Note: Descriptions are shown in the official language in which they were submitted.
10~3490
Back~round of the Invention
Much effort has been expended in discovering and developing useful
fire retardant polymer composition systems, and numerous examples of fire
retardant polymers have appeared in the literature and some of them are in
commercial use. But, the fire retardant re~uirements for polymeric materials
have become evermore stringent as technology has become more sophisticated.
Thus, whereas low burn~ng rates were once the sole ob~ective of research for
; fire retardant polymers, now low smoke generation and char formation charac-
teristics are also significant.
Concurrently, there has been a desire on the part of plastics
fabricators to retain the other beneficial qualities of the base polymer
while enhancing the fire retardant properties. But heretofore, efforts to
impart fire retardancy to polymer systems has resulted in diminishing the
other useful properties. Thus, normally translucent polyester resins have
15 been rendered opaque by the incorporation of sufficient qùantities of
antimony trioxide to render the polyester resins sufficiently fire retardant
for certain uses.
Accordingly, it is an ohject of this invention to provide superior
fire retardant unsaturated polyester resins that not only have low burning ;
rates, but also exhibit low smoke generation when in contact with a flame.
It is also an object of the invent~on to provide superior fire
retardant polyester resins that develop a benef~cial, insulating layer of
char in the presence of a flame which inhibits further combustion of the
polymer
It is still another ob~ect of the invention to render unsaturated
~ polyester resins fire retardant without diminishing or deteriorating other
-* useful properties of the polymer system.
These and other objects are accomplished by this invention which -
is described in detail hereinafter. -
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104;~490
Summary of the Invention
The superior fire retardant pol~Y~er compositions of the invention
comprise an ~ ethylenically unsaturated polyester of a polycarboxylic
compound and a pol~Yhydric alcohol which contains a halogen in a proportion
of greater than ahout 4 weight percent, and an effective fire retardant
proportion up to about 5 weight percent of iron or an iron compound,
wherein the foregoing proportions are based on the weight of the unsaturated
polyester and a copolymerizable unsaturated monomer.
The preferred halogen contain~ng polyesters of the invention are
those wherein the halogen is provided by a Diels Alder adduct of a
hexahalocyclopentadiene and a polycarboxylic com~ound or polyhydric
alcohol containing aliphatic carbon-to-carbon unsaturation. The preferred
adducts are chlorendic acid or chlorendic anhydride.
Various iron compounds can be employed in the compositions of the
` 15 invention depend~ng on the end results desired. Thus, where it is desired
j to retain the translucent character of the unsaturated polyester colorless
iron salts can be employed, or ~ron salts that permit the transmission of
light when incor~orated in the polyester resin system can be used. The
various iron oxides and other iron salts, including various organic
iron compounds can be employed.
The unsaturated polyester resin containing the iron compound
of the invention is copolymerized with an ethylenically unsaturated
monomer, optionally in the presence of a reinforcing agent or filler,
to provide the ff nal polyrerized product.
Description of Embodiments
' The Polyesters
T~e unsaturated polyesters useful in the invention are
generally those commonly known in the art, and are generally the
reaction product of a polycarboxylic compound and a polyhydric alcohol.
By polycarboxylic compounds is meant the polycarboxylic acids, polycarboxylic
,,
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104;~4~0
anhydrides, polycarboxylic acid halides, and polycarboxylic acid
esters. The unsaturation can be provided in either or both the polycarboxylic
compound or the polyhydric alcohol. Suitable unsaturated polycarboxylic acids
having aliphatic carbon-to-carbon double bonds, and the corresponding
acid halides, esters, and anhydrides can include maleic, fumaric, chloro-
maleic, ethylmaleic, itaconic, citraconic, zeronic, pyrocinchoninic,
mesaconic, aconitic and acetylene dicarboxylic, either alone or in mixtures.
Illustrative of the unsaturated polyhydric alcohols having
aliphatic carbon-to-carbon double bonds, which can be used in providing
the unsaturation in the linear polyester molecules are compounds such
as butene diol, pentene diol, the unsaturated hydroxy ethers such as
allyl or vinyl glycerol ethers, allyl or vinyl pentaerythritol ethers
and the like.
