This application claims priority to Provisional U.S. Patent Application No. 61/954,160, with a filing date of March 17, 2014, the entire contents of which are incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to the field of flame-retarded PVC nanocompo sites and more particularly to a flame-retarded PVC composition(s) and articles containing the same, e.g., a flame-retarded cable jacket, vinyl films/sheet goods, PVC tubing or automotive component(s).

BACKGROUND OF THE INVENTION

Polyvinyl chloride (PVC) is often employed to achieve a pass of high standardized levels of flammability and also to obtain improved light, oxidative stability as well as high resistance to abrasion all at low cost.

However, PVC has problems with process stability which can lead to discoloration, or in more severe cases, to the lost of physical properties. Thermal decomposition of PVC has been well studied and is attributed to a mechanism known as "autocatalytic dehydrohalogenation" or an "unzipping" reaction; i.e., the PVC may degrade before melting or during compounding.

Due to its high chlorine content (56.8%), unplasticized PVC products do not contribute to fire propagation and pass most flammability tests without flame retardants. The oxygen index (01) of PVC is 45.0 to 49.0, but when PVC is forced to burn, it can generate high levels of black smoke. In the case of flexible PVC, in most instances, the plasticizer(s) has flame resistance. The oxygen indices of piasiicized PVC in general obey a simple two-parameter equation wherein the plasticizer is often more flammable than the PVC itself. In order to meet flammability specifications such as oxygen index, heat release, smoke evolution, or cable tests, fiame- retardants and smoke-suppressants are often incorporated into plasticized PVC.

In the last two decades, it has been found that nanometer-sized particles dispersed in a polymer matrix helps to improve, not only the physical properties of the polymer matrix, but also, the polymer's resistance to fire. Most common nanocomposite materials comprise a polymeric matrix in which particles of clay of a nanometric size are dispersed therein, e.g., so- called organoclays, e.g. organophilically treated clays. Good dispersion has been shown to provide for a consistent improvement of the physical properties and resistance against fire. It is believed that the latter feature is due to the formation of a ceramic-carbonaceous protective layer (char) on the surface of the burning polymer, which impedes the evolution of combustible gases and therefore reduces the speed of fire propagation.

But unfortunately, previous attempts to obtain PVC nanocomposites that would provide similar desirable advantages, have not produced satisfactory results. This is because the quaternary amine quarts which are used for the intercalation of the clays that are compatible with PVC, have been shown to cause the catalytic "unzipping" reaction, described above. Numerous attempts of resolving this problem by using more thermally stable imidazolium quarts or other types of quarts have not been successful.

Nanocomposites are commercially available in various polymers such as polyamides, polyesters, polypropylene, poly(ethylvinyl acetate) and similar polymers, but nanocomposites are not available in PVC, because, commercially available organoclays have not been shown to be compatible with PVC.

SUMMARY OF THE INVENTION

It is therefore a feature of the present invention to provide a phosphate ester-modified clay composition, along with the process of making a phosphate ester-modified clay, as well as a PVC nanocomposite comprising PVC resin and the phosphate ester-modified clay composition, which has improved flame retardant properties, as well as articles comprising the PVC nanocomposite comprising the phosphate ester-modified clay such as the non-limiting examples of vinyl-based jackets for electric cables, vinyl film/sheet goods, PVC tubing or automotive component(s) with improved resistance to high temperatures and to flames.

The nanocomposite comprising PVC resin and phosphate ester-modified clay has the same or improved light, oxidative stability and resistance to abrasion as compared to

nanocomposites containing PVC resin and un-modified clay. Further the PVC nanocomposite of the present invention provides for flame retardant efficiency in PVC compounds while avoiding the aforementioned problems.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is an XRD scan of original clay (PGN) and clay treated with Phosflex 418 (418-PGN) as described in Example 1.

