity.

On the other hand, in recent years, when rigid polyurethane foam is used in electric refrigerators, etc., in addition to increasing the internal volume by making the insulation layer thinner, rigid polyurethane foam has a high degree of insulation performance, in other words, to reduce power consumption. There has been a strong demand for lower conductivity. The thermal conductivity of conventional rigid polyurethane foam is 23°
Usually 140-160 X l O-'kca in C
It is about l/mh'c, l 30 X l O-'k
It is extremely difficult to lower the temperature below cal/mh°C, especially when HCFC-123, 141b is used.

Means for Solving the Problems In view of the above-mentioned problems, the present inventors conducted intensive studies and found that HCFC-123 or/and H
When manufacturing rigid polyurethane foam using CFC-14lb, by combining a specific polyol and isocyanate, it has a fine cell structure with excellent heat insulation properties, and has excellent low-temperature dimensional stability and compressive strength. We have discovered a method for producing rigid polyurethane foam with excellent foam properties, and as a result of further study, we have completed the present invention.

That is, the present invention provides (i) as the organic polyisocyanate, (a) a prepolymer of polymethylene polyphenylisocyanate and a low molecular weight polyol, and (b) a prepolymer of tolylene diisocyanate and a low molecular weight polyol in a weight ratio. (a): (b) = l: a mixture containing in the ratio of 0.1-10, and (i) as polyol, (c) polyether polyol or/and with tolylene diamine and aliphatic amine as initiators; and (c') a polyether polyol using methyl gelcond as an initiator, (d) a polyether polyol using trimethylolpropane as an initiator, and (e) a low molecular weight diol or triol in weight ratio [(c) or/and (c')] : (d)
= 1: 0.25-4, [(c) or/and (
c') + (d)] : (e) = l : 0.05-0
A mixture containing R as a blowing agent was used.
The present invention relates to a method for producing rigid polyurethane foam, which is characterized by using a substitute for -11 and carrying out the reaction in the presence of a catalyst and a foam stabilizer.

The organic polyisocyanate used in the present invention includes:
(a) a prepolymer obtained by reacting polymethylene polyphenylisocyanate (hereinafter referred to as c-MDI) with a hydroxyl group-containing metal compound; and (b) tolylene diisocyanate (hereinafter referred to as TDI) or crude tolylene diisocyanate (hereinafter referred to as TDI). , c-TDI) and a hydroxyl group-containing compound at a weight ratio of (a):(b)-1:0.1-10. Preferably, a mixture containing the polyisocyanate at a ratio of 1:0.2 to 5 is used, and other organic polyisocyanates can also be used in combination.

The above (a) misalignment polymer has an amine equivalent of 140 to
As the prepolymer (b), one having an amine equivalent of about 130 to 300 is used.

The hydroxyl group-containing compounds used to produce the prepolymer of (a) above include, for example, monoalcohols and phenols with 1 functional group and a molecular weight of 32 to 300, and monoalcohols and phenols with a functional group of 1 and a molecular weight of 62 to 600. Examples include polyols, such as methanol, ethanol, n-butanol, and ethylene glycol monomethyl ether.

Monoalcohols such as diethylene glycol 7-methyl ether, phenol, phenols such as o-, m-, and p-cresol, and ethylene glycol.

Diethylene glycol, propylene glycol.

Examples include diols such as 1,4-butanediol and 1,6-hexane glycol, triols such as glycerin and trimethylolpropane, and di- to trifunctional polyether polyols and polyester polyols. Examples of the above-mentioned di- or tri-functional polyether polyols include alkylene oxides such as ethylene oxide, propylene oxide, Examples include polyether polyols obtained by polymerizing butylene oxide and the like alone or in combination of two or more. Examples of the above-mentioned di- or tri-functional polyester polyols include polyols such as ethylene glycol, diethylene glycol, 1,4-butanediol, and trimethylolpropane, and polyols such as adipic acid, succinic acid, maleic anhydride, and phthalic acid. Examples include those obtained by condensation of dicarboxylic acids.

In addition to the above-mentioned hydroxyl group-containing compounds, examples of the hydroxyl group-containing compounds used in producing the prepolymer (b) include methyl glucoside and sucrose.

Polyhydric alcohols such as sorbitol and dulcitol.

and alkylene oxides, such as ethylene oxide, propylene oxide, using them as initiators.

Polyether polyols obtained by polymerizing butylene oxide alone or in combination of two or more are used.

Among these, particularly preferred are propylene oxide adducts of bisphenol A, ethylene oxide adducts of bisphenol A, and polyester polyols obtained by condensation of phthalic acid and diethylene glycol.

Examples of the polyether polyol (c) using tolylene diamine and aliphatic amine as initiators used in the present invention include metatolylene diamine.

Tolylene diamines or mixtures thereof, such as orthotolylene diamine, and aliphatic amines, such as di-n-
Butylamine, ethylenediamine.