The saturated polycarboxylic compounds useful in the prepara-
tion of the polyesters can be aliphatic, cycloaliphatic, aromatic or
heterocyclic. Illustrative of these polycarboxylic acids, acid halides,
.: .
acid anhydrides and acid esters include phthalic, isophthalic, terephthalic,
tetrachlorophthalic, tetrabromophthalic, dibromotetrahydrophthalic,
chlorendic, adipic, succinic, dichlorosuccinic, and mixtures thereof.
Suitable saturated polyhydric alcohols for use in the preparation
of the polyester resins include ethylene glycol, diethylene glycol,
propylene glycol, dipropylene glycol, butane diol, pentane diol, hexane
diol, dibromoneopentyl glycol, 1,4-cyclohexane dimethanol, glycerol,
mannitol, sorbitol, bisphenols, substituted bisphenols, hydrogenated
bisphenols and mixtures thereof.
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1043~90
The properties of the polyester resins can be modified by the
incorporation of suitable monofunctional carboxylic compounds and alcohols.
Illustrative examples of such compounds are 2,2-dichloroethanol; 1,1-
dibromo-2-propanol; 2,2,2-tribromoethanol; 1,1,3,3-tetrabromo-2-propanol;
1,1,1-trifluoro-2-propanol and 2,3-dibromo-1-propanol. An example of a
carboxylic compound is pentachlorophenoxy acetic acid.
The properties of the polyesters can be varied by using mixtures
of the ~ar~ous types of acids and alcohols, such as an unsaturated acid,
a saturated acid and a saturated alcohol.
The preferred unsaturated polyesters of the ~nvention contain
etther an adduct of hexahalocyclopentadiene and a polycarboxylic compound
containing aliphatic carbon-to-carbon unsaturation or an adduct of hexa-
halocyclopentadiene and a polyhydric alcohol containing al~phatic carbon-
to-carbon unsaturation. The preferred unsaturated polyesters are the
reaction products of a polycarboxylic adduct of hexahalocyclopentadiene,
i another carboxylic compound containing carbon-to-carbon unsaturation and
a polyhydric alcohol. Such a product is disclosed and claimed in U.S.
Patent 2,779,7nl, issued January 29, 1957. Other methods for incorporating
either a polycarboxylic or polyhydric alcohol adduct of hexahalocyclo-
pentadiene include: tl) the reaction of a polycarboxylic adduct of hexa-
halocyclopentadiene, an unsaturated polyhydric alcohol containing aliphatic
carbon-to-carbon unsaturation, disclosed and claimed in U.S. Patent 2,863,794,
issued December 9, 1958; (2) the reaction of a polyhydric alcohol adduct
of hexahalocyclopentadiene with a polycarboxylic compound containing
aliphat~c carbon-to-carbon unsaturation disclosed and claimed in U.S. Patent
2,779.700, issucd January 29, 1957; and (3) the reaction of a polyhydric
alcohol adduct of hexahalocyclopentadiene with another alcohol containing
aliphatic carbon-to-carbon unsaturation and a polycarboxylic acid, disclosed
~ 5
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lV43~90
and claimed in U.S. Patent 2,863,795, issued December 9, 1958. An alternate
method for incorporating an adduct of hexahalocyclopentadiene into a
polyester resin involves reacting an unsaturated polyester resin with a
copolymerizable compound containing an adduct of hexahalocyclopentadiene,
such as disclosed and claimed in U.S. Patent 2,783,215, issued February 26,
1957. The polyester resins containing the polycarboxylic and polyhydric
alcohol adducts of hexahalocyclopentadiene can be modified by incorporating
therein saturated carboxylic acids and anhydrides, as disclosed and claimed
in U.S. Patent 2,8~0,144, issued ~une 9, 1959, and U.S. Patent 2,898,256,
issued August 4, 1959. When used in this specification, the tenm poly-
carboxylic compound refers to the polycarboxylic acids, acid anhydrides,
acid halides and acid esters, of either the aliphatic or aromatic type.