Figure 2 is a photograph of the process stability test at 185°C/55rpm/variable times as described in Examples 2-5.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to a phosphate ester-modified clay composition, along with the process of making a phosphate ester-modified clay, as well as a PVC nanocomposite comprising PVC resin and the phosphate ester-modified clay composition, which has improved flame retardant properties. The phosphate ester clay is made by reacting a clay, e.g., a smectite- type clay with a phosphate ester, wherein the phosphate ester doesn't destabilize PVC, e.g.

doesn't cause catalytic unzipping. Such flame-retarded PVC nanocomposite can be used in cable jacketing in production of PVC tubing or in production of automotive parts or a like while providing flame retardancy and maintaining good physical properties.

There is provided a phosphate ester-modified clay composition comprising a clay and a phosphate ester.

The phosphate ester modifier is a phosphate ester containing from one to three long aliphatic chains, more specifically one, two or three linear or branched alkyl, cycloalkyl, linear or branched alkyl-substituted cycloalkyl, linear or branched alkenyl, and linear or branched alkynyl groups containing up to about 30 carbon atoms, more specifically up to about 20 carbon atoms, even more specifically up to about 12 carbon atoms, yet even more specifically up to about 8 carbon atoms, wherein said ranges are understood in one embodiment to contain a lower endpoint of one, three or six carbon atoms, as can any of the other ranges of R ¹ , R ² or R ³ defined herein. In particular, the phosphate ester may have the following structure formula (I):

O

1 I! ,

R ¹ — O-P— (0)n— R

0

l ₂

^R (I) where R ¹ and R ² are independently phenyl, alkyl substituted phenyl or linear or branched, or saturated or unsaturated alkyl containing up to 22 carbon atoms, more specifically from 6 to about 22 carbon atoms and, R ³ is linear or branched or saturated or unsaturated alkyl containing up to about 22 carbon atoms, more specifically from 6 to about 22 carbon atoms, n is 1 or 0.

In one specific embodiment the phosphate ester is alkyl diphenyl phosphate of the general formula (II)

where R ³ is a linear or branched or saturated or unsaturated alkyl containing up to 22 carbon atoms, more specifically from 6 to 22 carbon atoms.

Examples of commercial phosphate esters specifically useful in this invention are those selected from the group consisting of triphenyl phosphate, tricresylphosphate, mixed phenyl- cresyl phosphates, trixylyl phosphate, mixed phenyl-xylyl phosphates, tris(propylphenyl) phosphate, mixed propylphenyl phenyl phosphates, tris(isopropylphenyl) phosphate, mixed isopropylphenyl-phenyl phosphates, tris(butylphenyl) phosphate, mixed butylphenyl-phenyl phosphates, tris(isobutylphenyl) phosphate, mixed isobutyl-phenyl phosphates, tri(ehylhexyi) phosphate, tri(isodecyl) phosphate, dimethyl hexylphosphonate, dimethyl octylphosphonate, diethyl hehylphosphonate, diethyl octylphosphonate and combinations thereof.

The most specific phosphate esters useful in this invention are selected from the group consisting of 2-ethylhehyl diphenyl phosphate available from ICL-IP as Phosflex 362, isodecyl diphenyl phosphate available from ICL-IP as Phosflex 390, a linear alkyl Cn-Ci3 diphenyl phosphate available from ICL-IP as Phosflex 418 and combinations thereof.

The phosphate ester-modified clay composition will contain from 5 to 40% by weight phosphate ester, specifically from 15 to 40% by weight of phosphate ester, more specifically from 25 to 40 % by weight of phosphate ester, based on the total weight of the phosphate ester- modified clay composition used to make the flame-retardant PVC nanocomposite.

In one particular embodiment, the clay is obtained from a smectitic-type clay selected from the group consisting of montmorillonite, hectorite, saponite and combinations thereof.

The clays useful for making the nanocomposites herein can be layered clay materials comprising an agglomeration of individual platelet particles that are closely stacked together in domains called tactoids. Individual platelet particles of the clays specifically can have tliickness of less than 2 nm. The clay material can be selected from the group of natural or synthetic phyllosilicates, or combinations thereof. Some suitable natural clays include smectite clays such as montmorillonite, saponite, hectorite, mica, vermiculite, bentonite, nontronite, beidellite, volkonskoite, saponite, magadite, kenyaite, and the like. Natural clays can be further refined or purified to remove undesirable impurities. Some suitable synthetic clays can include synthetic mica, synthetic saponite, synthetic hectorite, and the like.

