U.S. patent number RE32,606 [Application Number 06/857,242] was granted by the patent office on 1988-02-16 for process for the complete bromination of non-fused ring aromatic compounds.
This patent grant is currently assigned to Great Lakes Chemical Corporation. Invention is credited to Heinrich Stepniczka.
United States Patent |
RE32,606 |
Stepniczka |
February 16, 1988 |
**Please see images for:
( Certificate of Correction ) ** |
Process for the complete bromination of non-fused ring aromatic
compounds
Abstract
There is disclosed a process for the preparation of completely
brominated derivatives of aromatic compounds comprising one or more
phenyl groups which may contain substituents, side chains or be
partially-brominated. The complete bromination is effected by
utilizing liquid bromine as a reaction solvent whereby the starting
aromatic material is reacted with an excess of bromine which
contains a bromination catalyst and the mixture is refluxed for a
sufficient time. Use of these brominated derivatives as fire
retarding agents is nylon and polyester is also disclosed.
Inventors: |
Stepniczka; Heinrich (Alma,
MI) |
Assignee: |
Great Lakes Chemical
Corporation (West Lafayette, IN)
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Family
ID: |
26763097 |
Appl.
No.: |
06/857,242 |
Filed: |
April 29, 1986 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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80122 |
Oct 12, 1970 |
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Reissue of: |
222412 |
Jan 17, 1972 |
03965197 |
Jun 22, 1976 |
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Current U.S.
Class: |
568/779; 568/56;
568/637; 570/206 |
Current CPC
Class: |
C07B
39/00 (20130101); C07C 17/12 (20130101); C07C
37/62 (20130101); C07C 41/22 (20130101); C07C
323/00 (20130101); C07C 37/62 (20130101); C07C
39/27 (20130101); C07C 41/22 (20130101); C07C
43/29 (20130101) |
Current International
Class: |
C07B
39/00 (20060101); C07C 37/00 (20060101); C07C
41/00 (20060101); C07C 37/62 (20060101); C07C
41/22 (20060101); C07C 17/12 (20060101); C07C
17/00 (20060101); C07C 017/12 (); C07C 037/62 ();
C07C 041/22 (); C07C 148/00 () |
Field of
Search: |
;568/779,776,765,726,588,56 ;570/206,211 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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1469899 |
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Mar 1969 |
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DE |
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1175213 |
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Aug 1984 |
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DE |
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1029874 |
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May 1966 |
|
GB |
|
1278603 |
|
Feb 1969 |
|
GB |
|
Other References
Hennion & Anderson, "Studies on the Polybromination of
Alkylbenzenes-Preliminary Report," JACS, vol. 66, p. 1801 (1944).
.
Nightingale, "Alkylation and the Action of Aluminum Halides on
Alkylbenzenes," Chem. Review, vol. 25, pp. 344-372 (1939). .
Bodroux, Bull. Soc. Chim. Fr. (3), vol. 19, pp. 888-889 (1898).
.
Klages et al., "Stufenweise Einfuhrung von vier Aethylgruppen in
das Benzol", in: Chemische Berichte, vol. 36 (1903) pp. 1632-1645.
.
Tschitschibabin, "Hydrogenation of Normal Propyl Benzene", in: Bull
Soc. Chim. Fr. 3, vol. 12 (1894), p. 1220. .
Quist et al., Chem. Abstr., vol. 38, pp. 5205-5206 (1944). .
Pajeau, Compt. REnd., vol. 212, pp. 487-489 (1941) (translation
attached). .
Hennion & Anderson, "The Polybromination of Alkylbenzenes,"
JACS, vol. 68, pp. 424-426 (1946). .
Beilsteins Handbuch der organischen Chemie, 4th Ed., vol. 5, pp.
215, 310 (Berlin 1922) (translation attached). .
Bonneaud, Bull. Soc. Chim. Fr. (4), vol. 7, pp. 776-781 (1910)
(translation attached). .
Answers, "Reduction des Chlorids"; in: Chemische Berichte, vol. 38
(1905), pp. 1706-1709 (translation attached). .
