EP1023380A1

EP1023380A1 - Polyvinyl chloride based plenum cable compositions

Info

Publication number: EP1023380A1
Application number: EP98953618A
Authority: EP
Inventors: Arvind M. Rao; Vijay Kotak; Douglas G. Placek
Original assignee: Great Lakes Chemical Corp
Current assignee: Great Lakes Chemical Corp
Priority date: 1997-10-16
Filing date: 1998-10-16
Publication date: 2000-08-02
Also published as: IL135486A0; AU1094899A; KR20010024512A; WO1999019395A1

Abstract

Flame retardant compositions comprising a poly(vinyl chloride) resin, a chlorinated poly(vinyl chloride) resin, or a mixture thereof; a polyhaloalkylphosphate and/or polyhaloalkylthiophosphate flame retardant of formula (I) in which M is sulfur or oxygen and X?1, X2, and X3¿ are each independently a halogen selected from the group consisting of chlorine and bromine; and a compatibilising agent (exudation inhibitor), are disclosed. Preferably the compositions comprise sufficient flame retardant and other halogenated additives to provide a composition whose halogen content is about 2.0 % by weight greater than that of the poly(vinyl chloride) resin, chlorinated poly(vinyl chloride) resin, or mixture thereof. These compositions can meet flame retardant standards using smaller quantities of flame retardant, thereby reducing the cost of the composition, and also be formulated so as to be easier to use in wire and cable manufacturing processes.

Description

POLYVINYL CHLORIDE BASED PLENUM CABLE COMPOSITIONS

TECHNICAL FIELD

This invention relates to compositions having flame retardant properties with reduced smoke evolution upon burning, as well as improved stability and processing characteristics. In particular, this invention relates to flame retardant poly(vinyl chloride) compositions, which find particular application in the primary insulation and sheathing of plenum cables.

BACKGROUND

PNC (polyvinyl chloride) and CPVC (chlorinated polyvinyl chloride) are widely used in wire insulation and cable sheathing, typically in combination with a plasticizer so that they can be processed as a flexible material. Typically the compositions also comprise a thermal stabilizer.

One particular application, requiring enhanced flame and smoke resistance, is the manufacture of plenum cable. Plenum cables are electrical cables installed in confined spaces, such as the air handling plenums in buildings, to provide electrical connections (both voice and data) between different parts of the building.

Plenum cables typically consist of a number of conductors protected by a primary insulation layer, which provides electrical/signal insulation between adjacent conductors and physical protection where optical fibers are used. The primary insulation may be PVC, a fluorinated polymer such as FEP (e.g. , Teflon® FEP, DuPont), PNDF (e.g., Kynar® PNDF, Pennwalt) and E-CTFE (e.g., Halar®, Allied Chemical Co.) or a polyolefm such as polypropylene or peroxide cured polyethylene, which may additionally contain flame retardants. Surrounding the conductors is a jacket, which provides additional protection and assists in identification and installation. The jacket of a plenum cable is typically a suitably formulated vinyl chloride resin or a fluoropolymer.

Although unmodified PVC is thermally unstable, decomposing at about 150°C, unmodified PVC has relatively good flame retardant properties. However, the plasticizers required to overcome its rigidity and permit it to be processed as a flexible material increase its flammability, especially if used at higher levels. In addition, when PNC burns it produces a large amount of smoke, which not only contains toxic materials but also restricts visibility.

To prevent the spread of smoke and flame through the building via the plenums, the specifications for plenum cables are particularly stringent with regard to flame and smoke resistance. The most commonly used standard for measuring the acceptability of cable formulations for use in plenums is the UL 910

(Underwriters Laboratory Specification) test, which measures flame retardancy and resistance to smoke evolution.

Vinyl halide polymers can be formulated into compositions that pass the UL910 test. The formulations are typically complex and contain most or all of the following types of additives: flame retardant plasticizers, non-flame retardant plasticizers, additional flame retardants, smoke suppressants, stabilizers, antioxidants, lubricants, pigments, fillers and other additives.

Flame retarded wire insulation and cable jacket compositions comprising various combinations of additives have been disclosed in, for example, Sememza, Jr., U.S. Pat. No. 4,670,494; Kroushl, III, U.S. Pat. No. 5,227,417; Coaker, U.S. Pat. No. 5,036,121; and Popp, U.S. Pat. No. 4,246,158. Flame retardant additives such as antimony trioxide, antimony pentoxide, sodium antimonate, alumina trihydrate, zinc borate, zinc hydroxystannate and zinc stannate have used. Smoke suppressants include compounds such as molybdenum trioxide, hexa monium molybdate, magnesium oxide, zinc oxide, zinc molybdate and ferrocene. Plasticizers include compounds such as tricresyl phosphate, trixylenyl phosphate, iso-decyl diphenyl phosphate, and chlorinated parrafins. Fillers such as calcium carbonates and electrical grade clays (which may be included to achieve particular physical and electrical properties) as well as magnesium hydroxide, magnesium carbonate, huntite and hydromagnesite have also been described.