A bentonite or montmorillonite with mineral content large than 50% is appropriate for the composition/nanocomposite and applications described herein. The higher purity can be achieved via selective mining, purification or synthetic processes.

The most specific clays useful in this invention are purified montmorillonite clays available from Nanocor LLC, Hoffman Estates, IL 60192, USA. Typical products include PGN, PGW and PGV.

Advantageously, the clay can be previously purified of impurities embedded therein, thus, obtaining a purified clay, in particular, the purification process lowers the impurities to less than 2% by weight, preferably less than 1% by weight.

The selected natural or synthetic clay (purified or not) can be further treated to increase spacing between the platelets to facilitate separation of the platelet agglomerates to individual platelet particles to form smaller-sized tactoids. Such treatment prior to incorporation into the polymer also improves the polymer/platelet interface. Any method of treatment that achieves the above goals can be used. Many clay treatments used to modify the clay for the purpose of improving dispersion of clay materials are known and can be used.

Some of the more common treatments are made via ion exchange mechanisms, such as using organocations to treat natural clays. The organocations exchange with the natural interlayer cations of the clay to generate organophilic surfaces while maintaining a lamellar structure similar to the natural clay. In one embodiment herein, the organocations are not quaternary ammonium compounds, in that, as stated above, quaternary ammonium compounds are damaging to PVC because they catalyze dechlorination and unzipping of the resin.

Because of this limitation the treated layered clay material, alternatively called

"organoclay" or "phosphate ester-modified clay" herein is prepared by the reaction of a swellable layered clay with a phosphate ester. This is not the above noted cation exchange reaction, but rather, an absorption reaction which proceeds by coordination of dipolar phosphate group with the charged clay platelets. Similar to the organocation exchange reaction the absorption reaction results in production of the organophilic clay. If desired, two or more phosphate esters can be used to treat the clay.

In one specific embodiment the bentonite clay having Na ⁺ or Ca ²⁺ as interlayer cations is used. Most of the time, these cations are coordinated with H ₂ 0 molecules. The oxygen of the P=0 bond of a phosphate ester can form coordination bond with these cations when the phosphate ester come in contact with the Na ⁺ or Ca ²⁺ in the clay interlayer region. Once the Na ⁺ and Ca ²⁺ are coordinated to the phosphate ester, the clay become hydrophobic and can be dispersed into the PVC polymer resin system to form polymer-clay nanocomposite materials. Typically, 10% phosphate ester is needed to convert the clay to a hydrophobic state. The more specific ratios are 30%-40% of phosphate ester in the final phosphate ester-modified clay.

In one non-limiting embodiment, the phosphate ester is chemically intercalated between the layers of the clay.

Water is the more specific media for delivering phosphate ester in contact with interlayer cations in the clay. The formation of the phosphate ester-modified clay can be carried out in dilute clay suspension/slurry form and followed by drying using means such as the non-limiting embodiments of natural sun-dry, heated drum drying or high efficiency spray drying. The reaction can also occur in a solid-like environment via an extrusion process with the assistance of water. The process to prepare the phosphate ester-modified clays can be conducted in a batch, semi-batch, or continuous manner.

This and other features are accomplished with a non-limiting method for the production of a phosphate ester-modified clay comprising the steps of: blending a clay, e.g, a smectite-type clay, water and a phosphate ester in a mixture; and, drying the mixture to produce the phosphate ester -modified clay.

There is also provided herein a flame retarded PVC nanocomposite comprising a PVC resin and a flame retardant effective amount of phosphate ester-modified clay as described herein.

The clay is dispersed in the PVC resin so as to provide a mixture of nanoclay platelets dispersed among the PVC molecules. This feature avoids the production of HC1 and therefore the decomposition of polyvinylchloride.

In one embodiment herein, the phosphate ester-modified clay, or the flame retarded PVC nanocomposite further comprises an inorganic additive (filler). In particular, the inorganic additive can be selected from the group comprised of aluminum hydroxide, magnesium hydroxide, calcium carbonate, talc, antimony oxide, zinc borate, glass powder and combinations thereof.

