JPH0364312A - Production of rigid polyurethane foam - Google Patents

Abstract

PURPOSE:To produce a rigid polyurethane foam excellent in the thermal insulation properties with a reduced amt. of a chlorofluorocarbon without lowering the reactivity at the initial reaction stage by reacting a specific polyol mixture with a polyisocyanate in the presence of a specified amt. of formic acid as a blowing agent. CONSTITUTION:100 pts.wt. polyol mixture wherein a polyol prepd. by using tolylenediamine and/or an aliph, amine (e.g. diethanolamine) as the initiator (e.g. a polyol obtd. by adding ethylene oxide to the above-mentioned amines) and other polyols are contained and the formula, a+b>=1.8, is satisfied, wherein the content of tolylenediamine is (a) mmol/g and that of the aliph. amine, (b) mmol/g, is reacted with a polyisocyanate (e.g. MDI) in the presence of 0.5-5.0 pts.wt. formic acid as a blowing agent.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for manufacturing rigid urethane foam, and more particularly to a method for manufacturing rigid urethane foam using a specific polyol mixture and formic acid as a blowing agent. .

Conventional technology Rigid urethane foam is a good heat insulating material and has excellent moldability and workability, so it is used for the insulation of electric refrigerators, buildings, cold storage warehouses, storage tanks, reefer ships, piping, etc. It is used in a wide range of fields.

In order to produce a rigid urethane foam, a mixture reaction is performed between a component whose main components are polyol, a catalyst, a foam stabilizer, and a blowing agent, and a component B whose main component is polyisocyanate, and a foaming process and a curing process are performed. A one-sheet method in which a form is formed by proceeding in parallel is common.

In the production of such urethane foam, trichloromonofluoromethane (hereinafter referred to as fluorocarbon) is mainly used as a blowing agent.
Freon gas such as 11) is used.

However, since this CFC gas is chemically stable, it diffuses into the stratosphere and destroys the ozone layer that exists 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 are scheduled to be implemented after 1989, and fluorocarbon-11 for urethane foam will also be regulated.

Therefore, various studies have been made on foaming agents that can replace fluorocarbon gas, but no suitable foaming agent that can replace fluorocarbon-11 has yet appeared.

For example, 2,2-dichloro-1,1,t-trifluoroethane (hereinafter referred to as Freon-123); L,l-dichloro-I-fluoroethane (hereinafter referred to as Freon 141b);
etc. have been proposed as substitutes for Freon-11, but industrial production has not yet been achieved.

On the other hand, it has been proposed to produce urethane foam using the reaction between formic acid and polyisocyanate (Japanese Unexamined Patent Publication No. 58-29837), but when formic acid is used, the initial reactivity between polyisocyanate and polyol is reduced. Significantly decreased.

Furthermore, in Japanese Patent Application Laid-Open No. 63-59505, when producing a hard urethane foam, formic acid and a third! It has been proposed to use salts with i1 amine catalysts.

This method weakens the basicity of the tertiary amine by converting it into a salt form with formic acid, thereby lowering the initial reactivity between the polyisocyanate and the polyol.

Lowering the initial reaction has the advantage of not creating cavities or voids, but in the production of rigid urethane foam, if the initial reaction is too fast, the filling properties will be poor, and if the initial reaction is too slow, the productivity will be poor. Therefore, an appropriate balance between initial reactivity and curing reactivity is required. Freon-12, proposed as a replacement for Freon-11
At present, no means have been found to improve the low initial reactivity when using Fluorocarbon-141b, Freon-141b, or the like.

Problems to be Solved by the Invention The present inventors conducted extensive research in order to respond to the social demand of reducing fluorocarbons while maintaining vJ phase reactivity, and found that by using a specific polyol, a blowing agent It has been found that a rigid urethane foam having improved v'J light reactivity and heat insulation properties can be obtained even when formic acid is used as a binder. As a result of further studies based on this knowledge, the present invention was completed.

