CA1110439A

CA1110439A - Synthesis of smoke retardant and vinyl halide polymers containing same

Info

Publication number: CA1110439A
Application number: CA319,568A
Authority: CA
Inventors: Enrique G. Reynes
Original assignee: BF Goodrich Corp
Current assignee: Goodrich Corp
Priority date: 1978-01-23
Filing date: 1979-01-12
Publication date: 1981-10-13
Also published as: NL7900482A; AU520003B2; NL185570B; AU4340279A

Abstract

ABSTRACT OF THE DISCLOSURE
Process for preparation of smoke retardant compo-sition containing an amine molybdate and cupric oxalate.
According to the process of this invention, the individual components of the composition are synthesized in a common reaction slurry, thereby, resulting in their intimate assoc-iation with one another. This process generally involves reacting in this common reaction slurry an appropriate amine with a molybdenum compound, such as molybdenum trioxide, molybdic acid, an ammonium or alkali metal salt of molybdic acid or mixtures thereof. Oxalic acid and cupric sulfate can thereafter be introduced into this reaction medium. The amine and the molybdenum containing compounds will react with one another thereby forming an amine molybdate complex.
The oxalic acid and cupric sulfate will react with one another thereby forming cupric oxalate and sulfuric acid.
The generation of sulfuric acid during this latter reaction serves to stabilize the amine molybdate thus rendering it more readily acceptiblize for use in the smoke retardant compositions of this invention. The process parameters and relative proportion of ingredients of the above synthesis are carefully adjusted so that they yield a coherent particulate material comprising cupric oxalate and amine molybdate in intimate association. Compositions prepared in the above manner are highly effective smoke retardants for vinyl halide polymers.

Description

BACXGROUND OF THE INVENTION
.
Field of the Inven-tion - This invention rela-tes to a process, a composition, a method ancl articles o manu-facture containing the composition ~ore specifically, this invention is directed to a process for the synthesis of a smoke retardant composition, a method for supression of smoke during the combus-tion of polymeric materials, and polymeric materials containing such smoke retardant compositions. This invention also provides a novel technique for the recovery of finely divided particles o~ cupric oxalate and amine molybdates.
Description of the Prior Art - The use o~ physical mixtures of cupric oxalate and amine molybdates as smoke supressants in vinyl hal:ide polymers has been previously dis-closed by McRowe and Kroenke in U.S. Patent 4,053,453. Theindividual ingredients of their synergistic mixture are separately synthesized and thereafter combined, either prior to the addition of said mixture to the vinyl halide polymer, or said ingredients can be combined within the vinyl halide polymer.
The synthesis of cupric oxalate is fairly straight-forward. This salt can be readily prepared by contacting stoichiometric quantities of hot concentrated solutions of cupric sulfate and oxalic acid. The resulting precipitate, cupric oxalate, is recovered ~y filtration and thereafter dried. The effluent which remains subsequent to such synthesis contains sulfuric acid and can be disposed of by . ~

conventional treatment techniques. Although the chemistry involved in the preparation of the above material is fairly uncomplicated, recovery of the cupric oxalate from the reaction slurry is quite difficult due to the very fine particle size of the reaction product. These problems have been fully documented in the patent literature and techniques have been devised for the synthesis of cupric oxalate so as to produce a particulate product which can be readily re-covered by conventional filtration procedures, U.S. Patent 3,846,460 (to Fite~. The Fite synthesis does, however, have some serious drawbacks since the product which is prepared is invariably contaminated with minor quantikies oE iron. The presence of iron in vinyl halide polymers, even in very minor quantiti~s, is unde~irable because of the relative oxidative instability of this impurity and the influence such material can have upon the color of the polymer. Thus, cupric oxalate containing iron impurities is generally un-satisfactory for use in vinyl halide polymers where these polymers are to be used in the fabrication of articles which are to be exposed to the degradative forces of oxidation and/or require certain aesthetic and/or color charac-teristics.
The synthe~is of amine molybdates can be achieved by reacting an amine with a molybdenum containing compound such as molybdenum trioxide, molybdic acid, an ammonium or alkali metal salt of molybdic acid or mixtures thereof in an aqueous medium. It is essential to add acid to this aqueous medium, either prior to contact of the above reactants or '' :;: ', ':
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.

