FIELD OF THE INVENTION

This invention relates to stabilizer compositions for halogen-containing polymers and more particularly to stabi¬ lizer compositions for halogen-containing polymers compris¬ ing the combination of organotin, borate and thio-type compounds, as well as to the stabilized halogen-containing polymers prepared therewith.

BACKGROUND OF THE INVENTION

It is well known to add various metal compounds to halogen-containing polymers such as polyvinyl chloride resin for the purpose of inhibiting the degradation that occurs when these polymers are heated during processing, e.g., milling, extrusion, molding and calendering, or that arti¬ cles prepared therefrom encountered during exposure to the environment. Among the most effective stabilizers are 1) organotin compounds containing sulfur and one or two hydro¬ carbon groups bonded to the tin atom and various mixtures thereof, 2) sulfur-containing antimony compounds, particu¬ larly trivalent antimony compounds of the general formula Sb(SR)~ wherein R represents a hydrocarbyl group or the residue remaining following removal of the hydrogen atom from the sulfur atom of a mercaptan or mercaptocarboxylic acid ester, and 3) the alkaline earth metal, zinc and cadmium salts of carboxylic acids and lead salts. The relatively high cost of these stabilizers, particularly the organotin and antimony compounds, has provided an incentive to search for less expensive materials which can at least partially replace the metal compound without significantly

i pairing the stability imparted to the halogen-containing polymers or will actually enhance the stabilizing effects thereof.

Heretofore, various stabilizer systems containing one or more tin compounds or mixtures thereof have been proposed and/or used commercially in the stabilization of halogen- containing polymers. In general, the organotin groups, tin content, sulfur content and relative proportions thereof are associated with the stabilizing effectiveness of organotin compounds for polymers such as polyvinyl chloride resin.

However, so many exceptions to the rule have been found that the suitability of particular organotin compounds containing all of the individual components is quite unpredictable. For example, organotin sulfides such as dibutyltin sulfide or butylthiostannoic anhydride offer the highest tin and sulfur content per organotin group, and yet they are not the best stabilizers and have found little commercial accep¬ tance.

Mixtures of organotin compounds with various other materials have been suggested for use in stabilizing halogen-containing polymers such as polyvinyl chloride to achieve advantages for particular applications, including cost and odor effectiveness. While many prior art materials and combinations of materials have received varying degrees of commercial acceptance as stabilizers for halogen-containing polymers, no particular combination has been found to be entirely satisfactory for all types of applications as well as for considerations of cost, instability and compatibility. The present invention provides a synergistic combination of three types of compounds which results in unexpectedly high level of stabilization, full compatibility with halogen- containing polymers and surprisingly low cost since the second and third components are relatively inexpensive and may be used in significant amounts so as to thereby decrease

the amount of the relatively expensive organotin component which would otherwise be necessary to provide acceptable stabilization levels.

SUMMARY OF THE INVENTION

In accordance with the present invention, there is provided a composition for stabilizing halogen-containing polymers comprising three components:

A. at least one organotin compound;

B. at least one borate derivative of a thiol, a hydroxythiol or an alcohol; and

C. at least one thio-type of compound, containing a -C=S or -SH group.

Effectiveness of stabilizing halogen-containing polymers such as polyvinyl chloride is determined by the protection from the effects of heat and light with such effects being, in general, evidenced by a changing color and/or a progressive decrease in mechanical properties. The method of processing the polymer and the application for which articles prepared from such polymers will be used are generally the criteria used to determine the stabilization effectiveness required for particular polymer compositions.

For purposes of this invention, the terms "enhanced stabilization effectiveness" or "suitable to enhance the stabilization effectiveness" as used herein shall mean the enhanced ability to protect against a changing color or in mechanical properties without concurrently adversely effect¬ ing the ability of the organotin component to protect against a change in the other of the properties.

It has been unexpectedly discovered that the composi- tions of the present invention are highly effective for stabilizing halogen-containing polymers even though the amount of the organotin component that is used is

substantially less than would be conventionally added to achieve a similar degree of stabilization of the polymer. The borate component present in the composition of this invention imparts little, if any, stability to halogen- containing polymers by itself. Further, the third compo¬ nent, i.e. the thio-type of compound, imparts only a slight amount of stabilization. However, the combination of the three components results in a stabilization effect greater than could be achieved by any one of the components or by any two of the components. Thus, the stabilization of halogen-containing polymers that is provided during process¬ ing and the combination of color retention and long term stability that can be achieved by using substantially less of the conventional organotin stabilizer is quite surprising and unexpected. Furthermore, the second component as well as the third component are readily compatible with halogen- containing polymers and the benefits obtained from the compositions of this invention apply to both rigid and flexible halogen-containing polymers.

