IL45910A - Fire retradant stable aqueous polymer latices and their preparation - Google Patents

Description

Fire retardant stable aqueous polymer latices and their preparation F:L _ RETARDANT, STAPLE AQUEOUS POLYMER LATICES Background of the Invention Polymers of halogen-containing ethylenically unsaturated monomers, such as the vinyl or vinylidene halides, are often prepared as aqueous latices or emulsions in which form they may be conveniently used as coatings, adhesives, paint bases and in various other types of applications. In many instances, particularly where they are being considered for use in building interiors · or in uses requiring their prolonged exposure to high temperatures, it is highly desirable and advantageous that these latices should display enhanced fire or flame retardant properties and color stabilit so that they may be safely employed in place of more costly materials. Moreover, it is highly desirable and advantageou that these latices when applied to flexible substrates, should not substantially reduce the soft "hand" of said flexible substrates.

Prior attempts to .provide fire retardant, film-forming vinyl or vinylidene halide polymer latices have involved the preparation of various polymeric compositions including copolymer latices of vinyl halides and alkyl acrylates, copolymer latices of vinyl halides and vinylidene chloride and polyvinyl halide latices containing an extran-eously added phosphate ester plasticizer. Other attempts have involved the use of interpolymers of bis (beta-chloroeth vinyl phosphonate with lower alkyl excrylates or methacrylate and acrylic or methacrylic nitriles. These interpolymers could additionally optionally include vinyl halides or vinyl idene halides. Still other attempts have involved interpoly rnerization of vinylidene halide monomers with carboxylic acid monomers and N-alkylol amide monomers. These latter interpolymers could optionally include other polymerizable comonomers such as esters of acrylic acid or methacrylic acid, vinyl acetate, acrylonitrile , methacryloni rile, acrylamide or methacrylamide , styrene or bis (beta-haloalkyl) vinylphosphonates . However, despite the many and varied attempts to obtain a completely satisfactory polymeric latex, none of the above-described approaches has proven to be completely satisfactory as the resultant products are found, in many cases, to be lacking in either sufficient fire retardancy, softness of the polymer, color stability and mechanical stability or ultraviolet stability or the products are subject to the gradual loss of their extraneously added phosphate plasticizers .

Recent improvements in this technology have resulted in 'fire retardant aqueous polymer emulsions comprising a halogen-containing vinyl monomer such as vinylidene chloride, a phosphorus-containing vinyl monomer such as bis (beta-chloro ethyl) vinyl phosphonate, and another comoncrner such as an alkyl aerylate. These emulsions, while vastly superior to those previously known, can still stand further improvement. It is particularly desirable to obtain highly stable fire-retardant polymer compositions with even higher fire retarda properties.

Accordingly, it is an object of this invention to provide novel, fire retardant halogen-containing vinyl latic which may be used in a variety of coating, binding, and laminating applications and which are characterized by their essentially complete freedom from the various disadvanta¾ jpi..a¾ properties heretofore associated with this type of product.

It is another object of this invention to provide a novel class of polymers in the form of unusually stable aqueous emulsions of latices v/hich are particularly useful, as additives, for preparing fire retardant, polymer compositions V7hich are in the form of aqueous solutions, suspensions or, most preferably, emulsions.

It is a further object of the present invention to provide a method for preparing highly stable polymeric latices.

Various other objects and advantages of this invention v/ill be apparent from the disclosure thereof v/hich follows hereinafter.

Technical Disclosure of the Invention In its broadest aspect, this invention resides in the discovery that aqueous emulsions of fire retardant polymers comprising (1) one or more halogen-containing vinyl monomers with (2) one or more phosphorus containing vinyl monomers as hereinafter defined, and (3) one or more additional comonomers as hereinafter further defined, these polymers being in the form of unusually stable dispersions o particles in an aqueous emulsion or latex, are prepared bv a emulsion polymerization process using as an emulsifier a sodium sulfosuccinamate of the general formula : O NaOSC -CH-C-O-Na in which is hydrogen, a hydrocarbyl radical having to 18 carbon atoms, or di-sodium 1 , 2-dicarboxy ethyl; and R2 is a hydrocarbyl radical having from 1 to 18 carbon atoms. Preferred as R-j are hydrogen, alkyl radicals having from 16 to 18 carbon atoms, or di-sodium, 1 , -dicarboxy ethyl.

Preferred as R2 are alkyl radicals having from 16 to 18 carbon, atoms. Especially preferred as emulsifiers are tetra-sodium N- (1 , 2-dicarboxyethyl) -N-octadecyl sulfosuccinam and di-sodium N-octadecyl sulfosuccinamate; these emulsifiers are sold under the trademarks Aerosol 22 and Aerosol 18, respectively, by American Cyanamid Company.