Among the adducts of hexahalocyclopentadiene and polycarboxylic
compounds which may be used are: 1,4,5,6,7,7-hexachlorobicyclo-(2.2.1)-5-heptene-
2,3-dicarboxylic acid and anhydride, also known as chlorendic acid and
anhydride; 1,4,5,6,7,7-hexabromobicyclo-(2.2.1)-5-heptene-2,3-dicarboxylic
. acid; 1,4,5,6,7,7-hexachloro-2-methylbicyclo-(2.2.1)-5-heptene-
2,3-dicarboxylic anhydride; 1,4,5,6,7-tetrachloro-7,7-difluorobicyclo-
(2.2.1)-S-heptene-2,3-dicarboxylic acid; 1,4,5,6,7,7-hexachlorobicyclo-
(2.2.1)-5-heptene-2-acetic-2-carboxylic anhydride; 5,6,7,8,9,~-
` hexachloro-1,2,3,4,4a,5,8,8a-octahydro-5,8-methano-2,3-naphthalene -
dicarboxylic acid and anhydride; 1,2,3,4,5,6,7,7-octachloro-3,6-
methano-1,2,3,6-tetra-hydrophthalic acid and anhydride; 2,3-dicarboxy-
.~ .. .. .
5,8-endomethylene-5,6,7,8,9,9-hexachloro-1,2,3~4,4a,5,8,8a-octahydronaphthalene
~' 25 anhydride; 2,3-bis(ethylene carboxy~-1,4,5,6,7,7-hexachlorobicyclo(2.2.1)
S-heptene; and 1,4,5,6,7,7-hexachlorobicyclo-(2.2.1)-5-heptene-
2,3-dicarbonyl chloride. --
Among the adducts of hexahalocyclopentadiene and polyhydric
alcohots which may be used are: 1,4,5,6,7,7-hexachloro-2,3-bis-
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1043490
hydroxymethylbicyclo-(2.2.1)-5-heptene; 1,4,5,6,7,7-hexachloro-
2,3-bis-hydroxymethylbicyclo-(2.2.1)-2,5-heptad~ene; 3-(1,4,5,6,7,7-
hexachlorobicyclo-(2.2.1)-5-heptene-2-yl)-methoxy-1,2-propaned101;
1,4,5,6-tetrachloro-7,7-difluoro-2,3-bis-hydroxymethylb~cyclo-(2.2.1)-
5-heptene; 1,4,5,6,7,7-hexabromo-2,3-b~s-hydroxy-methylbicyclo-
(2.2.1)-5-heptene; 3-(1,4,5,6-tetrachloro-7,7-difluorobicyclo-(2.2.1)-
5-heptene-2-yl)-methoxy-1,2-propane diol. These compounds and methods
of preparat~on are disclosed ~n U.S. Patent No. 3,007,958, ~ssued
November 7, 1961.
It is also w~thin the scope of the invention to use other halogen-
conta~ning polyesters such as those der~ved from tetrachlorophthalic acid or
anhydride. and tetrabromophthalic acid or anhydrlde.
The halogen can be provided in the polyesters of the invention
by a combination of the foregoing methods. Thus, an unsaturated polyester
can be prepared using a halogenated dibasic acid such as chlorendic acid,
and a monobromlnated alcohol such as dibromopropanol.
The polycarboxylic compounds and polyhydric alcohols requ~red
~; in the production of the foregoing halogen-containing adducts and polyesters ~-
can be provided by using any of the compounds disclosed hereinbefore.
The temperature for the reaction between polyhydric alcohols
and polybasic acids ranges from about one hundred to two hundred degrees
centigrade, although higher or lower temperatures can be used. Esterifica-
tion catalysts such as para-toluene sulfonic ac~d, benzene sulfonic acid,
beta-naphthalene sulfonic acid and the like, or amines such as pyridine,
tr1ethyl amine, quinollne and the like can be added to the reaction mixture.
The proportion of polyhydric alcohol is approximately controlled by the
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1043490
total mole proportion of acids in the ester~fication reaction mixture. It
is also preferred to react the polyhydr~c alcohols and polybas~c ac~ds ~n
rou~hly equ~molar proport~on; however, e~ther the ac~ds or alcohols can
be used ~n substant~al excess, if ~t is des~red to form a low molecular
we~ght polyester res~n.
Unsaturated Monomers
A var~ety of ethylen~cally unsaturated monomers can be used for
cur~ng or cross-l~nklng the ethylen~cally unsaturated polyesters. It ~s
generally preferred that add~t~on polymer~zation be pract~ced s~nce no
by-product ammonla or water ~s fonmed, and the problems result~ng therefrom ;i
are not exper~enced. The v~nyt~dene monomers useful ~n cur~ng the thermo-
plast~c unsaturated polymers include v~nyllc compounds or m~xtures thereof
capable of cross-l~nk~ng ethylen~cally unsaturated polymer cha~ns at the~r
po~nts of unsaturat10n. Usually they contain the reactive groups H2C=C< .