Klages, "Uber die Reduction partiell hybrider Benzole", in:
Chemische Berichte, vol. 39 (1906) pp. 2306-2315 (translation
attached). .
Pajeau, "Preparation and Raman Spectra of Brominated Benzene
Derivatives," in: Chem. Abstr. vol. 37 (1943), p. 2268. .
Cook, "Phenyl Ether and some of its derivatives" in: JACS, vol. 32
(1910), pp. 1285-1289..
|
Primary Examiner: Lone; Werren B.
Attorney, Agent or Firm: Kirkland & Ellis
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
.[.This application is a division, of patent application Ser. No.
80,122, filed Oct. 12, 1970, now abandoned..].
.Iadd.This is an application for reissue of U.S. Pat. No.
3,965,197, issued June 22, 1976, on application Ser. No. 222,412,
filed Jan. 17, 1972, which is a division of application Ser. No.
80,122, filed Oct. 12, 1970, abandoned. .Iaddend.
Claims
What is claimed is:
1. A process for the complete bromination of aromatic compounds on
the ring portion thereof, said aromatic compounds having one or
more benzene rings and are selected from the group consisting of
benzene, toluene, phenol.[.xylene.]., biphenyl, biphenylether and
biphenyl sulfide, comprising the steps of:
a. reacting the aromatic compound with a large excess of liquid
bromine in the presence of a bromination catalyst selected from the
group consisting of iron, aluminum, .[.iodine,.]. iron halide, and
aluminum halide, at from about 10.degree. C. to ambient
temperatures to form a reaction mixture with the evolution of
gaseous hydrogen bromide, said bromine excess being at least 100
percent of the stoichiometric amount of bromine required for the
complete bromination;
b. thereafter refluxing said reaction mixture;
c. maintaining said reflux condition for a time sufficient whereby
hydrogen bromide ceases to form; and
d. separating the completely brominated aromatic reaction product
from the reaction mixture.
2. A process for the preparation of completely brominated
derivatives of aromatic compounds according to claim 1 wherein said
bromination catalyst is selected from aluminum halides, iron
halides .[.and iodine.]..
3. A process according to claim 1 wherein the reaction mixture
formed in step a. is maintained about 10 degrees Centigrade to
control the initial bromination reaction.
4. A process for the preparation of completely brominated
derivatives of aromatic compounds according to claim 1 which is
further characterized by having the reaction mixture stirred
throughout the bromination reaction.
5. A process for the preparation of completely brominated
derivatives of aromatic compounds according to claim 1 wherein the
derivative of step (d) is treated with super-heated steam to remove
any occluded bromine.
6. A process according to claim 1 wherein the completely brominated
aromatic reaction product is selected from the group consisting of
pentabromophenol, pentabromotoluene and tetrabromoxylene.
7. A process for the preparation of completely brominated
derivatives of aromatic compounds according to claim 2 wherein said
catalyst is selected from aluminum and iron chlorides.
8. A process according to claim 1 wherein the said completely
brominated aromatic derivative is washed and dried.
9. A process for completely brominating an aromatic compound
selected from biphenyl, biphenyl ether and biphenyl sulfide to
produce the corresponding decabrominated derivative, comprising the
steps of:
a. reacting the aromatic compound with liquid bromine in the
presence of a bromination catalyst selected from the group
consisting of iron, aluminum, .[.iodine,.]. iron halide and
aluminum halide at from about 10.degree. C. to ambient temperature
to form a reaction mixture with the evolution of gaseous hydrogen
bromide, said liquid bromine being present in said mixture in an
amount in excess of the stoichiometric amount of bromine by an
amount at least 100 percent of the stoichiometric amount required
for the complete bromination;
b. thereafter refluxing said reaction mixture;
c. maintaining said reflux condition for a sufficient time whereby
hydrogen bromide ceases to form; and
d. separating the formed decabrominated derivative from the
reaction mixture.
10. A process according to claim 9 wherein the reaction mixture
formed in step a. is maintained at about 10 degrees Centigrade to
control the initial bromination.
