Smoke retardant vinyl chloride and vinylidene chloride polymer compositions

Smoke retardant vinyl chloride and vinylidene chloride polymer compositions are obtained by including cobaltous oxide (CoO) in the composition.

BACKGROUND OF THE INVENTION 
Vinyl chloride and vinylidene chloride polymers are known to be 
self-extinguishing and relatively more flame retardant than other polymers 
such as polyethylene, polypropylene and the like. However, a substantial 
amount of smoke may be produced upon exposure of vinyl chloride and 
vinylidene chloride polymers to a flame. The fact that a polymer has good 
flame retardant properties does not necessarily mean that it will have 
good smoke retardant properties, as is well known to those skilled in the 
art. 
U.S. Pat. No. 4,053,452 teaches the use of combinations of (A) melamine 
molybdate or substituted melamine molybdate and (B) cobaltous carbonate 
(CoCO.sub.3) cobaltic oxide (Co.sub.2 O.sub.3), cobalt (II) 
acetylacetonate, and cobalt (III) acetylacetonate and hydrates thereof as 
smoke retardant systems in vinyl chloride and vinylidene chloride polymer 
compositions. The patent, further, discloses that cobaltic oxide, as the 
sole smoke retardant, imparts some degree of improvement in the smoke 
retardation properties of vinyl chloride and vinylidene chloride polymer 
compositions, although the degree of protection is not as high as when the 
combination is used. 
SUMMARY OF THE INVENTION 
In the present invention, smoke retardant vinyl chloride and vinylidene 
chloride polymer compositions are obtained utilizing cobaltous oxide (CoO) 
as a smoke retardant additive. Cobaltous oxide imparts unexpectedly 
superior smoke retardant properties to vinyl chloride and vinylidene 
chloride polymer compositions in comparison to other oxides of cobalt 
(i.e., cobaltic oxide and cobalto-cobaltic oxide)

DETAILED DESCRIPTION OF THE INVENTION 
Smoke retardant vinyl chloride and vinylidene chloride polymer compositions 
are obtained by including cobaltous oxide (cobalt monoxide) in the 
composition. The cobaltous oxide desirably has an average particle size 
from about 0.01 to about 800 microns, preferably from about 0.1 to about 
100 microns, and is present in an amount from about 0.1 to about 20 parts 
by weight per 100 parts by weight of the vinyl chloride or vinylidene 
chloride polymer. If desired, one or more other smoke retardant additives 
for vinyl chloride and vinylidene chloride polymers may be added to the 
composition. 
Vinyl chloride and vinylidene polymers used in this invention include 
homopolymers, copolymers and blends of homopolymers and/or copolymers. The 
vinyl chloride and vinylidene chloride polymers may contain from 0 to 
about 50 percent by weight of at least one other olefinically unsaturated 
monomer, more preferably from 0 to about 50 percent by weight of at least 
one other vinylidene monomer (i.e., a monomer containing at least one 
terminal CH.sub.2 .dbd.C&lt; group per molecule) copolymerized therewith, 
even more preferably from 0 to about 20 percent by weight of such 
vinylidene monomer. Suitable monomers include 1-olefins containing from 2 
to 12 carbon atoms, more preferably from 2 to 8 carbon atoms, such as 
ethylene, propylene, 1-butene, isobutylene, 1-hexene, 4-methyl-1-pentene, 
and the like; dienes containing from 4 to 10 carbon atoms, including 
conjugated dienes such as butadiene, isoprene, piperylene, and the like; 
ethylidene norobornene and dicyclopentadiene; vinyl esters and allyl 
esters such as vinyl acetate, vinyl chloroacetate, vinyl propionate, vinyl 
laurate, alkyl acetate, and the like; vinyl aromatics such as styrene, 
.alpha.-methyl styrene, chlorostyrene, vinyl toluene, vinyl naphthalene, 
and the like; vinyl and allyl ethers and ketones such as vinyl methyl 
ether, allyl methyl ether, vinyl isobutyl ether, vinyl n-butyl ether, 
vinyl chloroethyl ether, methylvinyl ketone, and the like; vinyl nitriles 
such as acrylonitrile, methacrylonitrile, and the like; cyanoalkyl 
acrylates such as .alpha.-cyanomethyl acrylate, the .alpha.-, .beta.- and 
.gamma.-cyanopropyl acrylates, and the like; olefinically unsaturated 
carboxylic acids and esters thereof, including .alpha.,.beta.-olefinically 
unsaturated acids and esters thereof such as methyl acrylate, ethyl 
acrylate, chloropropyl acrylate, butyl acrylate, hexyl acrylate, 
2-ethylhexyl acrylate, dodecyl acrylate, octadecyl acrylate, cyclohexyl 
acrylate, phenyl acrylate, glycidyl acrylate, methoxyethyl acrylate, 
ethoxyethyl acrylate, hexylthioethyl acrylate, methyl methacrylate, ethyl 
methacrylate, butyl methacrylate, glycidyl methacrylate, and the like; and 
including esters of maleic and fumaric acid, and the like; amides of the 
.alpha.,.beta.-olefinically unsaturated carboxylic acids such as 
acrylamide, and the like, divinyls, diacrylates and other polyfunctional 
monomers such as divinyl benzene, divinyl ether, diethylene glycol 
diacrylate, ethylene glycol dimethacrylate, methylene-bis-acrylamide, 
allyl pentaerythritol, and the like; and bis (.beta.-haloalkyl) alkenyl 
phosphonates such as bis(.beta.-chloroethyl) vinyl phosphonate, and the 
like. 
