CA1061037A - Process for producing environmentally degradable compositions - Google Patents

Abstract

ENVIRONMENTALLY DEGRADABLE ETHYLENE POLYMER
COMPOSITIONS BY MASTERBATCH MIXING

ABSTRACT OF THE DISCLOSURE

A two step process for producing a degradable polymer based composition which comprises a) dryblending a masterbatch of ethylene polymer, antioxidant and auto-oxidative susceptible additive with a masterbatch of such polymer, antioxidant and salt of at least one polyvalent metal having an atomic number of 21 to 30, 39 to 48 or 57 to 71 and then b) melt blending the dry blend.

Cross References To Related Patent Applications This patent application is a division of patent application Serial No. 150,087 filed August 24, 1972.
S P E C I F I C A T I O N

1.

Description

1061037 8731-l-c-This invention relates to ethylene polymer compositions. Specifically this invention relates to an ethylene polymer composition which when exposed to the elements of the environment undergoes degradation.
It has been made dramatically apparent that the huge volume of plastic products used by industry and the consumer has resulted in a significant disposal proble~. All too often many plastic products, after the use by the ultimate consumer, bec~me litter.
Over the course of the past several decades, in an effort to meet consumer demands, the plastics ind~9try has made such plastic products more stable and as a consequence littered articles have an increased dursbility. With the presence of these stable plastic systems and with the advent of the awareness of the ecological needs of society solutions to the litter problem aré now being sought.
While it was known and disclosed in U.S, 3,454,510 that certain pro-oxidant metal calts in 20 polyolefln filmY, specifically mulch films, would render 8ame envlroNmentally degradable, that disclosure was - inherently limited to opaque films.
It w~s further disclosed in U.S~ 3,320,695 and U.S. 3,341,357 that cert~in unsaturated hydrocarbons could be added to op~que polyolefin films to promote degradation.
These opaque films, also used in mulching operations, would require relatively large weight percentages of certain un9aturatet hydrocarbons which resl~lted in a "soft"
product; thst is one not normally considered suitsble for consumer product application.

2.
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8731-l-C-0 6 ~ 0 3 7 ~ here is described herein an ethylene polymer composition, suitable for fabrication of translucent to transpsrent consumer-type pla~tic products, which compositlon retains its structural stability during its norm~l useful life and when discarded to the environment the ambient environmental elements cause the plastic c~mposition to degrade. The degradation reaction of the ethylene polymer composition occurs at a significently fsster rate after exposure thereof to natural or artificial actinic light.
The ethylene polymer composition of this inven~ion, comprising the combinatlon of both an auto-oxidative susceptible organic additive and a polyvalent transition metal salt in an ethylene polymer, is a product which has been found to undergo weathering at a greater rate than a similar product containing the equivalent amounts of only the auto-oxidative su~çeptible organic additive or only the polyYalent transition metal salt. The ccmpositions can include the conventional additives such ~8 fillers, plgments, slip agents, antioxidants, anti-stats, antiblocks, antifogs, or other materials conventionall-) added to ethylene polymcrs In certain cases it has been found that the ccmbination of moderate amounts of both an auto-oxidative 8usceptible organic additive and a polyvalent transition mRtal salt in an ethylene polymer yields faster weathering rates than equivalent or larger amounts of either one of the individual components alone added to the same ethylene polymer.
It has been found that products formed with the ethylene polymer compositions of this invention will, ~hen exposed to weathering, undergo high levels of multi-

3.

~10 61 0 37 8731-1-C-l face~ed crazing, followed by cracking and ultimately resulting in particulate formation. With further passage of time the crazing continues on the particulates formed re~ulting in more and finer particulates. No additional external physical forces are necessary to cause the partlculate formation although such external physical ' orces can aid in the "sloughing off" of the outer parti-culate lsyers to expose a new surface to the environment.
Broadly speaking this invention is an environmentally degratable ethylene polymer composition of (i) an ethylene poly~er base resin, and as a synergistic combination of atditives, (ii) an auto-oxidative ~usceptible addi'tive as a polymer or low molecular weight Qrganic compound ant (iii) a polyvalent tra;nsition metal salt; there can also be present (iv) a stabilizer or antioxidant for the ethylene polymer. As used in this specification the term "ethylene polymer composition" has this broad meaning.
In more 9pecific terms the ethyle~ polymer composition of this invention contains (i) an ethylene polymer base resin, and ~s a synergistic combination of additives, (ii) a polymer wherein the predominance of the mer unit~ have, or a low molecular weight organic ' compound that has, at least one hydrogen bonded to a carbon atom having an auto-oxidative susceptibility 8reater than that of a hydrogen bonded to a nonmal'secondary carbon atom, (iii) an organic salt of a polyvalent metal' wherein at least one metal is a transition metal wherein electron transfer occurs in the 3d or 4f sub-shell and (iv) an organic antioxidant for the ethylene polymer.
4q ~0 61 0 3 7 ' 8731-1-C-l In even more specific terms the ethylenë polymer composition of. this invention contains polyethylene, polyether or polypr'opylene, an organic salt of a poly-valent transitlon metal wherein the me~al can be iron, ' manganese, zinc or cobalt, and an antioxidant such as the sterically hindered phenols, aryl amines, thiourea's, thiocarbamates, phosphites and thioether esters Antioxidants for ethylene polymers have been~
found useful to stabllize the ethylene polymer compositions 0 80 a8 - to provide compositions whereby the per~od required before embrittlement occurs may be "built into the compos-ition." Thi9 a9pect of the invention is of course valuable insofar a~ one knowing the normal useful li'fe (period before dispo~al) of an article, could proportIon 'the amounts of anti~xidant and ~dditlves to give a structurally stable product during the useful life period but ~hich will undergo embrittlement within a relatively short time after exposure to the elements~
The ethylene polymer compositions can be compounded according to any one of several known techniques, su~h as, direct addition of all constituents, ma8ter batching wherein any single master batch may contain several constituents but will not contain both the poly~
valent transition metal compound and the auto-oxida~ive su~c~ptible organic additive, or any other compounding procedure.
The production of the compositions by direct adtition of all constituents and blending until a sin~le ho~ogeneous mixture is obtained are well known techniques.
The master batching involves the preparation of two or more compo8~ tion~ which are ~ubsequently combined into 5.

1 0 61 Q 3 7 87~ C-l single homogeneous mixture, In the master batching procedure the polyvalent tran~ition metal compound and the auto-oxidative ~usceptible addltive are initi~
present in separate master bstch compositions. These separflte ~aster batch compositions are then combined or blended in proper proportions at a future date to'produce the ethylene pol~mer compositions of this invention~ This ~nables one to prolong the shel~ or storage life since the degradation reaction does not progress to any appreciable extent until there has been a homogeneous ~lxing of these two componentc in the ethylene po1~er composition, For example, one can produce a first master batch of ethylene polymer plus the polyvalent transition metal compound plus sufficient antioxidant to stabili7e the first master batch, and a second master batch of auto-oxldative susceptible additive (e,g~ propylene poly~er, or àlkylene oxide polymer) with or without ethylene polymer plus sufficient antioxidant to stabilize th'e aecond master batch, In addi~ion, either or both of the master batches can contain the conventional amount6 of the addi~ives usually known to be useful in ethylene polymers, Further, one can have more than two 80-called m~ster batches, if desired.
Dur~ng the period in which the first m~ster batch and second master batch are stored in sepsrate - - containers the environmental degradation discussed herein will not occur, Likewise , if one were to blend pellets of the two master batci~es the blcnded mixture will n~
8how any signs of environmental degradation However, a8 600n as thcre hes ~ccn fl homogcneous fluxing or melting 6, ,~

.. . .

0 6~ 0 37 8731-1-C-l of the two or more master batches such that the auto-oxidative susceptible additive and the polyvalent transition metal ccmpound are present together in a single, uniform, homogeneous ethylene polymer composition then environmental tegradation will commence~ This ultimate blending of the multiple master batches can be carried by any of the known procedures Ruch as solution blending, melt blending, milling;
Banburying, screw driven mixers, and the like. It can also be carried out in the proce~sing equipment used to produce the ultimate manufactured product, for example during the film extrusion or spinning process.
It was surprising to note that in certain instances ethylene polymer compositions having the same chemicfll contents produced by the master batch prbcedure had longer storage stability properties than those produced by the direct addition procedure.
The ethylene polymer compositions of ~his inve~tion can be produced by any suitable method normally employed in ethylene polymer processing, for example, extruding, such as blown tubular film extrusion, slot~
cast die sheet extrusion, slot-cast die extrusion coating;
molding such as lnjection, blow, rotary, transfer an~
the like; fiber-forming, such as melt spinning, drawing and the like; and so forth.

BASE RESIN
The base resin is a normally solid thenmoplastic ethylene polymer. The resin may be an ethylene homopolymer or copolymer wherein the ethylene fraction is predominant or mixtures thereof or with other polymers. Both high and low density polye~hylenes and mixtures thereof can be used 10 61 0 3 7 8731-1-C-l The high density ethylene polymers useful as the bàse resin~ in the present invention are essentially linear in structure, and are known as "linear polyethylenes."
It is known that high density linear polyethylenes can contain chain transfer agents, and/or chain terminating agents which are used to modify the melt viscosity,molecular weight or other properties of the resins and it is intended to encompass such modified polymers within the scope of this`invention. The high density polyethylenes are generally characterized by a density that i~ about equal to or greater than 0.94 g/ccu and is usually in the range of ; from 0.94 to about 0~97 g/cc~ The high density polyethylenes can have a melt index of from 0.005 to 100 and preferably from 0,15 to S0 decigrams per minute, tASTM D-1238), It should be noted, however, that mixtures of high density polyethylenes can be used as the ba~e resi~ in producing the ethylene polymer compositlons, and such mixtures can have a melt index le9s than-0.005 or greater than 100 decigrams per minute The low density ethylene homopolymers have densities of less than 0~94 g/cc~ and are usually in the range from 0.91 to 0,93 g/cc. The low density ethylene hcmopolymQrs have melt indices fr~m about 0,05 to about 100 decigrams per minute inclu9ive, and preferably frcm 0.5 to 20 decigrams per minute; mlxtures thereof can be used if des~red.
The ethylene copolymers useful as base resins are tho~e obtained by the copolymerization of ethylene with any monomer containi~g the -C~C- group which will copolymerize with the ethy~ene and form thermoplastic copolymers Illustrative of' such copolymerizable monomers 1061037 8731-1-C-l are the alpha olefins (in minor amounts) containing up to 18 carbon atoms such as propylene, l-butene; isobutene, and l-pentene; halogenated olefins such as chloroprene, tetrafluoroethylene, chlorotrifluoroethylene, hexafluoro-propylene; vinyl aryls such as styrene, o-methoxystyrene, p-methoxystyrene~ m~methoxystyrene, o-nitrostyrene, p~
nitrostyrene, o-methylstyrene, p-methylstyrene, m-methyl~tyrene, p-phenylstyrene, o-phenylstyrene, m-phenylstyrene, vinyl naphthalene, and the like; vinyl and vinylidene halides, such as vinyl chloride, vinyl fluoride, vinylidene chloride, vinylidene fluoride, vinylidene bromide, and the like; vinyl esters such as vinyl formate, vinyl acetate, vinyl propionate, vinyl butyrate, vlnyl chloroacetate, vinyl chloropropionate, vinyl benzoate, vinyl chlorobenzoate, and the like, acrylic and slpha-alkyl acrylic acids, their alkyl esters, their amides and their nitriles such as acrylic acid, chloro-acrylic acid, methacrylic acid~ ethacrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, n-octyl acrylate~
2-ethylhexyl acrylate, n-decyl acrylate, methyl methacrylate~
butyl methacrylate, methyl ethacrylate, ethyl ethacrylate, acrylamide, N-methyl acrylamide, N,N~dimethyl acrylamide, methacrylsmide, N-methyl methacrylamide, N,N dimethyl methacrylamide, acrylonitrile, chloroacrylonitrile, methacrylonitrile, ethacrylonitrile, and the like, maleic and fumaric acid and their anhydrides and alkyl esters such as maleic anhydride, dimethyl maleate, diethyl maleate and the like; vinyl alkyl ethers and ketones such - as vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether, 2-chloroethyl vinyl ether, methyl vinyl ketone, ethyl vinyl ketone, isobutyl vinyl ketone~ and butadiene~
isoprene, cyclopentadiene, hexadiene-1,6, norbornadiene;
9~

1061037 8731~ C-l dicyclopentadiene, and the like; also vinyl pyridine, N-vinyl carbazole, N-vinyl pyrollidine, acrolein, vinyl alcohol, vinyl acetal, vinyl butyral, and the like. Other monom0rs which may be interpolymerized with ethylene include, carbon monoxide and formaldehyde, but these are generally not preferred~
These copolymer resins should contain a major amount of ethylene units polymerized in the copolymer~~
Preferably the copolymer should contain from about 50 to about 99 weight per cent polymerized ethylene monomer and mo~t preferably from about 80 to about 99 weight per cent polymerized ethylene monomer, depending upon the ~`~
particular~ copolymerizable monomer employed and the intended end u~e of the ethylene polymer composition of this invention.
Other suitable polymers include by way of example ethylene/ethylidenenorbornene/propene-l terpolymers ~ and et~ylene/hexadiene/propene-l terpolymers~ In the .terpolymer~, the ethylene component is dominant and is present in amounts from about 50 to about 99 percent, The propene-l component is present in concentrations of from about 1 to about 50 percent by weight of the terpolymer;
the residual weight percent is of course the third component.
Preferred base resins are the ethylene homo-polymers while the preferred copolymer base resins are ethylene-vinyl acetate; ethylene-ethyl acrylate an~ the partially hydrolyzed ionic salt forms thereof; cthylene-acrylic acid and the ionic salt forms thereof, ethylene-propylene; and ethylene-styrene. The preferred ter-polymer is ethylene/propylene/ethylidene-norbornene~
The base resin constitutes the major component of the ethylene polyMer c ~Iposi~ion and is normally `li!~ -106iO37 8731-1-C-l pxesent at a concentration of from about 70 to about 99 percent by weight; the remainder of the composition being the other additives thereof. Preferably the base resin i~ present at a concentration of from about 90 to about 99 weight percent of the ethylene polymer c~mpositio~.
The selected weight percentages of each individual additive i8 of course dependent on several parameters, including but not necessarily limited to the desired rate of degradation, ~olecular weight of the additive, relative activity of the additive, desired physical properties of the~ethylene polymer composition of this invention being prepared and 80 forth.

