CA1070494A - Naphthofuranylnaphthol stabilizers - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

1-[1-Naphtho(2,1-b)furanyl]-2-naphthol is employed as a stabilizer for organic material particularly dienic polymers, subject to the deleterious effects of oxygen, heat and light.

Description

This inventionrelates to stabilization of organic materials subject to the deleterious effects of oxygen, heat and light; more especially the invention is concerned with the use of l-~l-naphtho(2,1-b)furanyl~-2-naphthol as a stabilizer for such materials.
This application is a division of Canadian patent application S.~. 2~1,888 filed April 22, 1976.
Dischendorfer, 73 Monatsch. 45 (1940), teaches preparation of l-[l-naphtho(2,1-b)furanyl]-2-naphthol without discussion of utility.
~ ew stabilizers and new stabilized organic compositions are desired.
It has been found that naphthofuranylnaphthols are effective stabilizers of a wide variety of organic materials against the deleterious effects of oxygen, heat and visible or ultraviolet light. The naphthofuranylnaphthols are especially useful as non-staining stabilizers for dienic polymers and styrene-acrylonitrile copolymers. The present invention is concerned with the uRe of l-~l-naphtho(2,1-b)furanyl]-2-naphthol having the formula OH
~~

as a stabilizer for organic materials against the deleterious effects of oxygen, heat and vis~ble or ultraviolet light.
According to the invention there is provided a stabilized composition comprising 100 parts by weight of an organic material sub~ect to the deleterious effects of oxygen, heat and light and ~rom about 0.1 part to about 10 parts by weight of l-{l-naphtho(2,1-b)furanyl}-2-nap~thol having the 1 - .~k.

formula In another aspect of the invention there is provided a method of stabilizing an organic material subject to the deleterious e~fects of oxygen, heat and light, which comprises incorporating in said organic material a stabilizing amount of ~ naphtho(2,1-b)furanyl~-2-naphthol in an amount from about 0.1 to about 10 parts by weight per 100 parts by weight of organic material.
The naphtho~uranylnaphthol may be used in an amount from about 0.1 part to about 10 parts by weight, more preferably from about 0.5 to about 5 parts by weight, per 100 parts by we$ght of organic material to be stabilized.
Naphthofuranylnaphthols are produced by first reacting glyoxal with a naphthol in the presence of an acidic catalyst at a temperature from about 0C. to about 100C., more preferably from about O~C. to about ~0C. An acetal is formed during the first step of the reaction, with acetal yield decreasing substantially if reaction temperature is abo~e 50C. during the first step. After acetal formation is completed, the second reaction step ` i9 performed. Water may be added to the reaction mixture, and the mixture i9 refluxed in order to hydrolyze the acetal and form a naphthofuranylnaphthol. Alternatively, a ~olid acetal may be separated from the reaction mixture by filtration in some cases and the acetal thereafter hydrolyzed by refluxing in the presence of an acid or base catalyst.

Naphthols used in the above process preferably have one unsubsti~uted po~ition adjacent to a hydroxyl group,

2-naphthol is employed to produce 1-[1-naphtho(2,1-b)furanyl~-2-naphthol.

The glyoxal may be used in the anhydrous form but the commercial a~ueous solutions of g~yoxal are more preferably used. Derlvatives of glyoxal which can generate glyoxal in situ may also be used, such as glyoxal NaHS04.
The glyoxal may be used in a molar ratio to the naphthol from about 1/10 to about 10/1. More preferably, the ratio is about 1/2.
. Ac~ds which may be used to catalyze the reaction of glyoxal with naphthols to form acetals include organic acids containing l to 12 carbon atoms such as acetic acid, propionic ac~d, benzoic acid, monoesters and die~ter~ of orthophosphoric acld, alkaryl sulfonic acids such as p-toluene~ulfonic acld, and the like; ~norganic acids capable of releasing protons such a8 boric ac~d, hydrochloric acld, phosphoric acid, sulfuric acid, and the.like; acid acti~ated clays capable o~ relea~ing protons such as Retrol*