The combination of a clay with an inorganic additive has a synergistic effect and provides a product with surprising flame retardant properties, e.g., in the flame retarded nanocomposite described herein.

Preferably, the nanocomposite is obtained by mixing from 1 to 60 parts by weight of a phosphate ester-modified clay per one hundred (100) parts of resin (phr), i.e., the polymeric PVC matrix.

More specifically, the nanocomposite comprises between 0 to 50 phr of inorganic additive. PVC resins suitable for use in the present invention include, but are not limited to, polyvinyl chloride (PVC), chlorinated polyvinyl chloride (CPVC), and other PVC resins, alloys/blends. The preferred resin for the present invention is polyvinyl chloride (PVC). The present invention may be applied to both rigid and flexible PVC formulations. As used herein, the definition of a "rigid" formulation is a formulation having a plasticizer in a concentration of zero to less than about 5 parts per hundred of resin (phr). A "flexible" formulation typically has a plasticizer in a concentration from greater than about 5 to as much as about 150 parts per hundred of resin (phr).

Several types of commercial PVC may be used. For particular applications, certain molecular weight PVC resins may be selected for optimum physical properties and process performance. Generally, suspension PVC resins have better thermal stability than PVC resins produced by mass or emulsion polymerization. Other properties such as average particle size, particle size distribution, porosity, and the like may greatly affect the performance of PVC resin in the same formulation.

PVC nanocomposite in the context of this invention is the combination of the phosphate ester-modified clay in a PVC matrix.

In one embodiment herein, the flame-retardant effective amount can vary greatly depending on the particular PVC resin being employed, the desired article and/or application to which the PVC nanocomposite directed and processing limitations. In one non-limiting embodiment, the flame-retardant effective amount is the amount of phosphate ester-modifed clay described above, i.e., 1 to 60 parts by weight of an phosphate ester-modified clay per one hundred (100) parts of resin (phr), i.e., the polymeric PVC matrix, more specifically from 5 to about 45 parts by weight and most specifically from about 10 to about 40 parts by weight.

To prepare the PVC nanocomposite, the components, e.g., the phosphate ester-modifed clay and the PVC resin, and any others, can be mixed by any known methods. Typically, there are two distinct mixing steps; a premixing step and a melt mixing ("melt blending") step. In the premixing step, the dry ingredients are mixed together. The premixing is typically performed using a tumbler mixer or ribbon blender. However, if desired, the premix can be manufactured using a high shear mixer such as a Henschel mixer or similar high intensity device. The process is typically followed by melt mixing in which the premix is melted and mixed again as a melt- blended composite. Alternatively, the premixing can be omitted, and raw materials can be added directly into the feed section of a melt mixing device, preferably via multiple feeding systems. In melt mixing, the ingredients are typically melt kneaded in a single screw or twin screw extruder, a Banbury mixer, a two roll mill, a batch mixer or similar device. The examples are batch mixed using a Brabender type bowl mixer with a temperature regime of 160° to 180° C.

Alternatively phosphate ester-modified clay of the present invention can be added to PVC resin in the form of a masterbatch (or concentrate) and further melt mixed with PVC and other ingredients. In the context of this invention, a masterbatch is a concentrated form of the additive blended into a compatible resin base to benefit dispersion and provide the clay in an exfoliated form for improved properties in the finished compound.

PVC nanocomposites offer flame-retardancy properties because such nanocomposite formulations burn at a noticeably reduced rate and form a hard char at the surface. They also exhibit minimum dripping and fire sparkling. In order to pass more stringent flame retardant tests (for example for the cable industry) the use of antimony based flame retardants may also required in the phosphate ester-modified clay composition, as well as the resultant PVC nanocomposite thereof.

In one specific embodiment the phosphate ester-modified clay composition, as well as the resultant PVC nanocomposite thereof may further comprise at least one of an antimony -based flame retardant (e.g., an antimony trioxide flame retardant), a flame retardant filler, an inert filler and a functional filler.

In one more specific embodiment the phosphate ester-modified clay composition, as well as the resultant PVC nanocomposite thereof may still further comprise, optionally in addition to any of the above noted components, at least one plasticizer.