Speclf~c examples include styrene, chlorostyrenes, methyl styrenes such
as alpha methyl styrene, p-methyl styrene, vinyl benzyl chlor~de, d~vinyl
benzene, ~ndene, unsaturated esters such as: methyl methacrylate, methyl
acrylate and other lower al~phat~c esters of acrylic and methacrylic
ac~ds, allyl acetate, d~allyl phthalate, diallyl succ~nate, d~allyl adipate, -
d~allyl sebacate, d~ethylene glycol b~s(allyl carbonate), trlallyl phosphate -
and other allyl esters, and v~nyl toluene, d~allyl chlorendate, d~allyl tetra-
chlorophthalate, ethylene glycol d~acrylate, ethylene glycol d~methacrylate,
ethylene glycol d~ethacrylate, and mtxtures thereof. The monomer may be ;
~ ddm~xed ~n the polymer ~n an amount suff~c~ent to produce a thermoset
25 polymer and the adm~xture heated to an elevated temperature in the presence
` of a su~table catalyst to cross-l~nk or cure the polymer. With proper
catalyst systems such as cobalt naphthenate and methylethyl ketone perox~de,
room temperature cures are obta~ned.
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lV43490
The cross-linking agent can be advantageously co~bined with the
poly~erizable polyester while the unsaturated polyester and the olefinic
cross-linking agent are at an elevated temperature thereby facilitating
solution and mixing. To prevent premature polymerization at this stage,
a polymerization inhibitor is advantageously added to the mixture, or
preferably to one of its components prior to mixing, especially if the
mixture is to be stored or shipped in commerce prior to curing. Alterna-
tively, or in addition to including a polymerization inhib~tor, a catalyst
and/or promoter for the copolymerization may be added, particularly if it
~s desired to make available in commerce a composition which is ready for
polymeri2ation and does not require further chemical additions in order
to be used, as ls commonly known in the art.
The polymerization inhibitors generally are added in the order
of 0.001 to 1 weight percent of the mixture. Among the inhibitors which
may advantageously be employed to prevent the premature polymerization of
the mixture of polymerizable polyester and olefinic cross-linking agents,
particularly if the mixture is to be stored or shipped in commerce prior
to curing, are substances such as hydroquinone, benzoquinone, para-
- tertiarybutyl catechol, para-phenylene diamine, trinitrobenzene, picric
acid, and the like. ~ -
~ The proportion of olefinic cross-link~ng agent to unsaturated
~~ polyester can be varied within the ultimate limits of each without departing
from the scope of the invention, necessary to produce an infusible,
~ lnsoluble, polyester resin. In general, the concentration of the unsatu-
; 25 rated polyester in the olefinlc cross-linking agent can vary between
3 about ten and nlnety percent. Polymerization catalysts are preferably
; added to the mixture of unsaturated polyester and olefinic cross-linking
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1043490
agent to effect setting or curing. Catalysts such as benzoyl peroxide,
acetyl peroxide, lauryl peroxide, methylethyl ketone peroxide, cumene
hydroperoxide and the like are satisfactory. Such catalysts are used in
proportions of 0.01 to ten percent of the total resin, depending on the
efficiency of their action and whether or not substances which inhibit
polymerization are present in the mixture. The polymerizatlon reaction
can also be hastened by adding promoters such as metals or metal salts,
cobalt resinates, cobalt maleate, cobalt naphthenate and the like, or
amines such as dibutylamine, or mercaptans such as dodecyl mercaptan.
These are used in proportions similar or smaller to that stated for the
catalysts.
The Iron Compounds
In the preparation of translucent polyester laminates and other
products of the invention, iron salts that permit the transmission of
-~ 15 11ght when incorporated in the cured polyester are employed. Sultable
iron salts are the colorless iron salts such as ferric sulfate hydrates.
Other suitable salts which permit light transmission in the cured polyester
include ferrous hydroxide, ferrous sulfate, ferrous tartrate, ferrous
stannate, ferrous chloride, ferrous ammonium sulfate, and the like.
