CA1139050A

CA1139050A - Smoke suppressed rigid polyurethane foam

Info

Publication number: CA1139050A
Application number: CA000319491A
Authority: CA
Inventors: Jeffrey D. Miano; Stanley R. Sandler
Original assignee: Pennwalt Corp
Current assignee: Arkema Inc
Priority date: 1978-04-19
Filing date: 1979-01-11
Publication date: 1983-01-04
Also published as: FR2423503A1; GB2019858B; BE875624A; JPS54139997A; DE2910278A1; IT1114736B; GB2019858A; IT7948482A0; NL7901318A

Abstract

SMOKE SUPPRESSED RIGID POLYURETHANE FOAM
Abstract of the Invention Smoke suppressed rigid polyurethane foams are prepared from a reaction mixture comprising as the smoke suppressant additive a metal salt of a: dialkyl dithiocarbamate, a mercaptobenzothiazole a 2,5-dimercapto-1,3,4-thiadiazole, a mercaptotriazine a hydroxy thiophenol or an aliphatic dimercapto compound of 2 to 10 carbons.

Description

~ tlon 1. Field of the Invention This invention rPlates to R smoke suppressed rigid polyurethane oam composition. More specifically, this inven~ion relates to the addition o~ organic sulfur-containing metal compounds to rigid polyurethane foam composition5 to reduce the smoke generated on burning the resulting foams.

2. Description of the Prior Art Rigid foams are becoming increasingly important as an insulatlon material in construction of new buildings to reduce energy losses. At the same time, building code agencies are requiring lower levels of smoke to be generated when foam burns in order to make the exits easily observable to facili-tate access by firemen and the escape of occupants.
Prior to the instant inventlon polyurethane foams could be smoke suppressed by using sulfur containing compounds such as elemental sulfur or certan organo-sulfur compounds such AS di-t-butyl pol~sul~ide and ethylene trithiocarbonate.
The use of these materials is illustrated in U.S. Patent Nos.
Z0 3,542,701, 3,876,568, and 3,933,694. These organosulfur compounds have the disadvantage of either being too volatile or imparting an objectionable odor during processing. Poly-urethane foam containing these pxior art sulfur compounds still produced substantial amounts of smoke.
The compounds used in the rigid foam compositions o the present invention overcome the disadvantages of the prior art because they substantially reduce the amount of smoke produced from burning polyurethane. This has been demonstrat-ed in the Examples inra.

St,atement of the Invent.ion The present invention is directed to a smok~ suppressed rigid polyurethane foam prepared from a reaction mi.xture which comprises a smoke suppresslng amount of a compound selectéd from the group consisting of:

S

~(R~2N-~-S~n~, ~S-Rl-S~M, _ _ .
L~ c ~ v ¦ I n N N -- _ _ ~ \ S / M, and -S ~ N \ S~

N~ ~N M
S

_ n wherein:
R is a lower al~yl of 1 to 5 carbons;
Rl is a cycloalkyl of 3-10 carbons or an alkyl of 2-10 carbons;
n is an integer equal to the valence of M; and X is selected from S/ O or N~I.
M ls selected from the group consisting of copper, zinc, aluminum, tin, antimony, bismuth, vanadium, chromium, molybdenum, manganese, lron, cobalt, and nickel.