Means for solving the problem, that is, the present invention contains a polyol having at least one selected from tolylene diamine and aliphatic amine as an initiator and another polyol, and the content of tolylene diamine is a mmol/g. , the content of aliphatic amines is f
fi/g, a polyol mixture in which a≧1.8 is reacted with polyisocyanate using 0.5 to 5.0 parts by weight of formic acid per 100 parts by weight of the total polyol components as a blowing agent. This is a method for manufacturing hard urethane foam, which is characterized by:

The main component of the polyol used in the present invention is a polyol containing at least one selected from tolylene diamine and aliphatic amine as an initiator, and the amount used is a mmol/g of tolylene diamine in the total polyol component. , when the aliphatic amine content is expressed as milliequivalents/g, a+b≧
1.8, preferably 1.8≦a+b<4.5. If the amount used is less than 1.8, the initial reactivity will be low;
The insulation performance also decreases.

The above polyol is one in which an alkylene oxide such as ethylene oxide (hereinafter referred to as EO) or propylene oxide (hereinafter referred to as PO) is added to at least one selected from tolylene diamine and aliphatic amine. Two or more types of alkylene oxide may be used. The hydroxyl value of this polyol is preferably 350 to 600 g KOII/g.

As the tolylene diamine used here, for example, 2.3
/3.4-tolylene diamine, 2.4/2°6-tolylene diamine, and the like.

Examples of aliphatic amines include aliphatic monoamines, aliphatic diamines, and aliphatic triamines.

Any of aliphatic polyamines, alicyclic amines, etc. may be used,
For example, monoethanolamine, jetanolamine,
triethanolamine, monoisopropanolamine,
Diisopropanolamine.

Monoamines such as triisopropanolamine, aminoethylethanolamine, diethylethanolamine, dimethylethanolamine, N-methyljetanolamine, ethylenediamine, trimethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine.

Diamines such as 1,7-diaminohbutane, i,8-diaminooctane, ■,9-diaminononane, l,to-diaminodecane, 1,2,3-triaminopropane,
Triamines such as diethylenetriamine.

Polyamines such as triethylenetetramine and tetraethylenepentamine, N-diethylaminoethylpiperazine,
Examples include alicyclic amines such as cyclopropylamine, cyclobutylamine, cyclopentylamine, and cyclohexylamine.

Each of the above tolylene diamine and aliphatic amine may be used alone or in combination. The polyol used in combination with the polyol containing at least one selected from tolylene diamine and aliphatic amine as an initiator may be any known polyol, such as sucrose, methyl glucoside, sorbitol, and pentaerythritol.

trimethylolpropane, glycerin, diglycerin,
Examples include those obtained by adding an alkylene oxide such as EO%PO to a di- to octahydric polyhydric alcohol such as propylene glycol, polyester polyols, polyols having a Mannich base, and the like.

The average hydroxyl value of all polyols after mixing is 350-500
mg KOH/g Kaish*.

If the hydroxyl value is too low, problems may arise in the dimensional stability and mechanical strength of the foam, while if it is too high, the obtained foam may become brittle and problems may arise in adhesive properties, etc.

In the present invention, a rigid urethane foam is produced by reacting the polyol mixture with a polyisocyanate in the presence of formic acid.

The polyisocyanate used in the present invention is crude MDI
, crude TDr, TDI-prepolymer and mixtures thereof.

A portion of TDI-80 may be mixed therein. The amount of polyisocyanate used is the amount of active hydrogen that can react with the polyisocyanate and the incyanate group (excluding formic acid).
equivalent ratio (isocyanate index: hereinafter N C
It is preferably 1.0 to 1.6 times the index (also referred to as OIndex).

The proportion of formic acid used in the present invention is 0.5 to 5.0 parts by weight per 100 parts by weight of the total polyol. If the amount used is less than 0.5 parts by weight, the effect of reducing fluorocarbons will be small, and if it is more than 5,0 parts by weight, the foam will become brittle, which is not preferable.

In the present invention, formic acid alone may be used as a blowing agent, but other known blowing agents may also be used in combination. Examples of foaming agents used in combination include Freon-11, Freon-123, and Freon-1.
41b, water and the like.

Furthermore, two or more of these may be used in combination, and a hydrocarbon such as pentane may also be used.

When producing rigid urethane foam, it is common to use, for example, foam stabilizers, catalysts, and the like.

