2-Trichloromethyloxazolidine and thiazolidine derivatives useful as flame retardants for polyurethane foam

A rigid polyurethane foam is prepared from a reaction mixture incorporating therein a 2-trichloromethyloxazolidine or a thiazolidine derivative for imparting to the foam smoke and flame retardancy.

BACKGROUND OF THE INVENTION 
This invention relates to flame-and smoke-retardant rigid polyurethane 
foam, and more particularly to 2-trichloromethyl-1, 3-oxazolidine, 
2-trichloromethyl-1, 3-thiazolidine and derivatives thereof which are 
especially useful in retarding smoke and flames in rigid polyurethane 
foams. 
Rigid polyurethane foams are becoming increasingly important as an 
insulation material in construction of new buildings to reduce energy 
losses. Building code regulations now require that these foams be not only 
flame retardant but also have low-smoke properties in order to make escape 
exits more easily observable by the occupants and to allow easy access by 
firemen. The prior art discloses the use of chlorinated compounds as flame 
retardants such as trichlorobutylene oxide for rigid polyurethane foam but 
these compounds have the disadvantage of generating too much smoke on 
combustion of the foam. (See U.S. Pat. No. 3,741,921). The flame and smoke 
retardants of this invention overcome the disadvantages of the prior art 
because they generate less smoke on combustion. 
STATEMENT OF THE INVENTION 
The present invention is directed to a rigid polyurethane foam prepared 
from a reaction mixture which comprises a smoke and flame retarding amount 
of a compound selected from the group consisting of 
##STR1## 
where (a) X is O or S; and 
(b) R is selected from the group consisting of H, 
##STR2## 
DETAILED DESCRIPTION OF THE INVENTION 
A variety of rigid polyurethanes can be used in this invention. Some 
typical examples are described in E. N. Doyle "The Development and Use of 
Polyurethane Products." McGraw Hill Book Company, New York, 1971, and in 
W. C. Kuryla and A. J. Papa "Flame Retardancy of Polymers Materials" 
Volume 3, Marcel Dekker, Inc., New York, 1975; these references are hereby 
incorporated herein and should be considered as a part of this disclosure. 
In general, the flame-and smoke-retardant rigid polyurethanes are prepared 
by adding 1 to 30 parts by weight of the retardant to the reactants, i.e., 
polyols, surfactants, catalyst, water, blowing agents, and isocyanate, to 
produce the rigid polyurethane foam. 
The preferred flame retardants for use in the instant invention are 
2-trichloromethyl-1, 3-oxazolidine, 2-trichloromethyl-1, 3-thiazolidine, 
3-(2-hydroxyethyl)-2-trichloromethyl-1, 3-thiazolidine, 
3-(2-hydroxyethyl)-2-trichloromethyl-1, 3-oxazolidine, 
3-(2-hydroxypropyl)-2-trichloromethyl-1, 3-oxazolidine, and 
3-(2,3-dihydroxypropyl)-2-trichloromethyl-1, 3-oxazolidine. 
In the following examples the foams are prepared by mixing the ingredients 
and adding the mix to a mold of the dimensions 8.times.8.times.5 inches. 
The foam is first aged for 7 days and then cut into 3.times.3.times.1-inch 
specimens that are burned in the NBS Smoke Chamber using the flaming mold 
in accordance with ASTM special technical publication 422 (1969) and NFPA 
258-T "Smoke Generated by Solid Materials" May, 1974. Flame retardancy was 
measured by ASTM D-1692 test which involves burning a 
2.times.5.times.1/2-inch sample horizontally in a draft-free hood with a 
propane flame. Samples burning the entire length are not considered 
flame-retarded. The values are reported in inches burned. The average of 
two or more values is reported. 
The following examples merely illustrate the present invention but are not 
intended to limit the invention thereto.