More particularly, it has now been discovered that the use of a sodium sulfosuccinamate emulsifier enables the preparation of highly stable aqueous emulsions or latices of polymers formed from one or more halogen-containing vinyl monomers with one or more bis (hydrocarbyl) vinyl phosphonate and one or more additional comonomers as hereinafter defined in an emulsion polymerization process. These stable polymeric emulsions when blended with an ordinarily flammable polymer, impart to the resulting polymer blend a high degree of fire retardance and excellent color stability without adversely affecting any of the significant physical properties of the polymer. In addition, it has been found that the polymer additives of the present invention impart a desirably soft hand to substrates upon which they are coated or within which they are impregnated. Moreover, it is truly surprising and advantageous, to find that the polymer blends resulting from the process of this invention, particularly those blends which are in the form of an aqueous emulsion or latex system, display an outstanding degree of compatibili y since, as is well known to those skilled n the art, physical blends of two or more polymers are almost always characterized by their inherently poor compatibili y The process of this invention provides highly stable aqu ou emulsion or latex polymers comprising: (1) at least one halogen-containing, alpha, beta-ethylenically unsaturated monomer, i.e., vinyl monomers including vinyl halides such as, for example, vinyl chlorid vinyl fluoride and vinyl bromide, halogenated C-^-C.^ alkyl acrylates and methacrylates such as, for example, methyl alpha-chloroacr-ylate and methyl alpha-bromoacrylate; vinyli-dene halides such as, for example, vinylidene chloride, vinylidene bromide, vinylidene chlorobromide and vinylidene fluoride; halo-substituted nitriles of ethylenically unsaturated carboxylic acids such as, "for example, alpha-chloroacrylonitrile; and the chlorinated styrenes such as, for' example alpha-chloro tyrene , o-chlorostyrene, m-chloro-styrene, p-chlorostyrene and 2 , -dichlorostyrene; (2) at least one bis (hydrocarbyl) inylphosphonate having the structure: X O CH = C - P \ I wherein X is selected from the group consisting of hydrogen halogen, cyano, aryl such as phenyl, C -C alkyl and JL JL o O , wherein R and R* are hydrocarbyl and substituted hydrocarbyl groups consisting essentially of hydrogen and carbon and containin up to about 18 carbon atoms inclusive .with the proviso fe¾t R and R ' may be the same, different or conjoint, i.e., R and R' may combine to form one single radical; and (3) optionally at least one comonomer including alpha olefins such as ethylene, propylene and butylene; vinyl esters of carboxylic acids, such as vinyl acetate, vinyl butyrate and vinyl stearate; and £ -^20 alkyl esters o acrylic and methacrylic acid such as methyl methacrylate, methyl aerylate, ethyl aerylate, n-butyl acrylate, sec. -buty aerylate, tert. -butyl acrylate, 2-ethylhexyl acrylate, laury acrylate and the like; ethylenically unsaturated dicarboxyli acids, their anhydrides and their mono- and dialkyl esters such as aconitic acid, fumaric acid, maleic acid, itaconic acid, citraconic acid, maleic anhydride, dibutyl fumarate and monoethyl maleate; amides of ethylenically unsaturated carboxylic acids such as acrylamide and meth- acrylamide and their N-methylol and diacetone derivatives such as N-methylol acrylamide, N-methylol methacrylamide and diacetone acrylamide; vinyl aryl compounds such as ,styrene and alpha-methyl styrene; CJ_-C2Q alkyl vinyl ethers such as methyl vinyl ether, ethyl vinyl ether and stearyl vinyl ether; dienes such as isoprene and butadiene; and glycidyl esters of acrylic and methacrylic acid such as glycidyl acrylate and glycidyl methacrylate . The preferred comonomers are the alkyl esters of acrylic and meth acrylic acid, especially the lower (C -Cg) alkyl acrylates.