Compositions that pass the UL910 test contain large amounts of flame resistant plasticizers (brominated phthalate esters) and smoke suppressants (ammonium octamolybdate). These high levels of additives render the compositions thermally unstable during processing and make them relatively expensive. Wire manufacturers must reduce their extrusion temperatures to prevent degradation, which can reduce production throughput. Consequently, a need exists for flame and smoke resistant in compositions that pass the UL910 test requirements and are relatively easy to process, without being prohibitively expensive.

DISCLOSURE OF THE INVENTION

The invention is a flame retardant, low smoke composition comprising:

(a) a poly (vinyl chloride) resin, chlorinated poly (vinyl chloride) resin, or a mixture thereof;

(b) at least one flame retardant of the following formula:

I

in which M is sulfur or oxygen and X , X , and X are each independently a halogen selected from the group consisting of chlorine and bromine; (c) a compatibilising agent. These compositions, which have superior flame and smoke resistance properties, are based upon vinyl halide resins such as poly(vinyl chloride) (PNC), chlorinated poly(vinyl chloride) (CPNC), their copolymers, and blends thereof. The compositions can be produced by the incorporation of the flame retardant into the vinyl halide resin. Although the flame retardants are not fully compatible with PNC and/or CPNC resins and may exude from the composition when exposed to elevated temperatures, inclusion of appropriate quantity of a compatibilizing agent provides a composition from which the flame retardant does not exude.

Preferred compositions comprise the vinyl halide resin (PNC and/or CPVC); from about 5 to 15 phr (parts per hundred parts of vinyl halide resin) polyhaloalkylphosphate and/or polyhaloalkylthiophosphate phosphate flame retardant, and from about 1 to 8 phr of a compatibilising agent. In a more preferred embodiment, these compositions further comprise from 2 to 10 phr of a boric oxide or boron containing salt. In one aspect this invention is a composition comprising a poly (vinyl chloride) resin, a chlorinated poly (vinyl chloride) resin, or a mixture thereof; a polyhaloalkylphosphate and/or polyhaloalkylthiophosphate flame retardant having the formula I; and a compatibilising agent. More preferably, the composition comprises boric oxide and/or more or more boron containing salts. The vinyl halide resins include vinyl halide homopolymers (i.e. PVC), graft or random copolymers of PVC with other comonomers and blends of homopolymers and copolymers. These include poly(vinyl chloride) as well as chlorinated polyvinyl chloride) containing between 58 and 73% chlorine by weight. Furthermore, the functional segments used in the copolymerization are those that influence the processability and physical properties of the resin.

The flame retardants include the indicated polyhaloalkylphosphates and polyhaloalkylthiophosphates. Polyhaloalkylphosphates are preferred. The preferred polyhaloalkylphosphates are tris-(trichloroneopentyl) phosphate, tris-(dichloro- bromoneopentyl)phosphate, tris-(dibromochloroneopentyl) phosphate and tris-(tri- bromoneopentyl) phosphate. The most preferred halogenated flame retardant is tris- (tribromoneopentyl) phosphate. The polyhaloalkylphosphate and/or polyhaloalkylthiophosphate flame retardant is incorporated into the composition in an amount sufficient to impart the desired degree of flame retardancy to the composition. This amount will vary with the degree of flame retardancy required for the intended application, the amounts of other flame retardant agents present (especially flame retardant plasticizers). It will also be dependent on application related variables, such as the construction of the cable, the number of conductors, etc.

In general, the amount of flame retardant required will be that which, in addition to the other additives present in the composition, will increase the halogen content of the composition by at least about 2% by weight from that of vinyl halide resin used in the composition. For example, poly(vinyl chloride), which is about 56.7% by weight halogen, would require sufficient flame retardant and, if present, other halogenated additives, to raise the overall halogen content of the flame retardant containing composition to at least about 58.7% by weight halogen. The maximum amount of flame retardant added will be dictated by economic and practical considerations, but will generally be no greater than that which will provide about an additional 7% by weight (of the total weight of the composition) of halogen. The preferred range is an additional between about 2.7% by weight and about 4.0%) by weight additional halogen, i.e., the composition contains sufficient flame retardant and other halogenated additives to provide a composition whose halogen content is from about 2.7% by weight to about 4.0 % by weight greater than that of the poly (vinyl chloride) resin, chlorinated poly (vinyl chloride) resin, or mixture thereof used to form the composition.

The compositions also comprise a compatibilising agent, which acts as an exudation inhibitor. The compatibilising agent, which may also be called an exudation inhibitor, is an additive that reduces the tendency of the polyhaloalkylphosphate and/or polyhaloalkylthiophosphate flame retardant to exude from the resin. Useful agents are those which enhance the compatibility of the components of the composition. Typically, the compatibilising agent, or exudation inhibitor, delays chalking of the composition for at least two days, preferably at least three days, during accelerated aging, i.e., heating a sample of the composition in an air circulated oven at 100°C. Preferably, the compatibilising agent prevents the exudation of any significant amount of the flame retardant both during processing and during the lifetime of the composition.

A wide variety of chemical compounds are potentially useful as compatibilising agents. Typical copolymers of ethylene and vinyl acetate, terpolymers of ethylene, vinyl acetate and carbon monoxide, chlorinated polyethylenes, vinyl chloride/ethylene copolymers and thermoplastic polyurethanes. Because brominated phosphates tend to exude from vinyl halide polymers, the compatibilising agent is not a brominated phosphate ester. Although useful as plasticizers, phosphate esters, such as triaryl phosphates and the aryl-alkyl phosphates, do not function as compatibilising agents in these compositions.

Preferred compatibilising agents are the flexibilizing agents currently used as part of PVC based compositions. In the art of PVC formulation, the term "flexibilizing agent" describes an additive that improves the low temperature flexibility and elongation of the compounded polymer. Useful compounds include copolymers of ethylene and vinyl acetate (such as those sold by US Industrial Chemicals under the designation Ultrathene or by DuPont under the trademark Elvax®), terpolymers of ethylene, vinyl acetate or n-butyl acrylate, and carbon monoxide (such terpolymers are sold by DuPont under the trademark Elvaloy®), chlorinated polyethylene (such as those sold by DuPont-Dow under the designation Tyrin), vinyl chloride/ethylene copolymers and thermoplastic polyurethanes (such as those sold by B.F. Goodrich under the designation Estane) or mixtures thereof.

Preferably the compositions comprise sufficient compatibilising agent to reduce the exudation of the phosphate flame retardant to the desired level or to prevent exudation altogether. In general the ratio of the weight of the compatibilising agent to the weight of the halogenated flame retardant will be in the range 0.1:1 to 2.0:1.

The compositions preferably further comprise a boron oxide or boron containing salt. The preferred boron salts/oxides are zinc borate, calcium metaborate, barium metaborate, calcium pyroborate, potassium tetraborate, boric oxide, boric acid and ammonium pentaborate. The term zinc borate includes the various hydrated and anhydrous forms thereof such as 4ZnO"6B₂O₃'7H₂O, 2ZnO-2B₂O₃3H₂O, 4ZnO B₂O₃ H₂O and 2ZnO 3B₂O₃. These boron salts/oxides may be used individually or as blends. The most preferred boron salt is zinc borate. The amount of the boron salt/oxide which is incorporated into the polymer will generally be in proportion to the amount of the polyhaloalkylphosphate and/or polyhaloalkylthiophosphate flame retardant present. The ratio of the weight of the boron compound to the weight of the flame retardant is preferably in the range of 0.1:1 to 1.0:1. The compositions preferably also comprise an anti-oxidant or stabilizer.

Such compounds are known in the art of plenum cable formulation. In these compositions they add a degree of protection to the flame retardant, which reduces its tendency to degrade during polymer manufacture or processing.

The compositions may also contain polymer stabilizers, flame retardant synergists, smoke suppressants, plasticizers, functional fillers and process aids, which are well known in the art. Polymer stabilizers include those based on lead as well as mixed metal soaps. Flame retardant synergists are those additives which are known to enhance the effectiveness of halogen containing flame retardant additives such as antimony pentoxide, antimony trioxide and sodium antimonate. Smoke suppressants are additives that, upon contact with heat or flame, alter the polymer degradation pathway to produce a char instead of smoke. Examples are ammonium octamolybdate, molybdenum oxide, hexaammonium molybdate, zinc molybdate, zinc stannate, zinc hydroxystannate, copper oxalate, ferrocene, magnesium oxide and zinc oxide. Conventional plenum cable formulations typically contain 10 to 20% by weight smoke suppressant. However, this high level of smoke suppressant reduces the stability of the composition, reduces the cable production rate, and adversely affects the physical properties of the cable, especially its resistivity, low temperature flexibility and color. The compositions may be formulated using much less or even no smoke suppressant. Although they may be acceptable in some low smoke applications, compositions that do not contain a smoke suppressant may not meet more stringent test requirements, such as the UL910 test.

Preferably, the composition will comprise from about 8 phr to about 15 phr of smoke suppressant. When a smoke suppressant is present, the preferred smoke suppressant is ammonium octamolybdate. These preferred compositions, comprising reduced quantities of smoke suppressant, are less expensive, are easier to process, and provide the opportunity to incorporate other additives to produce compositions having new and improved properties.

The compositions preferably also comprise a plasticizer. Plasticizers include, for example, phthalate esters, polyester plasticizers, citrate esters, trimellitate esters, pentaerythritol esters, trialkyl phosphates, triaryl phosphates, aryl- alkyl phosphates, chlorinated paraffins and brominated aromatic phthalate esters. Plasticizers may be used individually or in blends so that the resulting composition passes the physical property and heat aging provisions required by all cables (UL 444).

Certain plasticizers, especially triaryl phosphates, aryl-alkyl phosphates, chlorinated paraffins and brominated aromatic phthalate esters, impart flame resistant properties to the composition. Thus, compositions proposed for use in plenum cable generally contain plasticizers of these types. Alkyl-aryl phosphate plasticizers include, for example, the mixed phosphoric acid ester of phenols and C₁₂ to C₁₆ linear (or branched) alcohols such that the resulting phosphate ester contains a blend of the following components: (i) triphenyl phosphate (0-5%), (ii) dialkylphenyl phosphate (5-35%), (iii) alkyldiphenyl phosphate (65-95%) and (iv) trialkyl phosphate (less than 2%). Chlorinated paraffins contain 50 and 75% by weight chlorine. Brominated aromatic phthalate esters include bis-(di-2-ethylhexyl) tetrabromophthalate. Conventional compositions typically contain from about 1 to about 40 phr of plasticizer and low smoke compositions typically contain about 15 to about 40 phr of flame retardant plasticizers.

The compositions may not require a flame retardant plasticizer, but rather may use less expensive non-flame retardant plasticizers. However, if the cable is required to pass a more stringent flame retardant test such as the UL 910 test, the composition will preferably comprise a flame retardant plasticizer, preferably in an amount of from about 8 to about 15 phr. Although larger amounts of flame retardant plasticizers may be added, the preferred compositions may incorporate one or more non-flame retardant plasticizers to achieve the desired mechanical or aging properties at a lower cost.

The compositions may also comprise a filler, an additive that dilutes the resin, without adversely effecting the mechanical properties of the composition. The filler may also impart additional flame or smoke resistance and electrical resistivity to the composition. Typical fillers are alumina trihydrate, magnesium hydroxide, magnesium carbonate, huntite, hydromagnesite and calcium carbonate.

INDUSTRIAL APPLICABILITY

The compositions may be compounded using conventional techniques well known in the art. The ingredients may be added separately during the compounding process or some may be formulated into a premix , which is added to the compounding process. In a preferred method, the resin or resins are premixed with the flame retardant and the compatibilising agent to form a masterbatch, which is introduced into the compounding process. The compositions can be used in the manufacture of plenum cable, an application that requires enhanced flame and smoke resistance They meet flame retardant standards using smaller quantities of flame retardant, thereby reducing the cost. They may also be formulated so as to be easier to use in wire and cable manufacturing processes. The advantageous properties of this invention can be observed by reference to the following examples which illustrate, but do not limit, the invention.

EXAMPLES Testing Procedures The following testing procedures were used in these examples: Flame & Smoke Measurements: Flame and smoke measurements were obtained by a Stanton-Redcraft cone calorimeter in accordance with ASTM 1354-94. The 100x100x4 mm samples were evaluated in a horizontal orientation at heat fluxes between 20 and 90 kW/m . The data is reported at 75 kW/m , because the smoke characteristics of the compositions are most effectively differentiated at this heat flux. The results are reported as follows: Peak heat release rate (PHRR in kW/m ), cumulative heat released (THR in MJ/m ) at 5 and 10 minutes, Peak optical density (OD_P), maximum rate of specific extinction area (SEA in m /kg) and cumulative specific extinction area (TSEA in m -min/kg) at 5 and 10 min. Although peak optical density refers to the maximum amount of light obscuration, specific extinction area refers to the area, in a room, which is obscured by one kilogram of sample.

Dvnamic Thermal Stability: The dynamic thermal stability of the compositions described in this invention was obtained during high shear compounding in a Brabender Plasticorder at 50 rpm and 195°C. A change in visual appearance or deviation in the torque curve signaled the compound's degradation. The time taken to reach one of these two events is noted as the dynamic stability time.

Compatibility Evaluation: A representative flame retardant was pigmented with carbon black. The samples (20 mm x 20 mm x 0.89 mm) were placed on a flat metal sheet in an air circulated oven at a temperature of 100°C. The samples were observed daily for white exudate or chalking. The number of days required to observe any whitening of the sample was recorded.

Examples 1-5

The following compositions were prepared by the following : (i) ingredients were dry blended, in a high speed mixer, at room temperature, (ii) the dry-blend was compounded at 200°C for 4 min in a Brabender mixer and (iii) the resultant fused compound was pressed into the dimensions required for cone calorimeter testing.

Examples 1, 2 and 4 are comparative examples. Example 1 is a commercially available, minimally smoke inhibited PVC compound. Examples 2 and 4 are compositions further enhanced by current technologies available in the art. Examples 4 and 5 detail plenum compositions with other key smoke suppressants added. Example 5 is an example of the invention. Example 3, which does not include a compatibilising agent, demonstrates that the addition of tris (tribromoneo- pentyl) phosphate effectively inhibits flame and smoke. However, the composition is not useful in practice because the flame retardant exudes from the composition.

Table 1. Examples 1-5

Component (phr)¹ Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5

PVC 100 100 100 100

Dibasic lead phthalate (Dythal XL) 5 5 7 7

Alumina trihydrate (ATH) - - 30 30

Huntite (Ultracarb) 55 55 - -

Stearic acid 1 1 1 1

Ethylene/n4outylacrylate/carbon monoxide - - - 5 terpolymer (Elvaloy® HP441)

Antimony oxide 3 3 - -

Kemgard 911C - - 10 10

Ammonium octamolybdate (AOM) - - 20 20

Zinc Borate 2 2 - 2

Epoxidized soybean oil (ESO) - - 3 3

Alkyl-aryl phosphate ester (Santicizer 2148) 35 35 30 30

Brominated aromatic phthalate (DP-45) 20 - 20 -

Tris(tribromoneopentyl) phosphate - 13 - 10

Bromine Content (wt%) 0 4.2 4.2 4.1 3.1

Cone Calorimeter data (75kW/m²)

Cumulative Heat Released at 5 min (MJ/m2) 29.3 25.9 14.8 28.1 27.6

Cumulative Heat Released at 10 min (MJΛn2) 38.8 28.4 37.6 36.9

Cumulative SEA at 5 min (m.2-min/kg) 4575 3568 1250 2771 323

Cumulative SEA at 10 min (m2-min/kg) 19260 3817 4911 732

Peak Heat Release Rate (kW/m2) 231.8 153.8 143.4 136.0 131.5

Peak Optical Density 0.41 0.31 0.20 0.18 0.16

¹ Concentration of additives expressed in parts of additive per hundred parts of vinyl halide polymer.

Examples 6-9

Examples 7 and 9, which comprise a smaller amount of tris-(tribromoneo- pentyl) phosphate than Examples 3 and 5, are compositions of the invention. The flame retardant properties are not greatly reduced. Examples 6 and 8 are comparative examples using reduced quantities of the brominated aromatic phthalate. The flame retardant properties are significantly reduced.

Table 2. Examples 6-9

Component (phr)¹ Ex. 6 Ex. 7 Ex. 8 Ex. 9

PVC 100 100 100 100

Dibasic lead phthalate (Dythal XL) 5 5 5 5

Huntite (Ultracarb) 55 55 55 55

Stearic acid 1 1 0.5 0.5

Antimony oxide 3 1 1.5 1.5

Zinc borate 2 2 2 2

Ammonium octamolybdate (AOM) 12 12 20 12

Ethylene/n-butylacrylate/carbon monoxide - - 5 5 terpolymer (Elvaloy® HP441)

Pentaerythritol ester (Hercoflex 707A) 25 25 30 30

Alkyl-aryl phosphate ester (Santicizer 2148) 10 10 - -

Trialkyl phosphate ester (TBEP) - - 5 5

Brominated aromatic phthalate (DP-45) 15 - 15 -

Tris-(tribromoneopentyl) phosphate 9.6 - 7

Bromine Content (wt%) 3.0 3.0 2.9 2.2

Cone Calorimeter data (75kW/m2)

Cumulative Heat Released at 5 min (MJ/m2) 24.2 24.1 22.6 18.4 Cumulative Heat Released at 10 min (MJ/m²) - 28 30.4 24.7 Cumulative SEA at 5 min (m²-min/kg) 2265 1707 1991 1711 Cumulative SEA at 10 min (m²-min/kg) - 2271 2315 2101 Peak Heat Release Rate (kW/m ) 135.4 104.4 122.3 93.0

Peak Optical Density 0.17 0.12 0.15 0.14

Examples 10-13

Examples 10 to 13 are compositions of this invention. Example 10 uses a non-flame retardant plasticizer in place of the flame retardant plasticizer. Examples 11 to 13 illustrate the use of fillers. Table 3. Examples 10-13

Component (phr)¹ Ex. 10 Ex. 11 Ex. 12 Ex. 13

PVC 100 100 100 100

Dibasic lead phthalate (Dythal XL) 5 5 5 5

Huntite (Ultracarb) 55 55 40 27.5

Calcium carbonate - - - 27.5

Stearic acid 0.5 0.5 0.5 0.5

Ethylene/n4jutylacrylate /carbon monoxide - 5 5 5 terpolymer (Elvaloy® HP441)

Antimony oxide 3 3 3 3

Zinc Borate 2 2 2 2

Ammonium octamolybdate (AOM) 12 12 12 12

Citrate ester (Citroflex B-6) 35 - - -

Trialkyl phosphate ester (TBEP) - 5 5 5

Pentaerythritol ester (Hercoflex 707 A) - 30 30 30

Tris-(tribromoneopentyl) phosphate 10 10 10 10

Bromine Content (wt%) 3.0 3.0 3.2 3.0

Cone Calorimeter data (75kW/m²) Cumulative Heat Released at 5 min (MJ/m2) 24.7 26.9 24.3 21.3 Cumulative Heat Released at 10 min (MJ/m²) 27.1 39.4 32.9 28.7 Cumulative SEA at 5 min (m2-min/kg) 1925 1938 2254 1615 Cumulative SEA at 10 min (m2-min/kg) 2226 2791 3206 2810 Peak Heat Release Rate (kW/m ) 158.7 122.4 118.0 96.4

Peak Optical Density 0.15 0.17 0.16 0.15

Examples 14-16

Examples 14 and 15 are comparative examples and have relatively poor dynamic thermal stability. Example 16 is a composition of this invention, which exhibits relatively good dynamic thermal stability.

Table 4. Examples 14-16

Component (phr)¹ Ex. 14* Ex. 15 Ex. 16

PVC 100 100

Dibasic lead phthalate (Dythal XL) 7 5

Alumina trihydrate (ATH) 30 -

Huntite (Ultracarb) - 55

Stearic acid 1 0.5

Ethylene/n-butylacrylate/carbon monoxide - 5 terpolymer (Elvaloy® HP441)

Antimony oxide _ 3

Zinc Borate - 2

Barium Metaborate - 6

Ammonium octamolybdate (AOM) 30 12

Kemgard 911C 10 -

Epoxidized soybean oil (ESO) 3 -

Pentaerythritol ester (Hercoflex 707A) - 15

Alkyl-aryl phosphate ester (Santicizer 2148) 30 18

Brominated aromatic phthalate (DP-45) 20 -

Tris(tribromoneopentyl) phosphate - 10

Bromine Content (wt%) 2.7* 4.0 3.0

Dynamic Thermal Stability

DTS (min) 4.25 13.25 30+

¹ Concentration of additives expressed in parts of additive per hundred parts of vinyl halide polymer. ^* From U.S. Patent 5,036,121. Includes an additional 15% chlorine provided by chlorinated polyethylene in addition to the chlorine provided by the PVC.

Examples 17-23

These examples show the effect of various compatibilising agents or exudation inhibitors.

TABLE 5. Examples 17-23

Component (phr)¹ Ex. 17 Ex. 18 Ex. 19 Ex. 20 Ex. 21 Ex. 22 Ex. 23

PVC 100 100 100 100 100 100 100

Dibasic lead phthalate 5 5 5 5 5 5 5

Calcium carbonate 75.2 75.2 75.2 75.2 75.2 75.2 75.2

Stearic acid 0.5 0.5 0.5 0.5 0.5 0.5 0.5

Pentaerythritol ester 20 20 20 20 20 20 20

Alkyl-aryl phosphate ester 15 15 15 15 15 15 15

Tris-(tribromoneopentyl) 10 10 10 10 10 10 10 phosphate

Carbon black 3 3 3 3 3 3 3

Ethylene/n-BA/CO terpolymer2 5

(Elvaloy ®HP441)

Ethylene/n-BA/CO terpolymer 5

(Elvaloy® HP771)

Ethylene/VA/CO terpolymer³ 5

(Elvaloy® 741)

Ethylene/VA/CO terpolymer 5

(Elvaloy® 742)

Chlorinated polyethylene 5

(Tyrin 4211)

Ethylene vinylacetate 5

(Ultrathene UE634)

Compatibility data

Days until first observance of 1 5 4 3 8 16 8 chalking (days)⁴

2EthyleneΛvbutylacrylate/carbon monoxide terpolymer. ³Ethylene/vinylacetate/carbon monoxide terpolymer. 4|-|eated in an air circulated oven at 100°C.

Examples 24-25

These examples illustrate the stoichiometric substitution of boric acid and zinc oxide for zinc borate. Table 6. Examples 24-25

Component (phr)¹ Ex. 24 Ex. 25

PVC 100 100

Dibasic lead phthalate (Dythal XL) 5 5

Huntite (Ultracarb) 55 55

Stearic acid 1 1

Antimony oxide 1 1

Zinc borate 2 -

Zinc oxide 0.8

Boric acid 1.2

Ammonium octamolybdate (AOM) 12 12

Ethylene// butylacrylate/carbon monoxide terpolymer (Elvaloy® 441)

Pentaerythritol ester (Hercoflex 707A) 30 30

Alkyl-aryl phosphate ester (Santicizer 2148)

Trialkyl phosphate ester (TBEP) 5 5

Brominated aromatic phthalate (DP-45)

Tris-(tribromoneopentyl) phosphate 9.6 9.6

Bromine Content (wt%) 3.0 3.0

Cone Calorimeter data (75kW/m²)

Cumulative Heat Released at 5 min (MJ/m2) n/a n/a Cumulative Heat Released at 10 min (MJ/m2) n/a n/a Cumulative SEA at 5 min (m2-min/kg) n/a n/a Cumulative SEA at 10 min (m²-min/kg) n/a n/a Peak Heat Release Rate (kW/m²) 124.8 127.0

Peak Optical Density 0.17 0.17

Example 26

The composition of Example 7 was mixed in a high speed Henschel mixer and extruded into pellets and coated onto a 24 gauge copper conductor at average wall thickness of 0.20 mm. The insulated wire was cut and twisted into 4 pairs. The twisted conductors were covered with the composition in a 0.63 mm thick semi- pressure filled jacket. The resultant cable was evaluated in the UL 910 test protocol.

Table 7. Large scale UL 910 evaluation

Test parameter Example 26 Test specifications

Peak Optical Density 0.25 0.50 max. Average Optical Density 0.14 0.15 max. Flame Spread (ft) 1.5 5 max.

Having described the invention, we now claim the following and its equivalents.

Claims

CLAIMSWhat is claimed is:

1. A flame retardant, low smoke composition comprising:

(a) a poly (vinyl chloride) resin, chlorinated poly (vinyl chloride) resin, or mixture thereof;

(b) at least one flame retardant of the following formula:

in which M is sulfur or oxygen and X , X , and X are each independently a halogen selected from the group consisting of chlorine and bromine; and (c) a compatibilising agent.

2. The composition of claim 1 in which M is oxygen.

1 1

3. The composition of claim 2 in which X , X , and X are each bromine.

4. The composition of claim 3 in which the composition comprises from about 2 to about 20 phr of the flame retardant.

5. The composition of claim 4 in which the ratio of the weight of the compatibilising agent to the weight of the flame retardant is in the range 0.1 : 1.0 to 2.0:1.0.

6 The composition of claim 5 in which the compatibilising agent delays chalking of the composition for at least three days, during accelerated aging.

7 The composition of claim 6 in which the resin is poly( vinyl chloride).

8. The composition of claim 1 in which the compatibilising agent delays chalking of the composition for at least three days, during accelerated aging.

9. The composition of claim 8 in which X , X , and X are each bromine and M is oxygen.

10. The composition of claim 9 in which the compatibilising agent is selected from the group consisting of copolymers of ethylene and vinyl acetate, terpolymers of ethylene, vinyl acetate and carbon monoxide, chlorinated polyethylenes, vinyl chloride/ethylene copolymers and thermoplastic polyurethanes.

11. The composition of claim 1 in which the compatibilising agent is selected from the group consisting of copolymers of ethylene and vinyl acetate, terpolymers of ethylene, vinyl acetate and carbon monoxide, chlorinated polyethylenes, vinyl chloride/ethylene copolymers and thermoplastic polyurethanes.

12. The composition of claim 11 in which X 1 , X2 , and X 3 are each bromine and M is oxygen.

13. The composition of claim 12 in which the compatibilising agent is a terpolymer of ethylene, vinyl acetate or w-butyl acrylate, and carbon monoxide

14. The composition of claim 13 in which the composition comprises from about 2 phr to about 20 phr of the flame retardant and in which the ratio of the weight of the compatibilising agent to the weight of the flame retardant is in the range 0.1:1.0 to 2.0:1.0.

15. The composition of claim 14 in which the composition contains sufficient flame retardant and other halogenated additives to provide a composition whose halogen content is from about 2.0% by weight to about 7.0 % by weight greater than that of the poly (vinyl chloride) resin, chlorinated poly (vinyl chloride) resin, or mixture thereof.

16. The composition of claim 1 further comprising a boron oxide or a boron containing salt.

17. The composition of claim 1 further comprising a boron containing compound selected from the group consisting of zinc borate, calcium metaborate, barium metaborate, calcium pyroborate, potassium tetraborate, boric oxide, boric acid and ammonium pentaborate.

1 2 1

18. The composition of claim 17 in which X , X , and X are each bromine and M is oxygen.

19. The composition of claim 18 in which the composition comprises from about 2 to about 20 phr of the flame retardant and in which the ratio of the weight of the compatibilising agent to the weight of the flame retardant is in the range 0.1:1.0 to 2.0:1.0.

20. The composition of claim 19 in which the compatibilising agent is selected from the group consisting of copolymers of ethylene and vinyl acetate, terpolymers of ethylene, vinyl acetate and carbon monoxide, chlorinated polyethylenes, vinyl chloride/ethylene copolymers and thermoplastic polyurethanes.

21. The composition of claim 20 in which the boron oxide or boron containing salt is selected from the group consisting of zinc borate, calcium metaborate, barium metaborate, calcium pyrobroate, potassium tetraborate, boric oxide, boric acid and ammonium pentaborate.

22. The composition of claim 21 in which the composition contains sufficient flame retardant and other halogenated additives to provide a composition whose halogen content is from about 2.0% by weight to about 7.0 % by weight greater than that of the poly (vinyl chloride) resin, chlorinated poly (vinyl chloride) resin, or mixture thereof.

23. The composition of claim 22 in which the boron oxide or boron containing salt is zinc borate.

24. The composition of claim 1 in which the composition comprises about 8 phr to about 15 phr of a smoke suppressant.

25. The composition of claim 24 in which the smoke suppressant is ammonium octamolybdate.

26. The composition of claim 1 in which a smoke suppressant is absent.

27. The composition of claim 1 in which the composition comprises from 1 to 40 phr of a plasticizer.

28. The composition of claim 27 in which the composition comprises from 5 to 18 phr of a flame retardant plasticizer.

29. The composition of claim 28 in which the plasticizer is an alkyl aryl phosphate ester.

30. The composition of claim 1 further comprising a filler .

31. The composition of claim 30 in which the composition comprises from about 20 phr to about 70 phr of the filler.

32. The composition of claim 31 in which the filler is selected from the group consisting of alumina trihydrate, magnesium hydroxide, magnesium carbonate, huntite, hydromagnesite and calcium carbonate

33. The composition of claim 1 in which the composition passes the UL 910 test.

34. The composition of claim 33 in which M is oxygen; X , X , and X are each bromine; the composition comprises from about 2 to about 20 phr of the flame retardant; and the ratio of the weight of the compatibilising agent to the weight of the flame retardant is in the range 0.1:1.0 to 2.0:1.0.

35. The composition of claim 34 in which the compatibilising agent delays chalking of the composition for at least three days, during accelerated aging.

36. The composition of claim 34 in which the compatibilising agent is selected from the group consisting of copolymers of ethylene and vinyl acetate, terpolymers of ethylene, vinyl acetate and carbon monoxide, chlorinated polyethylenes, vinyl chloride/ethylene copolymers and thermoplastic polyurethanes.

37. The composition of claim 36 in which the composition comprises about 8 phr to about 15 phr of ammonium octamolybdate.

38. The composition of claim 36 in which the resin is poly(vinyl chloride).

39. The composition of claim 36 in which the composition contains sufficient flame retardant and other halogenated additives to provide a composition whose halogen content is from about 2.7% by weight to about 4.0 % by weight greater than that of the poly (vinyl chloride) resin, chlorinated poly (vinyl chloride) resin, or mixture thereof.

40. The composition of claim 33 in which the compatibilising agent is a terpolymer of ethylene, vinyl acetate or ┬½-butyl acrylate, and carbon monoxide and which the composition comprises from about 2 phr to about 20 phr of the flame retardant and in which the ratio of the weight of the compatibilising agent to the weight of the flame retardant is in the range 0.1 : 1.0 to 2.0: 1.0.

41. The composition of claim 40 in which the resin is poly(vinyl chloride).