subsequent to their reac~ion in order to effect conversion of the thermodynamically unstable complex which is formed between such materials into a more stable (and commercially acceptable) salt.
As is evident from the above discussion, the requirements for the synthesis o cupric ox~late and amine molybdates are quite specific, especially if such ingred-ients are to be used in conjunction with vinyl halide polymers. Unfortunately, neither o these ingredients can be conveniently prepared, especially the cupric oxalate, without introducing some contaminants (i.e., filtering aids) into the desired compound. As noted herein, cupric oxalate, and amine molybdates to a lesser degree, are generally pre-pared as very fine particulates and, thus, are difficult to recover from the reaction medium. Where modification of the reaction scheme is attempted, as described in the previously discussed patent to Fite, the ease of recovery is improved, however, at the expense of the purity o~ the :recovered product. Thus, there is a continuing need for an effective method for synthesis of the above materials in a fashion which f~cilitates their recovery and yet does not detract from the purity of the recovered product.

SUMM?.RY OF THE INVENTION
Accordingly, it is the object of this invention to remove the above as well as related deficiencies in the prior art.
More specifically, it is the principal object of this invention to provide a process for the synthesis o~
cupric oxalate which permits facile recovery thereof from a reaction slurry.
Another object of this invention is to provide a process for the synthesis of amine molybdates which permits facile recovery thereof from a reaction slurry.
Yet another object of this invention is to provide a process for the sequential synthesis of cupric oxalate and amine molybdates in a common reaction slurry under conditions which would permit facile recovery of both products from such slurry without filtering aids.
Still yet another object of this invention is to provide a composition suitable for reduction in the level of air borne combustion products resulting Erom the pyroLysis of polymers, especially vinyl halide polymers.
Additional objects of this invention include the provision of polymers and articles prepared therefrom which possess enhanced resistance to smoke generation during the combustion thereof.
The above and related objects are achieved by pro-viding a process for the synthesis of cupric oxala-te and amine molybdates in a common reaction slurry. In this process, an amine molybdate can be initially prepared by contacting, in an appropriate medium (such as water) and at elevated temperatures, molybdenum trioxide, molybdic acid, an ammonium or alkali metal salt of molybdic acid or mixtures thereof with an appropriate amine, followed thereater by _ 5 _ the addition, to the same medium, of oxalic a~id and cupric sulfate (preferably in equimolar amounts). The mole ratio of amine to molybdate containing compound is preferably about 1:1. The reactants are heated in this medium to a temperature in the range of or about 50 to 100C. for a period sufficient to effect substantia:L completion of the synthesis of desired products. The solids which are formed in the reaction medium can be easily recovered by filtration.
The recovered product is comprised of essentially unitary particles containing both cupric oxalate and an amine molyb-date in intimate physical association.

DESCRIPTION OF THE INVENTION
INCLUDING PREFERRED EMBODIMENTS
The process o~ this invention can be c:arried out 15 by addition to a common reaction medium oE the ingredient~
necessary to form amine molybdate, the ingredients necessary to form cupric oxalate or by essentially simultaneous addi-tion of the ingredients to form both the amine molybdate and the cupric oxalate. The sequence of addition of the various reactants to the medium can, however, effect the yield and the physical characteristics of the solids which are pro-duced as a result o~ their reaction with one another.
The amine molybdates prepared according to this process are produced by reacting an organic amine with a molybdenum containing compound, such as molybdenum trioxide, molybdic acid or an ammonium or alkali metal salt of molybdic acid. The amine molybdate normally con-tains from about 1 to : . ~. , ' "
..