It is considered preferable to include the N- methylol and diacetone derivatives of amides of ethylenicall unsaturated carboxylic acids such as, for example, N-methylo acrylamide or diacetone acrylamide which serve to provide th The use, in this disclosure, of the expression "hydrocarbyl " and "substituted hydrocarbyl groups" m the definition of the suitable bis (hydrocarbyl) viny].phosphonates given hereinabove refers to the radicals obtained upon the removal of a hydrogen from a hydrocarbon or substituted hydrocarbon group which may be either an aliphatic or aromatic group. These hydrocarbyl groups may be substituted with any non-interfeei g groups, i.e., with any group which does not interefere with the polymerization of the bis- (hydrocarbyl) vinylphosphonate. Such substituent groups include, for example, chloro, brorao, fluoro, nitro, hydroxy, sulfone, ethoxy, naethoxy, nitrile, ether, ester and keto groups and the like . · Illustrative of the aliphatic and aromatic groups as are represented by R and R1 in the structure of the bis- (hydrocarbyl) vinylphosphonate given hereinabove are alkyl groups, such as methyl, ethyl, propyl, butyl, pentyl, hexyl, nonyl , and the like; alkenyl groups such as pentenyl and hexenyl groups and all of their respective isomers ; cycloalkyl groups, such as cyclopropyl, cyclobutyl, cyclo-pentyl , cyclohexyl and the like; cycloalkenyl groups such as cyclohexenyl and the like; typical aryl groups include phenyl, benzyl, phenethyl , tolyl, naphthyl and the like.

Representative of the above-defined bis (hydrocarbyl) vinylphosphonates are : Bis (beta-chloroethyl) vinylphosphonate; Bis (beta-chloropropyl) vinylphosphonate; ' Bis (beta-chloroethyl) 1-methylvinylphosphonate ; Bis (beta-chloroethyl) - l~cyanovinylphosphonate; Bis (beta-chloroethyl) - 1-chlorovin lphosphonate; Bis (beta-chloroethyl) ~ l-phenylvin lphosphonate; Dimethyl vinylphosphonate; Diethyl vinylphosphonate; Bis (omega-chlorobutyl) vinylphosphonate; Di-n-butyl vinylphosphonate; Di-isobutyl vinylphosphonate; Bis (2-chloroisopropyl) -* 1-meth Ivinylphosphonate; Diphenyl .vinylphosphonate; and Bis (2 , 3-dibromopropyl) vinylphosphonate From the above group of bis (hydrocarbyl) vinyl-phosphonate monomers, it is preferred to employ bis (beta-chloroethyl) vinylphosphonate in preparing the novel aqueous emulsion polymers of this invention since the latter monomer is a commercially available material and lower in cost than any. of the other bis (hydrocarbyl) vinylphosphonates .

Although either a vinyl halide or a vinylidene halide monomer can be suitably employed as the halogen-containing ethylenically unsaturated monomer in the aqueous emulsion polymers of the present invention, it is considered preferable to employ vinylidene halide monomers since the vinylidene halide monomers when incorporated into polymers of the present invention impart a soft "hand" to substrates upon which they are coated or within which they are impregnat The preferred third comonomer for use in the polymers of the present invention is an alkyl acrylate, preferably the C4-C3 alkyl acrylates such as n-butyl acrylate and 2-ethylhexyl acrylate. It has been found that inclusion in the polymer of an alkyl acrylate aids in imparting good color s abiU^t-v and softness to the resulting polymer. It is to be noted/ at this point, that the use of the term "polymer" in this disclosure is meant to apply to polymers derived from two or more distinct monomeric species.

In addition to the above described bis (hydrocarbyl) vinylphosphonates , it is also possible to prepare aqueous emulsion polymers useful as flame retardant additives by employing: (1) mono (alkyl) acid vinylphosphonates such as, for example, mono(ethyl) hydrogen vinylphosphonate, mono(buty hydrogen vinylphosphonate, mono (octyl) hydrogen vinylphosphona mono (beta-chloroethyl) hydrogen vinylphosphonate, mono(omega-chlorooctyl) hydrogen vinylphosphonate; (2) mono (cycloalkyl) a mono (aryl) hydrogen vinylphosphonates such as, for example, mono (cyclohexyl) hydrogen vinylphosphonate, mono (phenyl) hydrog vinylphosphonate, mono (benzyl) hydrogen vinylphosphonate; (3) bis(cycloalkyl) and bis (aryl) vinylphosphonates , such as, for example, bis (cyclohexyl) vinylphosphonate and bis (benzyl) vinylphosphonates; and, (4)* bis(alkyl), bis (cycloalkyl) , and bis (aryl) all lphosphonates , such as, for example bis (beta-chloroethyl) allylphosphonate, bis (cyclohexyl) allylphosphona and bis (benzyl) allylphosphonate as well as mixtures of any two or more of the above described phosphonate monomers.

The polymers of the present invention are prepared by means of free radical initiated emulsion polymerization techniques well known to those skilled in the art. In these procedures, the various monomers and catalysts are emulsifie in water, by means of the emulsifiers of the present inventi whereupon the polymerization reaction is then initiated.

