Novel polyisocyanurate catalysts

Polyisocyanurate catalysts are disclosed which have the formula: ##STR1## where R.sub.1 and R.sub.2 are independently selected from alkyl groups of less than about 3 carbon atoms or where R.sub.1 and R.sub.2 together comprise cycloalkyl or morpholino groups and where R.sub.3 is hydrogen or alkyl groups containing less than about 3 carbon atoms. Said catalysts are useful in promoting the reaction between a polyol and an aromatic polyisocyanate to prepare a polymer containing recurring isocyanurate and urethane linkages.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to the preparation of polyisocyanurate polymers such 
as polymer foams, and is more particularly concerned with use of a class 
of catalyst which promote the trimerization of polyisocyanates to 
polyisocyanurate polymers. 
2. Description of the Prior Art 
Polyisocyanurate polymers such as rigid polyisocyanurate foams are known in 
the art. The prior art discloses methods for preparing such polymers by 
reacting an organic polyisocyanate with a polyether or polyester polyol 
utilizing a polyisocyanurate group formation catalyst. Foams are prepared 
by effecting such reaction in the presence of a blowing agent. In the 
optimum situation the isocyanurate catalyst utilized promotes formation of 
both isocyanurate linkages and urethane linkages to produce 
urethane-modified polyisocyanurate polymers. See, for example, U.S. Pat. 
Nos. 3,516,950; 3,580,868; 3,620,986; 3,625,872; 3,635,848; 3,725,319; and 
3,745,133. 
Compounds which are known as catalysts for polyisocyanurates are the 
N-alkal metal and N-alkaline earth metal compounds of primary and 
secondary aliphatic, arylaliphatic, aromatic amines and heterocyclic 
amines. Amines which may be employed are, for example, methylamine, 
N-butylamine, tert.-butylamine, methoxy-n-propylamine, oleylamine, 
diethylamine, di-n-butylamine, diisobutylamine, dicyclohexylamine, 
N-methylstearylamine, benzylamine, ethylbenzylamine, dibenzylamine, 
phenylbenzylamine, aniline, naphthylamine, 3-N-ethylaminotoluene, 
toluidine, methylaniline, N-isobutylaniline, diphenylamine, 
N-methylanisidine, and also pyrrolidine, piperidine, 
1,2,3,4-tetrahydroquinoline, pyrrole, indole, 2-methylindole, 
2,3-dimethylindole, 5-methoxy-2,3-dimethylindole, carbazole, 
3,6-dinitrocarbazole, N,N'-dimethylethylenediamine and 
N,N'-dimethyl-p-phenylenediamine. 
N-alkali metal and N-alkaline earth metal compounds of carboxylic acid 
amides are also known catalysts. These include aliphatic and aromatic 
carboxylic acid amides and also such cyclic acid amides as imides and 
lactams. The following compounds are examples of compounds suitable for 
the production of such N-metal compounds: acetamide, trimethylacetamide, 
myristinic acid amide, stearoyl amid, N-methylacetamide, phenylacetamide, 
benzamide, N-alkyl benzamides, succinimide, tetrapropenyl succinimide, 
phthalimide, pyrrolidone, butyrolactam, caprolactam, phthalimidine and 
saccharine. 
Also, as catalysts alkali or alkaline earth metal may be combined with the 
amines or carboxylic acid amides such as, for example, lithium, sodium, 
potassium, magnesium, barium, and calcium, with the preferred metals being 
lithium, sodium, potassium and calcium. 
Also, alkali or alkaline earth metal salts of carboxylic acids are useful 
as catalysts for isocyanurate polymers. 
The catalyst of this invention do not contain alkali or metals and provide 
an unexpected beneficial delay in the isocyanurate reaction which aids in 
processing. This delay is especially helpful where molding is undertaken. 
The catalyst herein also gives a complete product cure. 
SUMMARY OF THE INVENTION 
This invention comprises a novel process for preparing a polymer containing 
recurring isocyanurate and urethane linkages, which polymer comprises a 
reaction product of a polyol and an aromatic polyisocyanate utilizing as 
an isocyanurate formation catalyst a particularly useful and novel 
specific class of compounds known as falling within the formula: 
##STR2## 
where R.sub.1 and R.sub.2 are independently selected from alkyl groups of 
less than about 3 carbon atoms or where R.sub.1 and R.sub.2 together 
comprise cycloalkyl or morpholino groups and where R.sub.3 is hydrogen or 
alkyl groups containing less than about 3 carbon atoms. The invention is 
also the novel compositions described above. 
DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The catalysts of the invention are useful as catalysts for the production 
of isocyanurate either used alone or in combination with other known 
catalysts. Compounds having the general formula depicted in the summary of 
the invention are included within the scope of our invention. 
In a preferred embodiment R.sub.1 and R.sub.2 are alkyl groups having less 
than about 3 carbon atoms and R.sub.3 is hydrogen. 
In a particularly preferred embodiment R.sub.1 and R.sub.2 are methyl and 
R.sub.3 is hydrogen and the catalyst has the formula: 
EQU (CH.sub.3).sub.2 N--N.dbd.CH--CH.sub.2 OH (II) 
and is called 1-(2,2-dimethylhydrazono)-2-hydroxyethane, also known as 
hydroxyacetaldehyde, 2,2-dimethylhydrazone. 
Preparation of these materials can proceed as follows for example: 
In order to obtain compound II, unsymmetrical methylhydrazine, 
(CH.sub.3).sub.2 N--NH.sub.2, is added to formaldehyde at a temperature 
from about -50.degree. C. to 150.degree. C. but preferably from about 
0.degree. C. and 80.degree. C. at pressures ranging from about 0.01 atm to 
200 atm but preferably at about one (1) atm. A solvent may be used but is 
not necessary. Suitable solvents water, alcohols and others. 
If formaldehyde is added to unsymmetrical dimethylhydrazine instead of the 
reverse as above, 
1-(2,2-dimethylhydrazino)-2-(2,2-dimethylhydrazono)ethane, 
EQU (CH.sub.3).sub.2 N--NH--CH.sub.2 --CH.dbd.N--N(CH.sub.3).sub.2 (I) 
is produced along with the 1-(2,2-dimethylhydrazono)-2-hydroxyethane. 
The catalysts of this invention are surprisingly effective in catalyzing 
the isocyanurate reaction and provide a delayed reaction which is valuable 
for processing the foams. Furthermore, the catalysts of this invention are 
particularly advantageous in that they give a complete cure to the foam 
without other catalysts being present.

The Examples which follow depict the preparation of compounds I and II and 
the use of these materials as isocyanurate catalysts. 
EXAMPLE I 
To a 500 ml reactor equipped with a stirrer, thermometer, addition funnel 
and nitrogen atmosphere was charged 150 g unsym-dimethylhydrazine. With 
cooling to 5.degree. C., 212 g formalin (37% formaldehyde) was added 
dropwise over 2 hours. After the addition, the reaction mixture was 
warmed to room temperature over 1.5 hours and water distilled under 
aspirator vacuum of 35 to 50 mm Hg. When about 150 ml remained a 12 inch 
distillation column was added and the distillation was continued. When ca. 
30 ml remained, the column was removed and the remainder flash distilled; 
21.6 g was collected bp.sub.5-6 65.degree.-67.degree. C. This final 
distillate was used as a catalyst to prepare an isocyanurate foam in 
Example II below. 
EXAMPLE II 
A foam was prepared by premixing the B-component ingredients listed below, 
and mixing the B-component on a high speed stirrer with 57.6 parts 
THANATE.RTM.P-270 polyisocyanate, and pouring the blend into a standard 
box mold and allowing the formulation to rise. 
B-component ingredients: 
25.9 parts Novolak polyol (OH No.=187, F=2.5) 
0.5 parts DC-193 silicone surfactant 
12 parts R-11B FREON.RTM. fluorocarbon 
4 parts catalyst from Example 1 
The foam rise characteristics are recorded below: 
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Cream time 22 seconds 
Tack free time 60 seconds 
Rise time 53 seconds 
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This formulation exhibits desirable rise characteristics for many 
isocyanurate foam applications in that it has a relatively long cream time 
and yet still has a reasonably short track free and rise time. This 
permits mold filling of the fluid blend and yet provides rapid cycle times 
for repetitive molding operations. 
EXAMPLE III 
This example is similar to Example I but the products are identified. 
To a 1-l flask equipped with an additional funnel and stirrer and nitrogen 
atmosphere was charged 300 grams unsym.-dimethylhydrazine. After cooling 
to 7.degree. C., 424 grams formalin was added dropwise over 2 hours with 
cooling and stirring. After standing at ambient temperature for 64 hours 
following addition, vacuum distillation was conducted and fraction A 
boiling at 74.degree. C. (4-6 mm) and fraction B boiling at 73.degree. C. 
(3 mm) were collected. Analysis of these fractions showed them to contain 
the following compounds: 
Fraction A--contained a 1:1 molar ratio of compounds I and II. 
Fraction B contained compound II. 