11. A process for completely brominating an aromatic compound
selected from biphenyl, biphenyl ether and biphenyl sulfide
according to claim 9 wherein the decabrominated derivative is
treated with super-heated steam to remove any occluded elemental
bromine.
12. A process for completely brominating an aromatic compound
selected from biphenyl, biphenyl ether and biphenyl sulfide
according to claim 9 wherein the reaction mixture is kept stirred
throughout the bromination reaction.
13. A process according to claim 9 wherein said bromination
catalyst is selected from aluminum halides.[.,.]. .Iadd.and
.Iaddend.iron halides .[.and iodine.]..
14. A process according to claim 9 wherein said decabrominated
derivative is washed and dried.
Description
The present invention relates to completely brominated derivatives
of aromatic compounds and particularly to the process for the
preparation of said derivatives, said process being characterized
by utilizing liquid elementary bromine as a reaction solvent.
Moreover, the invention is concerned with the utility of these
brominated derivatives as fire-retarding agents in synthetic
polymeric systems such as polyester and polyamide.
Aromatic hydrocarbons comprising one or more benzene rings have
been partially brominated by various methods. In fact, introducing
up to three bromine atoms per one aromatic molecule is usually
accomplished with relative ease to the extent that a number of
brominating agents can be used. Difficulties are encountered,
however, when further bromination, beyond the tri-bromo level, is
desired. Encountering such difficulties is not unexpected since it
is known that substituted ring positions tend to reduce the
activity level of adjacent, but unsubstituted, positions. Thus more
drastic and stringent reaction conditions are necessary to effect
further introduction of bromine into the ring. For example, in the
prior art, to prepare hexabromobenzene from benzene, mono-, or
dibromobenzene the bromination is conducted in concentrated
sulfuric acid containing 29% free sulfur trioxide. The reaction
time is lengthy, usually between 9 to 16 hours and is generally
carried at elevated temperatures, i.e. about 150.degree. C.
Reaction conditions of comparable harshness are used to prepare
other highly brominated aromatic compounds such as
tetrabromoaniline, octabromobiphenyl and decabromobiphenyl, see
U.S. Pat. No. 3,232,959.
The bromination of aromatic compounds utilizing bromine or other
brominating agents is conducted generally in the presence of
solvents which provide convenient reaction media insofar as
solubilities, ease of handling and reaction with some formed
by-products as means of the elimination thereof. A number of
suitable solvents has been proposed including halogenated aliphatic
compounds, organic and inorganic acids. For example, carbon
tetrachloride, chloroform, alkylene dihalides containing 2 to 4
carbon atoms such as ethylene-, propylene-, butylene-, isobutylene
dichlorides or dibromides, acetic acid and concentrated sulfuric
acid have been utilized. Oleum containing some free sulfur trioxide
proved to be a very good solvent. Evidently the aromatic compound
reacts first with the sulfuric acid to form the corresponding
monosulfonic acid and water. When bromine is introduced into the
solvent, it will react with the monosulfonic acid to form the
bromo-derivative and hydrobromic acid. But two undesirable
by-products are constantly produced, i.e. water and HBr. Because
the solvent medium contains free SO.sub.3 which is a strong
oxidizer the HBr is reoxidized to bromine with the additional
formation of water. At this rate it can be seen that the
concentration of the sulfuric acid is continuously decreased which
in turn will affect adversely the sulfonation reaction which
requires a strong acidic medium. It is for this reason that
sufficient amounts of sulfur trioxide are added to maintain the
sulfuric acid concentration at the proper level.
In the oleum process, the reaction temperatures employed will often
influence the sulfonation of aromatic compounds which already
contain substituents. This influence is observed in the ring
position of the introduced sulfo group. In this respect formation
of m-sulfonic acids is undesirable and it is necessary, therefore,
to control the reaction temperature in such a manner as to
eliminate the formation of these by-products which are very
difficult to brominate completely.
Use of solvents, other than oleum, in the preparation of brominated
derivatives of aromatic compounds has been somewhat limited because
of the bromination of the solvent itself. Unless the brominated
solvent is in itself desirable the process becomes expensive. In
the event the solvent cannot be brominated such as carbon
tetrachloride or other perchloro compounds, problems relating to
decomposition, solubility, recovery of solvent and separations of
finished products are encountered.