THE HALOGEN-CONTAINING POLYMER

The stabilizer compositions described herein can be used with various types of halogen-containing polymers, including homopolymers, copolymers and polymer blends containing such homopolymers and/or copolymers. Among the homopolymers for which the compositions of this invention find application are polyvinyl chloride, chlorinated poly¬ vinyl chloride, polyvinylidene chloride, polychloroether, polydichlorostyrene, etc. Copolymers such as polyvinyl- acetates/chloride or other combinations or mixtures, such as, for example, vinyl chloride copolymerized with ethylene and/or propylene, acrylonitrile-butadiene-styrene, ethylene- vinylacetate, etc. are also types of halogen-containing

polymers for which the compositions of this invention are useful.

More generally, the stabilizer compositions of this invention are utilized in conjunction with vinyl halide polymers, i.e. vinyl halide homopolymers, vinyl halide copolymers and blends of such homo/copolymers. Among the typical halogen-containing homopolymers are, for example, polyvinyl chloride, polyvinylidene chloride, polyvinyl bromide, polyvinylidene fluoride, etc. Among the copolymers are those in which vinyl chloride is copolymerized with one or more ethylenically unsaturated monomers such as vinyl- idene chloride, vinyl acetate, vinylbutyrate, vinyl benzoate, diethyl fumarate, diethyl maleate, other alkyl fumarates and maleates, vinyl prσpionate, methyl acrylates, 2-ethylhexyl- acrylate, butylacrylate, ethylacrylate and other alkyl acrylates, methyl methacrylate, ethylmethacrylate, butyl methacrylates, hydroxyethyl methacrylate and other alkyl methacrylates, methyl α-chloroacrylate, styrene, vinyl ethers such as vinyl ethylether, vinyl chloroethylether, vinylphenolether, vinylketones such as vinyl methyl ketone, vinyl phenol ketone, 1-fluoroethylene, 1-chloroethylene, acrylonitrile, chloroacrylonitrile, allylidene diacetate, chloroallylidene diacetate, ethylene and propylene, etc.

The present invention is also quite useful for stabi- lizing polymer blends such as blends of polyvinyl chloride and polyethylene, polyvinyl chloride and polymethyl meth¬ acrylate, polyvinyl chloride and polybutylmethacrylate, polyvinyl chloride and polystyrene, polyvinyl chloride and acrylonitrile-butadiene-styrene copoly er and polyvinyl chloride and polyethylene and polymethylmethacr late. The polymer blends which benefit from the stabilizer composi¬ tions of this invention comprise physical blends of at least two distinct polymeric species and typically contain from about 25 to about 95 wt. percent of vinyl halide homopolymer

or vinyl halide copolymer. The vinyl halide copolymers which benefit from this invention are those which contain from about 25 to about 95 mole percent vinyl halide units.

ORGANOTIN COMPOUND

The organotin compounds useful herein are well-known for their stabilization of halogen-containing polymer and generally, their ability to prevent formation of, or react with and neutralize, the hydrogen halide evolved when vinyl halide polymers are heated to processing temperatures. The progressive elimination of hydrogen halide from the polymer chain ("unzipping") yields a polyene chain which is believed to be at least partially responsible for the discoloration that occurs during heating of the polymer.

One class of such compounds that is particularly effective comprises the mono- and diorgano- derivatives of tetravalent tin wherein the remaining valences of the tin atom are satisfied by bonds to halogen, oxygen, and/or sulfur and/or a residue resulting from

1) removal of the hydrogen atom from the oxygen atom of a carboxylic acid, an alcohol or a polyol; or

2) removal of the hydrogen atom from the sulfur atom of a mercaptan, mercaptoacid, mercaptoalcohol, ercaptoacid ester or mercaptoalcohol ester.

Oxygen a d/or a halogen such as chlorine may or may not be present; however, when present it is bonded to one or more of tin, carbon, hydrogen, phosphorus, aluminum, silicon, boron, bismuth and titanium.

The well-known members of this class include the organotin oxides, sulfides, halides, carboxylates, mercap- tides, derivatives of mercaptoacids, derivatives of mercaptoalcohols and the mercaptoacid and mercaptoalcohol esters.