Suitable water soluble, free radical initiating catalysts ^ for use in preparing the polymer latices of this invention include sodium, potassium and ammonium persulfate and hydrogen peroxide. Alternatively, one may use a redox system such, for example, as a mixture of a persulfate with an alkali metal bisulfite, thiosulfate or hydrosulfite.. These catalysts should be present in a concentration of from about 0.05 to 5.0%, by v/eight, of the total monomer charge.

The sodium sulfosuccxnamate emulsifxers employed in the present invention have been found to impart surprisingly enhanced stability to the emulsion of latex, polymer additives of the present invention. In the absence of at least about 0.03% by weight of the emulsifxers based on the total monomer charge, the gum and floe levels of the resulting emulsions or latices have been found to be exceedingly high; whereas, when the sulfosuccxnamate emulsifxers are employed, preferably in amounts of from about 0.03% to about 3% by weight, based on total monomer charge, gun and floe in the resulting emulsion or latex is substantially eliminated and the stability of the emulsion or latex is retained for extended periods of time. The emulsifxers can be employed in amounts greater than about 3%, if desired without detrimental effect.

• In addition, a protective colloid such as polyvinyl alcohol, polyvinyl pyrrolidone, methyl cellulose or gelatin can also, if desired, be present in the recipe in an effective concentration of from about 0.03 to 6.0%, by weight, of the total monomer charge. Alternatively, the protective colloid may be introduced into the polymer latex subsequent to its preparation. When post-added in this manner, the"^^, protective co.13.oid should be present in a concentration of from about 0.03 to 6.0%, by weight, of the total resin solid In any event, the presence of the protective colloid serves to further enhance the mechanical stability of the emulsion.

The actual polymerization reaction will ordinarily be conducted at a temperature of from about 0 to 100°C. for a period of from about 1 to 24 hours, depending upon such factors as the particular monomer, catalysts, surfactants and polymerization apparatus that is being utilized. The latices resulting from this polymerization process will ordinarily have a resin solids content of from about 5 to 70%, by weight, v/herein the particles have a diameter which ranges in size from about 0.03 to 3.0 microns.

With respect to proportions, these aqueous emulsion or late copolymer particles may contain from about 1 to 89% by weight, of one or more of the above-described bis(hydro-carbyl) vinylphosphonates, from about 10 to 98% by weight of one or more of the above-described halogen-containing ethylenically unsaturated monomers and from about 1 to 45% by weight of one or more of the above-described third co-monomers. Optimum results, as flame retardant additives exhibiting good color stability for ordinarily flammable polymer substrates adapted to impart good "hand" to said substrates are obtained by use of polymers in accordance with the present invention containing from about 10 to 75% by weight of one or more of the bis (hydrocarbyl) vinylphosphonates, from about 20 to 85% by weight of one or more of the above-described halogen-containing ethylenically unsaturated monomers ri d from about 5 to 3L¾ by weight of one or more of the above-described third comonomers .

Most preferred is a polymer containing about 45-55% by weight of bis (beta-chloroethyl) vinylphosphonate , 25-35% by weight of vinylidene chloride, 14-20% by weight of n-butyl aerylate 1-5% by 'weight of N-methylol acrylamide. n-butyl acrylate can be replaced, without affecting the properties of the latex polymer, by 2-ethyl hexyl acrylate. When 2-ethyl hexyl acrylate is used, the most preferred composition contains 65-75% by weight of vinylidene chloride, 12-22% by weight of bis (beta-chloroethyl) vinylphosphonate, 5-13% by weight of 2-ethylhexyl acrylate and 1-5% by weight of n-nethylol acrylamide. These two preferred compositions provide a proper balance of all the desired properties and are essentially free from the various disadvantageous properties associated heretofore with this type of polymer emulsion or latex.

With respect to the above-described proportions for the composition of the aqueous emulsion or latex co-polymers of this invention, it has been found that it becomes increasingly more difficult to attain good polymerization conversion rates as attempts are made to increase the amount of the bis (hydrocarbyl) vinylphosphonate in the resulting copolymer substantially above a concentration of about 60% by weight. On the other hand, the use of these copolymer emulsions as flame retardant additives for ordinarily flammable polymer substrates becomes progressivel more' inefficient when they contain substantially less than about 5% by weight of one or more bis (hydrocarbyl) vinyl-phosphonates, since the resulting blend will then require th contra ίύο:ι::; of these: polymer additives m , in. turn, res-^j ^ in some deterioration in the inherent phys cal properties of the thus modified polymer substrate.