In order to produce completely brominated derivatives of aromatic
compounds in high yields processes different from the above were
necessarily indicated.
According to the present invention a process has been devised
whereby completely brominated derivatives of aromatic compounds are
prepared from the action of bromine solvent on the corresponding
aromatic compound, in the presence of a bromine-transfer catalyst.
Thus bromine is used herein as a reactant-solvent. At this juncture
mention should be made that the present invention is not concerned
with aromatic compounds having fused or condensed rings such as
naphthalene, anthracene and similarly related compounds. The
invention, however, is concerned with aromatic compounds having one
or more benzene ring, which may have substituents, such as benzene,
toluene, phenol, xylene, biphenyl, biphenylether, biphenyl sulfide,
and the like. Also it is to be understood that the starting
material may be partially brominated such as brominated benzenes
and biphenyls.
The particular advantages of the process of the present invention
are the absence of a solvent other than bromine, the relatively low
reaction temperatures, the high yields and the purity of the
brominated products. The bromination is carried out in the presence
of a bromination catalyst such as iron, aluminum, their halides,
iodine and mixtures thereof. The quantity of the catalyst depends
on the reactants used. For example it has been found that about 2.5
g of AlBr.sub.3 per 1 mole of benzene was needed to effect the
complete bromination to hexabromobenzene. Below about 2.5 g/mol,
only mono- and dibromobenzene could be obtained. It appears that
the amount of catalyst required depends greatly on the amount of
water present, because of the hydrolysis of AlBr.sub.3. Water,
therefore, should be kept at minimum levels.
As to the hydrogen bromide produced during the reaction, it is
easily removed in its gaseous state. As such the HBr may entrain
some of the reactants, usually bromine which can be trapped and
recycled to the reaction vessel.
Inasmuch as the present invention contemplates a process of general
application, it should be borne in mind that minor modifications
may be necessary depending on the starting material, equipment
availability and desired product quality. The bromination reaction
may generate a great deal of heat because of the exothermic nature
of the reaction. Thus the time needed to complete the bromination
of the aromatic compound may depend on the size of reaction vessel,
the efficiency of the cooling system along with the stirring and
mixing operation. Moreover the amount of catalyst used will also
influence the reaction time.
The fact that bromine operates as a solvent as well as a reactant
the amount thereof is expected to be in a good excess over
stoichiometric requirements. It has been found that an excess of
100% of bromine is satisfactory in that little or no
under-bromination results. Of course, if desired, greater excess
can be used. After the reaction is complete the excess bromine can
be easily separated from the finished product. It is believed that
most, if not all completely brominated derivatives of aromatic
compounds are insoluble in liquid bromine. The final mixture,
therefore, can be filtered under slight pressure. Alternatively the
bromine can be steam-stripped out of the reaction vessel with
little loss. Air can also be used for that purpose. With steam,
however, recovery of bromine was over 94%.
It is well known that to maintain a reasonable rate of reaction
requires a higher temperature as each additional bromine is
substituted. This is true in the oleum process which starts at
ambient or lower temperatures and as the bromination proceeds heat
is supplied until the reaction temperature reaches usually about
150.degree. C. The process of the present invention starts
similarly at ambient or lower temperatures at which stage the
bromination is rapid and exothermic. As the reaction subsides,
indicating that the hydrocarbon has at least been partially
brominated, heat is supplied to the reaction vessel until the
bromine starts to reflux. Refluxing is continued until slightly
after the reaction is completed. Completion of the reaction is
observed when the evolution of hydrogen bromide ceases. The
additional refluxing is precautionary so that no underbromination
occurs.
In order to illustrate some of the advantages of the instant
invention the following examples are provided and in which the
proportions are given in parts by weight unless specified
otherwise.