Detailed De cri~tion of the Invention -The present invention is directed to a smoke suppressed, rigld polyurethane foam. Generally, polyurethanes are prepared by the reaction of toluene dii~ocyanate or polymethylene polyphenylisocyanate or mlxture thereof with polyfunctional hydroxy compounds. Some typical e~amples o~ rigid polyurethane foams are described ln E~ N. Doyle "The Development and Use of Polyurathane Products", McGraw-Hill Book Co., New York, 1971 and in W.CO Kuryla and A~J. Papa, "Flame Retardancy o~ Polymeric Materials", Volume 3, Marcel Dekker, Inc., New York, 1975.
The xigid polyurethane xesins of this invention may also con-tain flame retardants such as chloroethyl phosphates, phos~
phorous-nitrogen compounds, and brominated or chlorinated polyols~
The smoke suppressant additives used to prepare the rigid polyurethane foams of this invention may be prepared by the reaction of salts of metals selected from copper, zinc, aluminum, tin, antimony, bismuth, vanadium, chromium, moly-bdenum, manganese, iron, cobalt and nickel, with the sodium salts of sulfur containing compounds selected from mercapto-benzothiazoles, 2,5-di-mercapto-1,3~4-thiadiazoles, mercapto-triazines, dialkyl dithiocarbamates, hydroxy thiophenols and aliphatic dimercapto compounds having 2 to 10 carbons. These additives are either monomeric or polyme~ic salts and can be cyclic or linear; the~ are phy~ically mixed with the reactants for prepari~g ~he polyurethane ~oam pre~erably in the amount o~ 0.1 to 20 parts by weight of the formulation of reactants (i.e., polyols, surfactants, catalysts, water, blowing agents, flame retardant, and isocyanate) to give the polyurethane foam.
Representative smoke suppressant additives used in this invention are as follows:
ferrous 2-mer~aptobenzothiazole cupric 2-mercaptobenzothiazole zinc 2-mercaptobenzothiazole ferrous dlmethyl dithiocarbamate cupric dimethyl dlthiocarbamate ~ 3 ~

zinc dimethyl dithiocarbamate ferrous dibutyl dithiocarbamat~
cupric dibutyl di.thiocarbamate zinc dibutyl dithiocarbamate nickelous dibutyl dithiocarbamate antimonous dibutyl di~hiocarbamate ferrous dimercapto-1,3,4~dithladiazole cupric dimercapto-1,3,4-dithiadiazole zinc dimercapto-1,3,4-dithiadiazole ferrous salt o~ p-hydroxythiophenol zinc salt of p-hydroxythiophenol ferrous 2-mercaptobenzoxazole ferrous 2-mercaptobenzimidazole zinc salt of trimercaptotriazine ferrous salt of l,6-dimercaptohexane cupric salt of l,6-dimercaptohexane cobaltous dimethyl dithiocarbamate nickelous dimethyl dithiocarbama~e stannous 2-mercap~obenæothiazole In the practice of this invention, pre~erred metals used for the smoke suppressants are iron, copper~ and zinc.
The preferred organosul~ux compounds used to prepare the metal salts are selected from mercaptobenzothiazoles, dimercapto-1,3,4-thiadiazoles, and dlalkyl d:lthiocarbamates.
The preferred smoke suppressants are: ferrous 2-mer-captobenzo~hiazole, ferrous dimethyl dlthiocarbamate, ferrous 2,5-dimercapto-1,3,4-thiadiazole, cupric 2-mercapkobenzothia-zole, cuprlc dimethyl dithiocarbamate, cupric 2,5-dimercapto-1,3,4-thiad.iazole, æinc 2-mercaptobenzothiazole, zinc dimethyl di~hiocarbamate, zinc dibutyl dithiocarbamate, and zinc 2,5-dimercapto 1,3,4-thiadiazole.
The following examples illustrate the present -r - 4 ~
.~

invention bu~ are no~ interlded to limi~ the invention thereto.
Rigid polyurethan0 foams described in the following examples are prepared by stirring the smoke suppressant additive with the polyol ~ollowed by addition of catalysts, surfactant, ~ater and/or blowing agent and isocyanate as described by K.C. Fris~h and S.L. Reegan in t'Advances in Urethane Science and Technology1', Volumes 1 to 4, Technomlc, Conn., 1971-1976.
The rigid foams are made by pouring the stirred reaction mixture into an 8"x8"x5" box. The foam is aged for seven days, and then cut in~o 3"x3"xl" specimens that are burned in the NBS smoke chamber using the flaming mode in accordance with ASTM Special Technical Publication 422 tl969) and NFPA 258 - T, "Smoke Generated by Solld Materlals~, May, 1974. The averaye of two or more values is reported.
Example 1 shows that a rigid polyurethane foam contain-lng a phosphorus based flame retardant and no smoke suppressant produces a large quantity of smoke (DmC - 355).
Examples 2-5 show that xigid polyurethane foams of the same ~ormulaklon as Example 1 but contalning metal dialkyl-dithiocarbAmates or zinc mercap~obenzo~hiaæole produce les5smoke than a ~oam containing prior art elemental sul-fur at the same loadlng le~el by ~eight.