Specific aqueous emulsion polymer compositions which are particularly preferred are: (1) a terpoiymer of 81 parts by weight of vxnylxdene chloride., 5 parts b weight of n-butyl acrylate and 14 parts by weight of bis (beta-chloroethyl) vinyl phosphonate; (2) a terpoiymer containing 15 parts by weight of di-n-butyl vinyl phosphonate, 20 parts by weight of di-n-octy fumarate and 65 parts by weight of vxnylxdene chloride; (3) a terpoiymer containing 15 parts by, weight bis (beta-chloroethyl) vinyl phosphonate, 5 parts by weight propylene and 80 parts by weight vxnylxdene chloride; (4) a terpoiymer containing 25 parts by weight vxnylxdene bromide, 65 parts by weight bis (beta-chloroethyl) vinylphosphonate and 10 parts vinyl acetate; and (5) a polymer containing 50 parts by weight vinyl chloride, 35 parts by weight bis (2-chloroisopropyl) 1-methyl vinyl phosphonate, 15 parts by weight stearyl vinyl ether and 5 parts by weight N-methylol acrylamide.

It is important, with respect to this disclosure, to distinguish between the processes of suspension and emulsion polymerization. Thus, suspension polymerization refers to a method of polymerization whereby one or more monomers is dispersed in a suspension medium which is a non-solvent for both the monomer and the resulting polymer. Generally, water is utilized for this purpose and a monomer soluble polymerization initiator is thereupon introduced. Polymeri- y.at ion takes place within the- monomer phase, containing the polymerisation initiator. The: use of the sus ending nediur. ei sists in the dissipation of the heat of reaction and the polymerization reaction is therefore easier to control.

Suspension polymerization is generally accomplished by dispersing the monomer in the suspending medium either by constant agitation or by the use of a suspending agent or both. Various suspending agents are known in the art. These known suspending agents include gelatin, hydroxy methyl cellulose, hydroxy ethyl cellulose, hydroxy propyl cellulose, carboxy methyl cellulose, talc, clay, polyvinyl alcohol, and the like.

By contrast, emulsion polymerization, the process used in the present invention, involves a process whereby one or more monomers are emulsified i the form of droplets within a continuous phase which should be inert with respect to both the emulsified monomers and the resulting polymer.

Water is generally selected as the continuous phase.

Emulsif cation of the monomers is effected by the use of one or more of the above-described emulsif cation agents which tend to reduce the interfacial tension between the dispersed and continuous phases. Λ water soluble initiator is employed and it is believed that the polymer chains originate in the continuous, aqueous phase and then continue their growth in the dispersed monomer-polymer phase yielding the polymer product in finely divided state which remains emulsified within the continuous, i aqueous medium. Thus, an important distinction between emulsion and suspension polymerization is that in the former, the monomer is either dispersed into droplets which are ^ stabilized by an adsorbed layer of soap molecules or is solubilized in the soap micelle which is present in aqueous soap solutions. As a result, stable polymer emulsions are readily obtained whereas, in a suspension polymerization, the resulting polymer particles are of a relatively larger mass which tend to more readily separate out from the suspension.

In all cases, the aqueous emulsion or latex copolymers of this invention have been found to provide blends with ordinarily flammable polymeric materials which are characterized by their outstanding fire retardance. As used in this disclosure, the term "fire retardant" o "flame retardant" is intended to refer to that particular property of a material which provides it with a degree of resistance to ignition and burning. Thus, a fire or flame retardant composition is one which has a low level of flammability and flame spread. This property may be conveniently evaluated by means of any of the standard flame retardancy tests such as, for example, the AS M test D-635.

As has been indicated, hereinabove, the aqueous emulsion or latex copolymers of this invention are particularly suitable for blending with ordinarily flammable polymers which are in the form of aqueous systems such as solutions, suspensions, or, most preferably, emulsions.

The resulting aqueous blends may then be used in any of the various coating, adhesive, laminating and impregnating applications known to those skilled in the art. Thus, these aqueous blends may be coated upon and/or 'ib orbed Ί^ν all types of materials to which it is desired to impart fire retardant properties. They may, therefore, be used as coatings, impregnants, fillers, laminants, and adhesives for such substrates as wood; paper; metals; textiles based on either fibers or blends thereof; synthetic polymer films such as those based upon polyolefins, regenerated cellulose, i.e., cellophane polyvinyl chloride; polyesters, and the like; leather; natural and synthetic rubber; fiber-board; and synthetic plastics prepared by means of either addition or condensation polymerization techniques. In addition, the polymers of this invention may be employed as fire retardant additives in the spinning baths or dopes from which rayon and acrylic fibers are spun.