EXAMPLE I
Preparation of Hexabromobenzene
To a 300 ml three-necked flask equipped with a reflux condenser,
stirrer, a dropping funnel and a thermometer 425 g of liquid
bromine was added. 0.5 g of AlBr.sub.3 was also added to the
mixture which was agitated to allow the catalyst to dissolve in the
bromine completely. The bromine - AlBr.sub.3 mixture was then
cooled to about 15.degree. C. and maintained at that temperature
during the gradual addition of 15.6 g of benzene. The bromination
reaction is quite rapid and care should be taken so that not much
bromine and benzene are entrained with the evolving hydrogen
bromide. Thus the size of the reaction vessel and the efficiency of
the cooling and condenser system are important in this respect.
After the benzene was added, about one hour, the need for cooling
the reaction vessel was no longer necessary. In fact the mixture
was allowed to warm up slowly and afterwards heat was supplied to
bring the bromine to reflux to about 60.degree. C. The reflux was
maintained for an hour. Here the amount of catalyst added and the
stirring efficiency affect the length of the reflux period; more
catalyst and efficient stirring reduces the time of reflux
considerably. The excess bromine was removed by blowing superheated
steam (about 140.degree. C.) through the reaction vessel and
collecting the bromine in an outside vessel. Within a few minutes
only a thick slurry of hexabromobenzene remained which was
filtered, washed with hot dilute hydrochloric acid, filtered and
finally washed with hot water and dried at 75.degree. C. The yield
of the light tan crystalline product was 96.7% based on benzene.
Determination of bromine and IR spectrum showed the product to be
essentially hexabromobenzene, said product having a melting point
of 329.degree.-330.degree. C.
EXAMPLE II
Preparation of Pentabromotoluene
To a similar apparatus as described in Example I 471 g of liquid
bromine (151 mls) was added to the 300 ml flask. 2.0 g of
AlBr.sub.3 was also added and allowed to dissolve in the bromine.
0.2 moles of toluene (21.35 mls) was gradually added to the cooled
flask (about 10.degree.-15.degree. C.) making sure that sublimation
or rapid evolution of HBr was not such as to entrain too much of
the reactants. The addition of the toluene was carried out over one
hour after which the flask was allowed to warm up and later it was
heated until the bromine commenced to reflux (58.degree. C.) at
which temperature the reaction was continued until no further
evolution of HBr was observed (occasionally the temperature was
slightly increased to maintain continuous reflux).
The solid product was filtered after removing the bulk of bromine.
After washing with hot dlute HCl and hot water the product was
dried at 105.degree. C. Weight obtained was 93.5 g of slightly tan
crystals which on analytical examination showed to be
pentabromotoluene m.p. 286.degree.-287.degree. C.
EXAMPLE III
Preparation of Tetrabromo-p-xylene
To a similar apparatus as described in Example I, 220 g of Br.sub.2
was added and 1.0 g of AlBr.sub.3 was dissolved therein. To the
cold mixture 10.62 g of p-xylene was added very slowly over about
one hour. The mixture of bromine, catalyst and xylene was then
refluxed at about 60.degree. C. for about 2-3 hours until no HBr
was detected. The solid product was filtered, washed in the same
manner as described under Examples I and II. The slightly yellow
crystals weighed 39.6 g and analytical tests showed them to be
tetrabromo-p-xylene having a melting point of
247.degree.-249.degree. C. and a yield of about 94%.
EXAMPLE IV
Preparation of Pentabromophenol
a. From phenol
In this preparation 475 g of bromine in which 2 g of AlBr.sub.3 was
dissolved. 18.8 g of phenol was slowly added and later the mixture
was heated to about 60.degree. C. at which temperature the bromine
reflux was maintained for a period of 2 hours. HBr was observed to
evolve very rapidly in the early part of the reaction.
After removal of excess bromine the crystalline product was
filtered and washed as usual with hot dilute HCl and water
respectively. The dried product had a melting point of
225.degree.-227.degree. C. and based on analytical data it was
shown that the brominated derivative is pentabromophenol.
b. From anisole
To a similar apparatus as described in Example I 471 g of bromine
and 2 g of AlBr.sub.3 were added and allowed to dissolve. 21.6 g of
anisole was added slowly to the bromine-catalyst mixture. The
reaction was carried out in the same manner as described above.