Tetramethylene diamine, hexamethylene diamine, n
-hexylamine, 2-ethylhexylamine, monoethanolamine, jetanolamine, triethanolamine, impropaturamine, triethylamine,
n-propylamine.

di-n-propylamine, trilopropylamine,
n-amylamine, N,N-dimethylethanolamine,
Alkylene oxide, alkylene oxide, For example, hydroxyl value 300 to 100 obtained by polymerizing ethylene oxide, propylene oxide, butylene oxide, etc. alone or in combination of two or more of them.
0mg KOH/g, preferably 450-800 m
g KOH/g polyether polyol is used.

The polyether polyol (c') using methyl glucoside as an initiator used in the present invention may be prepared by polymerizing alkylene oxides, such as ethylene oxide, propylene oxide, butylene oxide, etc. alone or in combination of two or more, using methyl glucoside as an initiator. Obtained hydroxyl value 3
00-1000m100O/g, preferably 450-8
00 mg KOH/g of polyether polyol is used.

The polyether polyol (d) using trimethylolpropane as an initiator used in the present invention is an alkylene oxide such as ethylene oxide using trimethylolpropane as an initiator.

Hydroxyl value 300-1200 obtained by polymerizing propylene oxide, butylene oxide, etc. alone or in combination of two or more.
mg KOH/g, preferably 450-1000
mg KOI (/g) of polyether polyol is used.

(e) Low molecular weight diol used in the present invention includes ethylene glycol, diethylene glycol, propylene glycol, 1.4-butanediol, 1.6
-Hexanediol etc. are used, and as a low molecular weight triol, glycerin is used.

Trimethylolpropane or the like is used. The above polyol contains (c) or/and (c'), (d) and (e) in a weight ratio [(c) or/and (c')]
: (d)=l:0.25-4. Preferably l:
0.3-3゜ [(c) or/and (c') + (d)
]: (e)=l: 0.02-0.5. Preferably, it is a mixture containing in a ratio of 1:0.05 to 0.4, and if necessary, other known polyols, such as functional group number 2 to 8, hydroxyl value 300 to 800 mg KOH/g.
polyether polyol with a functional group number of 2 to 4. A polyester polyol having a hydroxyl value of 200 to 500 mg KOH/g, a phenol resin having a reactive methylol group, etc. can also be used in combination.

The blowing agent in the present invention is one used as a substitute for R-11, such as HCFC-123゜HCFC-14.
lb, dodecafluoropencune, etc., especially HC
FC-123 and HCFC-14th are preferred. The amount used is that the density of the polyurethane foam is 15 kg/m'
The above amount is adjusted according to the purpose of use, and is usually about 5 to 150 parts by weight per 100 parts by weight of the polyol.

In the present invention, water having the functions of both a blowing agent and a crosslinking agent, and other known blowing agents can also be used in combination.

Typical examples of catalysts used in the present invention are:
For example, tertiary amines such as dimethylethanolamine, triethylenediamine, tetramethylethylenediamine, tetramethylpropanediamine, tetramethylhexamethylenediamine, dimethylcyclohexylamine,
Examples include organometallic compounds such as stannath octoate, dibutyltin dilaurate, and lead octylate. Also, propanediamine if necessary.

Primary amines such as hexamethylene diamine can also be used in combination. The catalyst is usually 0.1 parts by weight per 100 parts by weight of polyol.
-10 parts by weight are used.

Further, as the foam stabilizer, various dimethylsiloxane/polyalkylene oxide block copolymers (silicon-based foam stabilizers) can be used. Foam stabilizer is usually polyol 1
About 0.2 to IO parts by weight are used per 00 parts by weight.

As a specific means for manufacturing rigid polyurethane foam from the above-mentioned raw materials, any device that can uniformly mix the raw materials may be used. Rigid polyurethane foam can be easily obtained by mixing.

Effects of the Invention The rigid polyurethane foam obtained by the present invention has an extremely low thermal conductivity, for example, 120 to 130 at 23°C.
XIO-'kcal/mh'c. Conventional R
The thermal conductivity of the rigid polyurethane foam obtained using No. 11 is 135-160Xlo-'kcal/mh℃
and alternatives to R-11, such as HCFC-1
Rigid polyurethane foams using materials such as 23,141b are even worse, reaching 140 to 165
Since it is about cal/mh'c, it is almost 20% smaller.

This means that, for example, when conventional rigid polyurethane foam is used as a heat insulating material, the insulation thickness required is 10 cm, but the insulation thickness is only 1 g cm, making it extremely economical, such as electric refrigerators, showcases, prefabricated refrigerators , it is possible to improve internal volume efficiency and reduce cooling energy by reducing the thickness of insulation walls during the manufacture of freezers, etc.

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to comparative examples and examples.