In effect, one may utilize any ordinarily flammable polymeric material in preparing fire retardant polyblends with the novel aqueous emulsion polymer of this invention. These ordinarily flammable polymeric materials may be thermoplastic polymers, i.e., polymers which can be softened by heat and which then regain their original properties on.--cooling. Also applicable are polymer systems, particularly those in aqueous emulsion form, comprising copolymers containing one or more crosslinkable comonomers, i.e., monomers containing two or more functional groups, such, for example, as N-methylol acr lamide, N-methylol methacrylamide , glycidyl acrylate and glycidyl methacrylate . Thus, the copolymers containing one or more of these crosslinkable comonomers can be cured or crosslinked, by the use of heat and/or catalysts and are thereby converted into a form in which they will no longer be thermoplastic but, will, rather, heated. vdeally, the novel aqueous emulsion copolymers this invention are blended with such crosslinkable copolymer systems prior to the time they undergo this curing or cross-linking operation.

The actual blending of the aqueous emulsion copolymers of this invention with other polymeric materials may be accomplished by means of any convenient procedure which will result in an intimate admixture of the instant copolymer within the polymeric mass. Thus, for example, the aqueous emulsion or latex of the present invention may simply be blended or otherwise admixed with a polymer v/hich should, preferably, be in the form of an aqueous solution, latex or suspension. The resulting aqueous blend can be useful i as such or can be co-coagulated to form a solid polymeric blend. Or, if desired, the aqueous polymeric emulsion of this invention cari be coagulated by freezing or by addition of NaCl solution, methanol or the like to recover the polymer in solid particulate form. The polymer additive and a polymer to be modified may be admixed while each is in the form of a solid.

The blending operation may also be carried out by means of a procedure in which the polymer which is to be modified is itself polymerized while in the presence of one of the previously polymerized aqueous emulsion polymers of this invention. Alternatively, the bis (hydrocarbyl) vinyl phosphonate-containing aqueous emulsion polymers may be polymerized, in a system which contains the previously polymerized polymer to be modified in an appropriate physical form, e.g. as an aqueous solution, suspension or emulsion.

With respect to proportions, the amount of bis (hydro carbyl) vxnyIphosphonate-containing aqueous emulsion, or latex polymer which may be admixed with an ordinarily flammable polymeric material will depend, primarily, upon such factors as the particular phosphonate polymer and the polymers which are to be blended with one another, the degree of fire retardancy desired in the resulting blend, the degree of clarity, hardness and other specific physical properties which are sought as well as other technical and economic considerations known and understood by those skilled in the art. However, in order to attain a composition which will be self-extinguishing , it is generally desirable to introduce an effective concentration of bis(alkyl) vinylphosphonate aqueous emulsion polymer solids which will be sufficient to provide the resulting . blend with at least about 0.5%,' by weight, of phosphorus and with at least about 10%, by weight, of halogen, i.e., chlorine and/or bromine, derived from the halogen containing ethylenically unsaturated monomer and also, if possible, from the bis (hydrocarbyl) vinylphosphonate.

The ire retardant polymer compositions of this invention can be prepared so as to contain various optional additives which may include plasticizers such as the alkyl esters of phthalic, adipic and sebacic acids such, for example, as dioctyl phthalate and ditridecyl phthalate and aryl phosphate esters such, for example, as triphenyl and tricresyl phosphate, etc.; lubricants and mold release agents such as stearic acid or its metal salts, petroleum based waxes, mineral oils and their halogenated products, polyethylene waxes and their halogenated products, etc.; organo-tin compounds, such as di-alkyi tin rnerciptides and di-alkyl tin maleates, thiolauric anhydride and n-butyl stannoic acid, epoxidized oils, alkyl diphenyl phosphites, triaryl phosphites, phenyl salicylates, o-hydroxy benzo-phenones and benzotriazoles , etc. For a more complete listing of plasticizers, lubricants, stabilizers and other functional additives, one may consult "Polyvinyl Chloride" by H.A. Sarvetnick published by Van Nostrand Reinhold Co. , New York, New York, in 1969.

The compositions of this invention may also contain fillers, pigments, dyes, opacifying agents, decorative additi such- as reflective metal foils or flakes, and other imbedded solid objects such as fiber glass, textile fibers, asbestos and the like, provided that they do not detract from the flame retardancy of these products. In addition, the compositions may contain other flame retardants such as antimony compounds, zinc borate, aluminum hydrate, halogenate alkyl phosphates or phosphonates , alkyl acid phosphates, or small concentrations of phosphoric acid.