AUTO-OXIDATIVE SUSCEPTIBLE ADDITIVE
The auto-oxidative susceptible additive can be either a polymer wherein the predominance o~ the repeating units have, or a low molecular weight organic compound that has, at least one hydrogen bonded to a carbon atom having an auto-oxidative susceptibility greater than that of a - hydrogen bonded to a normal secondary carbon at~m. For example the polymer used as the auto~oxidative susceptible agent has an auto-oxidative susceptibility that is greater than that of unbranched polyethylene.
Thus, polypropylene, which has hydrogen atoms bonded to tertiary carbon atoms that sre more readily oxidizab~e than the hydrogen atoms that are bonded to the normal secondary carbon atoms of polyethylene is a suit~ble auto-oxidative suscept~ble additive in polymer form. Illustrative of other readily auto-oxidative hydrogen atoms bonded to carbon at~ms are the hydrogen atcms found, for example, in the allylic~ benzylic, tertiary alip~atic, aldehydo, alpha-oxyhydrocarbyl or 11.

0 61 ~ 37 8731-1-C-l' alpha-halohydrocarbyl groups.
Among the auto-oxidative susceptible polymers one can include the alpha~olefin polymers which are normally solid at xoom temperature and contain the unit:

rH~CH;~ ' wherein R i9 an alkyl group containing from about 1 to 18 carbon at~ms. Illustrative of such alpha-olefin polymers sre polypropylene, poly(butene-l), poly(pentene~
poly(4-methylpentene-1), poly(hexene~l), poly(octene~
poly(octadecene-l), and the like~ It is considered pre-ferable in this invention that the repeating unit of the auto-oxidative susceptible alpha-olefin polymers employed pofisess ratios of tertiary carbon atoms to secondary carbon stoms in the range of 1:1 to 1:16 and most preferably 1:1 to ~:60 Other suitable auto-oxidative susceptible' addltives include the polyalkylene oxides such as poly-ethylene oxide, polypropylene oxide~including the"block 20 .and random copolymers thereof, and the like; polyunsaturated hydrocarbons 9UC~ a9 polyterpenes and the liXe.
The preferred auto~oxidative susceptible additive i8 polypropylene, stactic or isotactic, crystalline or amorpho~s. Polypropylene when employed in the ethylene polymer composition yields a product having the desired physical properties for consumer-type applications and furthermore more rapidly promotes high levels of crazing to form small particulates. Also included as suitable polymers are block polymers containing a predominant amount of propylene blocks.
12.

10 6 1 0 3 7 8731-1-C-l Among the suitable readily auto-oxidative qusceptible low molecular weight organic compounds are those having a molecular weight less than about 5,000, for example, derivative3 of allphatic and cycloaliphatic compounds containing one or more allylic hydrogens such as myrcene, ocimene, limononene (dipentene) 9 cyclohexadiene, dicyclopentadi`ene, decahydronaphthalene, indene, tetra-hydroindene, ethylidenenorbornene, and the like; the unsaturated fatty acids such as eleostearic acid, linolenic acid, linoleic ac~d, oleic acid, crotonic and sorbic acid as well as adducts of these and other unsaturated aliphatic and allcyclic compounds with such as m~leic acid, acrylic acid, acrolein, and the like; compounds w~th highly reactive benzylic hydrogens such as cumene, para-isopropylbenzoic açid, and the like~
Preferably the readily auto-oxidative susceptible polymers and low molecular weight compounds are hydro-carbons but they need not be~ The presence of functional groups is not precluded but neither is it generally considered desirable.
The auto-oxidative susceptible additives are normally present at concentrations of fr~m about OoOl ~O
about 40 weight percent of the ethylene polymer composition.
Preferably the auto-oxidative susceptible additive is pre~ent in amounts of fr~m 0.05 to about 20 percent and most preferably in amounts of fr~m Ool to about 10 percent by weight based on the ~otal weigh~ of the ethylene polymer compositisnO Greater or lesser quantities of auto-oxidative additive may be employed depending upon the r~te of degradation and the physical proper~les desired in the ethylene polymer composition, 1061037 8731-1-C-l POLYVALENT TRANSITION METAL SALT
.
This additive may be any metal salt, organic or inorganic, wherein at least one metal is a polyvalent trans~tion metal, and preferably is an organic salt of a polyvalent transition metal and most preferably is an organic salt of a polyvalert transition metal wherein the metal ~8 one wherein electron transfer occurs in the 3d sub-shell or the 4f sub-shell~ The transition metals referred to are as defined in the Periodic Chart at the la terminal leaf page ,of the Handboo~ of Chemistry and PhysicsO
The Chemlcal Rubber Co~, 49th edition, (1968-69)~ They are those elements in the Fourth Period having atomic numbers of 21 to 30, in the Fifth Period having atomic numbers of 39 to 48, and in the Sixth Period having atomic number9 of 57 to 71. Among the specif~c~transition metals wherein electron transfer occurs in the 3d sub-shell one can mention V, Cr, Mn, Fe, Co, Ni, Cu Zn, ~r and Ag of the Fourth and Fifth Periods, among the transition metals wherein el~ctron transfer occurs in the 4f sub-shell are Ce or.Pr in the Sixth PeriodP
Suitable polyvalent transition metal inorganic ~alts pursuant to this invention are by way of example, iron chloride, zinc chloride, mercurous chloride, chromium trichloride, copper ni~rate, copper sulfate, cobalt chloride, nic~el sulfate, iron sulfàte, iron bromide, zinc sulfate, mercuric ~ulfate ? and the like Typically the organic salt is the octoate, naph~henate, acetate, stearate or acetylacPtonoate metal salt, but it need not be so limited and other organic groups may be employed if desired~

106~037 8731-1-C-l Illustrative of suitable organic salts of poly-valent transition metals one can mention merely by way of exampl~s, cobalt acetate~ cobalt octoate, cobalt naphthenate, iron napthenate~ iron octoate, lead stearate, lead octoate, zirconium stearate,c~rium octoate, manganous stearate, manganous oleate, manganous dodecyl aceto-acotate, cobalt acetyl acetonate, cobaltous acetate, c.obaltous oleate, cobaltous stearate, cobaltous dodecyl acetoacetate, cupric steaxate, cupric oleate, ferric acetate, zinc octoate, zinc naphthenate, iron distearate, potassium permanganate, potassium trioxalatocobaltate (III), trisethylenediaminecobalt (III~ chloride,.sodium hexa~itro-cobaltate (III), potassium hexacyanocobaltate (III) and .the like.
Polyvalent transition metal salts pursuant to the practice of this invention may be used individually or in combination~ It has been found that certain combln-ations of po~yvalent transition metal salts promote degradation more so than the equivalent amount of any one salt of the c~mbination; this is particularly noticeable with mixturee of iron and cobalt salts, The polyvalent transition metal salts are normally present in amounts of fr~m about 00002 to about 2~0 weight percènt of metal atom9 based on the weight of the total compo~ition. Preferably the metal is present in amount of from about 0~005 to about 1.0 and most preferably ~n amounts of fr~m about 0~01 to about 0/1 weight percent, based on the weight of the total composition. The need for only such small amounts of the polyvalent transition metal 8alt to give suitable weathering characteristics is an attractive feature of this invention insofar as the small amounts of salt generally do not adversely 8731-1-C-l ~Q61037 effect the mechanical properties of the base resin.

ANTIOXIDANT
Any of the antioxidants used with ethylene polymers can be used in the compositions of this invention.
These include the sterically hindered phenols, the aryl amines, the thioureas, thiocarbamates, thioether esters, phosphites or mixtures or adducts thereof.
By the term sterically hindered phenol is meant a substituted or unsubstituted compound containing at least one sterically hindered group of the structure H ~

wherein X is hydrogen, alkyl of from 1 to about 10 carbon atoms or a substituted or unsubstituted phenyl and Xl is alkyl of from 1 to about 10 carbon atoms or a substituted or unsubstituted phenyl, said sterically hindered group being susceptible to proton donation. Generally the sterically hindered phenol will be one that does not volatilize or decompose appreciably below temperatures of about 200C.
Illustrative of suitable phenol antioxidants one can mention tetra~is[methylene-3-(3', 5'-di-tert-butyl-4'-hydroxyphenyl propionate]methane, stearyl 3-(3', 5'-di-tert-butyl-4'-hydroxyphenyl)propionate, distearyl 3,5-di-tert-butyl-4-hydroxybenzyl phosphite, 1,1,3-tris(5'-ter~-butyl-4'-hydroxy-2'-methyl-phenyl)butane, 4-methyl-1,-6-di(2'-hydroxy-3'-tert-butyl-5'-methylbenzyl)phenol, 2,4-di(3'-5'-di-tert-butyl-4'-hydroxyphen-oxy)triazine, 2,2'-thiob~s(4'-methyl'6'-16.

~ `3~

8731-1-C-l tert-butylphenol), 4,4'-thiobis(3-methyl-6-tert-butylphenol), 3,5-di-tert-butyl-4-hydroxyanisole, 2,6-di-tert-butyl-p-cresol.
Among the suitable amine antioxidants one can mention N-phenyl-beta-naphthylamine, N,NI-diphenyl-p-phenylenediamine, p-siopropoxy diphenylamine, N,N'-di-beta-naphthyl-p-phenylenediamine, N,~'-di-(2-octyl)-p-phenylenediamine, N,N'-di-3(5-methylheptyl)-p-phenylene-diamine, aldol-alpha-naphthylamine, 4,4'-dioctyldiphen-ylamine, 4-octyldiphenylamine, 4-t-butoxydiphenylamine, the polymer of l,2-dihydro-2,2,4-trimethylquinoline, and the like.
Among the suitable thioureas are the polyalkyl thioureas having up to about 4 carbon atoms in the alkyl groups such as trimethyl thirouea, l,3-diethyl thiourea or ethylene thiourea, and the like. Thiocarbamates include the alkali metals salts thereof such as sodium dibutyl dithiocarbamate, and the like. The thioether esters include dilauryl thiodipropionate, distearyl thiodipropionate, and the like. Among the known phosphites one can mention the mono-, di- and tri-nonylphenyl phosphites, distearyl pentaerythritol diphosphite, the adduct of trinonylphenyl phosphite with 1,1,3-tris(5-tert-butyl-4-hydroxy-2-methylphenyl)butane, and the like.
Other suitable antioxidants include dibutyl-para-cresol, p-cresol-formaldehyde resins, para-tertiary-alkylphenol formaldehyde resins in admixture with amino dithioformates, aliphatic polyepoxides, organic phosphites, thiophosphates, or dithiophosphites, para-tertiary alkyl-phenol formaldehyde resins in admixture with mercapto c~mpounds~ 2-thiono-2-mercaptodioxaphosphorinane compounds, 17.

8731-1-C-l tetraphenylsuccinodinitriles or triphenylmethane~ or dith~ophosphate metal sa1ts 3 and the like, as well as cGmbinations thereof; also, chelating agents, such as for example, carboxylic acids, such as malonlc acid, succinic acid and the llke; substituted oxamides such as oxanalide and the llke; amino aclds such as glycine, and the like; amino polycarboxylic acids~ such as ethylene~
diamine tetraacetic acid, diethylenetriamine pentaacetic acid, hydroxye~hyl ethylenediamine triacetic acid, nitrilo~
triacetic ac.id, hydroxyethylimino diacetic acîd, diaminG-cyclohexane tetraacetic acidJ diaminoethyl ether tetra~
acetic acid, ethylenediamine di(ohydroxyphenyl acetic acid); N-phenyl-NI-(p-toluene sulfonyl)op~phenylenediamine, N,N-disalicylidene propylenediamine, and the like~ penta-erythritol, sorbitol, resorcinol, and other polyfunctional alcohols and esters thereof; as well as combinations thereof.
The antioxidant is nor~ally present in quantities sufficient to stabilize the csmposition agalnst oxidative degradation for the entire useful life period deslred and is generally from about 0~0025 to about 1 weight percent preferably from about 0~025 to 0~1 we~ght percent, based on the weight of total e~hylene polymer eomposition~
It is of interest to note that almost all ethylene polymers often contain minute amounts of antio oxidant, but this amount is normally not sufficient to st~bilize the ethylene polymer composition of this invention and additional amoun~s are often requlredr However, in certain embodiments of this inventiorS
the antioxidant need not be present or need be presen~
in only minute amounts~ In these two cases the ethylene polymer composition will of course degrade very rapidly 18.