However instead of obtaining brominated anisole, analytical data
showed the product to be pentabromphenol. It appears that the
bromination in this reaction cleaved the molecule at the oxygen
bridge forming the phenolic product.
EXAMPLE V
Preparation of Decabromobiphenyl
To a 500 ml three-neck flask equipped similarly to those used in
prior Examples, was added about 80 ml of bromine (250 g). The flask
was cooled to about 10.degree. C. 30.84 g of biphenyl was added in
very small amounts to the bromine. To another portion of bromine
(about 150 ml; total of two portions was 725 g) was added 10 g of
AlBr.sub.3 which was allowed to dissolve therein. After all the
biphenyl was added to the first portion then the second portion was
added. It should be understood that the addition of the bromine was
effected via the dropping funnel, since the biphenyl is solid. In
all the experiments the apparatus is equipped with a stirrer and/or
suitable means. The mixture was then allowed to warm up and later
heated to 60.degree. C. at which temperature the refluxing of
bromine was observed. Bromine reflux was continued for about 4
hours and the solid tan colored crystals were collected, washed
with hot dilute HCl and water, respectively. Analysis showed that
the product contained 84.77% bromine and had a melting point of
385.degree.-389.degree. C. with a yield of 95%.
EXAMPLE VI
Preparation of Decabromobiphenyl ether
To an apparatus similar to the one used in Example V 34.05 g of
biphenylether and a total of 782 g of bromine (added in two
portions, the second containing 5 g of AlBr.sub.3) were reacted in
the same manner described in Example V above. The reaction is quite
rapid and slow addition was necessary. The mixture was allowed to
warm after the evolution of HBr slowed down. Heat was applied to
the mixture until the bromine started to reflux. The solid-liquid
bromine mixture was treated as described in the prior Examples to
separate the brominated derivative. The final product obtained was
yellowish in color. Analysis showed the product to be
decabromobiphenylether containing bromine to the extent of 83.42%
and oxygen=1.79%. The yield was also over 90% of theoretical based
on biphenylether.
EXAMPLE VII
Preparation of Decabromobiphenylsulfide
In an identical apparatus as used in Example VI 37.6 g of
biphenylsulfide was placed in the 300 ml three-neck flask. 780 g of
bromine in two portions were added; the second portion containing 5
g of AlBr.sub.3. Prior to the addition of the second portion the
mixture was kept cool at about 10.degree. C. Very strong evolution
of HBr was observed. The second portion was added after the
reaction subsided. The entire mixture was then refluxed for a
period of about 4 hours. Additional 150 g of bromine was added. The
final brominated product was filtered off after the evolution of
HBr ceased. Bromine was removed by steam as described in Example I.
The product was washed with hot dilute HCl and water several times
and was later dried at 60.degree. C. The grayish color crystals
weighed 198.3 g and were analyzed to be decabromobiphenylsulfide;
bromine content was 83.23%, S=2.65% O=negligible.
At this juncture mention should be made that other catalysts have
been used in experiments comparable to those described in Examples
I-VII. These catalysts were aluminum metal, aluminum chloride, iron
metal, ferric chloride and iodine. Of course some adjustments were
necessary such as increasing the amount of liquid bromine and/or
insuring that the final product was free of the chlorides or
iodides. It is also important to relate that the brominating
process of the present invention is not directed to aromatic
compounds having fused or condensed rings such as naphthalene,
anthracene and the like.
The effect of halogens and/or halogen-containing compounds on
retarding and extinguishing fires is well known. Many chlorinated
and brominated organic compounds have been incorporated or added to
many polymeric systems for fire retardation purposes. Selection of
the particular halogenated compound (s) for use with certain
polymeric systems is not easy but, indeed, the result of
considerable research efforts. In the case of fire retarding agents
of the additive type it is significant that the agent satisfies the
requirements of being (a) compatible with the polymeric system (b)
not migratory, and (c) of comparable thermal stability. To be
compatible specifies that the fire retarding agent can be blended
with the polymer without affecting its mechanical and chemical
properties. Further, it should not be of such a nature as to cause
the migration of its particles toward the surface of the polymer.