More preferred monomers include 1-olefins containing from 2 to 12 carbon 
atoms, more preferably from 2 to 8 carbon atoms, such as ethylene, 
propylene, 1-butene, isobutylene, 1-hexene, 4-methyl-1-pentene, and the 
like; vinyl esters and allyl esters such as vinyl acetate, vinyl 
chloroacetate, vinyl propionate, vinyl laurate, allyl acetate, and the 
like; olefinically unsaturated carboxylic acids and esters thereof, 
including .alpha.,.beta.-olefinically unsaturated acids and esters thereof 
such as methyl acrylate, ethyl acrylate, chloropropyl acrylate, butyl 
acrylate, hexyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, 
octadecyl acrylate, cyclohexyl acrylate, phenyl acrylate, glycidyl 
acrylate, methoxyethyl acrylate, ethoxyethyl acrylate, hexylthioacrylate, 
methyl methacrylate, ethyl methacrylate, butyl methacrylate, glycidyl 
methacrylate, and the like, and including esters of maleic and fumaric 
acid, and the like; and amides of .alpha.,.beta.-olefinically unsaturated 
carboxylic acids such as acrylamide, and the like. 
The vinyl chloride and vinylidene chloride polymers may be prepared by any 
method known to the art such as by emulsion, suspension, bulk or solution 
polymerization. Compounding ingredients may be mixed with the polymer 
emulsion, suspension, solution or bulk mass before monomer removal and/or 
drying. More preferably compounding ingredients are mixed with dry 
granular or powdered polymers. The polymers and compounding ingredients 
may be mixed thoroughly in granular or powder form in apparatus such as a 
Henschel mixer, or the like. Alternatively, the mixing may be done while 
the polymer mass is fluxed, fused and masticated to homogeneity under 
fairly intensive shear in or on a mixer apparatus having its metal surface 
in contact with the material such as on a roll mill or within a 
mixer-extruder. The fusion temperature and time will vary according to the 
polymer composition and amounts of compounding ingredients present but 
generally will be in the range of about 150.degree. to 200.degree. C. and 
2 to 10 minutes. 
The vinyl chloride and vinylidene chloride polymer compositions of this 
invention may contain the usual compounding ingredients known to the art 
such as filler, stabilizers, opacifiers, lubricants, processing aids, 
impact modifiers, plasticizers, antioxidants, and the like. 
Smoke retardancy may be measured using an NBS Smoke Chamber according to 
procedures described by Gross et al., "Method for Measuring Smoke from 
Burning Materials", Symposium on Fire Test Methods--Restraint & Smoke 
1966, ASTM STP 422, pp. 166-204. Maximum smoke density (Dm) is a 
dimensionless number and has the advantage of representing a smoke density 
independent of chamber volume, specimen size or photometer path length, 
provided a consistent dimensional system is used. Percent smoke reduction 
is calculated using the equation: 
##EQU1## 
The term "Dm/g" means maximum smoke density per gram of sample. Dm and 
other aspects of the physical optics of light transmission through smoke 
are discussed fully in the ASTM publication. 
Smoke retardance may be measured quickly using the Goodrich Smoke-Char 
Test. Test samples may be prepared by dry blending polymer resin and smoke 
retardant additives. The blend is ground in a liquid nitrogen-cooled 
grinder to assure uniform dispersion of the smoke retardant additive(s) in 
the resin. Small (about 0.3 g) samples of the polymer blend are pressed 
into pellets about 1/4 inch in diameter for testing, alternately, test 
samples may be prepared by blending resin, smoke retardant additive(s) and 
lubricant(s) or processing aid(s) in a blender such as an Osterizer 
blender. The blend is milled, pressed into sheets, and cut into small 
(about 0.3 gram) samples for testing. The test samples are placed on a 
screen and burned for 60 seconds with a propane gas flame rising 
vertically from beneath the samples. Sample geometry at a constant weight 
has been found not to be significant for the small samples used in this 
test. A Bernz-O-Matic pencil flame burner head is used with gas pressure 
maintained at about 40 psig. Each sample is immersed totally and 
continuously in the flame. Smoke from the burning sample rises in a 
vertical chimney and passes through the light beam of a Model 407 
Precision Wideband Photometer (Grace Electronics, Inc., Cleveland, Ohio) 
coupled with a photometer integrator. Smoke generation is measured as 
integrated area per gram of sample (SR/g). 