2 moles of molybdenum per mole of amine. The synthesis of such molybdates are fully described in U.S. Patents 4,053,453 and 4,053,455. As noted previously, it is preferable that amine molybdate formation occur in an acidic medium so as to insure the formation of a thermodynamically stable product.
Amines which are suitable for use in the preparation of amine molybdates can contain from about 1 to 40 carbon atoms and from about 1 -to 10 primary, secondary and tertiary amine groups or any combination thereof. In the most preferred embodiments of this invention, the organoamine molybdates will contain from about 1 to about 20 carbon atoms and 1 to 4 primary amines or heterocyclic secondary amine groups.
Examples of amines which are suitable for use in the synthesis of thesç compounds include the aliphatic, the alicyclic, the aromatic and heterocyclic amines. The aliphatic amines which are especiaIly preferred for use in this synthesis include ethylamine, ethylenediamine, 1,2-propanediamine, 1,3~propanediamine, 1,4-butanediamine, 2-methyl-1,2-propanediamine, 1,5-pentanediamine, 1,6-hexane-diamine, l,7-heptanediamine, 1,8-octanediamine, 1110-decane-diamine, l,12-dodecanediamine, and the like. Aliphatic polyamines which are suitable in preparation of the above compounds include d;ethylenetriamine, diethy]enetetramine, tetraethylenepentamine, bis(hexamethylene)triamine, 3,3'-iminobispropylamine, guanadine carbonate, and the like. The preferred alicyclic diamines and polyamines which can be used in the synthesis of the above compound include 1,2-diaminocyclohexane, 2',4-diamino-1-propyl-4-methylcyclo-hexane, and the like. Aromatic amines such as aniline and naphthalamine are also suitable for use in the preparation of the above compounds. Heterocyclic amines such as melamine, N,N-dimethylanaline, pyridine, piperazine, hexamethylene-tetraamine, 2,2,4-trimethyldecahydroquinoline, 2,4,6-tri-(morpholino)1,3,5-triazine and N-(aminoalkyl)-piperazineS
wherein each alkyl group contains from about 1 to 12 carbon atoms and preferably from 1 to 6 carbon atoms can also be employed in this process. Polymeric amines are also suitable for use in preparation of the above compounds and such suitable substances include polyethyleneimine, polyvinyl-pyridine, polyvinylpyrolidine, and poly~2,2,4-trimethyl-1,2-dihydroquinolyl).
Excellent results in preparation of the above com-pounds have been obtained wherein the amine is melamine, piperazine and alkyl amines wherein the alkyl substituent contains 1 to 8 carbon atoms.
Substituted melamines which are suitable in prepar-ation of the above compounds can be represented by the following ~ormula:

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'` X/ N ~ O ~ N \X~'~
N

X~ \X
wherein X is hydrogen or an alkyl, alicyclic, aralkyl, alka'ryl, aryl or heterocyclic group containing from - 1 to 10 atoms of C, O, S and/or N. Any -two of the substit-uents on each of two or more pendant nitrogen atoms may also be joined together to form a heterocyclic ring such as a mor-pholino group in 2,4,6-tri(morpholine)-1,3,5-triazine. Other examples of suitable substituted melamines include N,N',N " -hexaethylmelamine; 2-anilino-~-(2l,4'-dimethylanilino)-6-piperidino-1,3,5~triazin~; and 2,~,6-tr:i(N-methylarlilino)-1,3,5-triazine.
Cupric oxalate can be prepared by reacting stoich-iome~ric amounts of hot concentrated solution of cupric sulfate and oxalic acid. The formation of this product in the common reaction slurry can precede or follow the addition of other reactants thereto.
The reaction medium which can be used in this synthesis is preferably a solvent for the various reactants contemplated for addition thereto and essentially a non-solvent for the product o-E this synthesis. Any highly polar fluid, such as water, lower alkyl alcohols or mixtures thereof would appear to be suitable for use as the reaction medium in this process. The amount of reaction medium ' ~
.. ..
'' ' ~' ~ ~ ;, -relative to reactants should be adequate to effectively dis-solve such reactants and not present in such excess as to inhibit interaction thereof.
As noted previously, the sequence of addition of the reactants to the reaction medium can affect both the yield and the physical characteristics of the solvents thus produced. In a preferred embodiment of this invention the ingredients necessary for the formation of the amine molyb-date are initially added to the reaction medium and the cupric oxalate formed within the medium ~hereafter. The formation of acid during the subsequent synthes~s of cupric oxalate serves to stabilize the amine molybdate. The sequential synthesis of these materi~ls in a common reaction medium in the manner set orth hereinabove results in the formation of a unique partlculate product which contains both amiNe molybdate and cupric oxalate in intimate associ-ation. This particulate product can be readily separated from the reaction medium by conventional filtration tech-niques. Because both components of this composition are con-tained in a single physical entity, subsequent additionthereof to polymeric resins is greatly simplified.
The reaction conditions prevailing during such com-bined synthesis are essentially the same were such materials to be prepared in separate vessels. The parameters for synthesis of amine molybdates are set forth in V.S. Patents 4,053,453 and 4,053,455. Typically, such a synthesis simply ,. .
''';