8731-1-C-l upon exposure to the elemen~s. This aspect of rapid degradatio~ is importan~ in an application where a product prior to use is sealed in a coverlng which el~minates action by the elemen~s9 particuIarly sunlight, rain and oxygen. When sought ~o be used the particulsr product is removed fr~m the cove~ng, u~ed as req~ired within a pre-specified tlme, and discarded to the environment for rapid degradation, For such embodiments of this invention it has been fou~d~hat concentrat~ons as low as 0.0025 percent by weight of antioxidant can be used.
As other aspects of this invention it ~s recognized tha~ certain suitable antioxidants as afore-said offer addi~ional benefits which give further dimension to this invention. For example certain an~i-oxidants, such as thioureas, are water soluble. Products protuced from the ethylene polymer composit~ons of th~
- invention containing thioureas m~y be utili~ed for long - periods in a relatively dry environment; then after exposure to aqueous environmental elements such as rain or fog leaching of the thioureas occurs rendering the product more act~vely degradable. Another example is wherein the antioxidant is b~odegradable, such a~ cer~ain thioether esters, as for example dilauryl th~odipropionate and the like. In these case~ bacteria found ~n the environment consume the antloxidant ~n the product~
rendering the produc~ more act~vely degradable, Still ano~her example is wherein the antioxidant is volatile~
such as mercaptomalic acid9 and certain urea derivatlves such as lgl~diethyl urea. Because o its volatility such an anitaxidant would generally be applied to the plastic object after f~brica~ion by immerslon in 19~

1061037 8731-1-C-l a solution of the antioxidant or by the use of a roller coater or spray gun or other suitable application technique.
Such volatile sntioxidants may also be used in conjunction with less volatile antioxidants present in minor concentrations inthe ethylene polymer compos~tions. The volatile anti oxidants upon dlscard to ~he environmental elements volati lize rendering the plastic product more ac~ively degradable, A further example is wherein the antloxidant is heat stable but light unstable such as alpha-phenylindolP and diphenyl thiourea. A plastic product employing antioxidants of this nature may be stored in a dar~ environment and when exposed to sunlight will readily start to degradeO
In another aspect of thls inven~ion lt ha~ been found that a preliminary irradiation of the ethylene polymer composition will greatly enhance the rate of degradation as compared to non-irradiated ethylene polymer composition~
As prev~ously pointed out an antioxidant may additionally be included to maintain a more stable composition prior to irradiation.
Normally the requisite level of ionizing radiation to accelerate degradation is from about 1 to about 20 megareps (MGRPS). Greater or lesser dosages of radiation m~y be employed depending upon the par~icular des~red rate of degradation. Such sources include the van de Graaff accelerator, cobalt 60, and the like~ Other s~it-able modes of irradiation are, by way of example~ ultra~
violet lamp, sunlamp, swirl~flow plasma arc~ mercury lamp~
and the like~ Any known radiation source-can be used~
This irradiation aspect of ~his invention is important in large volume plastic waste disposal units wherein the waste plastic is irradiated prior to exposure to the elements to provide an accelerated ra~e of degradat~cn~

1~61037 , 873~ C_ 1 In the followlng ex~mples the proces~ing and analyt~cal methods used for ssmple preparation 6re as de8cribed immediately hereinbelow. Two ccmpounding '~' methods were employed. The f~rst and primary method of ~ample c~mpounding is by employing ~he two r~ll mill (hereinafter called "roll mil~ meth~d"). The second method employed a Banbury mixer ~her~inaf~er called ' ~ xer method"), A 6 ~nches x 1~ inches t~o-roll ~ill wi~h heat supplied by fu71 stream at 190C. and hea~ed for at least 15 minutes is used. With th~ blt a~ close as pcssible ~he ethylene base polymer is added and ~hen during a peri3d of about 1 minute ~he bite is cpened after the ethylene polymer has begu~ to flux. The polypropylene or cther -` auto-oxida~iye suscept~ble agent is addedq Ihereafter antioxldant and other fiiler (if ~pplicabie) are added.
The polyvalen~ transit~on metal sals is then,slowly added in about 30 seconds. The material is worked for 2 min~tes until homogeneous, then pulled off the rolls and cut into 8qu~re~ about 2 ~nch by 2 inch., It is recognized that any of the other conventional additlves usually present D s~ch a8 p~gment, slip agents~ ~nti-block agents; etc. can be present if desired. Unle~ otherwise stated this method w~8 u~ed in the exam~les.
- In the mixer method a 5 lb. Banbury mixer wa~
employed with full steam on the shell and rotors for 5 minutes to achieve 190C. The ethylene bsse polymer and ~uto-oxidativa suscept~ble agen~, such as polypropylene~
wer~ added. The ram wa~ moved downward at the full pressure o~ 80 p8i and the Banbury operated at maximum forward ~peed for 3 minutes or until the ma~erials are fluxed.
The ~ntiox~dant, f~ller (if applicable), and polyvalent 21.

8731-1-C-l transition metal salt were added with the ram backed down to 10 psi and the Banbury at its slowest forward speed for one minute. The ram pressure was then readjusted to 80 psi and the Banbury was then operated at full forward speed for 2 minutes. Cooling water was then supplied to the shell and rotors and the mixer was operated at its slowest forward speed for one mi~ute. Thereafter the compounded materials was discharged, sheeted and diced.
After compounding by either the mixer or roll mill method the samples were compression molded by the following method. A mold lined with a sheet of polyethylene terephthalate resin was charged with the ethylene polymer composition. It was placed between preheated (190C.) plattens and low pressure (1 ton on 6 in.2 ram) was applied for four minutes followed by full pressure (32 tons on 6 inO ram) for two minutes. The plattens were then water cooled and the sample was recovered.
Weathering tests were conducted by placing a plurality of identical specimens from the same molded sheet in an Atlax XW Weatherometer that uses a carbon arc radiation source with Corex D filters to simulate solar light spectral-distribution. The sample was maintained at a blackbody radiation temperature of 140F. over a four hour period, which included an 18 minute period of water spray. Water was permitted to accumulate at the bottom of the chamber to provide a humidified condition. The exposed samples are removed from the Weatherometer after certain periods of time and examined for embritt~ement, % elongation and FMIR. The period in hours that has transpired is recorded when the sample fails the test.
Normally the samples are rated at the end of 20~ 60, 100, 150, 200, 250, 350, 500, 750 and 1,000 hours of exposure.

106~037 8731-1-C~l The specimen fr~m the previous ratin~ period is remaved p~rmanently from the Weatherometer at ~he end of the 60, 150, 250, 500 and 1~000 hours periods ~or complete evaluation~
By this is meant that at the 20 hour period the first specimen is removed, rated and returned, at the 60 hour period it is permanently removed, rated and tested; at the 100 hour period the second specimen is removed, rated ~nd returned, at the 150 hour period it is p~rmanen~ly removed, rated and tested, This procedure is continued in the time pairs until all of the specimens have been con~umed and permanently removed. On occasion additional 8pecimens were permanen~ly removed, rated ~nd tested at the 20 or 100 hour periods~
l'he permanently removed weathered samples were examined by surface reflectance infrared spectroscopy, known in the art as frustrated multiple internal reflec~ion (FMIR), to examine buildup of the surface carbonyl layer due to weathering exposure. A W~lks ~Iodel-9D FMIR attach-ment on a Perkin-Elmer Model 21 infrared spectrophoto-meter was used to make the ratio measurements, hereinafterreferred to also as R. A measureof the surface carbonyl buildup relative to methylene is calcula~ed by the e~uation R ~ A5.8/A7.3; i.e. the absorbance of the carbonyl peak at 5.8 microns to the absorbance of the methylene peak at 7.3 microns. This is usually performed ons specimen that has not been exposed and on specimens after 60 ~nd 150 hours exposure; on occasion specimens were snalyzed after exposures of 20 hours, 40 hours, 80 hcurs or 100 hour~. The ratio R rarely exceeds 1~0 for westhered conventional polyethylene (which is still flexible)~
Embrittled polyethylene will have R values exceeding 1~0.
An R value of 1.7 may bc correlated with the onset of embrittlement~ R values of 1.9 to 2~2 ~re characterlstic .. , ~^ ~3.

~)6~037 8731-1-C-l of ~ fully developed surfa~e c~rbonyl layer. R values above 2.5 ~re due princip~aly to dimlnishing of ~he methylene peak, rather tharl to ar. increase ln surface carbonyl level~
. The impact of ~ f~lly developed surf~ce carbonyl layer i8 recognized to be that ~1) oxld~ion of the bulk of the resin i8 proceedin~ ~nd (2) fracture prone sites ex~st on the specimen surface~ Cracks initiated ~n the oxldized surface layer propogate through the less oxidized material in the interior of the polymer resulting in detericration thereof~
The tensile physical propert~es of the wea~hered 8amples, ten8ile modulu~, tensile strength, and ultim~te elo~gation were measured by a modified ASTM D882-67(Method A) procedure using an In~tron Tensile Tester.arter 0, 60, 150, 250 and 500 hours expoure, and occasionally - after 20 hours or 100 hours of expos~re~ In this modifi-catlon a one inch specimen i~ u~ed and stretched at ~
rate of 0.2 inch per minute to a one per cent stretch to obtsin the mcdulus; the sam~ specimen i9 then stretched at a rate of 2 inches per minute to obtain the stress-8tr8in curve. Elongation deteriorsLion correlates with the emSrittlement observed in the aforesaid Atlas*XW
Weatherometer ratings, Normally an ultimate elongation ~lue less than 50qO is slightly brittle and a value below 20% i8 brlttle.
It ~as observed thnt ~9 weathering exposure proceeds, surface crscklng eppsared. The crscks occux ~n polyethylene compo~itions generally ~fter the on~et o ~mbrittlement, usually between 150 to 250 hours of exposure. Through the optical microscope, the crnck pattarns which ~ppeared on the surf~ca of.~everely ~xldi~ed snmples were clearly visiblo. The cro~s section .~ ~4.

1061037 8731-1-C-l - fr~cture ~urface8 of bri~tla spec~mens were observed through tha optical microscope and at m~gniic~tions of 46X to 300 X lt wa~ possible ~o determine wh~ch areas of the cross sect~n were brittle. Scanning electron m~crographs of the weathered specimen ~t a m~gnification o~ SOOX show that the cracks were formed by brittle f~lure resulting in very sharp clean cuts. Prlm~ry cracks are normal to ~he curface and are beleived to be influenced by the ~nterrl~l stress d~sbtibution in the specimen, and will be pQrallel to the surface if the stress distribution in the sp~c~men is uniCorm~ Secondary cracks ~oin the primary crac~s, are ess-shaped, and slant inward ~t an angle less than 90 to the surface. Tertiary cracks ioin primary and secondary ones and also are e8s-~ha2~d and likew~se -~lant ~nwardly. This produces a network of crack-~ in wh~ch the sp~cing between the crscks progressively becomes smaller and results in particles on the order of 350 microns in width which can readily peel off or slough off due to the "61ant faul-s" s~milar 20 to that mechanism observed in exfoliating rocks~
The stability of the ~amples prior to weathering W8B determ~ned by Differential Scanning Calorlme~ry (DSC).
A du Pont 900 Thermal Analyzer with DSC module attachment and an external strip chart recorder were used for the ~sothermsl DSC induction time studle~. By measuring the len~th of time at 180C. or 200C. required for the hea~
o oxldation to be evolved, the ~tability of the c~mpound - can be determined. At 200C. well-~tab~l~zed commercial : polycthylene has a 3 to 6 minute inductlon time. All ~nductlon ~im~8 ~re ~iven in minutes unless otherwlse ~pecified.
25.

, >~
f '' ~ .

10 61 0 3 7 8731-1-C-l The DSC induction time measurements were made as ~ollows: Test batches of ethylene polymer compositions were prepared on a two roll mill on which were blended 100 gram batches of ethylene polymer and atditives. Minimum fluxing temperatures were used to avoid premAture oxidation effects. The fluxed mixtures were then pressed into plaques about 10 x 10 inches with a thickness of 10 mils on a heated hytraulic press. Circular specimens 0,20 inches in diameter were cut from the lO mils plaques and then placed in aluminu~ sample holders of the Differential Scanning Calori~eter (DSC) cell. In each case the sample holder plus sample were then placed on the raised sample position while an empty aluminum sample holder was placed on the raised reference position~ Nitrogen was passed through the assembled DSC cell at a gaæ flow rate of 500 ml./min. blanketing the sample and reference cells wit~ an inert atmosphere. The .ample and reference cells were then heated st a programm~d rate of 80C. per minute to a pres~lected isothermsl temperature. When equilibrium temperature was obtained, an accurate millivolt recorder (with a 1 inch per minute linear chart speed and a 0 to 25 millivolts chart span). began to record the amplified differential thermocouple signal from the DSC cell~ After one inch of chart travel the nitrogen flow was rapidly topped and air was passed through the DSC cell~ also at a flow rate of 500 ml per mlnute. The sharp inflection in the exothermic direction of the recorded curve indicated the end of the induction period~ Since the induction t~me i9 that period of time during which there is no exotherm or thermal oxidative degradation, it is a measure of the effectiveness of thenmal stabilizing 26.

1061037 8731-1-C-l additives which have been compounded with the ethylene polymers. A direct compsrison between controls and the compositions of this invention i8 therefore provided by this induction time measurement.
EXAMPLE I
Ethylene polymer compositions containing low density polyethylene LDPE (0.922 density) polypropylene PP (98% isotactic) a8 a polymeric auto-oxidative susceptible additlve in amounts of 0% (Control A), 0.1%, 0~3%, 2%, 5%, 107o~ 20% and 3~/0, and O~lOqo of cobalt metal (Co) as a - cob~lt naphthenate solution in mineral spirits were pre-pared in the aforedescribed manner. A control (Control B) sample consisting of the base res~n and the same ~mount of mineral ~pirits as was added above as solution, and a second control (Control C) sample consisting of the b~se resin and 10% polypropylene were also prepared. The aforesaid samples were fabricated into 20 m~l plaques and weathe~ed according to the aforementioned procedure~
The exposure time required for embrittlement, h~reinafter also referred to as "Embr ,!~l, to occur is listed in Table I, Parts A and B, as well as the time required for the surface carbonyl level to exceed 1.7~ hereinafter al80 referred to as "FMIR R ~ 1~7" and the ultimate elongation to fall below 20%, hereinafter also referred to as 1~ ~ 2~qo ELONG~" The effect of the added polypropylena in Control C in promoting embrittlement is to reduce the exposure time required for embrittlement to occur as compared to Control B without polypropylenee The effect of the cobalt metal salt in Control A is to reduce the cxl)osure time required for embrittlement over that neceelsary in Controls B or C without cobalt~
27.

8731-1-C-l The effect of the combined system of this invention is to produce an interaction which prcmotes embrittlement at a much faster rate than is ob~erved for any of the controls.
This embrittl~ment effect is also polypropylene concentration dependent; that is the expo~ure t~me required for ombrittlement ~o occur decrease3 a~ the polypropylene concentration increasQs and in all instances embrittlement of the ethylen~ polymer cumpositions of this invention proc~eted fa~ter than in Controis A, B or C~
Ethylene polym,er CO~pO8~ tions identical in every way with the above, but irradiated with a 5 mRgarep do~e prior to weathering, demonstrated reducet expoæure tim~s or embrittlement to occur as the polypropylene concentr~tion increased and required less exposure time to ombrittle than the equivalent unirradiated samples o~ Part A of Table I at polypropylene concentration~ of ~X ~nt hi8her~ The exposure time~ for the irradiated compo~itions are listed in Table I, Par~ B.

28.

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0 61 03 7 8731-1-C-l EXAMPLE II
Example I was repeated using cobalt octoate,in place of the coba~t naphthenate, at several varying concent-rations. In all instance~ the ethylene polymer compositions containet two weight per cent polypropylene. The results are reportet in Table II, Part~ A and B.
TAB~ F II
Ethylene Polymer ExposupARTi~-s Required. Hour~ ;
ComDosit~on. %
LDP~ Co Embr. ' R~ 1.7 ~ O ELONG.

98 0.10 100-150 100-150 150 98 0.075 100-150 100-~50 150 98 0.050 150 100~150 150 98 0.025 100-150 150 150 98 0,010 150 150-200 150-250 PART B
Co Embr. R> 1.7 ~2 0 ELONG.

9~ 0.10 100-150 60 150 98 ~.075 100-1~0 60 15~
98- 0.050 - 60-100 60 150 98 0.025 100-150 150 150 98 0.010 100 60 60-150 EXAMPLE III
Thi3 examRle de~onstrates the use of polyo propylenes of v~rious degrees of tacticity and molecular weight.
Ethylene polymer compositions containing 98Z
of a 0.922 de~sity LDPE, 2X polypropylene and 0.05%
cob~lt m~tal as a cobalt n~phthenate solution in mineral spir~ts were pr~pared ~sing A 98% isotactic polypropylene, an atactic polypropylene, and an isotactic polypropylene wax ~relatively low molecular weight) that had been pre-pared from the isotactic polymer by pyrolysis~ These co~positions were fabricated into 20 mils plaques and 30.

8731-1-C-l weathered according to the aforementioned procedure.
All of the above c~mpositions, which were weatheret in a similar manner, produced embrittlement by 150 hours~ a surface carbonyl level grester than 1.7 by 150 hours, ant an ult~mate elongat~ons below 2~qo by 150 hours exposure.
EXAMPLE IV
This example temonstrates the use of LDPE of several densities.
Ethylene polymer compositions containing 98%
of LDPE, ~Z polypropylene (98% isotactic) as the auto-oxldative susceptible polymer additive and 0.025% to 0,075% cobalt metal, as either the cobalt octate or cobalt naphthe~ate solution in minersl ~pirits, were prepared U8i~g LDPE having densities of 0.919, 00922, 0.924, 0~925 and 0~928 as the base resins. These compositions were fabricated into 20 mlls plaques or 2 mil~ films and weathered accorting to the aforementioned procedure~
All of the above c~mpositions showed accelerated ~mbr~ttlement and hat become brittle by lOO to 200 hqurs of exposureO
,EXAMP~ V `
Ethylene polymer compo8i ions containing 98%
of LDPE, 2% polypropylene ~98% isotactic) a~ the ~uto-oxidative susceptible polymer addltive, and 0~025% cobalt ~etal as cobalt naphthenate solution ln mineral ~pirits were prepared from a 00924 density LDPE of the type for~et by polymerization in a tubular reactor and a 0.925 density LDPE of tha type fonmed by polymerization in a stirred autoclave as the base resins~ These c~mposition~
were fabricated into 20 mils plaques and weathered 10 61 0 3 7 8731-1-C-l according to the aforement~oned procedure~
The weathering behav~or of these two samples was similar. Both embrittled by 150 hours of exposure, achieved surface carbonyl levels above 1.7 by 150 hours of exposure, and achie~ed ultimate elongation detericration below lOqo by 150 hours of expo~ure.
EXAMPLE VI
Ethylene polymer composit~ons containing a 0.922 density LDPE es the ba~e resin, polypropylene ~98% isotactic) in amounts of 070~ 2%, 570 and 107o and 0~1070 cobalt metal as cobalt n~phthenate solution in mlneral spirits were preparedO A control sample consis~ng d the base resin alone was al~o prepared. All of the above compositlons contained the ucual slip ~oleamlde), antiblock (silica)J and antioxidant (2,6~ditert-butyl-

4-methylphenol), system in the conventional amounts used in commercial LDPE. These ccmpositions were extruded through a 1" NRM extruder at 400F and reextruded through tha extruder until the composition had been reextruded five times, After each p~ss a 20 mlls plaque was fabricated9 te~ted for physlcal propertles~ and weathered accord~ng to the aforementioned procedures, The ult~m~te elongation data of each composit~cn7 including the control, showed that no premature deter~-ora~ion of elongation had occurred by virtue of the reextrusions~ The initial ultimate elongation values of all composltions prior to weatheri~g wa~ consl~ent with the behavior of the control s~mple. All of the plaques specimens containlng both polypropylene and cobalt salt exhibited accelerated embrittlement with~n 60 to 250 hours upon weathering~ The control specimen remained flexible after 500 hours of exposure.
32, 10 61 0 3 7 B731-l~C-l EXA~IP~E VII
Ethylene polymer compositions conta..ning .
of a 0.922 density LDPE as the base resin, 1~16% poly-propylene as the auto oxida~ive suseeptible additive, (98% i90tactic) and 0 05% of cobal~ metal dS the followln~
~lt8: l) solid robal~ acet~teD 2) cobalt octoate 801ution in mineral sp~rits~ 3) ccbalt naphthen~te 801ution in mineral spirits, and 4) the cobalt salts of B mixture of branched C8 and Cg acids in mineral spirlts3 known as cobalt Nuxtra. These compositisns were fabricated into 20 mil~ plaques and weathered according to Ihe ~forement~oned procedures~ The expos~re times required for embrittlement to occur~ surfPce carbonyl level to exceed 1~79 and ult~mate elongation to drop below 20%
ar¢ lis~ed in Part A of Table III~ All of ths c^bale 8alt form~ were active and promoted accelerated embrit~le ment in 200 hours exposure or less~ The salts dispersed in mineral spirits show enhanced activityS with the naphthenate being the most active form i.n the 1.16%
poly~ropylene compositions.
Ethylene polymer composi~ions identical to the above in ever.y way, but containing a 0.922 g/cc density polyethylene base resin, 6.48% polypropylene a-s the auto-ox~dative susceptible additive and 0,10% cobalt metal fr~m each of the same cobalt salts were prepared.
The exposure times required for the above phen~mena to occur are listed in P~rt B of Table lIla All of t.he cobalt ~alt form~ were flcti~e and promoted accelerated embrittlement in 200 hours exposure or less. The ~lt.s dlspersed in mineral spirits show enhanced activity in the 6.48Z polypropylene composltions, All of the octoate~
33.
h 8731-1-C-l naphthenate, or mixed branched C8 and C9 acid saIts o~
cobalt show comparable effectiveness in cau~ing accelerated embrittlement in combination with polypropylene in the preferred range of l to 6~57O in low density polyethyleneO
TABLE III
Part A
Exposure Times Required 9 llourg Co Sal~ Embr~ R ~ 107 - 20qo ELONG.
10 Acetate 200 > 150 ~ 150 Octoate 150-200 150 100-150 Naphthenate 150 100 100 Nuxtra 150-200 100 100-150 PART.B
Exposure Times Requiredn Hours FMIR
Co Salt Embr R~ 1.7 - '2~/o ELONG~
Acetate 200 ~ 150 ~150 Octoate 100 150 60 20 Naphthenate 100 100 60~100 Nuxtra 150 150 60~100 EXAMPLE VIII
Ethylene polymer c~mpositions containing 98%
of a 0o922 densi~y LDPE as base resin 2% polypropylene as the auto-oxidstive susceptible additive (98% isotact~c) ~nd 0.05% metal of the metal salt solution of cobalt octoate~ iron octoate, manganese octoate, cerium naphthenate~
zinc octoate, lead octoate, zlrconium octoate~ and calcium octoate in mineral spirits were prepared~ These compositions were pres~ed into pl~ques ant weathered accord~ng to the aforementioned proceduresO
The exposure times required for embrittlement to occur, surface carbonyl level to exceed 1.7 9 and ultim~te elongation to drop below 2~/o are listed in Pert A of Table IV for the above compositions~ In Part B
of Table IV are shown the results obtained on identlcal composit~ons which had been irradia~ed with a 5 megare~
does prior to weathering~

8731- l-C-l TABLE IV
PART A
__ - FM~R
Salt Embr~ R~ 1.7 C 20~!oELONG~
Co Octoate 150 60~150 60 Fe ~ctoate 100 60 60 Mh Octoate 150 150 150 Ce N~phthenatel50 150-250 Zn Octoflte 250 150 Pb Octoate 250-500 150 Zr Octoate 500 Ca Octoate 500 PART B

F~IR
S~lt EmbrO R> 1~7 ~ 20% ELONG.
Co Octoate 150 60 60 Fe Oc~oate ~50 60 150 20 Mn Octoate 150 150 150 Ce Naphthenatel50 150-~50 Zn Octoate 250 150 Pb Octoate 250-500 Zr Octoate 500 Ca Octoate 500 250+
EXAMPLE IX
E~hylene polymer compo3itions of 0~922 density LDPE as base resin, polypropylene ~98%isotactic) as auto-oxidative susceptible additive in amou~ts of 2% and

5%, and mixtures of 0.05% cobalt metal as cobalt n~phthenate solution in mineral spirits and 0.05% iron metal as iron octoate solution in mineral spirits were prepared. Both compositions were pressed into 20 mils plaques and waathered according to ~e aforem~ntioned procedure. Control samples of the same 0O922 density LDPE were prepared as extruded 20 mils sheets~ Compositions identical to the above, but contai ~ g 0010% cobalt metal as cobalt naphthenate solution in mineral spirits9 ins~ad of the mixed metal salt system of cobalt naphthenate and iron octoate wera also prepared9 pressed into 20 m~ls plaques and westhered by the aforementioned procedure.
35~

~061037 8731-1-C-l The exposure times required for embrittlement to occur~
surface carbonyl level to exceed 1.7 and ult~mate elongaticn to drop below 2~/o are listed in Table V. At both poly-propylene concentrat~on levels (27O and.5%) the mixed metal salt system promoted accelerated embr~ttlement in ~he ethylene polymer c~mpositions~ The LDPE control was still flexible after 750 hrs exposure and not embrlttled.
Compared to ~imilar compositions containing the same polypropylene content and the same total metal content 901ely as coba~t, the mixed me~al 9alt 9ystem-5 show a dec~ease in the expo6ure time requixed to achieve embrittleme~
and for the ultimate elongat~on o drop below 2~/o~ T~e results show that the use of a mlxture of cobalt and iron i8 more efficacious than cobalt alone; they also how that cobalt alone i8 al80 saticfactory.
TABLE V
Run 1 2 3 4 Control LDPE,% 98 98 95 95 100 pp,% . 2 2 5 5 0 Co,Z 0.05 0.1 0~05 0.1 0 Fe,% 0.05 0 0.05 ~ p Exposure Tim~ Required~ Hours Embr. 60-100 150 100-150 100 ~750 FMIR R~ 1.7~ 60 60 60 60 207o ELONG. 60 150 60 100 ~XAMPLE X
A first ethylene polymer composition containing 95% of a 0~928 density LDPE as base resin 5% polypropylene as ~uto-oxidative suscept~ble additive (98% iso~actic) and e mixture in mlneral 8piXit8 of 0~05% cobalt metal a~ cobalt octoate and 0~05% iron metal a~ iron octoate and a second ethylene polymer composltion conta~ning 98%
of a 0.928 density LDPE, 2~ polypropylene (98% i~otactic) and a mixture in mineral spirits of 0~025% cobalt octoate 36.

1 0 61 ~ 3 7 8731-1-C-l and 0.025% iron octoate were preparedO Bo~h of these campositions cont3~r.ed 0.OS% Irganox-1010 antioxidant 0.15% eruca~ide 81ip agentD and 0.15', silica anti-block agent. The campos~tions were pres~2d into 20 mlls pl-que~ extruded into 20 mil8 sheetg andextruded into 2 mils f~lm, ~11 o which were weathered by the afore-m~ntioned procedure. After weatherin~ for 60 hours the surface carbonyl level of both samples fabrica~ed as 20 mil9 plaques rose sharply. At lO0 hours a surface carbonyl level of 2.1 was achieved in both samples. E~brit~lement was ach~eved by 100 hour~ exposure and the ultimate - elongation dropped below lOZ after 60 hours of weathering for the first composition and after 100 hrs of weathering for the seco~d compo~ition.
The samples fabricated as extruded ~heet were examined after weathering in 20 hours exposure ~tervalsO
The aurface carbonyl level of both samples~rose ~harply in the interval between 40 and 60 hours of exp~sure, rising more rapidly for the first sample. The ultimate elongation dropped below 20% for the first composition after 60 ho~rs exposure and for the second c~mposition after 8Q hours exposure. Embrittlement occurred ~f~er 80 hours exposure for the fir~t c~mposition and after 100 hours exposure for the sec~nd composition~ and showed signs of ~plitting in the fir~t c~mposition after 500 hour~
expo2ure. ``
The sample~ fabricated as film developed a surface carbonyl level grea~er than 1.7 more slowly than did the other aforementioned spec~mens. This surface carbonyl level was obta~ned in the f~rst c~mposltion after 100 hours exposure 9 and in the second c3mpGsition ~fter 150 hours ~f exposure~ Embrittlement occurred in 37.

8731-1-C-l the film after 60 hours for the first composition and after 100 hours for the second composition~ After 500 hours exposure both fi~m samples had disintegrated and both shee~ samples showed signs of failure and splitting ~long th~ surface cracks.
.

The compositions of Example X9 as extruded fi~m and sheet, were tested for lubricity by the coefficient of friction (COF) test, ASTM D 18940 All film and sheet samples had kinetic COF values of 0.16 to 0.039 which i9 classified as high slip. A control film of the sflme 0.928 density LDPE without ~he 81ip and antiblock additives hàd a COF value of 0060, which ~s classified as very low 81ip, or no 81ip.
EXAMPLE XII
Samples of LDPE containing polypropylene in ~mounts of 0,3, 245 and lOqo and containing sal~s in mineral spirits of cobalt, iron~ cerium and zinc or c~mbinations thereof in a unts of 0.025, 0.1~/~ 0.05, 0.075 and without any antioxidant present were found untergo oxidation ~ ro~m temperature in the absence of sunlight or weatherometer exposure to produce embrittie-m~nt after one month duration or longerO Irrad~ation by sunlight, W , or very intense visible light accel2rates the rate at which embrittlement occurs. Embrittlement in the absence of the irradiation was found to sccur whether the sample was fabricated as a plaqueg ex~ruded qheet, or extruded film or whether it was in resin form and then ~ ter fabricated. Associated with the embrittle-ment in the absence of irradiation is the appearan e of odor recognizably associated with oxidation and believed indicative of the presences of short chain aldehydes and acids.
38.

8731-1-C-l EXA~PLE XIII
An ethylene polymer composition containing 98~/~
of a 0.922 density polyethylene (LDPE) as base resin, 2~ polypropylene (98% isota~tic) as auto-oxidative susceptible additive and 0.075% cobalt metal as a cobalt octoate solution in mineral spirits was prepared according to the procodure aforedescribet. Another composition 88 above was prepared additionally incluting a stabilizer 8y8tem consisting of 0~05% Topanol CA, ant 0.15% diiauryl thiotipxopionate. Control specimens (1) containing 270 polypropylene in the afores~id LDPE and (2) neat LDPE, were alsQ preparet. All of the aforementioned compositions were pressed into 20 mils plaques and weathered by the aforementionet procedures. All of the aforementioned sample~ were pressed into 10 ~il plaques for isothermal DSC intuction time analyses at 180C. according to the procedure as aforede~cribed. The stabilized composition had an lnduction period of 14.1 mdnute at 180C. while the unstabilized c~mposition had a 0.25 minute induction time at 180C. The controls hat induction times at 180C. of 0.40 and 0.16 minute respectively~
The above s3mples and controls were repeated~
but irradiated with 5 megareps prior to t~sting. The isothermal DSC.induction time for the irradiated stabilized sample was.4.4 mlnutes, the induction time for the irratiatet unstabilized sample was 0~15 minute, and the ~nduction ti~es for the irratiated controls were 0.20 and 0~05 minute respectlvely~
Addition of the stabilizers in the combination of polyethylene, polypropylene9 and cobalt salt was observet to provide stabilization against embrittlemen~
39.

- iO61037 8731-l -c -in the highly active systems~ whic~ normally undergo oxidative embrittlement in either the presence or absence of weathering without the stabilizers. Subsequent irradiation of the samples was observed to reduce the effect~voness of the ~tab~lizers. After irradiation the composltions embrittled ei~her in the presence or absence of weatheri~g by ehe procedure described~
EXAMPLE XIV
Ethylene polymer compositions of (1)9D% of a 0.922 den~ity LDPE as base res~n, 10% polypropylene (98% i~otactlc) a~ auto;oxidat~ve susceptible additive and O~l~/o cobalt metal as cobalt naphthenate solution 4n mlneral apirits, and (2) 98% of the LDPE9 2% poly-propylene (98% isotactic) and 0~025% ~obalt metal as ~bove, were prepared both with a stabilization system containlng (a) 0O05% of a pr~m~ry hindered phenol anti-oxidant A0 ~iOe. Irganox-lOlO);having four sterically hindered phenol groups linked to a central carbon by fatty acid ester linkages; (b) 0~05% of dilauryl thio-dipropionate (DLTDP) and (cj 0~05~/O o distearyl pent-aerythritol dipho~phite ~DSPD). Control samples w~ch --did not contain the stabilization system were also prepsret.
The composi~ions were pressed into 20 mil9 plaque~ and weathered by the afGrementioned procedures. They were also pressed ~nto 10 mils plaques for isothermal DSC
induction time analysis at 180~C~
The exposure times required for embrittlement, surface carbonyl level to exceed 1~7 and ultimate elongation to d~ p below 207o are listed in Part A of Table VIo The isothermal DSC induc~ion ~imes\obtained at 180C. are also reported in Part A of TabIe VI~

1061037 8731-1-C-l The exposure t$me for the stabilized samples at which ultimate elongatlon deteriorates below 20qo when comparet with the exposure time required for the unstabilized cont~D 1 Ramples was found to be sligh~ly longer. The presence of stabilizers ~n the second formulation has a re noticeabla effect on these propertie~ (elonga~ion deter~oration and surface carbonyl level build-up);
but does not retart ths embrittlement occurrence signifi-cantly~ The isothermal DSC induction time data ind~cà~es that in the ab~ence of weather~meter exposure these samp~ 8 ars quite stable and have ccnsiderably long induction times at 180C~
Compo~itions identical in every way with the above-two 8ample8, but irridated prior to testing with 5 mega~eps were also prepared. The exposure times required - by the various test procedures and the induction t~mes are reportet in Part B of Table VI~ Irradiation acts to reduce the exposure time required for the ~ltim~te elongation to drop below 20%~ After irradiation the irradisted stabilized samples embrittle in either the presence or absenca of weathering~

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42. :1 10 6 1 0 3 7 8731-1-C-l ,~, LE XV
Thi~ example demonstrates the use of mlxtures of organic metal salts with a~t without stabilizers.
An ethylene polymer composition çontaining 95%
a~ b~se resin, 5% polypropylene ~98% isot ctic) as the auto-oxidati~* susceptible add~tive and a m~xture of 0.05Z
cobalt ~s cobalt octoate a~d 0.05% iron as iron octoate in mlneral 8pirit8 ~olution wa8 prepared that al80 c~ntained ~ stabilization 8y8tem con81Bting of 0~05% of a hintered phenol antioxida~t (Irganox-1010), 0.15% of a thioester (tilauryl thlodipropionate) ant 0005% of distearyl pent-aerytbrLtoldiphc~phite~ A sample a8 above, but excluding ths stabilization syste~, and 8 control sample containing o~ly th~ afores~id 5% polypropylene mixture in 95% LDiE
were also prepared~ Specimen~ were p~ ssed as 20 ~i18 plaque~ and weathered by the aforementioned procedures~
Sp-cim~ns were also pressed into 10 ~118 plaques for isothermal DSC induct~on tim~ analys~s at ~80C. as aforedescribed, Both the stabilized and the unstabilizet plaques embrittled a~ter 60 hrs ~xposure in the weatherometer.
Th~ control ~ample of LDPE ant polypropylene only embrittled after 500 hours exposure~ The stabil~zed sample had a 19.6 minutes DSC induction time at 180C., while the ~nstabilized sample had a 0~76 minute DSC
intuction time. Th~ control sample had a ~.28 minute DSC intuction t~me.
Specimen~ as above w~re irradiated prior to testing. Both the irradiatedo~abili~et and the irrad~ated-unstab~lized s~mples embrittled after 60 hours of exposure in the weatheromet0r and the control embr~ttled after 250 hours of exposure. The ~rradiated-~tabilized sample had 43.

8731-1-C-l a 1~4 mlnute DSC induction time at 180C. The irradiated-unstabilized ~ample had a 0~11 mlnute DSC induction time and the irradiated control had a 0~20 minute intuction t~me.
-~ EXAMPLE XVI
Thi~ example demonstrates the use of several different antioxidants in ethyle~Q polymer compositions conta~ning 95% of a 0~928 density LDPE as the base resin, 5% polypropylene (98% isotactio) as the auto-oxidative 8~8ceptible additlve and a mlxture of 0.05% cobalt as cobalt octoate and 0.05% iron as iron octoate in mineral spirit~, Each composition contained 0005% of each of the following sterically hindered phenol antioxidants:
Irganox lO10, Santonox R, Topanol CA, Irganox 1076, and Ionol. Test 9pecimens were prepared as 10 mils plaques and the isothermal DSC induction time measured at 180C~
The DSC induction times were 908, 12.5, 6.2, 6.2 and 3.5 respectively, for the compositions containing the ~ndicated antioxidants~
EXAMPLE XVII
This example demonstrates the effect of ~econdary stabilizers w$th primary stabilizers in the presence of a mixture of organic metal salts of the transition metals.
An ethylene polymer composition containing 98%
of a 0.928 density polyethylene as the resin, 2% poly-propylene (98% isotactic3 a3 the au~o-oxidative susceptible atditive and a mixture of 0.025% cobalt as cobalt octoate and 0,025% iron as iron octoate in mineral spirits was prepared using 0;05% of the antioxldant Ir~anox 1010.
A second sample as above, but additionally containing 0.05% of distearyl pentaerythritol diphosphite was prepared. A third sample iden~ical with the second 44.

sample~ but additionally including 0.15% of dilaur~l thiodipropionate was prepared. Test specimens were prepared fr~m each as 10 mils plaque~ and the isothenmal DSC induction eimes at 180C. measured. The DSC induction times at 180C. for the first, second and third samples wera, respectively 9 7.9, 10.0 and 15.0 minutes.
EXAMPLE XVIII
An ethylena polymer composltion containing 99% of a 0.928 density polyethylene as base resin, 1%
polypropylene (98% isotactic) a~ auto-oxidative susceptible additive ~nd a mixture of 0.0125% cobalt metal as cobalt octoate and 0.0125% iron a~ iron octoate (.025% mixture) and additionally including 0.05% of the hindered phenol antioxidant, Irganox-lOlO,and 0.05% of distearyl penta erythritol diphosphite was prepared. A second sample as above, but containing 98% polyethylene, 2% polypropylene and 0.05% of the above organic metal salts mixture was propared. A third sample a~ above, but containing 95%
polyethylene, 5% polypropylene and O~lOqo of the above organic metal salts mixture was prepared. Test specimens were fabricated as pressed lO mils plaques and the isothermal DSC induction times at 180C. and 200C. were measured.
The s~mples were aged in a forced air oven at 43C. (110F) for 1500 hours without showing any significant loss in isothenmal DSC induction time at 200C. However when expo~ed to a W lamp for 8 hours, the isothermal DSC
intuctioh times at 180C. decreased by 99~5/O~ 99.0%
and 86.~/. respectively, and there was found to be no me~surable induction time at 200C. ? indicatin~ loss of stability of the compositions expoced to W .
EXAXPLE XIX
Ethylene polymer c~mpositions ~imilar to tho~e described in Example XVIII were prepared containing 45.

8731-1-C-l ~10% of the hindered phenol antioxidant and 0.10%
of distearyl pentaerythritol disphosphite~ The test plaq~es hsving increased antioxidant content showed t~e same stability behavior upon oven aging at 43C~ (110) for 1500 hour~, and the same percentage loss of DSC
induction time at 180C. after 8 hours of ultraviolet exposure as reported in Example XVIII.
EXA~LE XX ' Test plaques of the compositions of Example XVIII were irradiated by a van de Graaff generator to impart a 5 megarep dose. This irradiation resulted in an 80X to 55% tecrease isothermal DSC induction time at 180C.
Plaques of the c~mpositions of Example XVIII
were irradiated by exposure to the in~ense light emsnating from an argon swirl-flow plasma arc having 30%
of the light content below 4000 A. for a 6 second exposure;
this re~ulted in a 28% to 43% decrease in isothenmal DSC
intuction timR at 180C.
Plaques of the compositions of Example XVIII
were irradiated by ultraviolet light from a mercury lamp for 8 ~ours, this resulted in a 99.5% to 86% decreasa in isothenmal DSC induction time at 180C.
EXAMPLE XXI
An ethylene polymer composition containing 98%
of a 0.922 density LDPE as base resin, 2% polypropylene (98Z isotactic) as the auto oxidative susceptible additive, 0.05% cobalt as cobalt octoate~and 0.05% of the hindered phenol antioxidant, Irganox-1010, was prepa~ed. Test s~mples were pressed as lO mils plaques in the manner aforedescribed and irradi~ted with do~ages of 0, 1, 46.

~06~037 8731-1-C-l 21 5, 7 and 10 megareps by the van de Graaff accelerator.
These spe'cimens were exsmined by isothenmal DSC analysis for induction times at 180C. and it was found that a dose of 1, 2, 5 and 10 megareps is sufficient to reduce the isothermal DSC induction time at 180C. by 55%, 73%, 84% and 99~, respectively, when compared to the unirr~diated c~mpo3ition.
~XAMPLE XXII
The example te nstrate3 the effect of an opaclfier on the embrittlement rate (Embr,). An ethylene polymer composition containing 98% of a 0.922 density - LDPE as base resin, 2% polypropylene (98% isotactic) as the auto-oxidative susceptible additive, 0.05% cobalt as a cobalt octoate solution in mineral 9pirit9, 0.05%
of the hindered phenol antioxidant Irganox-1010, was prepared. A second c~mpo~ition 2S above, but additionally including 270 titanium dioxide, was prepared. A contro containing 98% of the LDPE, 2% polypropylene and 2%
ti~anium dioxide was also prepared. Test specimens were pressed as 20 mils plaques and weathered by the afore~
mentioned procedures. The exposure times required for a brittleness rate, surface carbonyl level to exceed 1 7, and elongation to drop below 20qo are 100, 100 and 100 to 150 hour9, respectively, for the first c~mposition and 150, 100 and 150 hours, respectively, for the second' l'~
compositlon. The control showed none of these signs after 250 hours exposure under the ame conditions.
EXAMPLE XXIII
Three ethylene polymer compo9ition9 containing 98% of a 0.922 density LDPE as base resin, 2% polypropylene (98% lsotactic) as auto-oxidatlve susceptible addi~ive, 47.

106~037 8731-1-C-l 0.10~ of cobait a~ a cobalt octoate 801ution in m~neral spirits and 0-057O of a hindered phenol antioxidant, Irganox-1010 and additionally containing 2% of the opacifiers ti~anium dioxide, zinc oxide and calcium carbonate, respectively, were prepared by direct addition.
Three control samples of 98% LDPE and 2% polypropylene with 2~ of each of the opacif~ers were prepared similarly.
~est specimen~ were pressed into 20 mils plaques and weathered by the aforementioned procedures. After 200 ~0 hours the first three compositions all showed signs of surface crac~ing and brittleness. The cracking was ob8erved to be more prounced inthe zinc oxide and titanium tioxide containing specimens. Surface carbonyl level exceeded 1.7 and elongation dropped below 207o after exposures ~ 150 and 150-200 hours, respectively, for the ccmposition~ containing titanium dioxide; 100-150 and 100 hours, respectively, for the compositions containing zinc oxide; and 150 and 150-200 hours, respectively, for the compo~itions containing calcium carbonate. The co~trol 8amples showed none of these signs af_er 350 hours of exposure.
EXAMPLE XXIV
Ethylene polymer compositions conta~ning 98%
of a 0.922 density LDPE as base resin, 2% polypropylene (987. isotactic) as auto~oxidative susceptible additive, 0.05% cobalt as a cobalt octoate solution in mineral spirits and 0.05% of a hindered phenol antioxidan~, IrganDx-lOld, and 0.05Z of distearyl pentaerythritol dlphosphite and also including 0.05% of each the following FD & C Aluminum Lake pigments,Blue #1, Blue #2, Red #3 Violet ~1, Yellow #5,and Yellow #6, were prepared. A
control exactly the same as above, but without the pigment was prepared. Test specimens were pre~sed as 48.

8731-1-C-l 20 mils plaques and weathered by the aforementioned procedures. After 150 hours exposure, all samples including the control wexe rated brittle and all had ultimate elongation values below 20qo~ The presence of the colorant did not interfere with the weathering behavior of the - d~gradable polyethylene composition of this invention.
EXAMPLE XXV
Ethylene polymer c~mpositions containing 98%
of a 0.922 density polyethylene as base resin, 2%,po1y-propylene (98% isotactic) as the auto-oxidative susceptible additive,and 0.05% metal of the solid metal salts3cobalt naphthenate, cobalt octoate, co~alt stearate, cobalt acetylacetonate,iron distearate,copper stearate,and manganese stear~te were prepared containing 0.05% of a hindered phenol antioxidant, Irganox-1010. Specimens were pressed as 20 mil5 plaques and weathered by the aforementioned procedures. All of the samples hsd surface carbonyl levels greater than 1.7 within 150 hours of exposure and all exhibited embrittlement and elongation deterioration between 150-250 hours exposure.
EXAMPLE XXVI
Ethylene polymer compositions contsining 9870 of a 0.922 density LDPE as base resin, 2~ polypropylene (98Z isotactic) as auto~oxidative susceptible additive, O~lOqo metal fram esch of the following metal salts,and 0.05Z of the hindered phenol antloxidant, Irganox-l~10, were prepared. The metal ~alts used were chromium tri-chloride, cobalt chloride 9 cupric acetate, cupric chloride, cupric oxalate, ferrous chloride, ferric oxalate, lead acetate, man~anese acetate, mercuric chloride, potassium permanganate, cuprous chloride, and ammonium vanadate.
49.

10 6 1 0 3 7 8731-1-C-l Test specimens were pressed as 20 mils plaques and weathered by the aforementioned procedures. All of the compositions embrittlet by 500 hours exposure; with cupric acetate, ferrous chloride, manganese acetate and ammonium vanatate showing promoted embrittlement between 2500350 hours of exposure.
EXAMPLE XXVII A
Ethylene polymer compositions containing a high density (0.962 density) polyethylene as base resin, 0, l, 2 and 5Z polypropylene, which is 98% isotactic, as auto-oxidative susceptible additive and 0.05% cobalt metal a8 cobalt octoate were prepared. Similar compositions containing a 0.958 density polyethylene, 0, 1, 2 and 5Z
polypropylene, a~ above, and cobalt octoate, as above, were also preparet. All of the c~mpositions contained 0.05Z of the hindered phenol antioxidant, Irganox-1010.
Test 9pecimen~ were precsed as 20 mils plaques and westhered by the aforement~oned procedures and after 60 hours exposure all of the compositions were embrittled.
EXAMPLE ~ II B
Ethylene polymer compositions similar to those described in Ex~mple XXVII A were prepared but containing iron octoate instead of cobalt octoate. After 20-60 hours exposure all of these compositions were embrittled.
EXAMPLE XXVIII
Ethylane polymer compositions containing a high density (0.962 density)polyethylene as base resin, 0, 1, 2 and 5% polypropylene, (98% isotactic) as auto-oxidative su9ceptible additive and 0.05% metal of an equal mixture of cobalt metal and iron metal as cobalt octoate and iron octoate solutions in mineral spirits were prepared.
Similarly compositions of a 0~958 density polyethylene con-50.

~731-1-C-l taining 0 9 1, 2 and 5~ polypropylene, as above, and 0.05%
metal, a~ above, were also prepared. All of the above samples contained 0.05% of a hindered phenol antioxidant~
Irganox-lQlO. Test specimens were pxessed as 20 mils plaques and weathered by the aforementioned procedures.
After 20-60 hours exposure, all the compositions containing polypropylene had embrittled. However, those compositions that did not contain polypropylene required the full 60 hour period for embrittlement.
EXAMPLE XXIX
A-Three composition~ of 99% of a high density ~.962) density polyethylene, 1% polgpropylene (98%
isotactic),and 0.05% metal of (1) manganese octoate, (2~
zinc octoate, and ~3) an equal mixture thereof were pre pared.
B-Similar c~mpositions as the above, but with-out the polypropylene auto~oxidative susceptible additive were prepared.
C-Three ccmpositions of 99Z of a 0.958 density polyethylene, 1% polypropylene as above, and 0.05% of each of the above metal salts were also prepared.
D-Similar compositions of the 0.958 density polyethylene of Group C but w~thout the polypropylene auto-oxidatlve susceptible additive were prepared.
E-Three compositions containing 99% of a 0.960 density polyethylene, formed by mixing 78% of a 0.9~2 density polyethylene with 22% of a 0.958 density poly~
ethylene, 1% polypropylene as above, and 0.05% of each of the above met~l salts were prepared.
All of the campositions of Groups A to E
contained 0,05% of the hindered phenol antioxidant~
Irganox-1010. Test specimens pressed into plaques and 51.

1061037 8731-1-C-l weathered by the aforementioned procedures embrittled aiter 60 hours exposure. The sole exception was the composition containing manganese octoate in the 0.962 density polyethylene without the polypropylene; this camposition embrittled after 100 hours eXpocure~
EXAMPLES XXX
Ethylene polymer c~mpositions containing a 0.922 density LDPE as base resin, polyethylene glycol of molecular weight range from 6000 to 7500 (CARBOWAX *
6000) in amounts of 0~5% and 2~/o as auto~oxidative susceptible additive (PEO),and 0.05% cobalt metal as cobalt octoate solution in mineral spirits were prepared.
A first control sample of virgin LDPE, a second control of a mixture of 2% PEO in the LDPE, anc athird control of 0.05Z cobalt metal as cobalt octoate solution in mineral spirits in the LDPE were also prepared. All of these compositions were pressed into 20 mils plaques and weathered by the aforementioned procedures.
The exposure times required for embrittlement to occur, surface carbonyl level to exceed 1.7, ultimate elongat~on to fall below 20%, and the appearance of surface cracking are listed in Part A of Table VII. The time required for embrittlement by the addition of PEO
in the second control over the time required for the first control is evident. The addition of 0.05% cobalt further decreased the time required for all of the above degradation phen~mena to occur. The level to which accelerated embrittlement is accomplished by a mixture of 2% PEO in LDPE plus the presence of 0.05% cobalt is not as great as that accomplished by 0.05% cobalt in virgin LDPE, the third control. The ~ixture of 0.5%
52.
~Trade Mark 106~)37 8731-1-C-l PEO ~n LDPE in the presence of 0.05% cobalt showed acceleration ~n all of the sign~ of failure, except brittleness rating, at a faster rate than was observed for the 0.05% cobalt in LDPE, the third control. At the 2% PEO concentration the LDPE/PEO mixture acts unexpectedly to retard specimen failure in the presence of 0.05%
cobalt, while at 0.5% PEO concentration the LDPE/PEO
mixture acts to accelerate specimen failure.
Compositions and controls identical in all respects with the above, but irradiated with a five megareps dose prior to weathering were also te~ted. The exposure times required for the above phenomena to occur are li~ted in Part B of Table VII. Irradiation has a pronounced acceleration effect on the mixture of 0.5%
PEO in LDPE in ~e pre~ence of 0.05% cobalt. All of the signs of failure occurred at shor~er exposure times then either the unirradiated specimen or the unirradiated ant irradiated third control specimens.
TABLE VII
ExPosure Times Requiret~Hours FMIR SURFACE
%PE %PEO %Co Embr. R ~ 1.7 ~20qoELONG~ CRACKS
98 2 0.05 500 250 500 99.5 ~.5 0.05 500 60 60-150 150 CONTROLS
100 0 0 ~1000 109 0 0~05 250 150 150 500 ~061037. 8731-1-C-l and 0% were prepared. The lstter is a control in both EAA copolymers. ~he exposure ~imes r~quired in the ~valuatlons are listed in Part B of Table V~II, as well as ~he tim~c required for unexposed samples to embrittle, ~ he ~/0 M copolymers composltions containing cobalt acetate embrit~led after 150 hours exposure, regardless of the cobalt conce~tration in the range from 0.05% to 1~0%, and embrittled in less than 3 months if unexposed to weatherîng. ~he 7% AA copolymer compositions containing cobalt acetate all embrittied before 500 hours cxposure, produced surface cracks by 150 hours exposure, and embrittled in less than 6 months if left unexposed, ThBLE VIII
Exp~sure Times Required, Hours PART A
~, ~
~/UAA %Co Co Salt Embr. ~2~/oELONG~ CRACKING
, 2 0.05 Acetate 250 150 200 2 0.05 Octoate 100 100 200 2 ' 0~05 Naphthenate 100 100 200 2 0.05 Nux~ra 150 100-150 200 7 0.10 Acetate ~250 lSO
7 0.10 Octoate ~250 100 7 0.10 Naphthena~e~250 150 7 0.10 ~uxtr~ ~250 150 PART B
%AA %Co Co Salt Embr. CRACKING Unexposed Embr~
~ 1.0 Acet~te 150 250 f3 mos 2 0.1 Acet~te 150 250 ~3 mos 2 0.05 Acetate 150 200 C3 mos 7 1.0 Acetate 500 100 ~3 mos ~ 0.1 Acetate 250 150 4^6 mos 7 0.05 Acetate 500 150 3-4 mo~

55.

.~'~ .. . - '.
: !~

~ 61 0 37 873l-l-C-l PART B
FMIR SURFACE
%PE ~PEO ZCo Embr. R~ 1.7 ~20%ELONG. CRACKS
98 2 0.05 500 150 250 2SO
99.5 0.5 O.Q5 150 60 ~0 150 CONTROLS

lOO O 0.05 250 60 150 250 EXA~LE ~YXXI
Ethylene polymer composit~ons containing ethylene ~crylic scid (EAA) copolymer have an acrylic acid content of ~b as base resin with 0.05% cobalt metal as the following salts: ~olld cobalt acetate, cobalt octoate solution in mineral spirits, cobalt naphthenate solution ~n minersl spiri~s, and the cobalt salts of a mlxture o br~nchejd C8 and Cg acids, known as N~xtra, were prepared.
C~mpositions of an EAA copolymer having a 7% acrylic - ac~d cont.ent with o~ o cobalt metal as these same metal gslts were also prepared. The compositlons were pressed into 20 mils plaques and weathered by the aforementioned procedures. The exposure times required for embri~tlement to occur, the ultimate elongation to drop below 20~/o~
and cracking to occur are listed in Part A of Table VIII.
In the 2% AA copolymer samples all forms of cobalt salts tested were active in promoting accelerated degradation In the 7Z AA copolymer samples embrittlement occurs less rapidly, but ~he appearance of surface cracks occurs e~rller than for the 2L AA copolymer samples. All forms of cobalt a6 llsted abcv~ ~re active in promoting degradation.
Ethylene polymer cc~po~itions of the same EAA
copolymers as above, but conta~ning only cobalt acetate, having cob~lt metal concentrations of 1.0%, 0.1~, O.OSZ
54. -i'~ ., 106~037 8731-1-C-l EXAMPLE XXXII
' Compo9itions samples of ethylen0 vinyl acetate copolymer resin (EVA) containing 10%, 18%~ 287o and 33%
vinyl acetate in combination with O.lOZ cobalt metal as cobalt octoate solution in mineral spirits were prepared.
Control samples of the above without the cobalt octoate were prepared. All of the compositions were pressed lnto test plaques and weathered by the aforementioned procedures. After 200 hours exposure the 10% VA composition developed surface cracks and it embrittled after 35D
h rs exposure. After 250 hours exposure the 18% VA
specimen developed surface cracks, and it underwent non-brittle failure upon flexing at 350 hours exposure.
After 250 hours exposure the 28% VA specimen underwent non-brittle failure upon flexing. Both of these non-brittle failure specimens exhibi~ed splitting rather than cracking behavior. The 33% VA specimen underwent non-b~ittle failure after 500 hours exposure. All of the control specimens were flexible and did not exhibit failure upon flexing after 500 hours exposure~
EXAMPLE XXXIII
Ethylene polymer compositions were produced containing 8 low density polyethylene as the ba,se resin (0.922 g/cc3 and the following concentrations, in per cent by weight of the composition, 2% of i~otactic poly-propylene ~8 the auto-oxidative susceptible additive, and trans~tion metal atoms and antioxidants as shown in the table. The h~mogeneous compositions were then compression molded to obtain 10 mils plaques and these were tested for thermal stability by the DSC induction time method at 200C. All of the ccmpositions were 56.

10 61 0 3 7 8731-1-C-l weathered in an Atlas XW Weatherometer and all embrittled and had ultimate elongations of less than 20qo by 150 hours of exposure. The unmodified polyethylene had an original ultimate elongation value of ~bout 400% and this showed no visible change after 150 hours of exposureO
The data and results are set forth in Table IX.

57.

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o ol I I I o 58 .

8731-l-C-EXA~LE XXXIV
In this example two types of masterbatches were prepared using the same ingredients employed in Example XXXIII and these were then blended to produce degrsd~ble ethylene polymer compositions having the identical chemical c~mpositions of Runs a to o of Table IX for Example XXXIII.
The first masterbatch contained the low density polyethylene, 2% of the isotactic polypropylene and 0~005/O of Antioxidant A, The second masterba~ch contained the low density polyethylene, 2% of the transition metal atoms added in the forms defined in Example XXXIII and Anti-oxidants B, C and D in the proper amounts to give the desired concentrations thereof in the final blend after mixing the two m~sterbatches.
The degradable ethylene polymer compositions were produced by compounding on a two roll mill 97.5 parts of the first masterbatch and 2.5 parts of the gecond masterbatch. Plaques 10 mil9 thick were compression molded from the homogeneous blends. Upon weathering all embrittled and all had ultimate elongations of less than 20% by 150 hours of exposure. The DSC
induction times at 200C. in minutes, for each composition tested are set forth below: ;
Run minutes Run minutes a 9.6 g 3~0 b 13.6 h 9,8 c 13.3 i 0,05 ~ 18.g j 0.15 e 3,0 k 1~0 8 econd All of the/masterbatches per se, before blending, had DSC induction times in excess of 60 minutes, 59.

EXAMPLE XXXV
In this example the degradable e~hylene polymer compositions were produced by blending three separate masterbatches. The same ingredients were used as in Example XXXIII and the final compositions tested had the itentical chemical contents as Runs a to o of that example.
The first masterbatch contained the low density polyethylene, 20% of the isotactic polypropyiene and 0.05% of Antioxidant A.
The second masterbatch contained the low density polyethylene, 2% of the transitionmetal atoms added in the fonms defined in Example XXXIII and Antioxidants B, C and D in the proper amounts to give the desired concentrations thereof in the final blend after mixing the three masterbatches~
~ he third masterbatch was the low density polyethylene per se.
The degradable ethylene polymer compositions were produced by compounding on a two roll mill 9 75 parts of the first masterbatch, 2,5 parts of the second masterbatch and 87.75 parts of the third masterbatch~
Plaques 10 mils thick were compression molded from the ho~ogeneous blends. Upon weathering all embrittled and all had ultimate elongations of less than 20% by 150 hours of exposure. The DSC induction times at 200C~, in minutes, for each composition tested are set forth below:

-- 60.

1061037 8731-1-C-l R minutes Run minutes a 8.5 g 3.8 b 14 h 8 c 11.7 i 0O05 d 19 j 0.1 e 2.9 k 1.1 All of the second masterbatches per se, before blending, had DSC induction times in excess of 60 minutes.
EXAMPLE XXXVI
A series of transition metal atom-oontaining and antioxidant containing masterbatches were prepa-red.
The transition metal was ~obal~ added as a cobalt naphthenate solution in mineral spirits. Degradable ethylene polymer compositions or blends were then produced by compounding, on a two roll mill, 95.5 parts of ~ low density polyethylene (0.922 g/cc), 2 parts of polypropylene and 2.5 parts of the masterba~ch. These latter compositions were used to prepare 10 mils plaques by compression molding and the DSC induction times, in minutès, were determined at various temperatur2s. The data and results are set forth below:
Masterbatch 1 2 3 4 Polyethylene 96.0 96.8 97.0 97.96 Cobalt metal 2.0 2.0 2.0 2.0 Antioxidant A(Table IX) 2.0 1.2 1.0 0.04 DSC Induction Time, in minutes, of blendso at 200C. 11.5 0.1-1.3 0.1 0.1 at 180C. - Q25-3.6 0.2 0.27 at 170C. - 6.4 0.15 at 160C. - - - 0.2 The ~asterbatches per se, before blending with the additional polyethylene and polypropylene, showed DSC
induction times at 200C. in excess of 60 minutes for 1, 2 and 3 and of 37 minutes for 4. The data shows that the masterbatches are far more stable than the degradable c~positions prepared fr~m them even though they have a higher metal atom content~
61.

~061037 8731-1-C-l ' EXAMPLE XXXVII
Part 1. A first masterbatch was prepared containing low density polyethylene S0.922 g/cc), 2.05% polypropylene and 0.005% Antioxidant A(Table IX).
A second masterbatch was prepared containing the low density polyethylene, ~/O cobalt added as a cobalt octoate solut~on in mineral spirits, 2% Antioxidant A(Table IX) and 4% Antioxidant D(Table IX)o An ethylene polymer c~mposition was produced by dry blending 97.5 parts of the first masterbatch and 2.5 parts of the second masterbatch. This dry blended camposition does not degrade on storage.

Part 2. A third masterbatch was prepared containing the low density polyethylene, 20.5% polypropyiene as the auto-oxidative susceptible additive and 0.05% of Anti-oxidant A(Table IX).
- An ethylene polymer composition was produced by dry blending 87.75 parts of the low density polyethylene, 9.75 parts of the third masterbatch and 2.5 parts of the secont mssterbatch of Part 1. This dry blended composition does not degrade on storage, Part 3. A dry blend of 95.5 parts of the low density polyethylene base resin,2.5 parts of the s,econd master-batch and 2 parts of the polypropylene auto-oxidative susceptible additive. This composition was stable on storage.

62.

8731-1-C-l EXAMPLE XXXVIII
Part 1. The dry blended degradable ethylene polymer c~position produced in Part 1 of Example XXXVII was hot extruded on a one ~nch extruder to form a uniform sheet from 20 to 30 mils thick. A portion of the sheet was then compression molded to form a 10 mils plaque which had a thermal stability by the DSC induction time method at 200C. of 25.9 minutes. Another portion of the sheet was compounded on a hot two roll mill and then compression molded to fonm a 10 mils plaque which had an induction time of 28.3 mlnutes.

Part 2. The dry blended degradable ethylene polymer composition of Part 2 of Example XXXVII was subjected to the same treatments de~cribed in Part 1 of this instant example. The DSC induction times measured on the plaques were 26.9 and 23.0 minutes respectively.

Part 3. A degradable ethylene polymer ccmposition was produced by dry blending 95.5% of the low density poly-ethylene base resin, 2% of the polypropylene auto-oxidative susceptible additive and 2.5% of the secondFasterbat_h of Part 1 of Example XXgVII. The dry blended mixture was then hot extruded ~n- a one inch extruder to form a sheet from 20 to 30 mils thick having a uniform appearancé. Plaques were prepared from this extruded sheet by the same procedures described in Part 1 of this instant example; they had DSC induction times of 22.0 and 19.6 minutes, respectively.
EXAMPLE XXXIX
.
Part 1. Mixtures of cobalt octoate in solution in mineral spirits and the proper amounts of antioxidant 63.

8731-1-C-l were coated onto finely divided silica to produce free-flowing dry powders that were used to prepare degradable ethylene polymer compositions. Three degradable compositions were prepared by compounding on a two roll mill and then 10 mils thick plaques were produced by compression molding.
The degradable compositions and their DSC induction times at 200C~ are set forth below:
Composition l 2 3 Polyethylene ~0.922 g/cc-),% 97.3 97 2 97 2 lO Polypropylene, % 2 2 2 Cobalt met~l, % 0.05 0.0~ 0.05 A~tioxidant (see Table IX) A OOO5 0.05 0.05 B _ 0 075 C ~ - 0.075 DSC induction time, min. 17.1 13J5 18.1 Part 2. Three additional degradable compositions were produced in the identical manner described above with the exception that in these instances the anitoxidants were added directly and the cobalt octoate only was coated onto the finely divided silica. The DSC induction times were 5.8, 8.2 and 14.2 minutes, respectively.
All of the compositions of Example XXXIX
embrittled on weathering and all had ultimate elongations of less than 20% after 150 hours of exposureO In contrast, the starting polyethylene did not embrittle and had an ultimate elongation of over 400 percent before and after exposure under the same conditions.
EXAMPLE ~L
In order to evaluate the degradability of ethylene polymer compositions on storage two such c~mpos~tions were made and stored. The first composition was produced by hot compounding all of the components into one homogeneous productO The second composition was produced by preparing two separate masterbatches, one containing the auto-oxidative additive polypropylene and the other containing the metal salt, and then dry 1061037 8731-1-C-l blending the two masterbatches. The degradable compositions had the identical chemical c~mpositions but were prepared by different procedures.

Part 1. A first masterbatch was produced containing 78.76 parts ¢f polyethyleneJ 0.2 part of erucamide, 1.0 part of 9ilica, 10 parts of polypropylene, 0.02 part each of Anti~xidants A and B (Table IX) and 10 parts of a buff color concentrate of colorant in polyethylene by compounding on a roll mill and then granulated.
A 9econd masterbatch was produced containing 97.68 parts of polyethylene, 0.06 part each of Anti~
oxidants A and B and 2.2 parts of cobalt stearate by compounding on a roll mill and then granulatet.
Equal quantities of the two masterbatches were dry blended together in a high speed laboratory mixer.

Part 2. A degradable composition was produced by hot melt blending on a roll m~ll 88.22 parts of the same polyethylene, 0.1 part of erucamide, 0.5 part of silica, 0.04 part each of Antioxidants A and B, 5 parts of poly-propylene, 1.1 parts of cobalt stearate an~5 parts of ~he buff color concentrate and then granulating the uniform mixture.
Sin~e degradation is accompanied by a sharp rise in melt index, this property was used to determine whether or not degradation had occurred~ The granular materials were stored in air at 80C. and samples were withdrawn at intervals for melt index measurement It was observed that the granules of Part 2 showed a sharp rise in melt index and odor development between the fourth and sixth weeX of storage while the granules of 65.

1061037 8731-1-C-l Part 1 showed no signs of melt index rise or odor develop-- ment. The results are set forth below:
Melt index. dgm/min.
Part 1 Pa t 2 Unaged 2.01 1.92 One week 2.15 2.13 Two weeks l.g4 2.0S
Three weeks 1.'66 1.88 Four weeks 1.92 2.21 Six weeks 2.13 7'.55 Equally significant was th'e fact that'after removal from the oven and contin~ed storage at room temperature the granules of the composition of Part 2 continued to degrade while, on the other hand, the granules of the composltion of Part 1 showed no degradation under t~e same conditions. The~e results are set forth below:
Melt index~ dgm/min.
Part 1 Part 2 On removal 2.13 7.55 One week later 1.93 35.7 Two weeks later 1.99 47~2 Exsmples XXXIV to XL show that'the use of the separate masterbatch technique permits one to store the masterbatch components, separately or as dry blended mixtures, for prolonged periods of time without danger of the degradatisn reaction starting. The degradation commences and continues only after the individual master-batch components have been hot blended with each oth~r to produce' a uniform homogeneous mixture or if a hot blended unifonm composition is produced initially.
EXAMPLE XLI
Degradable ethylene polymer compositions were produced by hot blending on a roll mill various ethylene ethyl acrylate copolymers of different ethyl acrylate content with cobal~ octoate (in mineral spirits solution) at 0.025% cobalt metal content, different conrentrations 66.

8731-1-C-l of low molecular weight polypropylene wax as the auto-oxidative susceptible additive and 0.05% of Antioxidant A(Tdble IX). For comparative purposes a control blend was prepared which did not contain the polypropylene.
Ten mils plaques were c~mpresCion molded fr~m each composition and weathered and the times for surface cracking to appear and for failure to occur were determined; these are set ~orth in Table X. In all instances the campositions of this invention degraded within a shorter period of time.
A range i9 given when degradation started during that time interval.

67.

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o~ C~
, oO O

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o o ~l 0 ~
~n o ~ n ::
oc~ooO

o ~ n o~ ~s 000000 ~D
~o~'o~o ~

68.

~06~037 873l-l-C-EXAMPLE XLII
Ethylene polymer compositions containing a low density polyethylene, 0.922 g/cc, 0.5%-polypropylene as the auto-oxidative susceptible additive, and the amounts of solid ferrous stearate and antioxidants in-dicated were prepared. The blends were prapared by fluxing on a two roll mill, sheeted and then granulated.
Twenty mils plaques were c~mpression mol,ded and ~
c~mpositions containing iron atom are degradable as shown by embrittlement on weathering, These c~mpositions can be extruded t~ fonm shaped articies such as pipes.
lrrigation pipes produced from the compositions will embrittle and need not be removed after a growing season but can be plowed into the field and eventually become granular and blend into the soil. The compositions are set forth in Table XI.

69.

8731-1-C-l c~. 1 :n :~
c~ e~ ~ c~ D X

X 1~ X N o~ n ~D ~' ~
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70.

Claims (58)

WHAT IS CLAIMED IS:

1. A method for producing an environmentally degradable polymer based composition comprising the steps of:
(a) forming (i) a masterbatch comprising ethylene polymer base resin, antioxidant for said base resin and at least one salt of at least one polyvalent transition metal having an atomic number of 21 to 30, 39 to 48, or 57 to 71, and (ii) a masterbatch comprising at least one auto-oxidative susceptible additive having at least one hydrogen atom bonded to a carbon atom having an auto-oxidative susceptibility greater than that of a hydrogen atom bonded to a normal secondary carbon and antioxidant for said base resin, with the provisos that said masterbatch (i) does not contain degrading amounts of auto-oxidative susceptible additives and masterbatch (ii) does not contain degrading amounts of polyvalent transition metal salt; and (b) homogeneously mixing (i) and (ii) to form said composition.

2. A method as claimed in claim 1 wherein said masterbatch (ii) comprises ethylene polymer base resin.

71.

3. A method as claimed in claim 1 wherein (b) comprises mixing and pelletizing (i) and (ii).

4. A method as claimed in claim 1 wherein (b) comprises melt blending and pelletizing (i) and (ii).

5. A method as claimed in claim 1 wherein said composition comprises about 70 to about 99 weight percent of at least one ethylene polymer.

6. A method as claimed in claim 1 wherein said masterbatches are blended with additional ethylene polymer.

7. A method as claimed in claim 1 wherein the metal salt is coated onto an inert carrier.

8. A method as claimed in claim 1 wherein the auto-oxidative susceptible additive is an auto-oxidative susceptible polymer wherein the predominance of the repeating units have at least one hydrogen atom bonded to a carbon atom having an auto-oxidative susceptibility greater than that of a hydrogen atom bonded to a normal secondary carbon atom.

9. A method as claimed in claim 1 wherein the auto-oxidative susceptible additive is an auto-oxidative susceptible low molecular organic compound having at least one hydrogen atom bonded to a carbon atom having an auto-oxidative susceptibility greater than that of a hydrogen atom bonded to a normal secondary carbon atom.

72.

10. A method as claimed in claim 1 wherein the auto-oxidative susceptible additive is present in an amount of from 0.5 to about 20 percent by weight of the total composition and wherein the salt of the polyvalent transition metal is present in the total composition in an amount to impart thereto from 0.005 to about 1.0 weight percent of metal atom.

11. A method as claimed in claim 1 wherein the polyvalent metal salt is an organic salt of said poly-valent metal.

12. A method as claimed in claim 1 wherein said base resin is an ethylene homopolymer.

13. A method as claimed in claim 1 wherein said base resin is an ethylene copolymer.

14. A method as claimed in claim 8 wherein said hydrogen atom is present in an allylic, benzylic, tertiary-aliphatic, aldehydo, alpha-oxyhydrocarbyl or alpha-halohydrocarbyl group.

15. A method as claimed in claim 8 wherein said auto-oxidative susceptible low molecular weight organic compound has a molecular weight of less than 5,000.

16. A method as claimed in claim 8 wherein said auto-oxidative susceptible polymer is a polymer of an alpha-olefin having from 3 to 20 carbon atoms.

73.

17. A method as claimed in claim 16 wherein said auto-oxidative susceptible polymer is polypropylene.

18. A method as claimed in claim 8 wherein said auto-oxidative susceptible polymer is a poly(alkylene oxide).

19. A method as claimed in claim 18 wherein said poly(alkylene oxide) is poly(ethylene oxide).

20. A method as claimed in claim 9 wherein said auto-oxidative susceptible low molecular weight compound is an unsaturated fatty acid.

21. A method as claimed in claim 11 wherein said polyvalent metal salt is an octoate, naphthenate, acetate, stearate or acetylacetonate.

22. A method as claimed in claim 1 wherein the auto-oxidative susceptible additive is polypropylene and said salt is an organic salt of a polyvalent transition metal wherein electron transfer occurs in the 3d sub-shell.

23. A method as claimed in claim 1 wherein the auto-oxidative susceptible additive is present in an amount of from 0.1 to about 10 weight percent, based on the weight of the total composition.

74.

24. A method as claimed in claim 1 wherein the salt of the polyvalent transition metal is present in an amount to impart from 0.01 to about 0.1 weight percent of the metal atom based on the weight of the total composition.

25. A method as claimed in claim 9 wherein the auto-oxidative susceptible low molecular weight organic compound is present in an amount of from 0.1 to 10 percent by weight and the salt of the polyvalent metal is present in an amount to impart from 0.01 to 0.1 weight percent of metal atom, based on the weight of the total composition.

26. A method as claimed in claim 1 wherein a combination of polyvalent metals is present.

27. A method as claimed in claim 26 wherein the polyvalent metal comprises cobalt and iron.

28. A method as claimed in claim 26 wherein the polyvalent metal comprises cobalt and zinc.

29. A method as claimed in claim 1 wherein the polyvalent metal comprises cobalt.

30. A method as claimed in claim 1 wherein the polyvalent metal comprises iron.

31. A method as claimed in claim 1 wherein the polyvalent metal comprises zinc.

75.

32. A method for producing an environmentally degradable polymer composition comprising the steps of (a) dryblending to a uniform homogeneous mass (i) a masterbatch of ethylene polymer as a base resin, antioxidant for said base resin and at least one auto-oxidative susceptible additive having at least one hydrogen atom bonded to a carbon atom having an auto-oxidative susceptibility greater than that of a hydrogen atom bonded to a normal secondary carbon atom with (ii) a masterbatch of said base resin, antioxidant for said base resin and at least one salt of at least one polyvalent transition metal having an atomic number of 21 to 30, 39 to 48, or 57 to 71, said dry blend comprises a major portion by weight of said base resin, and stabilizingly effective amounts of said antioxidant and said auto-oxidative susceptible additive, and with the provisos that said masterbatch (i) does not contain degrading amounts of polyvalent salt, and said masterbatch (ii) does not contain degrading amounts of said auto-oxidative susceptible additive, and (b) then melt blending the dry blend to form said composition.

76.

33. A method as claimed in claim 32 wherein said composition comprises about 70 to about 99 weight percent of said base resin.

34. A method as claimed in claim 32 wherein said masterbatches are blended with an additional amount of ethylene polymer.

35. A method as claimed in claim 32 wherein the metal salt is coated onto an inert carrier before blending.

36. A method as claimed in claim 32 wherein the auto-oxidative susceptible additive is an auto-oxidative susceptible polymer wherein the predominance of the repeating units have at least one hydrogen atom bonded to a carbon atom having an auto-oxidative susceptibility greater than that of a hydrogen atom bonded to a normal secondary carbon atom.

37. A method as claimed in claim 32 wherein the auto-oxidative susceptible additive is an auto-oxidative susceptible low molecular organic compound having at least one hydrogen atom bonded to a carbon atom having an auto-oxidative susceptibility greater than that of a hydrogen atom bonded to a normal secondary carbon atom.

38. A method as claimed in claim 32 wherein the auto-oxidative susceptible additive is present in an amount from 0.05 to about 20 per cent by weight of the total blend 77.

and wherein the salt of the polyvalent transition metal is present in the total blend in an amount to impart from 0.005 to about 1.0 weight per cent of metal atom.

39. A method as claimed in claim 32 wherein the polyvalent metal salt is an organic salt of said poly-valent metal.

40. A method as claimed in claim 32 wherein said base resin is an ethylene homopolymer.

41. A method as claimed in claim 32 wherein said base resin is an ethylene copolymer.

42. A method as claimed in claim 37 wherein said hydrogen atom is present in an allylic, benzylic, tertiary aliphatic, aldehydo, alpha-oxyhydrocarbyl or alpha-halohydrocarbyl group.

43. A method as claimed in claim 37 wherein said auto-oxidative susceptible low molecular weight organic compound has a molecular weight of less than 5,000.

44. A method as claimed in claim 36 wherein said auto-oxidative susceptible polymer is a polymer of an alpha-olefin having from 3 to 20 carbon atoms.

45. A method as claimed in claim 44 wherein said auto-oxidative susceptible polymer is polypropylene.

78.

46. A method as claimed in claim 36 wherein said auto-oxidative susceptible polymer is a poly(alkylene oxide).

47. A method as claimed in claim 46 wherein said poly(alkylene oxide) is poly(ethylene oxide).

48. A method as claimed in claim 37 wherein said auto-oxidative susceptible low molecular weight com-pound is an unsaturated fatty acid.

49. A method as claimed in claim 39 wherein said polyvalent metal salt is an octoate, naphthenate, acetate, stearate or acetylacetonate.

50. A method as claimed in claim 32 wherein the auto-oxidative susceptible additive is polypropylene and said salt is an organic salt of a polyvalent transition metal wherein electron transfer occurs in the 3d sub-shell.

51. A method as claimed in claim 32 wherein the auto-oxidative susceptible additive is present in an amount of from 0.1 to about 10 weight percent, based on the weight of the total composition.

52. A method as claimed in claim 32 wherein the salt of the polyvalent transition metal is present in an amount to impart from 0.01 to about 0.1 weight percent of the metal atom based on the weight of the total composition.

79.

53. A method as claimed in claim 37 wherein the auto-oxidative susceptible low molecular weight organic compound is present in an amount of from 0.1 to 10 percent by weight, and the salt of the polyvalent metal is present in an amount to impart from 0.01 to 0.1 weight percent of metal atom, based on the weight of the total composition.

54. A method as claimed in claim 32 wherein a combination of polyvalent metals is present.

55. A method as claimed in claim 54 wherein the polyvalent metal comprises cobalt and iron.

56. A method as claimed in claim 32 wherein the polyvalent metal comprises cobalt.

57. A method as claimed in claim 32 wherein the polyvalent metal comprises iron.

58. A method as in claim 33 wherein said composition comprises about 90 to about 99 weight percent of said base resin.

80.