EXA~PLES 1~5 : Parts Polyol~ Pluracol* 383 (BASF Wyandotte)(a~ 100.0 Surfactant - DC - 193* (Dow Corning)( ) 1.0 Dimethylaminoethanol (Pennwalt) 2~94 Dibutyltin Dilaurate (M & T) 0.06 Water 0.9 Blowing Agent - Isotron II* ~Pennwalt~(Cj50.0 Flame Retardant - Fyrol* 6 (Stauf~er)( )35.0 Isocyanate - PAPI* (Upjohn)( ) 182.0 Smoke Suppressant as shown below ___ (a) Sucrose - based polyol, OH number = 483, contains ~1%
phosphorus (b) Silicone surfactant (c) Dlethyl N,N-Bis(2-hydroxyethyl)aminomethylphosphonate ~d) Polymethylene polyphenylisocyanate, NCO equivalent = 133 Smoke ~ Smoke D cReduction 1 None - 355 0 2 Sulfur 20 266 25

3 Ferrouq 2-mercapto- 20 216 39 benzothiazole

4 Zinc dimethyl di- 20 143 60 thiocarbamate Zinc ~,5-dimercapto- 20 135 62 1,3,4 thiadiazole Examples 6 - 10 show that rigid polyurethane foams flame retarded with an organobromine compound and containing the mekal oryano sulfur compounds of this invention produce less smoke than a foam containing prior art elemental sulfur at the same percent sulfur content~

*Trade Mark ~f ~

EX~PLES 6~10 . Parts Polyol - Pluracol 383 (B~SF Wyandotte)(a) lOOoO
Surfactant - DC - 193 (Dow Corning)(b) 1.0 Dimethylaminoethanol 2.94 Dibutyltin Dilaurate 0.06 Water 0 9 Blowing Agent - Isotron II (Pennwalt)(C) 50.0 Flame Retardant - FR - 1138 (DOW)(d) 30.0 Isocyanate - PAPI (Upjohn)( ) 173~0 Smoke Suppressant as shown below __ (a) Sucrose based polyol, OH number - 483, contalns 1%
phosphorus ~b) Silicone surfactant ~c ) F luorocarbon I ~
(d) Dibromoneopentyl glycol (e) Polymethylene polyphen~llsoc~an~te, NCO equivalent = 133 Smoke % Smo]ce D Reduction ~mc 6 None - 344 0 7 Sulfur ~ 6~ 23 B Ferrous dimethyl dithio- 20.1 163 53 carbamate 9 Zinc dim~thyl dithio- 20.8 179 48 carbarnate Cupric dimethyl dithio- 20.4 194 ~4 carbamate __ __. ____ *All present at the same percent sulfur by weight.

Examples 11-12 are presented to show the effectiveness of zinc dimethyl dithiocarbarnate as a smoke suppre~sant for rigld polyurethane containing a chlorinated flame retardant (Thermolin* RF230). This metal sulfur~containing salt was earlier shown in Example 4 to also be e~fec~ive as a smoke *Trade Mark _ 7 _ ~3~

suppressant for rlgid polyure~hane ~oam containing a phosphorus/
nitrogen flame retardant (Fyrol 6).

Parts Polyol - Thermolin RF230 (Olin)(a)25.0 Polyol - Pluracol 383 (BASF Wyandotte)(b) 75,0 Surfactant - DC-193 (Dow Corning )(C) 1.0 Dimethylaminoetha~ol 2.94 Dibutyltin Dilaurate 0.06 Water 0-9 Blowing Agent - Isotron 11 (Pennwalt)( ) 50.0 Isocyanate - PAPI (Upjohn)(e) 132.4 Smoke Suppressant as shown below (a) Hydroxyl~number = 365, 47% chlorine (b) Sucrose based polyol, OEI number = 483, contains c phosphorus (c) Silicone surfactant (d) Fluorocarbon 11 (e) Polymethylene polyphenylisocyanate, NCO equivalent ~ 133 Smoke % Smoke D c Reduction 11 None - 220 0 12 Zinc dimethyl dithio- 11.6 136 38 carbamate ~o a rigid polyurethane recipe as described in Examples 11-1~ is added llo 6 pph o~ zinc dibutyl dithio-carbamate Zn L(C4H9 ~2NCS2]2 (Pennwalt~s Butyl Ziram). The resulting rigid polyurethane foam on combustion gave smoke ~eductions on the order o~ about 38% or about the same as that from zinc dlmethyl dithiocarbamate sho~n in Example 12.