In one specific embodiment of this invention, the antimony based flame retardant is antimony trioxide. The typical particle size of antimony based flame retardants is from 0.5 μιη to 5 μηι. Antimony based flame retardants may be surface-treated with an epoxy compound, silane compound, isocyanate compound, titanate compound, or the like as required. In addition to antimony trioxide, other examples of antimony based flame retardants can be antimony pentaoxide or sodium antimonate and combinations of any of the noted antimony synergists.

In one non-limiting embodiment the antimony the antimony can be present in an amount from 0.5 to 10 parts per one hundred parts of PVC resin (p.h.r.), more preferably from 2 to 7 p.h.r.

Apart of the clay of this invention and antimony based flame retardant, the PVC nanocomposite can contain other flame retardant fillers for example aluminium trihydroxide (ATH) or inert fillers such as chalk or talc or glass powder. ATH is particularly preferred because of its FR efficacy and low costs. Other known inert fillers or flame retardant fillers could be used instead of or in addition to those listed above and still produce a synergistic effect.

Examples of these include: magnesium carbonate, magnesium hydroxide (which could be added as either the refined compound or the ore brucite), hydromagnesite, huntite, boehmite, bauxite. Other functional filler which are typically used for smoke suppression are borates (e.g., zinc borates, calcium borates or barium borate) and molybdates (e.g., ammonium molybdates, ammonium octamolybdates). It is to be understood that these inorganic fillers may be added to PVC nanocomposites either individually or in combinations of two or more.

In one non-limiting embodiment the flame retardant filler (or any of the fillers described herein) can be present in an amount from 20 to 100 parts per one hundred parts of PVC resin (p.h.r.), more preferably from 20 to 70 phr.

In addition to the phosphate ester chemically coordinated between the layers of clay, additional phosphate ester plasticizer can be added to the phosphate ester-modified composition and flame-retarded PVC nanocomposite as the primary plasticizer or in combination with other types of plasticizers. The phosphate ester herein can be the same phosphate ester employed in the clay or different. The phosphate ester employed herein can be halogenated or non-halo genated.

Representative halogenated compounds used herein with generally good results include tris(chloropropyl)phosphate (TCPP), tris(dichloroisopropyl)phosphate (TDCP) and 2,2- bis(chloromethyl)trimethylene bis[bis(2-chloroethyl)phosphate] (chlorinated diphosphate or V6 type product) and their mixtures. Mixtures of different phosphate ester compounds are also contemplated, e.g., mixtures of halogenated and non-halogenated.

In one embodiment the phosphate ester can be any phosphate ester than contains at least one aryl moiety, wherein the aryl moiety can be alkyl substituted or non-substituted. When the aryl moiety is alkyl substituted it can comprise substitution by an alkyl of from 1 to 6 carbon atoms, preferably from 1 to 4 carbon atoms, most preferably, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl and the like, wherein such alkyl substitution can occur in any one or more of the available carbon atoms of the aryl moiety.

In one embodiment, the aryl phosphate ester is selected from the group consisting of butylated aryl phosphate, a propylated aryl phosphate, or a methylated aryl phosphate. In one embodiment such a butylated aryl phosphate could be t-butyl substituted. In one other embodiment such a propylated aryl phosphate could be isopropyl-substituted.

In one more specific embodiment, the aryl phosphate ester is selected from the group consisting of dibutyl phenyl phosphate, butyl diphenyl phosphate, 2-ethylhexyl diphenyl phosphate, isodecyl diphenyl phosphate, cresyl diphenyl phosphate, triphenyl phosphate, tricresyl phosphate, butylated or isopropylated triphenyl phosphate and combinations thereof.

In one specific embodiment the aryl phosphate ester herein is available as Phosflex 7 IB or Phosflex 31L, both available from ICL-IP.

In another specific embodiment herein the phosphate ester is selected from the group consisting of ethylhexyl diphenyl phosphate, such as Phosflex 362, isodecyl diphenyl phosphate ester, such as Phosflex 390 and, C ₎₂ -Ci4 linear alkyl ester of diphenyl phosphate, such as Phosflex 418 all available from ICL-IP.