Other substantially insoluble iron compounds that can be used
in accordance with the invention include ferric acetate, ferric formate,
ferric borate, ferric tungstate, ferric Yanadate, ferric molybdate, fer- ;
rous tungstate, ferric oxalate, ferric ferrocyanide, ferr~c chlorendate,
and ferric hexachloronorbornene carboxylate.
Also useful in the compositions of the invention are the lron
oxides, such as Fe2n3 (yellow and red iron oxide), Fe304 and FeO.
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1043490
The iron com~ound~ named hereinabove are suhstantially insoluble
in the polyester when admixed with a copolymerizable unsaturated monomer.
Also useful are iron compounds that are soluble in the admixture of poly-
ester and copolymerizable unsaturated monomer, but which are free of
S iron-to-carbon bonds.
Useful soluble iron compounds include the metal or metalloxy
beta-ketoenolates of the formula:
1 C- O
R2 1 ~ M
R3 - C o / n
; ~n which M is an iron ion, an ironoxy ion, or an iron hydroxy ion, in
which n is an integer equal to the valence of the iron, ironoxy ~on
or iron hydroxy ion, in wh~ch each of Rl and R3 is a substituent selected
from the group consisting of hydrogen and an or~anic substituent selected
from alkyl, aryl, cycloalkyl, aralkyl, alkaryl, alkoxy, and aryloxy
having one to eight carbon atoms and wherein each aryl substituent is
carbocycl~c, and in which R2 is selected from the group consisting of
Rl, R3, halogen, nitro, and sulfo. Typical beta-ketoenolates are the
ferrous or ferric acetylacetonates.
Other soluble iron compounds include the iron carboxylates,
particularly der~vatives of carboxylic acids for example of about 3
to 22 carbon atoms. Illustrative iron carboxylates are iron acrylate,
iron oleate, iron naphthenate, iron stearate, iron laurate, iron linoleate,
and the like.
~, 25 Other iron compounds which have desirable fire retardant proper-
ties but which adversely affect the stability or the cure of the polymer
compositions can be employed if such iron compounds are used in an inactive
.
form such as encapsulated or reacted or complexed with another compound. Such
iron compounds are ferric chloride and ferric oxychloride. These compounds -
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lV4~90
can be encapsulated Wit~l qelatin or other polymeric materials. Alterna-
tively, the compounds can be reacted or complexed with nitro compounds or
aromatic ethers or amines. ~n example of a suitable co~pound is an amine
salt of ferric chloride.
The metallic iron and insoluble iron compounds are incorporated
into the polyesters in ftnely divided form. Preferred are particles passing
through a 200 mesh standard sieve. Where translucent plastics are desired,
the particu~ate iron or iron compounds should not contain a sufficient
quantity of fine particles around the wave length of light, i.e., about
0.1 to 1 micron, to cause undesirable light scattering and resultant
decrease in translucence. In practice, it has been observ~d that iron
compounds pulverized to pass completely through a 325 mesh screen contain -
sufficient fine particles to reduce translucency of the polyester.
The iron or iron compounds are ~enerally incorporated in the
, ~ ~ .....
lS compositions of the invention in a proportion up to about 5 weight percent
of iron or iron compound based on the weight of the unsaturated polyester
` and the copolymerizahle unsaturated monomer. Preferably, the proportion -
~, of iron or iron compound is in the ran~e of about 0.5 to about 2 weight percent
of iron or iron compound based on the weight of unsaturated polyester resins
and monomer.
The unsaturated polyester resins of the invention generally contain
greater than ahout 4 weight percent up to about 40 weight percent of
halogen based on the weight of the unsaturated polyester resin and the
copolymerizable unsaturated monomer. The proportion of halogen is
preferably greater than 15 weight percent when the halogen is chlorine.
For best results, the compositions of the invention are phos- -
, phorus-free, i.e., exclude phosphorus and compounds of phosphorus.
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1(~43490
Phosphorus tends to neutralize the synergistic effect of the iron on the
halogen moiety. The compositions of the invention also exclude ferrocene
and related compounds that have iron-to-carbon bonds. The compositions
of the invention prnvide very effective fire retardance without the need
for antimony trioxide which is so often used in commercial formulations
to achieve low burning rates. The exclusion of antimony trioxide is
especiall,y preferred when it is desired to retain the translucent character
of the polyester resins of the invention. The iron compounds and halogen
component of the polyester can be the sole fire retardant agents present
in the compositions of the invention.