As the foam stabilizer, any known commercially available foam stabilizer for rigid foams may be used. For example B-8404,
B-8407, B-8425 (manufactured by Goldschmidt), F-305, F-345, F-373 (manufactured by Shin-Etsu Chemical)
(manufactured by Toshi Silicone Co., Ltd.), S H193 (manufactured by Toshi Silicone Co., Ltd.),
Examples include L-5420, L-5430, and L-5350 (manufactured by Nippon Unicar Co., Ltd.). In addition to the silicone for hard foam, there is no problem in producing the foam even if a more active general silicone for soft foam (for example, B-8017, etc.) is used. The amount of foam stabilizer to be used may be the amount normally used, and is 0.00 parts by weight per 100 parts by weight of all polyol components.
One part of 5-5.0 weight is used.

The catalyst may be any known amine catalyst, tin catalyst, or combination thereof, such as tetramethylhexanediamine, triethylenediamine, dimethylcyclohexylamine, etc., and complex structures such as DBU (catalyst manufactured by Sun Abbott). It may also be from.

In addition, depending on the use and purpose, flame retardants (e.g. trischloropropyl phosphate, etc.), inhibitors (e.g. tertiary dioctyl phthalate, etc.), coloring agents, antioxidants, viscosity-lowering agents (e.g. propylene carbonate, etc.) Other known additives may also be added.

The hard urethane foam obtained in this way has a low density, and the density of the free-blown foam is 20.
~50 kg/m'.

Effects of the Invention According to the present invention, by using a specific polyol, the initial reactivity does not decrease even when formic acid is used as a blowing agent.
In some cases, initial reactivity can even be increased. In addition, it is possible to reduce fluorocarbons, which is a social requirement.

When formic acid is used as a blowing agent, the carbon dioxide concentration inside the foam increases, which generally causes a decrease in insulation performance, but the hard urethane foam obtained by the present invention shows almost no decrease in insulation performance.

EXAMPLES The present invention will be specifically explained below with reference to Examples, Comparative Examples, and Reference Examples.

In the examples, parts and percentages are by weight.

Examples Reference Example 1 2,3/
3.4) Lylene diamine (hereinafter referred to as OTD) 12.
Prepare 2kg, EO9.68k at 100-110℃
g was reacted. Next, 400 g of 50% KO2 aqueous solution was added, and 29 kg of PO was reacted at 100 to 110'C. After aging for 2 hours, the remaining unreacted PO was stripped off, and then 200 g of oxalic acid was added in aqueous solution to obtain l[o
ll was neutralized. After filtering the generated potassium oxalate, 2,6
-Ditertiary-butyl-4-methylphenol (Yoshitomi! [12) 500 PI)! 1 was added.

This polyol is designated as A. The analytical values etc. are shown in Table-1.

Reference Example 2 Into the same apparatus as Reference Example 1, 2.3 kg of 2.4/2.6 tolylene diamine (hereinafter referred to as TDA) was charged, and 12.
React 2 kg EO, then 2.2 kg jetanolamine, 200 g xoH ml water.

I can do it. After further reacting 28.6 kg of PO, B was obtained by processing in the same manner as in Reference Example 1.

Reference Examples 3 to 8 Polyols of Reference Examples 3 to 8 were produced in the same manner as Reference Examples 1 and 2. The polyol composition, analytical values, etc. are shown in Table 1.

Example 1. Comparative Example 1 Using mixed polyol A shown in Table 1, a rigid urethane foam was produced by free foaming using a hand mixing method using the recipe shown in Table 2. That is, polyol 200~
Foam stabilizers, catalysts, blowing agents and other additives were premixed to 300 g, and the liquid temperature was maintained at 20±1'C.

Then, add the required amount of polyisocyanate, which has been separately maintained at 20±1° C., to the polyol premix,
Quickly stir for 3 to 5 seconds using a turbine mixer (1600 ppm), then pour the mixture into a box with an open top (2
A urethane foam was manufactured by injecting the foam into an area measuring 5 cm x 25 cm x 25 cm, and predetermined physical properties were measured.

The results are shown in Table 3-1.3-2.

(Margin below) Table-2 ■): Shin-Etsu Chemical Silicone 2): Tosoh Co., Ltd. A-N catalyst Tetramethyl to bovine diamine 3): 99% formic acid 4): BAS F Crude MDI Table 3-1 There was no significant decrease in reactivity.