Instead of phosphate ester plasticizer the flame retarded P V C nanocomposite can contain non flame retardant plasticizers. Representatives of non flame retardant plasticizers are adipates, citrates; non-halogenated phthalates (e.g., di-2-ethyl-hexyl, di-n-octyl, dioctyl, diisooctyl, diisodecyl, dibutyl, dihexyl, or diheptylnonyl); bisphthalates; benzoates; trimellitates;

pyromellitates; azelates; polymeric plasticizers based on adipic, azelaic, or sebacic acids and glycols such as ethylene, propylene, and butylene, with either alcohol or monobasic acid termination (e.g., benzoate diester of 2,2,4 trimethyl pentanediol or triethylene glycol di-2- ethylhexanoate); epoxies; esters of dibasic acids (e.g., aliphatic ester adipates such as dioctyl adipate, aliphatic ester sebacates such as dioctyl sebacate); alkyl sulfonate esters; aliphatic hydrocarbons; aromatic hydrocarbons; alkylated aromatic hydrocarbons; butyl phthalyl butyl glycollate, isobutyrate; dipentaerythritol esters; and combinations thereof.

In should be understood that phosphate ester plasticizers and non flame retardant plasticizers can be employed in the flame-retarded PVC nanocomposite composition as a mixture thereof. Specific proportion of each plasticizer depends on the final application and the flammability test.

In addition to phosphate ester plasticizers and non-flame retardant plasticizers, halogenated non phosphate ester based plasticizers can be employed in the flame retardant PVC nanocomposite composition. Dialkyl or dialkenyl tetracholophthalates and tetrabromophthalates represent one common class of halogenated phthalate plasticizers. More specifically the dialkyl or dialkenyl tetrahalophthalate is a C5-C15 alkyl or alkenyl tetrahalophthalate. Even more specifically the dialkyl tetrahalophthalate is bis-2-ethylhexyl tetrachlorophthalate, bis-2- ethylhexyl tetrabromophthalate, bis-trimethylhexyl tetrabromophthalate, bis-isodecyl

tetrabromophthalate, bis-isotridecyl tetrabromophthalate or bis-octyl tetrabromophthalate.

Another class of halogenated non phosphate based plasticizers is halogenated paraffins. Halogenated paraffins can provide secondary plasticizing effects and also flame retardant properties. The halogenated paraffin can be brominated paraffin, chlorinated paraffin, bromochlorinated paraffin, and mixtures thereof, produced from a straight chain C ₁₀ to Q20 paraffins.

Unlike most thermoplastics, PVC is a shear-sensitive, heat-sensitive, and ultraviolet light sensitive polymer. Most applications for PVC require a well-balanced formulation with all ingredients carefully selected. Therefore the phosphate ester-modifed clay composition and the PVC nanocompo sites thereof of present invention can be stabilized and mixed with other formulating ingredients, including, but not limited to, thermal stabilizers, plasticizers, lubricants, processing aids, impact modifiers, other inert and functional fillers, antioxidants, ultraviolet light stabilizers, hindered amine light stabilizers, pigments, anti-static agents; foaming agents;

blowing agents; metal deactivators, and combinations thereof, then processed into useful articles. The phosphate ester-modified clay composition and the PVC nanocomposites thereof of present invention are useful for producing flame-retarded cable jacket, a film, a sheet, PVC tubing or automotive component(s).

The following examples are used to illustrate the present invention.

EXAMPLES

Example 1 : Production of organoclay

Purified bentonite clay PGN produced by Nanocor was used. It is a Na+ rich bentonite. Phosflex 418 from ICL-IP is the selection of phosphate ester. Phosflex 418/water/PGN (weight ratio: 30/30/100) were fed into the main feed of a continuous mixer. The mixture was mixed under high shear at 120°C temperature. The compounded mixture was placed on a dryer to remove water. The dryer was set at 150°C heating temperature. The dried mixture had less than 5% moisture. The dried mixture was milled to fine powder with a mean particle size in the range of 10-20 microns. As Figure 1 shows, X-ray diffraction was used to investigate the structural change of the clay after the Phosflex reaction. The line of original PGN has a dOOl interlayer spacing (7 degree, 2 theta) at 12- 13 A, which is typical for hydrated bentonite clay. The peak at 4.5 A (19.5 degree, 2 theta) belongs to the clay d020 silicate structure. The line for the clay reacted with Phosphlex 418 marked as 418-PGN has a dOOl interlayer spacing (2.45 degree, 2 theta) at 36-37A. The original dOOl of PGN did not exist in the mixture. Therefore, the