- 3 -* trademar~

(produced by F~ltrol Corp.), bentonite, and the like; acldic resins capable of releasing protons such as Dowex 50-X10 (a cationic exchange resin which is a sulfonated copolymer of styrene and divinylbenzene and is produced by Dow Chemical Company), and the like; and Lewis acids capable of accepting electrons such as aluminum chloride, zinc chloride, boron trifluoride, and the like. The amount of acid catalyst used may be as l~ttle as about 0.01% based on total reactant weight, or the catalyst may be used as the solvent ~n which the reaction i~ run. Mixtures of ac~ds may also be used.
Excellent results were obtained using mixtures of acetic acid and sulfuric acid, zinc chloride and hydrochloric acid, and p-toluenesul~onic acid and acetic acid.
me ac~d~ described above may also be used at higher temperatures to catalyze hydrolyais of the acetals ln the second react$on step, thereby ~orming naphthofuranyl-naphthols. Bases may be used in place of acids in the second reaction step. Suitable bases include inorganic ba~es such a~ sodium hydroxlde, potassium hydroxide,and the like. Excellent results were obtained using potassium hydrox~de.
Acetic acid is a preferred solvent for these reactions because o~ it~ avai~ability, boiling point, water mi~cibillty, abil~ty to dissolve a wide variety of naphthols, and catalyt1c e~fect on the reaction. The reaction may also be run in other solvents which 1nclude carboxy~c ac~ds such as o-toluic acid, esters such as n-butyl acetate, ethers such as b~s{2-(2-~ethoxyethoxy3ethyl3ether, alcohols such as 1-pent~nol, ketones such as benzophenone, and the like. The re~ction may also be run ~n a two-pha6e system where one reactant ~8 soluble ln one phase and the other reactant is soluble ln a second phase, such as a hydrocarbon and water * trademark ~07Q494 system. An emulsifying agent may be used to facilitate the reaction in the two-phase system.
A preferred method for producing naphthofuranyl-naphthol~ comprises mixing glyoxal and a naphthol with a ma~or amount of acetic ac~d and a minor amount of sulfuric acid.
The reaction mixture ls stirred and cooled below 30~C. for about one to three hours. After that time, the temperature 1B raised to about 5~C.~ and thereaction ~s cont~nued for about 0.5 to t~ree more hours in order to complete acetal formation. The second react~on step is performed by adding water to the acetal reaction mixture and heating to reflux temperature. After about one to five hours, the acetal ~s acid-hydrolyzed substantially to a naphthofuranylnaphthol~
Another preferred method for performlng the second react~on step (h~droly5is) comprises separating a solid acetal from the reaction mixture by filtration, mixing the acetal with water and an acid or base, and acid-hydrolyz~ng or ba~e-hydrolyzing the acetal to a naphthofuranylnaphthol.
~eflux~ng i6 generally required for acidic hydrolysls, but basic hydroIysis can be performed by s~mply warming the mlxture to be hydrolyzed at about 50 - 100C. in a dimethyl ~ulfox~de solution.
The naphthofurany~naphthol product may be separated from the hydro}ysis mixture by any of several methods.
If the product ~8 a solid lt can be fi~tered and opt10nally washed with a solvent ~uch as hexane or water. Tf the product 18 an o~l ~t can ~e extracted ~ith an aromati~
solvent such as benzene. I~ acidlc hydrolysis is used, the extract can be washed with a weak base or a basic salt 3~ solution such as Na2C~3 ln water. ~f ba~ic hydrolysis ~8 used, the extract can be washed with a weak acid or an acidic salt solutlon inwater BUCh as (NH4)2S04 ln water.