Furthermore, as is clear from Table 3-2, as the amount of added fluorocarbon gas increases, both the foam density and the reactivity decrease.

Example 2. Comparative Example 2 Similar rigid urethane foams were produced using the mixed polyol A shown in Table 1 and the formulation shown in Table 4 in the same manner as in Example 1, and the foam density and reactivity were compared with and without formic acid. The results are shown in Table 5-1.5-2.

As is clear from Table 3-1, the addition of formic acid decreases the foam density, which is generally considered to be the case.
Even if ex was changed, the influence of formic acid on reactivity did not change, and the density also decreased.

Examples 3-5. Comparative Examples 3 to 5 In the same manner as in Example 1, similar rigid urethane foams were manufactured using various polio mixtures shown in Table 1 and crude MDI-ru mixtures manufactured by MD Kasei Co., Ltd. according to the formulations shown in Table 6. A hard urethane foam was also produced in the same manner as above without adding formic acid. The results of comparing the physical properties of each foam are also summarized in Table 6.

As is clear from Table 6, when the amine amount a+b is particularly large, the reactivity increases due to the addition of formic acid, and there is almost no deterioration in heat insulation performance.

(Left below) Examples 6 to 8. Comparative Examples 6 to 15 Similar rigid urethane foams were produced in the same manner as in Example 1 using the polyol composition, catalyst amount, and prescription shown in Table 7.

Table 7 also summarizes the results of comparing the physical properties of the foams.

(The following is a blank space) Comparative Examples 14 and 15 are examples using the most commonly used polyols.

Although the addition of formic acid has the effect of lowering the density, it also significantly lowers the initial reactivity and the heat insulation performance.

In Comparative Examples 10 to 13, polyols other than those of the present invention were used, and it is clear that the amount of catalyst had to be increased by about 50% in order to recover the decreased initial reactivity.

Table 8 Comparative Examples 16 to 20 Similarly to Example 1, similar hard urethane foams were manufactured using polyols other than those of the present invention and according to the formulations shown in Table 8. Table 8 also summarizes the results of comparing the physical properties of the foams.

(The following is a blank space) As is clear from Table 8, when a polyol that deviates from the present invention is used, the initial reactivity cannot be increased.

Examples 9-13. Comparative Examples 21 to 25 In the same manner as in Example 1, similar rigid urethane foams were manufactured using the mixed polyol A shown in Table 1 and the formulation shown in Table 9. Table 9 also summarizes the results of comparing the physical properties of the foams.

The polyisocyanate and the blowing agent used together with the catalyst 2 that can be used in the present invention are not limited to Crude MDi, Toyocat MR, and Freon-11, but some examples are listed below.

(Left below) 6) Amine catalyst manufactured by Kaoh Co., Ltd. 7) Amine catalyst manufactured by Tosoh Corporation 8) Amine catalyst manufactured by Sun Abbott 9) Manufactured by Nippon Polyurethane Co., Ltd. 10) Contains crude TDI manufactured by Narita Pharmaceutical Co., Ltd. Incyanate Comparative Examples 26 to 30 Similarly to Example I, similar rigid urethane foams were manufactured using mixed polyol A shown in Table 1 and the formulation shown in Table 10.

The results of comparing the physical properties of the foams are also summarized in Tables 10 to 10.

Table 10 (blank below) As is clear from Table 10, using organic acids other than formic acid does not have a great effect as a blowing agent, and does not accelerate the reaction or speed up the initial reaction (cream time). No effect was observed.

Claims (1)

[Claims] 1. Contains a polyol having at least one selected from tolylene diamine and aliphatic amine as an initiator and another polyol, the content of tolylene diamine is a mmol/g, and the aliphatic amine When the content of is expressed as milliequivalents/g, a polyol mixture in which a+b≧1.8 is used as a blowing agent at a concentration of 0.00000000000000000000000000000000000,000 per 100 parts by weight of all polyol components.
A method for producing a rigid urethane foam, which comprises reacting with a polyisocyanate using 5 to 5.0 parts by weight of formic acid. 2. Some or all of the other blowing agents used in combination with formic acid are 2.
, 2-dichloro-1,1,1-trifluoroethane, or 1,1-dichloro-1-fluoroethane. 2. The method for producing a rigid urethane foam according to claim 1.