., , involves dissolving an organic amine and a molybdenum con-taining compound in separate containexs, heating each solution to a temperature in the range of from about 50 to 100C. and combining the solutions under controlled conditions over a relatively brief period of time with agitation. Ordinarily, were such amine molybdates to be pre-pared separately, dilute acid must also be intr~duced into the reaction medium in order to effect stabilization of the amine molybdate compounds which are ormed therein. However, in the combined synthesis of this invention such acid addition is not required since the reaction of oxalic acid and cupric sulfate in this reaction medium will ~enerate sufficient acid to effect the stabilization of the amine molybdate compound. In a similar fashion, separate solutions of oxalic acid and cupric sulfate (generally a hydrated Eorm of cupric sulfate) are prepared and added to the reaction medium in sequence following the addition thereto of the organic amine compound and the molybdenum containing com-pound. The solution containing the cupric sulfate is, however, carefully metered into the reaction medium by drop-wise addition over a relatively brief period of time. The entire reaction medium is agitated during such addition and the temperature thereof generally increased until refluxing thereof is achieved. The system is heated for an additional two hours from this point, allowed to cool and the resultant product separated from the reaction slurry by filtration.
The recovered product can thereafter be washed with water or ..

other suitable solvent and dried under vacuum. The solid materials recovered from the reaction slurry comprise essentially unitary particles of amine molybdate and cupric sulfate in intimate association. The solids recovered from the reaction medi~m in this fashion are generally of a particle size suitable for use in polymer compositions. The particle size o~ the recovered solids prepared according to the process of this invention can range from about 0.01 to about 800 microns, and preferably from about 0.5 to about 200 microns. In the event that the particle size of solids recovered from the reaction medium is in excess of that stated hereinabove, or in excess of the preferred dimension, such solid can be subjected to the attritive forces o a ball-mill or other equivalent deviae for a period suficient to reduce its size to the desired level.
The polymers of the compositions of this invention can include vinyl halide homopolymers, copolymers, blends and~or mixtures of homopolymers and/or copolymers. The vinyl halides which are preferred in such compositions include vinyl chloride and vinylidene chloride polymers that contain up to about 50~ by weight of at least one other olefinically unsaturated monomer, more preferably at le~st one other vinylidene monomer (i.e., a monomer containing at least one terminal CH2=C~ group per molecule) copolymerized therewith, even more preferably up to about 20% by weight of such monomers. Monomers which are suitable in preparation of such polymer compositions include ~-olefins containing from 2 to 12 carbon atoms, more preferably from 2 to 8 carbon atoms, such as ethylene, propylene, l-butene, isobutylene, l-hexene, 4-methyl-1-pentene, and the like; dienes contain-ing from 4 to 10 carbon atoms including conjugated dienes as butadiene, isoprene, piperylene, and the like; ethylidene norbornene and dicyclopentadiene; vinyl esters and allyl esters such as vinyl acetate, vinyl chloroacetate, vinyl propionate, vinyl butyrate, vinyl laurate, vinyl benzoate, allyl acetate, and the like; vinyl aromatics such as styrene, a-methyl styrene, chlorostyrene, vinyl toluene, vinyl naphthalene, and the likei vinyl and allyl ethers and ketones such as vinyl methyl ether, allyl methyl ether, vinyl iso-butyl ether, vinyl n-butyl ether, vinyl chloroethyl ether, methyl vinyl ketone, and the like; vinyl nitrile~ such as acrylonitrile, methacrylon:Ltxile, and the like; cyanoalkyl acrylates such as ~-cyanomethyl acrylate, the a-, ~- and y-cyanopropyl acrylates, and the like; olefinically unsaturated carboxylic acids and esters thereof, including ~
olefinically unsaturated acids and esters thereof such as acrylic acid, methacrylic acid, ethacrylic acid, methyl acrylate, ethyl acrylate, chloropxopyl acrylate, butyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, octadecyl acrylate, cyclohexyl acrylate, phenyl acrylate, glycidyl acrylate, methoxyethyl acrylate, ethoxy-ethyl acrylate, hexylthioethyl acrylate, m~thylmethacrylate,ethyl methacrylate, butyl methacrylate, glycidyl meth-acrylate, and the like~ wherein the alkyl groups contain 1 . _ ': . ~ , . ;, :, , ~q~