Finally it is important that the fire retarding agent has a
decomposition range similar to the polymer itself. For the last
mentioned property, it should be noted that should the fire
retarding agent decompose or break-down prior to the decomposition
of the polymeric system then it will afford little, if any, fire
retardation. In the same manner should the fire retarding agent
commence to decompose after the break-down of the polymer, the time
lag or delay may be such that the fire retarding agent will be of
no value. Thus it is an ideal property to provide a fire retarding
agent possessing identical decomposition properties as the polymer.
In practice one usually finds that the decompositions of the two
materials, i.e., the polymer and the fire retarding agent are
closely related.
In view of the above it becomes apparent that the selection of a
suitable fire retarding agent is not arbitrary, especially in the
case of high melting polymers or those requiring hot temperature
processes for their manufacture such as polyamide (nylon) or linear
polyester, respectively.
Completely brominated derivatives of biphenyl compounds such as
decabromobiphenyl, decabromobiphenyl ether and decabromobiphenyl
sulfide have been found to possess excellent fire retarding
characteristics. Tests of these compounds on polyamide and
polyester have given excellent results as will be shown
hereinafter. The fire retardancy of the polymers was determined by
the Oxygen Index Method which is now recognized for use on plastic
materials by the American Society for Testing and Materials (ASTM)
of 1916 Race Street, Philadelphia, Penn. 19103, and said test has
been given the designation D 2863-70 (See Annual Book of ASTM
Standards -- effective May 8, 1970). The Oxygen Index, also known
as the Limiting Oxygen Index (L.O.I.) is defined as the minimum
volume-fraction of oxygen in an atmosphere of oxygen and nitrogen,
which is needed to sustain the candle-like burning of a polymeric
specimen. For further explanation and theoretical discussion,
reference is made to a paper by J. DiPietro and H. Stepniczka
presented at the Society of Plastic Engineers Conference, New York,
N.Y., May 6, 1970, and published in Plastic Engineer Society, Inc.,
Volume XVI, pp. 463-468.
The Oxygen Index (O.I.) for air is 0.209. The higher the value the
less likely it is for the polymeric system to burn or sustain
burning. In fact it is known that polymer systems having O.I.
values about 0.27-0.28 can be considered self-extinguishing in
nature.
In Table I below there are provided data on the fire retardancy of
both nylon and linear polyester, said data being expressed in terms
of the Oxygen Index. Synergists such as antimony trioxide can be
added to enhance the fire retardancy.
TABLE I ______________________________________ Fire Retarding Agent
and Sb.sub.2 O.sub.3 Oxygen Polymer Percent % Index
______________________________________ Nylon 0 0 0.202 Nylon
DBBPS.sup.(a), 6.1 0 0.214 Nylon DBBPS.sup.(a), 12.2 0 0.229 Nylon
DBBPS.sup.(a), 18.3 0 0.239 Nylon DBBPS.sup.(a), 24.4 0 0.250 Nylon
DBBPS.sup.(a), 6.1 1.2 0.221 Nylon DBBPS.sup.(a), 12.2 2.4 0.251
Nylon DBBPS.sup.(a), 18.3 3.6 0.280 Nylon DBBPS.sup.(a), 24.4 4.8
0.303 Polyester (Dacron)* 0 0 0.212 Polyester (Dacron)*
DBBP.sup.(b), 5.0 0 0.259 Polyester (Dacron)* DBBP.sup.(b), 10.0 0
0.293 Polyester (Dacron)* DBBP.sup.(b), 20.0 0 0.372 Polyester
(Dacron)* DBBP.sup.(b), 10.0 2.0 0.385
______________________________________ *Trade-Mark of E. I. DuPont
De Nemours & Co., Inc. .sup.(a) Decarbromobiphenylsulfide
.sup.(b) Decarbromobiphenyl
It is to be understood that the foregoing detailed description is
merely given by way of illustration and that other variations may
be made therein without departing from the scope of the invention
as defined by the following claims.
* * * * *