me extract can then be distilled to obtain a substantially pure naphthofuranylnaphthol.
l-[l-Naphtho(2,1-b)furanyl]-2-naphthol ha~ been found to be an effective stabilizer of a wide variety of organic materials against the deleterious ef~ects of oxygen, heat and ylsible or ultraviolet light.
The naphthofuranylnaphthol i~ a nonsta~ning stabil~zers o~
both natural and synthetic polymers, such as uncured and vulcanized dienic polymers. me dienic polymers are sul~ur-vu~canizable and may contain about 0.5% to about 50% byweight of olefinic ~C=C~) unsaturation based upon total polymer weight. ~he olefinic groups may be ln the polymeric main chain (backbone) or in pendant (side-chain) groups, or both. Examples o~ suitable dienlc polymers include polymer~ such a~ natural rubber, c1s-polyisoprene, cis-polybutad~éne (CB), acrylonitrile-butadiene-styrene copolymers (ABS), butadlene-acrylonitrile rubbers (NBR), lsoprene-acrylonitr~le rubbers, polyisobutylene, polychloro-prene, butadiene-styrene rubbers (SBR), isoprene-styrene rubbers, and the like. Also sultable are polymers such as l~oprene-isobutylene (butyl) rubbers, copo~ymers o~
con~ugated dienes w~th lower alkyl and alkoxy acrylates such as ethyl acrylate, butyl acrylate, methoxyethyl acrylate, an~ the l~e, and ethylene-propy~ene-diene polymers (EPDM) cont~ining from about 0.~ percent to about 20 percent by we~ght of a~ leas~ one dienic termonomer.
Su~table EPDM dienic termonomers inc~ude con~ugated dienes such as butadiene, 1,3-pentadiene, and the li~e, non-con~ugated dlene~ such as 1,4-pentadiene, 1,4-hexadiene, and the like, cyc7ic dienes such as cyclopentadiene, dicyclopentadiene, and the like; and alkenyl nor~ornenes ~uch as 5-ethylidene-2-nor~ornene~ and the ~ike.

~070494 me dienic polymers may be vulcan~zed by methods known to the art. Suitable vulcaniz~ng agents include elemental sulfur and compounds capable of yielding elemental sulfur such as tetramethylthiuram di~ulfide, tetraethyl-thiuram disulfide, dipentamethylenethiuram hexasulfide, and the like.
A broad range o~ compounding ingredients can be ueed in the dienic polymer vulcanizates, including sulfur-containing and n~trogen-containing accelerators. Examples of Ruitable accelerators include metal salts of dial~yl, diaryl and alkaryl dithiocarbamates such as bismuth, copper, lead :~ and zinc dimethyl dithiocarbamates, cadmium, selenium, tellurium and zinc diethyl dithiocarbamates, sodium and zinc dibutyl dithiocarbamates, zinc ethyl phenyl dithio-carbamate, zinc dlbenzyl dithiocarbamate, and the like;
other dithiocarbamates such as piperidinium pentamethylene d$thlocarbamate, N-cyclohexylethyl ammonium cyclohexylethyl dithiocarbamate, N-pentamethylene-ammonium-N-pentamethylene dithiocarbamate, and the like; benzothiazoles such as 2-mercaptobenzothiazole and the zinc salt thereo~, 2,2'-benzo-thlazyl disulfide, 2-morpholinothiobenzothiazole, 2-(2,6-dimethyl-4-morpholinothio)~enzothiazole, and the like;
benzothiazole-sul~enamide6 such as ~-diethyl-2-benzothiazyl sulfenam~de, N-t-butyl-2-benzothiazole sul~enamide, N-. cyclohexyl-2-benzothiazole sulfenamide, N-oxy~ethylene-2-~enzothiazole sul~enam~de, and t~e li~e; thiuram SU7 ~ides such as tetramethy~ thiuram disul~de, tetraet.hyl th~uram disulfide, dimethyl dtphenyl thiuram d~sul~de, dipenta-methylene thluram hexssulf1de, and the li~e; thioureas such as ethylene th~ourea, trimethyl thiourea, N,N'-diethy~ th~ourea, N,N'-d~butyl thiourea, N,N'-di~heny~
thtourea, and the l~e; morphollnes such as 4,4'-dith~o-~070494 morpholine, and the like; polyamines such as triethylened~amlne, hexamethylene tetraamine, tricretonyl~dene tetra-amlne, and the like; aldehyde-amine condensation products such as acetaldehyde-ammonia, heptaldehyde-ammon~a, butyr-aldehyde-aniline, and the like; imidazol~nes such as 2-mercaptoimidazoline, an~ the like; and guanidines such as d~phenyl guanidine, di-o-tolyl guanid~ne, and the like.
Excellent results were obtained using 2-morpholinothiobenzo-thlazole 1~ Naphtho(2,1-b)furanyl]-2-naphthol is al~o an effective non~taining antioxidant in styrene-acrylonitr~le copolymers.
Suitable copolymers for use in the compositions-of tAts invention contain polymerized therein (1) from about ~0% to about 90% by weight based upon total copolymer weight o~ styrene, or at least one alkyl 8tyrene, alkoxy styrene or halostyrene, or a mixture thereof~ wherein the alkyl or alkoxy group contains from 1 to 8 carbon atoms, (2) from about 10% to about 50% by weight ~ased upon total copolymer weight of at least one vinyl nitrile having the formula .
CH2=C- C~