The Curinq Process i ;
The polymeri2ation conditions for effecting the cross-linking
reaction between the unsaturated polyesters of this invention and the
; olefinic cross-linking agent may be selected from a wide variety of
' lS techniques but usually involve the application of heat or light. Although
pressure is not a required condition for effecting polymerization of the
polymerizahle mixtures embraced within this invention, it is sometimes
advantageousl~y employed, particularly when it is desired to make laminates
in preformed shape. The pressures found satisfactory for this purpose
are relatively low compared to those required for molding or laminating
other type resins than involved herein and may be of the order of that
obtained by pressing glass plates having a fiber glass mat or laminate
impregnated with the polyester resin sandwiched therebetween.
The temperature at which polymerization is effected depends on
; 25 a variety of factors, particularly the boiling point of the olefinic
cross-linking agent and the exothermic characteristics of the polymer- -
ization mixture. A temperature is selected which will give a suitable
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1(~434~0
reaction rate and yet not cause substantial volatilization, and in the
case of producing very thic~ castings, which will not produce a product
which is crack-crazed.
The properties of the compositions of this invention can be
varied substantially by incorporating modifying agents before, during
or after any of the processing steps employed. For example, instead
of producing articles of commerce from the compositions of this invention
which are in the form of castings or laminates as previously described
herein, a fnamed type article may be made by incorporating a small ~ -
percentage of a foaming agent such as sodium bicarbonate into the solu-
tion of unsaturated polyester dissolved in mono-olefin and thereafter
effecting the copolymerization in the presence of catalyst and heat to
produce the foamed article. Formulations which are useful for making
moldings embodying the compositions of this invention may be made by mixing
into the unsaturated linear polyester and olefinic cross-linking agent
mixture, an inert filler such as chopped fiber glass rovings, macerated
fabric, asbestos fibers, mica, etc., which serve as fibrous reinforcing
media and incorporating a small percentage of a mold lubricant, catalyst
and/or promoter. Auxiliary fire retardant additives such as hydrated alumina
can be used to add to the fire retardance provided by the halogen and iron.
It is to be understood that dyes, pigments, plasticizers,
lubricants and various other modifying agents are contemplated as being
incorporated in certain formulations to produce compositions embraced in - ;
` this Invention in order to obtain or accentuate any given property.
The following examples are presented to illustrate this inven-
tion. It is to be understood that the examples are not to be construed
, as limit1ng the invention. In this specification and claims, all tempera- - `~
tures are in degrees centigrade and all parts are by weight, unless other-
wise indicated. `
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1043490
E~ f~ Pol~esters
Example 1 (Resin I)
An unpolymerized li~uid unsaturated polyester resin was prepared
by esterifying about 53 parts of ethylene glycol and 90 parts of diethylene
glycol with about 395 parts of 1,4,5,6,7,7-hexachlorobicyclo-(2.2.1)-5-
heptene-2,3-dicarhoxylic anhydride and about 71 parts of maleic anhydride.
About 3n parts of styrene and ahout 70 parts of product produced by the
esterification reaction were mixed togetller until complete solution was
obtained to give a clear, suhstantially colorless solution of liquid polyester
resin having a viscosity of about 30 poises at 25 degrees centigrade on a
Gardner bubble viscometer and hav~ng a chlorine content of about 30 percent
by weight of the total.
Example ? (Resin II )
An unpolymerized liquid unsaturated polyester resin was prepared
by esterifying about 76 parts of propylene glycol with about 128 parts of
1,4,5,6,7,7-hexachlorobicyclo-(2.2.1)-5-heptene-2,3-dicarboxylic acid and
~,.
about 66 parts of maleic anhydrlde. About 45 parts of styrene and about
55 parts of product produced by the esterification reaction were mixed
together until comp1ete solution was obtained to give a clear, substantially
colorless solution of liquid polyester resin having a viscosity of about
19 poises at 25 de~rees centigrade on a Gardner bubble viscometer and
having a chlorine content of about 19 percent by weight of the total.
Example 3 (Resin III)
An unpolymerized liquid unsaturated polyester resin was prepared
by esterifying about 250 parts of propylene glycol with about 245 parts of
fumaric acid and about 304 parts of tetrachlorophthalic anhydride. About
-15- ~ :
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1043490
28n ~arts of styrene were mixed with the esterification product until com-
plete solution was obtained to ~ive a clear substantially colorless solution
of liquid polyester having a viscosity of about 20 poises at about 25
degrees centi~rade on a Gardner bubble viscometer and having a chlor1ne
content of about 15 percent.