Combined isolated yields of I and II were 1.72% and 4.7% respectively. 
EXAMPLES IV AND V 
Rigid urethane/isocyanurate foams were prepared from the compounds of 
Example III by a technique similar to that described in Example II. 
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#4 #5 
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A Component 
THANATE.RTM.P-270 isocyanate 
58.3 parts 
58.3 parts 
B Component 
Novolak polyol (OH No. 194, F 2.4) 
25.2 parts 
25.2 parts 
DC-193 silicone surfactant 
0.5 parts 0.5 parts 
FREON.RTM.R-11B fluorocarbon 
12 parts 12 parts 
Catalyst - Example III, Fraction 
4 parts 0 parts 
Catalyst - Example III, Fraction B 
0 parts 4 parts 
Foam Cure Data 
Cream time, sec. 4-5 18-20 
Tack free time, sec. 
28-30 60 
Rise time, Sec. 45 105 
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Thus, compound I seems to be more active a catalyst providing a more rapid 
cure whereas compound II provides more of a delay. 
EXAMPLE VI 
To a nitrogen padded flask containing 81 g of formalin, 37% formaldehyde 
solution (1 mole), a stirrer, and thermometer was added 30 g 
unsym.-dimethylhydrazine dropwise over 110 minutes. The reaction solution 
was then warmed in a water bath 3 hours at temperatures not exceeding 
44.degree. C. 
Gas liquid chromatographic analysis of the reaction mixture at this point 
revealed the presence of compound II. Although 33 g additional 
dimethylhydrazine was added and the temperature increased to 87.degree. C. 
(reflux), none of compound I was detected and little additional II was 
formed. 
Dimethylhydrazine and water were removed by heating the mixture at 
60.degree. C. while applying aspirator vaccum. The residue weighed 40 g 
and analysis showed it to be hydroxyacetaldehyde dimethylhydrazone (II). 
Both nmr and glpc analysis showed the product to be greater than 90% pure. 
The next example illustrates the effectiveness of compound II as an 
isocyanurate catalyst in the absence of polyols. 
EXAMPLE VII 
To a nitrogen padded bottle containing 5.0 ml phenylisocyanate and 25 ml 
petroleum ether was added 2 drops of the catalyst of Example VI and 2 ml 
of allyl cyanide as a cosolvent. The bottle was sealed and allowed to 
stand at ambient temperature one hour. The solids which crystallized were 
filtered and washed pentane and reprecipitated from acetone/heptane. The 
crystals, 2.6 g, which were collected were identified as 
triphenylisocyanurate. 
The following examples illustrate the comparison between the catalysts of 
this invention and commercially available amine based isocyanurate 
catalysts. 
EXAMPLES VIII-XII 
Foams were prepared by blending the A component and premixed B-components 
on a high speed stirrer. 
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Experiment Number 
A B C D 
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A-Component (parts by wt.) 
MONDUR.RTM.MR 59 -- -- -- 
polyisocyanate 
THANATE.RTM.P-270 
-- 60 56.6 58 
polyisocyanate 
B-Component (parts by wt.) 
Novolak based polyol 
(OH#194, F 2.4) 25.5 26 -- -- 
Novolak based polyol 
(OH#192, F 2.4) -- -- 24.9 25.5 
DC-193 silicone surfactant 
0.5 0.5 0.5 0.5 
FRENON.RTM.R-11B fluorocarbon 
blowing agent 12 12 12 12 
Catalyst from Example VI 
5 -- -- -- 
50% potassium octoate in 
700 molecular wt. triol 
-- 1.5 -- -- 
DMP-30 (2,4,6-tris-(dimethyl- 
aminomethyl)phenol from 
Rohm and Haas -- -- 6 -- 
1,3,5-tris-(dimethylamino- 
propyl)hexahydrotriazine 
-- -- -- 4 
Foam Cure Characteristics 
Cream time, sec. 13 4 4 5 
Tack free time, sec. 
59 45 55 35 
Rise time, sec. 100 50 120 90 
Comments about cured foam 
Good Good Poor Skin 
exter- 
cracks 
nal under 
friabi- 
slight 
lity pres- 
sure 
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In comparison of the catalysts above, only the catalyst from Example VI 
gave a cream time delay. Other amine catalysts such as DMP-30 and 
1,3,5-tris(dimethylaminopropyl)-hexahydro-1,3,5-triazine do not give good 
isocyanurate foams when used as the only catalyst. Alkali metal 
carboxylates give good foams but do not give the desired delay useful in 
many applications. Lower levels of alkali metals in formulations give 
incompletely cured foams.