EXAMPLE 1 
2-Trichloromethyl-1, 3-oxazolidine 
To a 2 liter 3-necked flask equipped with a stirrer, Dean-Stark trap, a 
condenser and dropping funnel were added 214 g (3.51 moles) ethanolamine 
and 450 g. toluene. Then 273 g (4.55 moles) of glacial acetic acid were 
added slowly to keep the temperature (cooling if necessary) at 
30.degree.-45.degree. C. Then 568 g (3.85 moles) of chloral were added at 
40.degree.-50.degree. C. The reaction mixture was refluxed to remove water 
and, when complete, the temperature increased to 115.degree.-120.degree. 
C. The reaction mixture was cooled in an ice bath and the product 
precipitated after standing for several hours to give 189.5 g (28.5%) m.p. 
72.degree.-74.degree. C. The filtrate was washed with 5.0 moles of 20% 
sodium hydroxide and more product precipitated. Filtration and drying 
yielded 228.5 g (34.3%), m.p. 73.degree.-75.degree. C. The toluene layer 
was washed with water and evaporated to give a solid. Washing with water 
and filtration yielded upon drying 328 g. (49.2%), m.p. 
62.degree.-72.degree. C. for a total yield of 556.0 g (83.5%). The 
analysis was consistent with the assigned structure. 
The composition of Example 1 may be reacted with epichlorohydrin or other 
oxiranes (ethylene oxide, propylene oxide) to give the hydroxy containing 
derivatives of this invention which are useful as flame retardants. 
EXAMPLE 2 
3-(2-Hydroxyethyl)-2-Trichloromethyl-1, 3-Oxazolidine 
One mole of the composition of Example 1 was reacted with 1.1 moles of 
ethylene oxide under pressure to give 
3-(2-hydroxyethyl)-2-trichloromethyl-1, 3-oxazolidine which analyzed well 
for the assigned structure. The analogous thiazolidine compound is 
prepared in a similar manner. 
______________________________________ 
Examples 3-5 
Foam Formulation: Parts 
______________________________________ 
Polyol (Poly G-71-530 Olin) 
100.0 
Surfactant (DC-193-Dow Corning) 
1.5 
Water 0.5 
Catalyst (Penncat 283-Pennwalt) 
3.0 
Blowing Agent (Pennwalt's Isotron-11) 
50.0 
Flame Retardant as shown 
Polyisocyanate (PAPI-UpJohn) 
as shown 
______________________________________ 
Ex. 3 Ex. 4 Ex. 5 
______________________________________ 
Flame Retardant (php).sup.a 
none Thermolin RF230.sup.b 
Comp. 
(25) of Ex. 1 
(22) 
PAPI (parts by wt.) 
153 140 153 
NBS-Maximum 
Smoke Density (corrected) 
138 166 127 
ASTM D-1692 
(inches of burn) 
2.0 1.25 0.78 
______________________________________ 
.sup.a php = parts per hundred parts of polyol. 
.sup.b a trademark for trichlorobutylene oxide polyol marketed by Olin 
Corporation. 
Examples 3-5 show in a comparison that when no flame retardant is used the 
foam strip burns completely (Example 3); when a prior art composition is 
used (Example 4), the inches of burning are only slightly less than the 
control; and when the composition of this invention is used (Example 5), 
the inches burned are substantially reduced. Furthermore, note that the 
maximum smoke density for Example 5 is also significantly less than in 
Examples 3 and 4. 
EXAMPLE 6 
To the formulation shown in Examples 3-5 was added 22.5 php of 
3-phenylsulfonyl-2-trichloromethyl-1, 3-oxazolidine. The sample burned the 
entire length in the ASTM D 1692 test and the smoke density was similar to 
that of Example 5. This example demonstrates that not all oxazolidines 
give acceptable flame retardancy rating nor come within the scope of this 
invention. 
EXAMPLE 7 
To the formulation shown in Examples 3-5 was added 17 php of 
3-formyl-2-trichloromethyl-1, 3-oxazolidine. The sample burned the entire 
length in the ASTM D 1692 test and the smoke density was similar to that 
of Example 5. This is another substituted oxazolidine not within the scope 
of this invention that does not produce acceptable flame retardancy 
rating. 
EXAMPLE 8 
To the formulation in Examples 3-5 was added 30 php of 
3-(2-hydroxyethyl)-2-trichloromethyl-1, 3-oxazolidine (Example 2) followed 
later by 171 parts PAPI. The flame and smoke density results were 
equivalent to Example 5. 
EXAMPLE 9 
3-(2-Hydroxypropyl)-2-Trichloromethyl-1, 3-Oxazolidine 
To a three-necked flask equipped with a mechanical stirrer, Dry Ice 
condenser, addition funnel and thermometer were charged 191 g (1.0 mole) 
of 2-trichloromethyloxazolidine, 400 g. toluene and 1 ml of triethylamine. 
Then 64 g (1.1 mole) of propylene oxide was added and the temperature 
raised to 55.degree. C. The reaction was over when the propylene oxide 
stopped refluxing. The reaction mixture was then concentrated under 
reduced pressure to yield the product. The analysis was consistent with 
the assigned structure. The analogous thiazolidine is prepared in a 
similar manner. 
EXAMPLE 10 
To the formulation in Examples 3-5 was added 31 php of 
3-(2-hydroxypropyl)-2-trichloromethyl-1, 3-oxazolidine (Example 9) 
followed later by 171 parts PAPI. The flame and smoke density results were 
equivalent to that of Example 5. 
EXAMPLE 11 
3-(2,3-Dihydroxypropyl)-2-Trichloromethyl-1,3-Oxazolidine 
To a three-necked flask equipped with a mechanical stirrer, condenser, 
addition funnel and thermometer were charged 191 g (1.0 mole) of 
2-trichloromethyloxazolidine, 101 g (1.0 mole) of triethylamine and 400 g 
of tetrahydrofuran. Then 93 g (1.0 mole) of epichlorohydrin was slowly 
added while heating the reaction mixture to 66.degree. C. After the 
reaction was complete, the precipitate of triethylamine hydrochloride was 
filtered and the filtrate added to a flask containing 100 ml of 10% 
aqueous triethylamine solution. The reaction mixture was gently refluxed 
for 3 hours and the product isolated by removing the volatiles under 
reduced pressure. The analysis was consistent with the assigned structure. 
The analogous thiazolidine is prepared in a similar manner. 
EXAMPLE 12 
To the formulation in Examples 3-5 was added 35 php of 
3-(2,3-dihydroxypropyl)-2-trichloromethyl-1, 3-oxazolidine (Example 11) 
followed later by 174 parts PAPI. The flame and smoke density results were 
equivalent to that of Example 5. 
EXAMPLE 13 
To the formulation in Examples 3-5 was added 24 php of 2-trichloromethyl-1, 
3-thiazolidine followed later by 153 parts PAPI. The flame and smoke 
density results were equivalent to that of Example 5.