Phosflex 418 had entered the clay interlayer region to form a complex with Na ⁺ . The d020 silicate structure of the mixture was identical to the original PGN clay since tliere was no change in the clay silicate layer structure after the Phospflex interaction with the clay.

Materials: a - Suspension grade PVC resin, Oxychem 240 PVC, ex. Oxychem b _\ - phosphate ester treated organoclay (example 1), 25% Phosflex 418 b _{2 -} phosphate ester treated organoclay (example 1), 40% Phosflex 418 b ₃ ~ untreated bentonite clay, PGN, ex. Nanocor b ₄ - clay treated with quaternary amine, Nanomer I.44P, ex. Nanocor C] - phthalate ester plasticizer, DINP, Jayflex 911, ex. Exxon-Mobil

C2 - phosphate ester plasticizer, Phosflex 418, ex. ICL-IP

C3 - phosphate ester plasticizer, Phosflex 7 IB, ex. ICL-IP d - Flame retardant, antimony trioxide, ex. Laurel si - Ca ^' Zn stabilizer, MC90265-KA, ex Baerlocher e ₂ - Epoxidized soya oil stabilizer, Estabex 2307, ex. Akcros

Examples 2-5: Process Stability

Formulations used in process stability experiments are shown in Table 1.The

formulations were tested in the Brabender bowl mixer at 185° C, at 55 rpm rotation speed for various time. All materials were pre-blended prior to Brabender mixing. Using the chute attachment, the mixtures were charged into the bowl and timed immediately after all the materials were transferred into the mixing head. Small portions of fluxed compound were pulled from the bowl and immediately formed into disks. These disks were mounted onto a folder and presented as a side to side comparison of time vs. color development in Figure 2. Timed mixing intervals were set at 1.5, 3, 5, 7, 10, 15, 20, 25 and 30 minutes. As it is seen in Figure 2, Comparative example containing the untreated clay (PGN) showed essentially no color development except for the natural color of the clay itself. Comparative example 3 with the quaternary amine treated clay exhibited significant discoloration after ten minutes of processing and within the next five minutes developed a deep brown hue with obvious polymer degradation agglomerates (black specks). The trial containing Nanomer I.44P (amine treated clay was terminated at this point (fifteen minutes). Both phosphate ester treated organoclays (at 25% and 40% Phosflex 418 content) showed no color development after thirty minutes of this aggressive process regime similar to untreated clay. Table 1 , Compositions of PVC compounds used in process stability study

Examples 6- 4; Combustion and Physical Properties

Processing:

The formulations were mixed in the Brabender bowl mixer at 165° C, at 55 rpm rotation speed for 5 minutes. All materials were pre-blended prior to Brabender mixing. Compositions are shown in Table 2.

Test methods:

Limiting Oxygen Index - flammability test, ASTM 2863, LOI Apparatus, ex. Tinius

Olsen

Heat release rate, smoke - flammability test, ASTM El 354, Heat flux 50 kW/m ² , Cone calorimeter, ex. Stanton Redcroft

Tensile strength - physical property, ASTM D638, D5565 Tester, ex. Instron

Shore A hardness - physical property, ASTM D2240, Shore A Durometer. Two numbers were measured; the initial (value when the probe is first plunged into the composite) and

"creeped" hardness (after fifteen seconds of applied pressure).

Results of the combustion tests and physical properties for flame-retarded PVC nanocomposites are shown in Table 2. As it is seen, phosphate treated clay allows replacement of 50% of antimony trioxide without loss of flame retardant efficiency in these vinyl compounds. Table 2: Composition, flammability data and physical properties of flame-retarded PVC nanocomposites