They can be represented by the formulae, such as

(R ¹ SnZ _1>5 ) _χ

(R ^X ) ₂ SnZ

(R ¹ ) ₂ SnZ ₂

R ¹ Sn(Z)Z"

(R ¹ ) _a Sn(00CR ² ) ₄ _ _a

(R ^X ) _a Sn(SR ³ ) ₄ _ _a

[R ¹ SnSR ³ ] ₂ (Z _b ) ₂

[(R ¹ ) ₂ SnSR ³ ] ₂ Z _b t(R ¹ ) _a Sn] ₂ (OOCR ² COO) ₄ _ _a

[(R ¹ ) _a Sn] ₂ (ZR ³ Z') ₄ _ _a

[(R ¹ ) _a Sn] ₂ (ZR ³ COO) ₄ _ _a

(R ¹ ) _a Sn(Z")(SR ³ ) ₃ _ _a wherein a is 1 or 2; x is integer of at least 2;

Z is oxygen or sulfur; Z' is oxygen or sulfur; Z" is halogen; b is an integer of 1 to 4 when Z is sulfur and is 1 when Z is oxygen;

R 1, R2 and R3 are each independently substituted or unsubstituted C.-C„ ₀ alkyl, C ₂ -C _2Q alkenyl, C^-Cg cyclo- alkyl, C^-C n ^~ - ^τ Y- _> ^or C,-C, _fl alkaryl or aralkyl, and R additionally may be C ₆ -C _2Q aryloxy or -R -C00R ⁵ or -R^OOCR ⁵ wherein R is C, -C« _n alkylene, and R is substituted or unsubstituted C. -C__ alkylene, C--C_- alkenylene, C,-C_ _n arylene, or C ₇ -C _4fi alkarylene or aralkylene.

The metal-containing compounds, in one well-known embodiment, comprise the reaction products of monoorganotin

trihalide, a diorganotin dihalide or mixture thereof with an alkali metal sulfide and one or more of a monocarboxylie acid, a polycarboxylic acid, a mercaptan, a mercaptoacid, a mercaptoalcohol, a mercaptoacid ester or a mercaptoalcohol ester.

Preferred organotin compounds for the purpose of this invention include monobutyl stannoic anhydride, monobutyl thiostannoic anhydride, dibutyltin maleate, dibutyltin di(stearyl maleate) , butyl(2-hydroxyethylmercapto)tin sulfide, monobutyltin(isooctylmercaptoacetate)sulfide, monobutyltin(dodecylmercapto)sulfide, monobutylmercaptoethyloleate)sulfide, monobutyltin trimercaptoethyloleate, monobutyltin tris(hydroxyethyImercaptide) , monobutyltin (mercaptoethyloleate) (sulfide) , and bridged sulfur compounds of formula

wherein

A and A are each independently C, to C, alkyl; A , A , A and A are each independently C, -C- alkylene;

1 2 3 D, D , D and D are each independently -OH, Cg to C, _g

0 alkyl, -0-C-(Cg to C _2Q )alkyl, or D and D , or D and D ³

0 together form the group -0-C-C H« -C-0, where m is an integer of 0 to 8.

Some organotin halides such as organotin chloride may also be present in the organotin component, generally in small amounts such as less than about 5 % by weight. Of course, the organotin component may be a single compound or may be a combination of compounds.

THE BORATE COMPONENT

The borate component of the stabilizer compositions of this invention is a borate derivative of a thiol, a hydroxy¬ thiol, or an alcohol. The stabilizer composition of this invention comprises at least one such borate derivative and accordingly, mixtures of different types of borate deriv¬ atives are feasible for the purposes of this invention.

The borate derivatives may. be represented by the following formulae:

(HSR ^C 0) _n -B- (0R ⁷ ).

or

or

or

(HSR ⁶ 0) ) -0B-(0R ⁶ SH) IV

( tnOnR'' \),

or

wherein

R is substituted or unsubstituted C ₆ -C,-,« alkylene, ^C 2~ ^C 20 ^a ^enylene, C.,-Cg cycloalkylene, Cg-C ₂₀ arylene or

C ₇ -C _Q alkarylene or aralkylene;

R is substituted or unsubstituted C,-C, _n alkyl, C ₉ -C _n alkenyl, ^C 3~ ^C Q cycloalkyl, -^- - n ^ar y^ °r ^C 7 ^-C _ΛQ alkaryl or aralkyl; z and z' are each independently oxygen or sulfur, n is an integer of 0 to 3, preferably 1-3, x is an integer having a value of 3-n, j is an integer of 1 to 3 t is an integer having a value of 3-j k is an integer of at least 1, g is 1 or 2, h is equal to 2-g, and m is an integer of 1 to 20

For the purposes of the present invention, the borate derivative represented by formula I is preferred herein.