wheretn R iB hydrog~n or an alkyl radical contain~ng ~rom 1 to 3 car~on atoms, and (33 from ~ to a~out 20% by weight ba~ed upon total copo~ymer welght Or at ~e~st one other monoolefin. Preferred alky~ styrenes are those wherein an alkyl gro~p conta~ns from 1 to 6 carbon atoms, more prefer-ably from 1 to 4 carbon atoms. Preferred alkoxy styrenes are those wherein an alkoxy group containæ ~rom 1 to 6 carbon atoms, more preferably from 1 to 4 carbon atomæ.
Preferred halostyrenes are tho~e whereln a halogen group is chloro or bromo. Examples o~ suitable alkyl styrenes, alkoxy styrenes and halostyrenes include methyl styrene, ethyl styrene, methoxyethylstyrene, chlorostyrene, d~chloro-styrene, and the like. Examples of suitable vinyl nitr~les include acrylonitrile, methacrylonitrile, ethacrylonitrile, and the like. EXcellent results were obtained using copoly-mers of styrene and acrylonitr~le~
Other compounding ingredients usable in the dienic polymer compositions and styrene-acrylon~trile copolymers include fillers such as carbon blacks, caicium and magnesium carbonates, calcium and barium sulfates, aluminum silicates, silicon dloxlde, phenol-~ormaldehyde and polystyrene resins, asbestos and the like; plasticizers and extenders lncluding dialkyl and diaryl acid esters such as diisobutyl~
diisooctyl, d1isodecyl and dibenzyl oleates, stearates, sebacates, azelates, phthalates, and the like, and - naphthenic and para~inic 0118, castor oil, tall oil, and the like; and antioxidant~, antiozonants and stabilizers such as di-~-naphthyl-p-phenylenediamlne, phenyl-~-naphthylamine, N,~'-di-(2-octyl)-p-phenylened~amine, 2,2'-methylene-bis(4-methyl-6-t-butylphenol), 2~6-d1-t-but cresol, 2,2'-thiobi~(4-methyl-6-t-butylphenol), d~stearyl thiodipropionate, dilauryl thiodipropionate, 2,4-bis(4-hydroxy-3,5-t-~utylphenoxy~ n-octylthio3-133,5-tr~azine, tetrakls methylene 3-(3',5'-di-t-butyl-~'-hydroxyphenyl)-propionate methane, 4-~opropylam~no d~phenylamine, tri-~o~ylated phenyl)phosphite, and the li~e. Other compound-$n~ ingred~ents may also ~e used, such as pigments, tackifiers, flame retardants, fungicide~, and the like.
In addition to polymeric materials, the present naphtho~uranylnaphthols act to sta~lize a wide variety o~
other organic materia~s Such material~ tnc~ude: waxe6;

_ a 1070~94 synthetic and petroleum-derived lubricating oils and gre~ses; animal oils such as fat, tallow, lard, cod-liver oil, sperm oil and the like; vegetable oils such as castor, linseed, peanut, palm, cotton seed, and the like; fuel oil;
diesel oil; gasoline; and the like.
The following example~ illustrate the present invention more fully.
EXAMPLE 1 - ~reparation o~ l-tl-naphtho(2,1-b)-furanyll-2-naphthol 2-Naphthol (43 g. or 0.3 mole), 40% aqueous glyoxal (22.5 g. or 0.15 mole), and p-toluenesulfonic acid (30 g. or 0.16 mole) were dissolved in glacial acetic acid (200 ml.).
The mixture was stirred for about 3 hours with cooling as necessary to keepreaction temperature at 30C. The mixture was heated thereafter to 50C., stirred ror about 0.5 hour, cooled, and flltered to separate 40 g. acetal having a melting po1nt of 234-239C. m e ~lltrate was recycled tw~ce to the react1on mixture to produce 66 g. more of acetal.
One liter of water then was mixed with the remaininB
filtrate and 28 g. more Or acetal was separated by filtration.
Total acetal yiéld was 9 ~.
A portlon o~ the acetal (30 g. or 0.12 mole) was dissolved in 250 ml. of acetic acid, and 20 ml. concentrated ~Cl was added to the ~olution. The solution was heated to a~out 80~C. ror a~out }.5 hours and therea~ter poured into about 1 llter o~ water. A solid was ff ltered ~rom the solut~on and round to haYe a melt~ng po~nt o~ 176-180C.
Its NM~ and IR spectra were consistent with the structural ass~gnment of l-tl-naphtho(2,1-~)furanyl~-2-naphthol Calculated: C,8~,14; ~,4 55 ~ound: C,85 9~; ~,4.45 Examples 2 - 15 demon~trate the stabiliæing properties of l-[l-naphtho(2,1-b)furanyl]-2-naphthol in cured rubber vulcanizates. A masterbatch was prepared by mixing the following material~ in a Banbury mixer:

TABLE I
-MaterialsParts by ~eight Rlbbed Smoked Sheet100.0 Natural Rubber HAF Carbon Black .50.0 Zlnc Oxide ~.0 Stearic Acid 3.0 Sulfur 2.5 160.5 In each examplej 176 g. of the ma~terbatch described in Table I was compounded and cured ~ith l.l gram of 2-mo~pholinothiobenzothiazole accelerator and 1.1 gram of a given stabillzer. The compounding and cur1ng procedure was as follows. A 4-~nch, 2-roll mill ~as heated to 160F. and each ingredient was charged to the mill in the order listed w~th thorough milling between each addition. Each milled rubber composit~on was sheeted off the mill and cut into approximate 6 in. x 6 in. x 0.090 in. sections. The sections were wrapped separately in aluminum foil and cured for 35 minutes at 302F.
Physical testing of the vulcanizates was performed and the results are set forth in Tables II, III and IV.
300% Modulus, tensile strength, and ultimate elongation were determined according to ASTM D412-68 using Die C
dumbbells. Test tube aging was performed according to ASTM D865-62 for 24 hours at 100C. Crack Growth Test results in Table II were measured using the B.F.Goodrich Rotating Ring Crack Growth Test described in 38 Rubber Chemistry & Technology 719 (1965). Standard conditions used for the latter test were 70~C., 3 lbs. load and 300 cycles/minute.
The data in Tables TI, III and IV indicates that the 1~ naphtho(2,1-b)furanyl~-2-naphthol has stabilizing properties as good as or better than control stabilizers when tested in cured rubber vulcanizates.

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In each example, 0.68 g. of a given stabilizer was mixed with 68 g. of reprecipitated SN rubber in a Brabender Plasticorder for 2 minutes at 80C. Each sample was prepared and tested for Mooney viscosity before and after aging according to ASTM

DL1646-72 minutes using a large rotor and a l-minute warm-up time. Mooney buttons were aged at 70C for 10 days in an oven according to ASTM D~573-67. Test results are summarized ln Table V. The Mooney viscosity data indicates that the naphthofuranylnaphthol maintains Mooney viscosity as well as or better than the control stabilizer.

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Examples 18 21 demonstrate stabil$zing properties of naphthofuranylnaphthol in a styrene-acrylonitrile (SAN) copolymer composition. The SAN copolymer contained about 30% by weight acrylonitrile based upon total copolymer weight and had a welght average molecular weight of about 118,000 and a number-average molecular weight of about 51,000.
In each example, about 75 g. of SAN copolymer was mixed in a Brabender Plasticorder fitted with a cam head. Mixing was performed at 175C and 30 rpm until fluxing occurred (typi~
cally about 1.5 minutes after mixing began). At that time, 75 g. more of SAN copolymer and 0.75 gram of a given stabil-izer were charged to the Brabender, and mix$ng was continued for about another 2.5 minutes. The mix was dumped,-cold-pressed into sheets about 0.25 inch thick, cut into 0.25 inch cubes, pressed into 6 in. x 6 in. x 0.02 in. sheets at 175C
ror about 4.5 minutes, cooled, and cut into 1 in. x 1 in. x 0.02 ln. squares which were aged at 100C in a circulating oven`for varying times shown in Table VI. A Brinkman Fiber ` 20 0ptics Probe Colorimeter Model PC-100 was used to measure percent light transm$ssion at 450 nm of heat-aged samples ln comparison to unaged samples. Reduced light transmission indicates increased color development and is a measure of increased copolymer oxidation. Test results are summarized ~n Table VI. The data indicates the naphthofuranylnaphthol has stab$1$zing properties as good as or better than the control st O illzers.