Example 4 (Resin IV)
An unpolymerized liquid unsaturated polyester resin was prepared
by esterifying about 20 parts of diethylene ~lycol and about 140 parts of
ethylene glycol with 11~ parts of maleic anhydride, 56 parts of phthalic
ln anhydride, 38n parts of tetrabromophthalic anhydride and 3 parts of sodium
acetate. About 275 parts of styrene and 0.1 part of hydroquinone were
mixed with polyester until complete solution was obtained to give a clear,
substantially colorless solution of liquid polyester having a viscosity of
about 10 poises at 25 degrees centigrade on a Gardner buhble viscometer
and having a bromine content of about 25 percent.
Example 5 (Resin V)
A mixture of 194.5 parts (0.5 mole) of chlorendic acid, 98.1
parts (1.0 mole) of maleic anhydride, 217.9 parts (1.0 mole) of 1,2- ~ -
dibromopropanol and 24.~ parts (0.40 mole) of ethylene glycol and 36.8
parts (0.40 mole) glycerol were heated, under a steady nitrogen sparge, to
and maintained at about 165 degrees, while collecting the water formed as a
. , .
distillate. After about 12 hours, the acid number of the reaction mixture
had decreased to 46. A small quantity, about 0.10 part, of tolylhydro-
quinone was added to the mixture and the reaction was continued for an
. 25 additional fnur hours at which time the acid number was about 34. The
resultant polyester product was analyzed and found to contain 26.0 percent
~ bromine, 2n.0 percent chlorine and the average molecular weight of the
- polymer chains was 1150. An amount of styrene equivalent to about one - ~ -
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16)43490
third the wei~ht of the ~olyester mass was added to the hot mass and the
resultant solution was cooled to ambient temperature. The viscosity (Brook-
field) of the solution was 1620 cps at 25 degrees.
Exam~les_6 to 10
Tahles I through V below show the results of fire retardance tests
by the ASTM D-757-65 test method on castings of the resin prepared as de-
scribed in Examp1es 1 to 5, (Res~ns I to V, respectively). The cast~ngs
were prepared by mlxing lnO parts by weight of resin with iron compound in
the amount indicated in the tables, 0.2 part of 12 percent cobalt octoate,
and such other addit~ves as are indicated in the tables. After at least
`~ 10 minutes' stirring to assure unlform dispersion of the ~mm~scible materials,
the catalyst, methyl ethyl ketone peroxide (60X in dimethyl phthalate),
1 part was added, stirred for 1 to 2 minutes, and then the mixture was
allowed to cure at 25 degrees centigrade for 16 hours and at 65 deqrees
centigrade for 8 hours. The castings were then removed from the mold, cut
into specimen bars for testing by ASTM D-757-65 test method, for smoke by
ASTM D-2843-70, and for heat deflection temperature (identlfied in the -
tables as "HDT"), by ASTM D-648-72 test method. Data on light absorption ~ ~ -
due to smoke obscuration was acquired by a computer wh~ch printed out the -
li~ht absorption and percent smoke at one second intervals. The "Smoke
Density Rating" of this modification of the ASTM test is the percent smoke
at 60 seconds. Samples wh k h were used for the ASTM D-648-72 test measured
0.5 inch x 0.5 inch x 0.125 inch.
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In the testing of synergism with Resin V, it was seen in Table V
that the D-757 test was insufficient in differentiating synergistic effects
of iron and antimony compounds. The samples that contained levels of
l percent or more of fire retardant additives did not ignite, so the
"burning rate" which was variable and poorly reproduc~ble, was really a
"charrin~ rate". It is often preferable in fire retardant plastics to
ohtain a rap~d charring material (that can insulate against the heat source)
rather than a slow-charring material. (See for instance, "Flammabil~ty of
Plast~cs III," Learmonth and Thwaite, Br~tish Polymer Journal, 2, 104,
(1970).