6 7 Further, the groups R and R may be unsubstituted or may contain non-interfering substituents such as hydroxy, C, -C« _n alkoxy, oxo, oxirane, ^- ~~2 ~ ^& lkoxycarbonyl, C _fi -C„ ₀ aryloxy,

C ₇ -C ₂₀ aryloxycarbonyl, C ₂ -C ₂₀ acyl, C ₂ -C _{20 acyloχy> fluoro>} chloro, bro o, iodo, cyano, C«-C ₀ alkylamido, mercapto, ^c ι ^~c 2o ^al ^ ^yltn:LO » ^c ι" ^c 2o ^{alkylsulf amy1 ■ c} ι" ^c ?o ^alky1 " sulfonyl, and by alkyl, alkenyl, cycloalkyl, aryl, aralkyl and alkaryl as previously defined. R and R as well as their substituents may also include oxygen atoms in the chain, to provide ether groups, for example, pol (alkylene oxide) chains such as polyethylene oxide, polypropylene

oxide and copolymers thereof, and to provide ester groups such as linear polyesters; there may also be sulfur atoms in the chain so as to provide sulfides or alkylene disulfides, and there may also be nitrogen atoms in the chain to provide groups such as amides, aromatic amines and weakly basic heterocyclic nitrogen groups.

The group R in the above formulae I-IV may, for example, be groups such as methyl, ethyl, propyl, propenyl, isopropyl, n-butyl, butenyl, vinyl, isobutyl, tert. butyl, sec. butyl, amyl, hexyl, octyl, oleyl, 2-ethylhexyl, isooctyl, lauryl, stearyl, behenyl, allyl, furfuryl, cyclohexyl, cyclopentyl, tetrahydropyranyl and the like.

Such groups can be conveniently derived from monohydric alcohols such methyl, ethyl, propyl, n-butyl, t-butyl, isobutyl, octyl, decyl and lauryl alcohols or from poly- hydric alcohols such as glycols including ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, tetramethylene glycol, neopentyl glycol, polyethylene glycol and the like. R can also be derived from carboxylic acids such as acetic acid, acrylic acid, methacrylate acid, crotonic acid, propionic acid, oleic acid, ricinoleic acid, linoleic acid, stearic acid, butyric acid, valeric acid, chloroacetic acid, hexanoic acid, octanoic acid, 4-methoxybutyric acid, lauric acid, behenic acid, palmitic acid, benzoic acid, cyclohexane carboxylic acid and the like.

The R may also be aryl, aralkyl or alkaryl groups such as phenyl, methylphenyl, octylphenyl, nonylphenyl, hydroxy- phenyl, naphthyl and the like. A simple way of preparing a preferred type of borate derivative is to react a hydroxythiol with a borate; since hydroxythiols are readily available, R may conveniently be the residue of a hydroxythiol. Thus, for example, R may be ~ _? ~ ~^2~ ^a -- ^~ Υ- ^eτιe which may or may not be substituted as

desired. Preferably, R will contain from 2 to 12 carbon atoms and thus R may be derived from compounds such as monothioeth lene glycol, monothiopropylene glycol, thio- glycerol, butanol-l-thiol-4, 1-thiosorbitol and the like. Most preferably, R is an alkylene group or a hydroxy alkylene group containing from 2 to 8 carbon atoms. For reasons of cost and availability, R is preferably ethylene, 2-hydroxyprop lene or methylethylene.

Obviously, R may be linear or branched and may be interrupted in the chain by one or more of oxygen, sulfur and nitrogen. For example, R or the branching may be a poly(alkylene oxide) , a poly(alkylene sulfide) an alkylene disulfide, or alkylene amide.

Exemplary suitable borate derivatives of hydroxythiols are: tris(2-thioethyl)borate isooctyl bis(2-thioethyl) borate diisooctyl(2-thioethyl) borate ethyl bis(2-thioethyl) borate phenyl bis(2-thioethyl) borate diethyl (2-thioethyl) borate 2-isooctyl-l-oxa-3-thia-2-boracyclopentane As mentioned above, the borate derivative may be conveniently prepared by reacting a boron halide or alkoxy derivative thereof with a stoichiometric amount of the desired hydroxythiol. The reaction can be conveniently conducted at ambient temperatures with or without an organic acid catalyst such as p-toluenesulfonic acid, and with an organic liquid diluent such as an aromatic hydrocarbon, e.g. benzene, toluene or x lene.

Another preferred type of borate derivatives for use in the compositions of this invention comprise sulfur bridged borate compounds. These sulfur bridged borate compounds are generally the reaction product of a divalent sufide compound

such as hydrogen sulfide, ammonium sulfide, sodium sulfide, sodium hydrosulfide, etc. with a hydroxythiol, thiol and/or alkoxy substituted organocompound having a suitable reactive site or sites, e.g. chloride. Such sulfur bridged borate compounds can be formed, for example, by the reaction of a divalent sulfide compound with boron derivatives such those represented hereinabove by formulae I and IV, or mixtures thereof wherein each of the boron-containing reactants contain at least one reactive site capable of reacting with an equivalent weight of a divalent sulfide compound.

Preferably the sulfur-bridged borate compound is one which contains a B-S-B linkage. Most preferred are those sulfur bridged borate compounds encompassed by the formula

wherein

R is as defined above. c,d,e and f are integers of 1 to 3 , with the proviso that c + d and e + f have values of 1 to 3.

Alternatively, the sulfur bridged borate compounds may contain cyclic methio or alkoxy groups attached to the boron atom of one or both of the borate moieties along with an alkyl or alkoxy radical.

As previously described, the group R of the various borate derivatives useful for the stabilizer compositions of this invention may contain reactive substituents such as hydroxyl groups. In such instances, borate derivatives employed for the present invention may include a molecular structure that can be represented by the formulae

-0.

>B'

with the remaining valences of the boron atom satisfied as previously defined. In accordance with the present inven¬ tion, it is understood that the borate derivatives repre¬ sented by the formulae I-VI include compounds having such molecular structures. It should be further understood that there may also be present, in addition to the borate deriv¬ atives hereinabove described, small amounts (e.g. less than about 5 wt. 1 ) of a boron halide.

THE THIO-TYPE COMPOUND

The third component which makes up the stabilizer compositions of the present invention comprises at least one thio-type of compound. The term "thio-type" is intended to denote those types of compounds in which at least one oxygen atom in an acid radical is replaced by at least one divalent sulfur atom. Accordingly, such compounds will have a -SH or -C=S group. The term "thio-type" of compound excludes those compounds in which the only sulfur atom contained therein is present in the form of a sulfide, di-sulfide, sulfoxide or sulfone. However, compounds containing at least 2 sulfur atoms in which at least one sulfur atom is present in the form of a -SH radical or -C=S radical and the other sulfur atoms are present as sulfide, disulfide, sulfoxide or sulfone, are suitable for use as the third component in the stabilizer compositions of the present invention.

The thio-type compound for use in the present invention may thus be of the following types:

____£__ Structure

thiol RSH

substituted thiol HORSH, H0 ₂ CRSH,

thioaldehydes

thioketones R-C-R'

thiocarbonyl carboxylic S

II acids R-C-R' C0 ₂ H

thiocarbonyl carboxylic S acid ester R-C-R'C0 ₂ R ^*

H .SR'

I thioacetate R-C

\

SR'

thioketals

' '

0

II thiolic acids R-C-SH

0

II thiolic acid esters R-C-SR'

thiolic acid anhydrides

S li thionic acids RC-OH

S M thionic acid esters RC-OR'

S II C thionic acid anhydrides R'

S

II dithionic acids R-C-SH

S

II dithionic acid esters R-S-SR'

S

II dithionic acid anhydrides

thioamides R-C-NH ₀ , R-C-NHR* ,

In the structural formulae set forth above, R, R' , R I"' and R' ' ' represent substituted or unsubstituted hydro- carbylene radicals such as C-,-C ₂₀ alkyl, C ₂ -C ₂₀ alkenyl, C ₃ -C ₈ cycloalkyl, Cg-C n ~- ^τ~~ - t ^C ₇ ~ ^C 0 ^a lk *yl or aralkyl, and the like. Substituents on such radicals include the halogens, hydroxyls, carboxyl, carbonyl, sulfide, sulfoxide, sulfone, ether, cyanide, cyanate, isocyanate, amino, amido, heterocyclics, nitro, nitrile, etc. Furthermore, the compounds set forth above may exist in monomeric or poly¬ meric form (this is particularly true in the case of the thiols which frequently exist in the form of oligomers having from 2 to 10 or more recurring units) . These thio- type compounds are well-known and a comprehensive listing of such compounds together with references to well-recognized methods for their synthesis may be found in the multi-volume text entitled "Organic Chemistry of Divalent Sulfur", by E. Emmet Reid, Chemical Publishing Co., Inc. (New York, N.Y.) 1958.

For the purposes of the present invention, the pre¬ ferred thio-type compound is a hydroxythiol, thiocarbonyl carboxylic acid or ester thereof, a substituted or unsub¬ stituted thioamide, or a substituted or unsubstituted mercaptobenzothiazole. Furthermore, the thio-type compound is generally utilized in the stabilizer compositions of the

present invention in an amount of about 0.1 to about 35 times the amount of tin metal present in the organotin compound.

THE STABILIZER COMPOSITION

The borate derivatives employed as the second component and the thio-type of compounds employed as the third component in the stabilizer compositions of the present invention impart little, if any, stability to the halogen- containing polymers when utilized as separate components. It is therefore quite surprising that they enhance the stabilization effectiveness of the organotin compound conventionally used as a stabilizer for the halogen- containing polymers and can be used to replace a substantial amount of the organotin compound such that the resultant polymer composition, containing the reduced amount of organotin compound, displays heat stability comparable to the same composition containing a far greater concentration of organotin compound. Moreover, the second and third components of the stabilizer composition of the present invention will not alter the stabilization characteristics of the organotin compound.

Organotin compounds containing from about 3 to about 18 percent by weight of tin typically are utilized in an amount of from about 0.01 to 1.5 parts, preferably 0.3 to 0.5 part by weight of stabilizer per hundred parts of polymer for pipe applications and from about 0.8 to about 1.5 parts by weight of stabilizer per hundred parts of polymer for profile applications. The borate derivative described hereinabove is generally utilized in an amount of from about 0.1 to about 30 times the amount of tin metal present in the organotin compound. The thio-type compound can be utilized in an amount of about 0.1 to about 35 times the amount of tin metal present in the organotin compound. As a result,

the tin content in the overall stabilizer composition can be reduced by as much as 90% depending on the method of pro¬ cessing to be employed and the desired performance. The stabilizer composition, i.e. the total amount of all three components, ranges from about 0.1 to about 101 , preferably from about 0.1 to about 21 , by weight of the halogen-containing polymer.

Although the three components of the stabilizer compo¬ sition of the present invention may be added to the halogen- containing polymer separately, it is generally more conve¬ nient to formulate a mixture of the three components for addition to the polymer. In addition to the stabilizer composition of the present invention, other well-known polymer adjuvants may be added such as plasticizerε, pig- ments, fillers, dyes, lubricants, ultraviolet light- absorbing agents, densifying agents and the like.

The present invention is further illustrated by the examples which follow. All parts and percentages are by weight unless otherwise indicated. In the examples set forth below abbreviations for the organotin compound component, borate derivative component and the thio-type of compound component have been utilized for the sake of brevity. The name of such compounds and their respective abbreviations are as follows:

NAME ABBREVIATION

butylstannoic anhydride BSA butyl(isooctylthioacetate)tin sulfide BIOTATS isooctyl bis(2-thioethyl)borate IBTB

2-thioethyl tallate TET dodecanethiol DDT isooctyl thioacetoacetate ITAA mercaptobenzothiazole MBT

The examples set forth below illustrate the stabiliza¬ tion effectiveness of stabilizer compositions for polyvinyl chloride. These examples point out that a definite syner- gism exists when all three components of the stabilizer composition are employed vs. one or two components utilized for stabilization.

In these examples, a series of polyvinyl chloride formulations were prepared using the following proportion of ingredients:

Ingredient Parts b Wei ht

Polyvinyl chloride homopolyme (Tenneco PVC 225 PG) Ti0 ₂ CaC0 ₃ Paraffin wax (165°F)

Calcium stea ate Stabilizer composition

Each of the formulations of this example was prepared using a roll-mill heated to a temperature of 175°C, with each formulation being milled for five minutes after band¬ ing. Sheets of each formulation were then pressed for ten minutes at 175°C at a pressure of 40,000 psi. The whiteness index (W.I.) of the pressed samples was measured using a MacBeth MC-1500 Colorimeter. The stabilizer compositions for all of the examples were prepared by mixing all of the components together and thereafter adding the mixture to the polyvinyl chloride. In those cases where a diluent was utilized in order to enhance the mixing of the components, the diluent was mineral oil. All amounts shown in the examples represent proportions in terms of percent by weight.

EXAMPLE 1

EXAMPLE 2

EXAMPLE 3