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Examples 22 - 24 demonstrate stabilizing properties of naphthofuranylnaphthol in cured rubber wlcanizates.
A masterbatch was prepared by mixing the followlng materials s in a Banbury mixer:
TABLE VII

Materials Parts by Wt.
Natural Rubber 40.0 SN ~ubber 20.0 Cis-polybutadiene 20.0 Styrene-butadiene Copolymer 19.2 Carbon ~lack 50.0 Zinc Oxide 5.0 Stearic Acid lr5 Filler 2.0 - Paraffinic Oil 5!0 Sulfur - 3.3 Antioxidant O. 5 Bactericide 0.1 1~

Compounding, curing and testing were performed according to the procedures used for Examples 2 - 15 with 1. 05 parts of accelerator and 1.1 part-s of a given stabilizer being added during milling. Test results are set forth in Table VIII. The data in Table VIII indicates that the naphthofuranylnaphthol haR stabilizing properties as good as or better than the control stabilizers.

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~70494 EXAMPLES 26 - 27 i . .
Examples 26 _ 27 demonstrate stab~lizing properties of naphthofuranylphenol in white cured rubber vulcanizates.
A masterbatch was prepared by mixing the following materials in a Banbury mixer:
TABLE IX
- Materials Parts by Wt.
Natural Rubber ~~ c~cr~
2 50.0 Zinc Oxide 5.0 Stearic Acid 2.0 Sulrur 2.75 159.75 Compounding, curing and testing were performed according to the procedures us,ed for Examples ~ - 19, with 1.0 ~-part of mercaptobenzothiazole disulride and 0.1 part of tetramethylthiuram disulride being added during milling.
Test results are set forth in Table X. The data in Table X
indicates that the naphthofuranylnaphthol ha~ stabilizing properties about the am~ A8 the control staO1l1zers, , ' . .

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Claims (12)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A stabilized composition comprising 100 parts by weight of an organic material subject to the deleterious effects of oxygen, heat and light and from about 0.1 part to about 10 parts by weight of 1-[1-naphtho(2,1-b)furanyl]-2-naphthol having the formula

2. A composition of claim 1 wherein the organic material is a polymer.

3. A composition of claim 2 wherein the polymer is a dienic polymer.

4. A composition of claim 3 wherein said dienic polymer is an isoprene homopolymer or copolymer.

5. A composition of claim 4 wherein said dienic polymer is polyisoprene.

6. A vulcanized composition of claim 3.

7. A composition of claim 2 wherein the polymer contains polymerized therein (1) from about 50% to about 90% by weight based upon total copolymer weight of styrene, or at least one alkyl styrene, alkoxy styrene or halostyrene, or a mixture thereof, wherein the alkyl or alkoxy group contains from 1 to 8 carbon atoms, (2) from about 10% to about 50% by weight based upon total copolymer weight of at least one vinyl nitrile having the formula wherein R is hydrogen or an alkyl radical containing from 1 to 3 carbon atoms, and (3) from 0% to about 20% by weight of at least one other monoolefin.

8. A composition according to claim 1, 2 or 3 wherein said naphthol is present in an amount of about 0.5 to about 5 parts, by weight per 100 parts by weight of said organic material.

9. A method of stabilizing an organic material subject to the deleterious effects of oxygen, heat and light, which comprises incorporating in said organic material a stabilizing amount of 1-[1-naphtho(2,1-b)furanyl]-2-naphthol in an amount from about 0.1 to about 10 parts by weight per 100 parts by weight of organic material.

10. A method according to claim 9 wherein said amount is about 0.5 to about 5 parts by weight per 100 parts by weight of said organic material.

11. A method according to claim 9 or 10 wherein said organic material is a polymer.

12. A method according to claim 9 or 10 wherein said organic material is a dienic polymer.