Resin Y materials were therefore evaluated by another method
than the ASTM D-757 Test. Samples of material were heated at lO degrees
centigrade per minute while the weight loss of the samples was observed
cont1nuously by the thenmogravimetric analysis technique. Results are
shown in Table VI. At low rates of heating to 600 degrees centigrade,
it was observed that there was little change in weight loss after the
~, samples had reached 400 degrees centigrade. It was observed that Resin V
lost weight more rapidly than Resin I which is consistant with the lower
!' Time to Flameout of Resin V. With l percent iron oxide added to Resin V,
it was observed that weight loss occurred much more rapidly and that a
30 percent weight loss had already occurred at 264 degrees as compared
to a comparable we~ght loss at 308 degrees for Res~n V without additive
' or with antimony ox~de. The addition of iron oxide also catalyzed the ~formation of a large char residue (47X) which made less material available -
for gaseous fuel and less material available for smoke formation. From ~ --
these data it is concluded that under flaming conditions where Resin V
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is ex~osed to conditions of extremely rapid temperature rise, neither
the addition of iron compounds nor antimony compounds will improve the
fire retardant and low smoke properties much; but in oven-like conditions
where the temperature rise to the flaming condition is slower, the Resin
S V compositions that contain a synergistic amount of iron compound willgive improved fire retardance and low smoke properties.
TABLE VI
Synergism in Wei~ht Loss on Heating (10/min) of Resins I and V
Char
We~ght Res~d~e, ~ Temperature, C
Resin _ditive Percent 400 C 30X Wei~ht_Loss
V None -- 18 308
V Iron oxide 1 47 264
V Antimon~y oxide 5 16 313
I None -- 36 327
lS Example 11 - Resin-Soluble Iron Compounds as FR Synergists
Compounds of iron that are soluble in styrenated resin composi-
tions, such as Resins I-V, are also effective fire retardant synerg1stic
components with halogens. Examples of such a soluble compound, ferric
- acrylate, are shown in Table I, Casting Nos. AN and A0.
Soluble iron compounds in the resin can cause effects on the
peroxide-initiated cure of the resin to a greater degree than the in-
soluble compounds. Ferric acetylacetonate, for instance, accelerates
the methyl ethyl ketone peroxide initiated cure of Resin I so that no
cobalt octoate is required to obtain a room temperature cure. Polymeriza-
tion inhibitors may be added, such as chloranil and t-butyl catechol, to
obtain sufficientlY long pot life.
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11143490 -:
Resin ~, 130 parts; dibromopropyl hydroxyethyl fumarate, 7 parts;
styrene, 6 parts; chloranil, 0.02 parts; t-butyl catechol, 0.01 parts; and
methyl ethyl ketone peroxide, 1 part were blended to provide a polymerizable
mixture which had a gel time at 25 de~rees centigrade of 30 minutes. The
composition was tested as in the preceding Examples 6 to 10 and found to
give the results shown in Table YII.
TABLE VII
Fire Retardant Synergism of Iron Acetylacetonate in Resin I
ASTM D-757-65
10 Cast~ng Weight HDT Burn Rate Flameout.
No. Compound Percent C ~ Time(secs
GA None 98 0~17 180
GB Iron Acetyl-
acetonate 1.5 70 0.07 0
Example 12 - Iron-Phosphorus Interaction in FR Polyesters
It has been observed that iron compounds are antagonistic with
compounds of phosphorus, such as triethyl phosphate, in the fire retardant ~ -
~ resins of our invention. Iron compounds of phosphorus are also inactive
! as shown in Table VIII. Testing was conducted in accordance with the
~ 20 procedure of Examples 6-10.
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TABLE VIII
.
Inactive Iron-Phosphorus Compounds in Resin I
ASTM D-757-65
Casting Weight oDT Burn Rate Flameout
tlo. Com~ound Percent C (in/min) Time(secs¦
HA None 115 0.20 160
HB ~Ferric ~lycer-
ophosphate 1 114 0.21 155
HC Ferrous
phosphate 1 113 0.20 107
; HD Ferrous
phosphate 2 111 0.21 180
' HE Ferrous
phosphate 4 112 0.19 160
'~ 15 HF Ferric phos-
phate 2 84 0.20 147
HG Ferric acetyl-
acetonate and 1.75 ~ 62 0.25 170
phate P 5 J
.:
The foregoing specification is intended to illustrate the : ;
invention with certain preferred embodiments, but it is understood that
the details disclosed herein can be modified without departing from the
splrit and scope of the invention.
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