The fire retardant compositions of this invention, whether comprising blends of polymeric materials with one or more of the fire retardant additives of this invention or whether comprising the fire retardant polymers of the present invention, per se, may be utilized in any of the coating, adhesive, impregnating laminating, binding and painting applications known to those skilled in the art wherein it is desired to provide fire retardancy to the resulting end product. For example, these compositions may be used in such applications as rug and carpet backing adhesives, as adhesives for fiber glass, as a backing co ting for fabrics, as heat sealable binders for non-woven fabrics, as flooring, coatings, as paper coatings, as paint bases and as adhesives for preparing laminated structures.

In addition to being used as fire retardant additives for the prepsiration of fire retardant polymer blends with flammable polymer substrates, the aqueous emulsion polymers of this invention may be used, per se, in any of the various coating, painting adhesive, laminating, impregnanting and binding applications known to those skilled in the art.

Thus, they may be coated upon and/or adsorbed by all types of substrates to which it is desired to impart fire retardant properties. They may, therefore, be used as coatings, impregnants, fillers, laminants, and adhesives for such substrates as wood; paper; metals; non-woven fabrics and textiles based on either natural, synthetic, mineral or glass fibers or blends thereof; synthetic polymer films such as those based upon polyolefins, regenerated cellulose, i.e. cellophane, polyvinyl chloride, polyesters and the like; leather, natural and synthetic rubber; fiberboard;-and, synthetic plastics prepared by means of either additio or condensation polymerization techniques.

The following examples will further illustrate the various embodiments of this invention. In these examples, all parts and percentages given are by weight unless otherwise noted.

EXAMPLE I This example illustrates the effectiveness of sodium sulfosuccinamates as emulsifiers for preparing stable polymeric latices. This example also illustrates that other pared from one or more of the monomers employed in the ^ present invention (See, for example, U.S. 3,489,706 and 3,682,871), are in fact, not equivalent and essentially unsuitable for use in the preparation of the stable latices of the present invention.

Into a 32 ounce polymerization vessel, there are charged 150 grams of bis (beta-chloroethyl) vinylphosphonate , hereinafter referred to as "bis-beta", 15 grams -methylol acrylamide, 60 grams vinylidene chloride, 280 grams deionized water and 60 grams of a 10% aqueous solution of tetrasodium - (1, 2-dicarboxyethyl) -N-octadecyl sulfbsuccinamate . The pH of the resulting mixture is adjusted to a value of 7 by addition of 3.3 mis of 58% aqueous solution of ammonium hydroxide, whereupon 40 grams of a 10% aqueous ammonium persulfate solution is added to the mixture. The air space above the liquid level in the reactor is purged with nitrogen and the vessel is sealed. The vessel is shaken to form a stable emulsion. Polymerization is effected at a temperature of 50°C. over a period of 12 hours with a polymerization vessel being continuously subjected to a tumbling agitation. An extremely stable latex of good color stability is obtained exhibiting a gum and floe level of less than 1%. When the latex is poured onto a Petri dish and dried, a film exhibiting a soft hand is recovered. When ignited with a Bunsen burner for two seconds and the burner than removed, the film does not support combustion and therefore exhibits good FR properties. Λ portion of the emulsion prepared above is blended with an aqueous emulsion containing 46% of polybutyl acrylate polymer particles whose films are ordinarily flammable. The concentration of the bis-beta polymer uolids in the blend is 20% based o the polybutyl aerylate solids. A -film having a dry thickness of 5 mils is cast from the polymer blend ind is found to exhibit a good fire retardance.

COMPARATIVE EXAMPLE 1 Example 1 is repeated except that 60 grams of a 10% aqueous sodium lauryl sulfate solution is employed in the emulsifier in lieu of the sodium sulfosuccinamate employed. Polymerization is effected under identical conditions. The resulting emulsion is characterized by all floe.

EXAMPLE 2 Example 1 is repeated except that disodium N-octadec sulfosuccinamate is employed in lieu of tetrasodium N- (lf2-dicarboxyethyl) -N-octadecyl sulfosuccinamate . A stable latex is similarly obtained.