The unexpected superiority of cobaltous oxide over other oxides of cobalt 
is illustrated by the following examples. 
EXAMPLES 1-3 
The following recipe was used: 
______________________________________ 
Material Parts by Weight 
______________________________________ 
Polyvinyl Chloride* 100.0 
Additive (CoO, Co.sub.2 O.sub.3 or 
10.0 
Co.sub.3 O.sub.4) 
______________________________________ 
*Homopolymer of vinyl chloride having an inherent viscosity of about 1.02 
ASTM classification GP5-15543. 
Each experimental sample was prepared by dry blending the polyvinyl 
chloride polymer and additive. The blend then was ground in a liquid 
nitrogen-cooled grinder. Small samples (about 0.3 g) of the polymer blends 
were pressed into pellets about 1/4 inch in diameter and were tested by 
the Goodrich Smoke-Char Test described heretofore. Test results are given 
in Table I. 
TABLE I 
______________________________________ 
Smoke 
Reduction 
Example Additive % Char SR/g* % 
______________________________________ 
Control -- 6.2 67.4 -- 
1 Co0 24.4 17.8 74 
2 Co.sub.2 O3 
20.8 31.0 54 
3 Co.sub.2 O4 
14.2 52.9 22 
______________________________________ 
*SR/g = Intergrated area per gram of sample from smoke curve. 
EXAMPLES 4-5 
The following recipe was used: 
______________________________________ 
Material Parts by Weight 
______________________________________ 
polyvinyl Chloride* 100.00 
Lubricant** 1.5 
Additive (CoO or Co.sub.2 O.sub.3) 
5.0 
______________________________________ 
*Homopolymer of vinyl chloride having an inherent viscosity of about 1.02 
ASTM classification GO5-15543. 
**A commercial polyethylene powder lubricant (Microthene 510). 
The ingredients of the recipe were dry-mixed and banded on a two-roll mill 
for about 5 minutes at a roll temperature of about 160.degree. C. The 
milled compositions were pressed into 6.times.6.times.0.050 inch sheets. 
Pressing was done at about 160.degree. C. for five minutes using 40,000 
pounds (about 14,900 Kg) of force applied to a 4-inch ram. The sample 
received a two minute preheat before being pressed. 
The molded samples were cut into a 27/8.times.23/4.times.0.050 inch 
sections. Testing was performed using the flaming mode of the NBS Smoke 
Chamber Test (ASTM STP 422, pp. 166-204) described heretofore. Test 
results are given in Table II. 
TABLE II 
______________________________________ 
Smoke 
Reduction 
Example Additive Dm/g* % 
______________________________________ 
Control -- 68.6 -- 
4 CoO 25.1 63 
5 Co.sub.2 O.sub.3 
37.2 46 
______________________________________ 
*Dm/g = Maximum smoke density per gram of sample. 
EXAMPLES 6-7 
______________________________________ 
Material Parts by Weight 
______________________________________ 
Polyvinyl Chloride* 100.0 
Lubricant 2.0 
Dibutyltin dithioglycolate 
2.0 
Additive (CoO or Co.sub.3 O.sub.4) 
5.0 
______________________________________ 
*Homopolymer of vinyl chloride having an inherent viscosity of about 1.02 
ASTM classification GP5-15543. 
**A commercial polyethylene powder lubricant (Microthene 510). 
The ingredients of the recipe were dry-mixed and banded on a two-mill roll 
for about 5 minutes at a roll temperature of about 160.degree. C. After a 
two minute preheat, the milled samples were pressed into 
6.times.6.times.0.050 inch sheets. Pressing was done at about 160.degree. 
C. for five minutes using 40,000 pounds (about 14,900 Kg) of force applied 
to a 4-inch ram. 
The molded samples were cut into 1/4.times.1/4.times.0.030 inch sections. 
Testing was performed using the Goodrich Smoke-Char Test described 
heretofore. Test results are given in Table III. 
TABLE III 
______________________________________ 
Smoke 
Reduction 
Example Additive SR/g* % 
______________________________________ 
Control -- 78.7 -- 
6 CoO 8.2 90 
7 Co.sub.3 O.sub.4 
31.5 60 
______________________________________ 
*SR/g = Integrated area per gram of sample from smoke curve. 
The improved smoke retardant vinyl chloride and vinylidene chloride polymer 
compositions of this invention are useful wherever smoke resistance is 
desirable, such as in carpets, house siding, plastic components for 
airplane and passenger car interiors, and the like.