to 12 carbon atoms, and including esters o~ maleic and fumaric acid, and the like; amides of the ~,e-olefinically unsaturated carboxylic acids such as acrylamide, meth-acrylamide, and the like; divinyls, diacrylates and other poly~unctional monomers such as divinyl benzene, divinyl ether, diethylene glycol diacrylate, ethylene glycol dimeth-acrylate, methylenebis-acrylamide, allyl pentaerythritol, and the like; and bis(~-haloalkyl) alkenyl phosphonates such as bis(~-chloroethyl) vinyl phosphonate, and the likeD
A group of particularly useful comonomers include l-olefins containing from 2 to 8 carbon atoms; vinyl esters and allyl esters; olefinically unsatuxated carboxylic acids and.esters thereof, especially a,B-olefinicall~ unsaturated acids and esters thereo~; esters o:E male.ic and :Eumaric acid, and the like; amide5 o~ u,~-ole~inically unsaturated carbox-ylic acids; and vinylidene or vinyl chloride.
Also included are chlorinated vinyl chloride and blends of vinyl and vinylidene chloride polymers and co-polymers with other polymers, both plastics and elastomers, for example, with an ABS resin containing 10 to 40% of copolymers of styrene and acrylonitrile or styrene and methyl meth-acrylate wherein styrene i.s the major component, elastomers containing about equal amounts of styrene and acrylonitrile with butadiene, polyurethanss, nitrile elast~mers, both liquid and solid containing from about 15 to 40% acrylo-nitrile with the remainder butadiene, polyolefins, and the like. These vinyl chloride polymers normally are high .
" , ' ' '` " ' ~, molecular weight polymers having a specific viscosity greaterthan 0.4 measured as a 0.4% solution in nitrobenzene.
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. The smoke suppressant composition prepared according to the process of this invention may be mixed with the polymer emulsion, suspension, solution or bulk mass before monomer xecovery and/or drying. More preferably, the smoke suppres-sant may be mixed with dry granular or powdered polymers.The above mixture may be blended thoroughly in granular or powder form in apparatus such as aHensche~mixer,or ~equivalent device. Alternatively, this step may be eliminated and the mixing 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. The fusion temperature and time will vary according to the polymer compositions and level of smoke suppressant and will generally be in the range o~
about 300 to 400F. for 2 to 10 minutes.
The vinyl chloride polymers can also be pre-mixed with standard compounding ingredients known to those skilled in the art,(e.g., plasticizers, lubricants, stabilizers, fillers, colorants, processing aids, other flame and smoke retardants, and the like). While the smoke suppressants of this invention are most effective in vinyl chloride polymers substantially free of plasticizers, they are also of value * trademark ,'' ~.~

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,... . . . .