The raw materials used in the examples are as follows.

Polyol A: Tolylenediamine/ethylenediamine-based polyether polyol with a hydroxyl value of 500 mg KOH/g Polyol B: Methyl glucoside-based polyether polyol with a hydroxyl value of 550 mg KOH/g Polyol C
: Trimethylolpropane polyether polyol with hydroxyl value 880 mg KDH 7g Polyol D: Ethylene glycol polyol E nitrimethylolpropane Foam stabilizer A: Silicone foam stabilizer; F-373 manufactured by Shin-Etsu Chemical Co., Ltd. Catalyst A: Tetramethyl Hexamethylenediamine blowing agent A
:R-11 Foaming agent B: HCFC-123 Foaming agent C: HCFC-14lb Foaming agent D: Water polyisocyanate Arc-MDI Polyisocyanate B: c-MDI and bisphenol A
Prepolymer with propylene oxide adduct of and T
Isomorphic mixture of DI and prepolymer of glycerin-sucrose-propylene oxide adduct (amine equivalent 153) Polyisocyanate C: weight ratio (prepolymer of c-MDI and propylene oxide adduct of bisphenol A)/ (prepolymer of TDI and glycerin-sucrose-propylene oxide adduct) - 1:0.25 mixture (amine equivalent: 159) Polyisocyanate C: weight ratio (prepolymer of c-MDI and propylene oxide adduct of bisphenol A) Polymer)/(prepolymer of TDI and glycerin-sucrose-propylene oxide adduct)-1:4 mixture (amine equivalent weight 148) 1st. According to the foaming recipe shown in @28 and Table 3, these raw materials were heated to 20±1° C. and reacted by high-speed mixing and stirring for 5 seconds. The expanded rigid polyurethane foam was cut and sampled the next day according to conventional methods, and various physical properties were measured, and the results were reported at @I.

It is shown in Tables 2 and 3. In addition, the thermal conductivity is ANAC
The values were measured using an ON model 88 measuring machine at an average temperature of 23°C, and the compressive strength was measured at 10% compression in the direction perpendicular to the foaming direction, and the low-temperature dimensional stability was -30°C.
The rate of dimensional change in the direction perpendicular to the foaming direction after cooling at ℃ for 24 hours was measured.

Comparative Examples 1 and 11 used R-11 as a foaming agent, had a fine cell structure, and had excellent heat insulation properties. This is a so-called microcell formulation and exhibits extremely low thermal conductivity. However, as is clear from Comparative Examples 2 and 12, in these formulations, when the blowing agent is increased to reduce the density to some extent, the compressive strength, especially the low-temperature dimensional stability, deteriorates significantly, and the thermal conductivity also slightly deteriorates. As shown in Comparative Examples 3 and 13, when water is added as a blowing agent to these formulations, the compressive strength and low-temperature dimensional stability are improved despite the low density, but the thermal conductivity is extremely deteriorated. . This also applies when HCFC-123 is used (Comparative Examples 4 and 14 and Comparative Example 5°15).
The same can be said when using (Comparative Example 6.I6 and Comparative Example 7.17).

Also, Comparative Examples 8, 18, Comparative Examples 9, 19, or Comparative Example 1
0.20, the polyisocyanate is c-M
By mixing trimethylolpropane-based polyether polyol with amine-based or/and methyl glucoside-based polyether polyol instead of the isotropic mixture of DI to c-MDI prepolymer and TDI prepolymer, thermal conductivity, Compressive strength and low temperature dimensional stability show excellent values comparable to the microcell formulation (Comparative Example 1.11).

Furthermore, low molecular weight diols such as ethylene glycol (Examples 1 to 3, 6 to 8) or low molecular weight triols such as trimethylolpropane (Examples 4, 5, 9) are added to these formulations.
．． By adding 10), it was possible to lower the density without deteriorating various physical properties.

Procedural amendment February 22, 1991

Claims (1)

[Scope of Claims] (i) As the organic polyisocyanate, (a) a prepolymer of polymethylene polyphenylisocyanate and a low molecular weight polyol, and (b) a prepolymer of tolylene diisocyanate and a low molecular weight polyol, by weight (a):(b)=1:0.1 to 10 in the ratio; and (ii) as the polyol, (c) a polyether polyol using tolylene diamine and aliphatic amine as an initiator; or / and (c') a polyether polyol using methyl glucoside as an initiator, (d) a polyether polyol using trimethylolpropane as an initiator, and (
e) low molecular weight diol or triol in weight ratio [(c) or/and (c')]:(d) = 1:0
．． 25-4, [(c) or/and (c') + (d)
]: (e) = 1: Using a mixture containing in the ratio of 0.05 to 0.3, using a substitute for trichloromonofluoromethane as a blowing agent, and reacting in the presence of a catalyst and a foam stabilizer. A method for producing rigid polyurethane foam characterized by: