BACKGROUND OF THE INVENTION Halogenated polymers, such as chlorinated polyethylene (CPE), polychloroprene (CR), polyvinyl chloride (PVC) and chiorosulfonated polyethylene (CSPE), are commonly used for many useful articles such as wire of cable insulation, electrical component housings and electrical conductors. Insulated products include residential and commercial building wire; portable power cord and fixture wires; automotive primary (harness) wire; telephone and other communications wires; instrument and appliance wires; motor lead wires, etc.

Compositions based on halogenated polymers typically provide required flame resistance, oil resistance, and resistance to environmental factors such as ozone and ultraviolet light to a greater extent than would similar nonhalogenated polymers (e. g., olefin polymers and copoiymers).

Therefore, the use of compositions based on halogenated polymers in useful products is widespread.

The wire and cable industry has relied on insulating halogenated polymers containing heat stabilizers based on lead compounds. Thus, electrically insulating CPE and CSPE compositions usually include dibasic lead phthalate, dibasic lead phosphite, tribasic lead sulfate, or lead stearate, among others, as heat stabilizers. With chlorinated polyethylene or chlorosulfonated polyethylene, litharge and red lead oxide are also used.

On June, 22,1990, Part 261 of CFR 40, Protection of Environment, was amended to include (as Appendix II) Method 1311, Toxicity Characteristic Leaching Procedure (TCLP), as a prerequisite for any solid waste to be landfilled as nonhazardous waste. When tested per Method 1311, the solid waste must yield an extract containing less than 5.0 mg/I of lead. Thus, reduction in the level of lead extractables from halogenated polymers by the TCLP has been an objective in the above mentioned industries.

SUMMARY OF THE INVENTION The present invention is directed to halogenated polymer compositions containing heavy metal stabilizers, such as lead compounds, having reduced extractable heavy metal. It has been found that the extractable lead levels of a molded halogenated polymer composition having a lead stabilizer can be reduced by adding a metal phosphate in an effective amount to the polymer composition.

In a preferred embodiment the extractable lead of lead- stabilized CPE, CR, PVC or CSPE polymer is substantially improved by including a minor amount of about 0.2 to 5 parts, or up to about 20 parts, of a metal phosphate per 100 parts of polymer. In particular, calcium phosphate is preferred. However, other alkali or Group II metal phosphates can be used.

The invention provides for greatly reduced extractable lead on exposure of molded compositions to environmental landfill conditions.

In particular, it has been found that a significant reduction of extractable lead from halogenated polymer compositions can be achieved by adding a metal phosphate to the polymer in an effective amount to reduce extraction of the heavy metals when exposed to the toxicity characteristic leaching procedure of 40 CFR 261. The function of the metal phosphate, such as calcium phosphate, as an additive to reduce extractable lead from halogenated polymer compositions is considered unexpected and surprising. Furthermore, it has been found that the metal phosphates reduce the toxicity of lead when blended therewith. These blends also appear to be less soluble in digestive fluids.

The invention is particularly applicable to halogenated polymer compositions having lead stabilizers in electric wire or cable applications. In a broader aspect, the invention is applicable to other heavy metals, such as barium and cadmium, in stabilized halogenated polymer products. The invention in these broader aspects, as well as

specific embodiments and other parameters, may be further understood with reference to the following detailed description.

DETAILED DESCRIPTION OF THE INVENTION A. Halogenated Polymer Halogen-containing polymers or resins which are employed and which illustrate the principles of this invention include chlorinated polyethylene, chlorosulfonated polyethylene, polychloroprene, polyvinyl chloride, and other vinyl halide resin types. Halogenated polymer or vinyl halide resin, as understood herein, and as appreciated in the art, are common terms and are adopted to define those resins or polymers usually derived by polymerization or copolymerization of vinyl monomers including vinyl chloride with or without other comonomers such as ethylene, propylene, vinyl acetate, vinyl ethers, vinylidene chloride, methacrylate, acrylates, styrene, etc. A simple case is the conversion of vinyl chloride H2C=CHCI to polyvinyl chloride (CH2C=CHCl) n wherein the halogen is bonded to the carbon atoms of the carbon chain of the polymer. Other examples of such vinyl halide resins would include vinylidene chloride polymers, vinyl chloride-vinyl ester copolymers, vinyl chloride-vinyl ester copolymers, vinyl chloride-vinyl ether copolymers, vinyl chloride-vinylidene copolymers, vinyl chloride-propylene copolymers, chlorinated polyethylene, and the like. Of course, the vinyl halide commonly used in the industry is the chloride, although others such as

bromide and fluoride may be used. Examples of the latter polymers include polyvinyl bromide, polyvinyl fluoride, and copolymers thereof.

B. Heavy Metal Stabilizers Heavy metal stabilizers in halogenated polymer compositions are well known. These metal compounds serve to capture HCI liberated during heat processing of the vinyl halide resin composition into its final shape. The heavy metal can be lead, cadmium or barium, for example.

The lead stabilizers comprise litharge, red lead, dibasic lead phthalate, dibasic lead phosphite, tribasic lead sulfate, tetrabasic lead sulfate, tribasic lead maleate, tetrabasic lead fumarate, basic lead carbonate and dibasic lead stearate. The stabilizers may include heavy metal salts of a carboxylic acid, advantageously a C8-C24 carbon link monocarboxylic acid such lauric, oleic, stearic, octoic, or similar fatty acid salts. Mixed metal salts of such acids, and their preparation, are familiar to those skilled in the art to which this present invention pertains.

C. Metal Phosphates The metal phosphates suitable for use in accordance with the principes of this invention may be derived from a broad ciass of compounds. In short, the term"metal phosphate"is used hereinafter to define a member of this class. The metal salts are alkali or alkaline earth metal, and Group li or Ila cations, which are exemplified by calcium, magnesium, zinc, strontium and barium. Preferably, the metal cation is calcium and especially preferred calcium phosphates include CaHPO4,

mixtures of CaHPO4, and Ca3 (PO4) 2 which are essentially ground phosphate rock. Alkali metal phosphates, such as Na2HPO4, can be used.

Other alkali and alkaline metal earth metal phosphates may be included.

D. Amounts of Components Broad ranges of components of the halogenated polymer compositions may be employed in the invention. In general, the metal phosphate is used in an effective amount in the halogenated polymer composition to reduce extractable lead. Particularly useful compositions of the invention are achieved containing about 0.5 to about 5 parts, up to about 40 parts, of the heavy metal compound heat stabilizer, about 0.2 to about 5 parts, up to about 20 parts, of the metal phosphate, said parts on the basis of 100 parts of the halogenated polymer. The compositions of the present invention can also include various additional compounds including lubricants for providing the polymer or resin with lubricity and plasticizers of the phthalic ester or fatty acid ester type, hydrocarbon resins or chlorinated olefins or paraffins. Other additives may include auxiliary stabilizers, antioxidants, light stabilizers, pigments, dyes or extenders. The compositions may optionally contain an inorganic acid acceptor, such as various hydrotalcites and Type A hydrous zeolites, or coordinating multidentate metal blend ligands, such as 1,3-diketone, or an antioxidant such as bisphenol A, or a phosphite costabilizer such as diphenyl decyl phosphite. Fillers may be added including coarse ground limestone, fine ground limestone, clay, talc or other particulate fillers.

The advantages of this invention and its operating parameters will be further understood with reference to the following detailed examples.

EXAMPLE 1 A cable jacket for use in power supply to electric locomotives consisted of 100 parts chlorosulfonated polyethylene elastomer (ASTM designation CSM, trade name Hypalon), 80 parts kaolin clay, 20 parts carbon black, 30 parts trioctyl trimellitate plasticizer, 44 parts litharge stabilizer, and minor amounts of curatives. After extrusion as a cable jacket, and vulcanization, this compound yielded TCLP lead extraction of 90-100 mg/l. The TCLP analysis of 40 CFR 261 is incorporated herein in its entirety by reference.

EXAMPLE 2 The cable jacket of Example 1 was made employing the same composition except that 22 parts of calcium phosphate were added to the composition and, after extrusion as a cable jacket and vulcanization, the product yielded TCLP lead extraction of 22 mg/l. Thus, employing the metal phosphate of this invention in the halogenated polymer composition enabled the reduction of extractable lead from 90-100 mg/I to 22 mg/l.

EXAMPLE 3 The cable jacket of Example 1 was made and the identical procedures were followed except that 44 parts of litharge were replaced

with 25 parts of red lead. TCLP lead extraction of this cable jacket was 1 0 mg/l.

EXAMPLE 4 The procedure of Example 3 was repeated except that 12.5 parts of calcium phosphate was added to the formulation and, after extrusion as a cable jacket and vulcanization, the product yielded TCLP lead extraction of 3.6 mg/l. Thus, employing a metal phosphate of this invention enabled the reduction of extractable lead from 10 mg/I to 3.6 mg/l.

EXAMPLE 5 Chloropolyethylene wire insulation product consisting of 100 parts chloropolyethylene, 60 parts clay, 40 parts calcium carbonate, 20 parts ester plasticizer, 12 parts litharge stabilizer, plus antioxidant and cross linking agents was made. After extrusion and vulcanization, the product yielded TCLP lead extraction values of 20-30 mg/I which is above the limiting value of 5 mg/I needed for qualification as nonhazardous waste.

EXAMPLE 6 The procedures of Example 5 were repeated except that litharge was replaced with a preblended stabilizer containing 60% by weight litharge and 40% by weight calcium phosphate (CaHPO4). The product yielded TCLP lead extraction values of 2-3 mg/l, thereby qualifying as nonhazardous waste. Thus, this invention enables the

reduction of hazardous waste materials and greatly reduces the cost of transportation to a suitable recycling site.

EXAMPLE 7 Dibasic lead phthalate was found to have an oral LD50 value in rats of between 2000-5000 mg/kg body weight, placing it in Category III (formerly known as Slightly Toxic). A blend of 67% dibasic lead phthalate, 33% zinc phosphate, was found to have an oral LD50 value in rats of greater than 5000 mg/kg body weight, corresponding to Category IV (formerly known as Nontoxic). It is not believed that any lead stabilizer has previously been found to have an oral LD value above 5000 mg/kg. Accordingly, this invention offers the advantage of producing nontoxic lead stabilizer systems. It has also been found that the blends appear to be less soluble in digestive fluids which would reduce the toxicity in animals where compositions containing lead stabilizer components were ingested.

EXAMPLE 8 A composition was prepared comprising polyvinyl chloride (PVC) 100 parts by wt., calcium carbonate 40, di-iso-decyl phthalate 65, stearic acid 0.3, and tribasic lead sulfate 4. This composition is routinely used as a nonmetallic (Underwriters Laboratories Type NM) jacket to cover residential building wire. This composition was mixed to a homogeneous state and extruded, simulating wire manufacture. The composition yielded TCLP extraction of 7 mg/l.

EXAMPLE 9 The composition of EXAMPLE 8 was mixed using a blend of 4 parts of tribasic lead sulfate with 2 parts of Na2HPO4 in piace of the above 4 parts of pure tribasic lead sulfate. This composition yielded TCLP extraction of 1.5 mg/l.

The above data establishes that minor amounts of an alkaii or alkaline earth metal, Group II and Group Ila metal phosphate, when employed as an additive in halogenated polymer compositions reduces extractable lead, as a heavy metal, of the lead stabilizer employed in the compositions. The above examples are not intended to limit the invention. In accordance with the principles, other halogenated polymers that are stabilized with heavy metals may be landfillable as non-hazardous waste by adding an effective quantity of the metal phosphate to pass the TCLP as provided in 40 CFR 261.

Having described this invention, its advantages and operating parameters, it will be obvious to persons of ordinary skill in the art, in view of the above description, that variations hereof may be made without departing from the spirit and scope thereof.

WHAT IS CLAIMED IS :