in reducing smoke formation during combustion of plasticized vinyl chloride polymers.
Smoke retardation 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 ~ethods - Restraint ~ Smoke, 1966, ASTM STP 422, pp. 166-~04. Maximum smoke density (Dm) is a dimension~ess number and has the advantage of representing a smoke density independent Oe cham~er volume, specimen size or photometer path length, provided a consistent dimensional system is used. ~Iaximum rate of smoke generation (Rm) is defined in units of min. -1. Percent smoke reduction is calculated using this equation:
Dm/y of sample - Dm/g oE control ~c 100 .
Dm/g of control The term "Dm/g" represents maximumsmoke densi~y per gram of sample. Dm and other aspects of the physical optics of light transmission through smoke are discussed fully in the above ASTM publication.
The Examples which follow further define, describe and illustrate the improved process Oe this invention.
Apparatus and techniques used in this process and in the evaluation of the products prepared by this process are standard or as hereinbefore described. Parts and percentages appearing in such ~xamples are by weight unless otherwise indicated.

EXAMPLE I
To a one liter reactor fitted with a stirrer, heater, and reflux candenser was charged 300 grams of water and 15.~4 grams (0.1193 moles) melamine. The slurry was stirred and heated to 100C. In three separate beakers the following ingredients were dissolved with heating and stirring:
W'eight Amount in of Water Temp.
Compound Grams Moles in Grams (C.) Ammonium 40.56 0.1193 50 85 dimolybdate Oxalic Acid43.64 0.3462 118 90 Cupric Sulfata, 81.82 0.3277 100 95 pentahydrate The hot ammonium dlTnolybdate solution was con-veniently added to the melamine reaction flask over a period of 15 minutes with stirring at 150 rpm. The slurry was allowed to cool at 85C. and thereafter the oxalic acid solution (also at 85C.) was added in a similar fashion over a 15 minute period. The cupric sulfate solution was metered into the reaction slurry by dropwise addition from an electrically heated addition funnel. The duration required for the addition of such material was 20 mimltes. The entire reaction mix-ture was stirred and heated to 100C. under reflux conditions for an additional two hours. The slurry was then allowed to cool, the solids separated from the reaction medium by filtration and washed with cold water.
The solids were dried in a vacuum oven. The yield was approximately 97~ of -the lO~ grams theoretical yield.
EXAMPLE II
The procedures o .F.xamp:Le ~ we~e repeatec~ excep~
for -the substitution of one of the Eol.Iowing amin~ mo~ybdate~
~o.r melam.i~e molybdates:
(a) Ethylene mol~bdat:~
(b) Pyrid.ine molybdate (c) P.iDerazine molybd~te (cl) Hexame-thylene tetram:i.n~ moly~at~?
(e) Guanad.ine mo:Lybdate (f) AnJ.line molybdat~
(g) ~,N~dimethylan.ilille moly~d<~ke (h) N,M',N''-hexa~l:hy.l.n~e~.c~ ;n~ ~no:Ly)~c1cl~.c~
(i.) 2-~lnll:i.no~2',4'~-c1:i.1n~ n:i~Ln.o)~
piperadi.no :1.,3,5-1:riazi.r1~ mo:Lybd~c-~
(j) 2,4,6~tri(N-meth~:L ani~ino)~l t 3~S--triazi.ne mo:L~bcla~e (k) 2,4,6-tri(morphol;lno)-l,3,5 tx:iaz.inc?
molybclate (l) 2,2,4-trlm~thy:l.decah~dro~u.i.nol.ine mol~bdate .
EX~~L
The smoke supprcss~nt p~epar.ed in the m~r1n~r cle~-~cribecl in Example I is combin~d w.ith po:lyvinylc~h:lori.c~e ~esin (the resin having a specifi.c ~fiSCC>Sity ~f 0. 3~0~f~ in nitrobenzene at 30C,) by dry m~ ing these inc1redierli:s ir a relative welght ratio of ahoul: 2.~ parts b~ weic1ht: s]~ok~

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; ' ' ' ~

, ~ , . .

a~ hA~

suppressant per 100 parts by weight polymer. In addition to the above constituents, the following standard ingredients are also added to the mixture in the following concentrations:
2 parts by weight of dibutyltin bisiso-octothioglycolate (antioxidant) 4 parts by weight processing aid