~ .

-o~

EX~MPLE 14 2,5 dlmercapto 1,3,4-th~adiazole (50g, 0.33 mole) is stirred in 100 ml H200 NaOH (26.7g, 0.66 mole) is slowly added with stirring and cooling. A ZnC12 solution (45.4g, 0.33 mole dissolved ln 300 ml H203 is added to the sodium dimercapto-1,3,4 thiadiaæole salt solution resulting in the formation of a white precipitate. The pre~ipitate is filtered and dried to give a quantitative yield of zinc 2,5-dimercapto-1 t 3,4-thiadia-zole.
Elemental and spect~oscopic analyses are consistent with the assigned structure.

xAMæLE 15 Pre aration of Zinc Dimeth 1 Dithiocarbamate Sodium dimethyl dithiochrbamate (75~2g, 0.66 mole) is dissolved in 100 ml H20. A ZnC12 solution (45.4g, 0033 mole dissolved in 300 ml H20) is added to the sodium dimethyl dithiocarbamate solution~ Immediately, a whi~e precipitate forms which ls ~iltered and dried to give a quantitatlve yleld of zinc dimethyl dithiocarbamate.
Elemental an~ spectroscopic analyses are consistent with the assigned structure as beins S

~CH3)2N-C S ~2 ExAMæLE 16 ~ _ ~ ~
Sodium dimethyl dithiocarbamate (75.2g, 0.66 mole) is dissolved in'100 ml H20. A CuC12 solution (44.3g, 0.33 mole dissolved in 300 ml H20) is added to the sodlum dlmethyl dithiocarbamate solution. Immediately, a precipita~ forms which is filtered and dried to give a ~uantitative yi~ld of _ g cupric dimethyl dithiocarbamate~
Elemental and speckroscopic analyse~ are consistent with the assigned structure as being:
S

[(CH3)2N~;C-S~2Cu ~. .

-- 10 ~

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A rigid polyurethane foam prepared from a reaction mixture which comprises a smoke suppressing amount of a com-pound selected from the group consisting of:

, , , , and wherein:
R is a lower alkyl of 1 to 5 carbons;
Rl is a cycloalkyl of 3-10 carbons or an alkyl of 2-10 carbons;
n is an integer equal to the valence of M; and X is selected from S, O or NH.
M is selected from the group consisting of copper, zinc, aluminum, tin, antimony, bismuth, vanadium, chromium, molybdenum, manganese, iron, cobalt, and nickel.

2. The rigid polyurethane foam of claim 1 wherein the compound is selected from the group consisting of mercapto-benzothiazoles, dialkyldithiocarbamates and 2,5-dlmercapto 1,3,4-thiadiazoles and M is selected from the group consisting of iron copper, zinc, cobalt, nickel, molybdenum, tin antimony, bismuth, vanadium, manganese, and chromium,

3. The polyurethane oam o claim l wherein the com-pound is ferrous mercaptobenzothioazole

4. The polyurethane foam o claim l wherein the com-pound is zinc dimethyldithiocarbamate.

5. The polyurethane foam of claim 1 wherein the com-pound is zinc 2, 5-dimercapto-1,3,4-thiadiazole.

6. The polyurethane foam of claim l wherein the compound is ferrous dimethyl dithiocarbamate.

7. The polyurethane foam of claim l wherein the compound is cupric dimethyl dithiocarbamate.

8. The polyurethane foam of claim 1 wherein the compound is zinc dibutyl dithiocarbamate.

9. The polyurethane foam of claim 1 wherein the compound is ferrous 2,5-dimercapto 1,3,4,-thiadiazole.

lO. The polyurethane foam of claim l wherein the compound is cupric mercaptobenzothioazole.

ll. The polyurethane foam o claim 1 wherein the compound is cupric 2,5 dimercapto-l,3,4-thiadiazole.

12. The polyurethane foam of claim l wherein the compound is zinc 2-mercaptobenzothioazole.

13. The polyurethane foam of claim 1 wherein the smoke suppressing amount of the compound is 0.1 to 20 parts by weight of the foam.