Claims (11)

WHAT IS CLAIMED IS: C • J

1. A stable fire retardant polymer latex comprising (1) at least one halogen-containing a, β-ethylenically unsaturated monomer, (2) at least one bis (hydrocarbyl) vinyl-phosphonate of the formula: in v/hich X is selected from the group consisting of hydrogen, halogen, c and, phenyl, alkyl of from 1 to 18 carbon atoms and the grouping 0 and each R and R' are hydrocarbyl of from 1 to 13 carbon atoms, and (3) at least one monomer selected from the group consisting of alpha olefins, vinyl esters of carboxylic acids, alkyl esters of acrylic and methacrylic acid, ethylenxcally unsaturated dicarboxylic acids, anhydrides of ethyleniccxlly unsaturated dicarboxylic acid, C1-C20 rnono-and di-alkyl esters of ethylenxcally unsaturated dicarboxylic acids, amides of ethylenxcally unsaturated carboxylic acid and their N-meth lol and diacetone derivatives; vinyl aryl compounds; CJ-C2Q alkyl vinyl ethers; C4-C20 dienes, and glycidyl esters of acrylic and methacrylic acid; said latex prepared by an emulsion polymerization process in which the emulsifier is a sodium sulfosuccinamate of the formula: CH2-C-N 1 VR2 NaOSO?-CII-C-0-Na tl 0 V in "which -, is hydrogen, a hydrocarbyl radical having fro:?, 1 to 18 carbon atoms, or di-sodium, 1, 2-dicarboxy ethyl, and R2 is a hydrocarbyl radical having from 1 to 18 carbon atoms .

2. A fire retardant polymer latex according to claim 1 in which, in the sodium sulfosuccinaraate emulsifier, is hydrogen, alkyl of from 16 to 18 carbon atoms or di-sodium, 1 , 2-dicarboxy . ethyl, and R2 is alkyl of from 16 to 18 carbon atoms.

3. A fire retardant polymer latex according to claim 2 in which the emulsifier is tetrasodium N-(l,2-di-carboxyethyl) -N-octadecyl sulfosuccinamate .

4. A fire retardant polymer latex according to claim 2 in which the emulsifier is di-sodium N-octadecyl sulfosuccinamate .

5. A fire retardant polymer latex comprising: (1) a vinyl halide or vinylidene halide, (2) a bis (hydrocarbyl) vin Iphosphonate of the formula: o in which X is selected from the group consisting of hydrogen, halogen, cyano, phenyl, alkyl of from 1 to 18 carbon atoms and the grouping 0 0R- 1 and each of R and R' is selected from the group consisting , of alkyl of from 1 to 18 carbon atoms, alkenyl of from 2 to 18 carbon atoms, cycloalkyl of from 3 to 8 carbon atoms, phenyl, benzyl, phenethyl, tolyl and naphthyl, and (3) a comonomer selected from the group consisting of the 0-^-020 alkyl esters of acrylic and methacrylic acid and the N-methylol and diacetone derivatives of amides of ethylenically unsaturated carboxylic acids^ said latex prepared by an emulsion polymerization process in which the emulsifier is tetrasodium N- (1, 2-dicarboxyethyl) -N-octadec 1 sulfosuccinama or di-sodium N-octadecy1 sulfosuccinamate.

6. A fire retardant polymer latex according to claim 5 which comprises: (1) vinylidene chloride, (2) bis ( fS-chloroethyl) vinylpnosphonate, (3) a C^-Cg alkyl ester of acrylic acid and (4) N-methylol acrylarnide.

7. A fire retardant polymer latex according to claim 6 in which the alkyl ester of acrylic acid is n-butyl acrylate.

8. A fire retardant polymer latex according to claim 6 in which the alkyl ester of acrylic acid is 2-ethylhe acrylate.

9. Process for preparing a stable fire retardant polymer latex comprising: i) admixing water and (1) a halogen-containing ethylenically unsaturated monomer, (2) a bis (hydrocarbyl) vinyl phosphcnate and (3) at least one monomer selected from the group consisting of alpha olefins, vinyl esters of ( ( carboxylic acids, C-^-C alkyl esters of acrylic and 20 methacrylic acid, ethylenically unsaturated dicarboxylic acids, anhydrides of ethylenically unsaturated dicarboxylic acid, C-i-C n mono- and di-alkyl esters of ethylenically unsaturated carboxylic acid and their N-methylol and diacetone derivatives; vinyl aryl compounds; cJL_C2Q alkyl vinyl ethers; C ~"C2o dienes, and glycidyl esters of acrylic and methacrylic acid; ii) admixing therewith a sodium sulfosuccinamate emulsifier of the formula: O O in which R-^ is hydrogen, a hydrocarbyl radical having from 1 to 18 carbon atoms or di-sodium 1, 2-dicarboxyethyl, and R is a hydrocarbyl radical having from 1 to 18 carbon atoms; iii) admixing therewith a free radical generating catalyst, and effecting polymerization of the monomer admixtu to obtain a stable latex.

10. Process as defined in claim 9 where the emulsifi is tetrasodium N- (1, 2-dicarboxyethyl) -N-octadecyl sulfosuccin amate.

11. Process as defined in claim 9 wherein the emulsifier is di-sodium N-octadecyl sulfosuccinamate .