3 parts by weight titanium d:ioxide 1 part by weight calcium stearate 1 par-t by weight methylene bis stearamide +The concentration of the above ingredients is given per 100 parts by weight polymer.
Subsequent to admixture of the above ingredients, the resultant powder is placed upon a heated 10 inch 2-roll mill and formed into sheets. The resultant sheets are cut into samples of predetermined sizes. A sample approximately 6" square is placed in a sheet mold and pressed at 320F.
for three minutes until its thickness is redued to about 25 mils. A 3x3 inch sample of this sheet is t:hereafter tested in an NBS smoke chamber operated in the flaming mode.
Test results from this evaluation compare very avorably with samples of materiais devoid of smoke suppressant. On the average, smoke suppression is reduced by at least 50 and in some instances up to 75~. Samples which have been subjected to the above evaluation also exhibit enhanced stability over tin-sulfur stabilized compositions with respect to the color characteristics of the material.

.~. ' .
.

EXAMPLE IV
The procedure of Example III is repeated with the smoke suppressant compositions of Example IIa-l. In each and every instance, the comparative results obtained are substantially equivalent to those reported for Example III.
The foregoing examples have been providea to illustrate some of the preferred embodiments of this inven-tion and not intended to delineate its scope, which is set forth in the claims which follow.

.. . . . .
, ' ' ' : . ,

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A process which comprises:
preparing, in intimate physical association, a synergistic mixture of an organic amine molybdate and cupric oxalate suitable for suppression of smoke during the combustion of polymeric material, said preparation involving:
(a) contacting, in a reaction medium, an organic amine and a molybdenum containing compound selected from the group consisting of molybdenum trioxide, molybdic acid, ammonium salts of molybdic acid, alkali metal salts of molybdic acid and mixtures thereof whereby at least some of the organic amine and at least some of the molybdenum con-taining compound react with one another and form an amine molybdate, and (b) contacting, in said same reaction medium and in the presence of the amine molybdate, cupric sulfate and oxalic acid whereby at least some of the cupric sulfate and at least some of oxalic acid react with one another and form cupric oxalate and sulfuric acid;
both the organic amine molybdate formed in (a) and cupric oxalate formed in (b) being substantially in-soluble in the reaction medium and precipitating therefrom as a single distinct physical entity.

2. The process of Claim 1 wherein the organic amine is melamine or a substituted melamine.

3. The process of Claim 1 wherein the molybdenum containing compound is ammonium dimolybdate.

4. A smoke retardant composition comprising in intimate physical association, a mixture of an organic amine molybdate and cupric oxalate produced by a process according to Claim 1.

5. A smoke retardant composition comprising in intimate physical association, a mixture of an organic amine molybdate and cupric oxalate, said organic amine being melamine or a substituted melamine, produced by a process according to Claim 1.

6. A smoke retardant composition comprising in intimate physical association, a mixture of an organic amine molybdate and cupric oxalate produced by a process according to Claim 3.

7. A method for reducing the level of air borne combustion products resulting from the pyrolysis of poly-meric materials, said method comprising, incorporating within said polymeric materials a smoke suppressant effective amount of a synergistic mixture comprising an organic amine molybdate and cupric oxalate, said synergistic mixture being in the form of unitary particles wherein the organic amine molybdate and cupric oxalate are present in intimate physical association, said unitary particles having been prepared by:
(a) contacting, in a reaction medium, an organic amine and a molybdenum containing compound selected from the group consisting of molybdenum trioxide, molybdic acid, ammonium salts of molybdic acid, alkali metal salts of molybdic acid, and mixtures thereof whereby at least some of the organic amine and at least some of the molybdenum con-taining compound react with one another and form an amine molybdate: and (b) contacting, in said same reaction medium and in the presence of the amine molybdate, cupric sulfate and oxalic acid whereby at least some of the cupric sulfate and at least some of oxalic acid react with one another and form cupric oxalate and sulfuric acid;
both the organic amine molybdate formed in (a) and cupric oxalate formed in (b) being substantially in-soluble in the reaction medium and precipitating thereform as a single distinct physical entity.

8. The method of Claim 1, wherein the organic amine is melamine or a substituted melamine.

9. The method of Claim 1, wherein the molybdenum containing compound is ammonium dimolybdate.