Repairing elastomeric articles

תיקוו מוצרים אלסטומייים

REPAIRING ELASTOMERIC ARTICLES

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TECHNICAL FIELD

The present invention relates to a composi-tion and method for repairing reinforced elastomerarticles having a hollow or deformity, E.G. a cut orcavity therein. More specifically, the presentinvention relates to the utilization of a patch inassociation with the elas- tomer article and an amine curable polymer or pre-polymer optionally having rubber particles thereinwhich is cured at ambient temperatures. A gum rubbercan also be utilized but must be cured.

BACKGROUND ART

Heretofore, reinforced rubber articles suchas tires having a cut or opening therein have beenrepaired generally by filling the cut with uncuredrubber. Such a repair required a source of heat tocure the rubber and the formed repair usually had ashort life. If the opening extended through some ofthe cords or through the entire tire, a patch wasgenerally used. That is, an uncured rubber compoundwas first added to the aperture or hole and thencured with heat. Next, the patch area, for examplethe inside of the tire, was buffed. An uncured patchwas then positioned and cured with heat. This repairroute was not only long and tedious, but required theutilization of heat, usually a tire mold, and thelike. Thus, except for a chemical cure patch, anon-the-spot or in-situ repair could not be made, norcould repair be made at an ambient temperature.Moreover, the chemical patch method generally re-suited in low or poor adhesion. 5 10 15 20 25 30 35 τ » Μ -2-

Considering the prior art, U. S. Patent Nos.3,755,261 to VanGulick; 3,888,831 to Kogon; 3,834,934to Broisman, 3,644,256 also to Broisman; and 3,718,587 to Bhakuni relate to amine curable curing agents,amine curable polymers, or R-F-L type adhesives.However, these patents lack any suggestion of appli-cants' treating agent or repair of an elastomer ar-tide. U. S. Patent No. 3,779,794 to DeSantis re-lates to a moisture-curable polyurethane sealant pri-mer system, whereas U. S. Patent No. 4,085,283 to DenOtter relates to flame retardants utilized in cya-nuric acid derivatives. Hughson Chemical Division,Lord Corporation, Product No. TS-2682-71 relates to asurface primer for elastomeric substances utilizing aproprietary compound thought to be mono- or dichloro-isocyanuric acid. An article entitled "Room Temper-ature Vulcanizing Adhesive Based on Ethylene-Propy-lene-Diene Terpolymer," Cantor, Uniroyal, Paper No. 18 presented to the Division of Rubber Chemistry ofthe American Chemical Society, Denver, Colorado,October 10, 1973, relates to various oxidants whicheffect ambient temperature cures of EPDM. U. S. Patent No. 4,136,219 to Oldam relatesto a polyurethane paint which is applied to vulcan-ized rubbers. British Patent No. 1,352,645 relatesto a polyurethane paint which is applied to vulcan-ized rubbers.

British Patent No. 1,352,645 relates toN-halogen sulphonamide treating agents which halo-genize surfaces of synthetic and/or natural rubbers. U. S. Patent No. 4,125,522 to Becker relatesto a polyurethane adhesive, whereas U. S. Patent No.3,966,530 to Cutts relates to triazoline diones whichare utilized in lieu of chlorinated or halogenateddonors for treating elastomeric surfaces to improveadhesion. S«״- 5 15 25 j 30 35

V 71284/2 ־3- U. S. Patent No. 4,143,454 to Utsunomiyarelates to a method of attaching connecting parts ofan offshore structure wherein a liquid rubber isapplied over a treating solution which may contain ahalogen molecule. As such, this reference lacks ap-plicants' treating agent as well as repair of anelastomer article having a patch thereon. U. S. Patent No. 4,158,378 to Pearson re-lates to a cured rubber tire having a specific poly-urethane therein and to a chlorine water treatment.

Hence, Pearson also fails to teach or suggest appli-cants' recited treating agent as well as patched ar-tide. U. S. Patent No. 3,991,255 to Blaskjiewiczrelates to the adhesion of a polyurethane to an EPDMsurface utilizing various adhesives. However,

Blaskjiewicz does not use his treating agent to forma treating layer and utilizes elevated temperatures. U. S. Patent No. 4,300,9.70 to Honda does notdisclose amine curable resins or an ambient tempera-ture cure. U. S. Patent No. 4,240,852 to Gomberg re- .י¬ lates only to the use of a cyanoacrylate adhesive . U. S. Patent No. 4,352,704 to Williams re- lates to applying tire tread to a tire. This patent lacks any suggestion of applicants' treating agent or the repair of a tire aperture. U. S. Patent No. 4,327,138 to Hausch fails to disclose a cured rubber patch in repairing a rubber article. U.S Patent no. 4,327,138 discloses a cord-reinforced article having thereon a treating agent and an amine curable polymer or prepolymer.

It does not discloses the cord-reinforced patch in accordance with the present invention,.. One prior art method of repairing a tire relates to the utilization of a proprietary compound, thought to be a mixture of rubber and accelerators which is applied to the aperture and then cured. In general, very poor adhesion results and heat is re- quired. 5 10 15 20 25 30 35

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DISCLOSURE OF INVENTION

It is therefore, an aspect of the presentinvention to provide a repaired, reinforced elastomerarticle having a hollow therein utilizing a curedrubber patch and an amine curable polymer or prepoly-mer.

It is yet another aspect of the present in-vention to provide a repaired, reinforced elastomerarticle, as above, in which the hollow extends intoor through the reinforced material in which a layerof a treating agent resides in said hollow and in anarea between said patch and said article and the re-pair is made at ambient temperatures.

It is a still further aspect of the presentinvention to provide a repaired, reinforced elastomerarticle, as above, wherein said repaired elastomerarticle is a tire, a conveyor belt, and the like.

It is yet another aspect of the present in-vention to provide a repaired, reinforced elastomerarticle, as above, wherein said patch has one or morecords therein.

In another aspect of the present invention areinforced, repaired elastomer article has an openingor deformity therein such as a cut, or a hollow suchas a cavity, or aperture and utilizes a cured rubberpatch and an amine curable polymer or prepolymer.

It is yet another aspect of the present in-vention to provide a reinforced, repaired elastomerarticle, as above, in which said amine curable poly-mer or prepolymer fills said opening or said hollowand has a rubber filler therein.

It is still a further aspect of the presentinvention to provide a reinforced, repaired elastomer 5 10 15 20 25 30 1 1־ 35 f . ־5־ article, as above, in which said amine curable poly-mer or prepolymer resides in said patch area and doesnot contain any rubber filler therein.

In another aspect of the invention, a re-paired reinforced elastomer article having a hollowis filled with gum rubber and utilizes a cured rubberpatch and an amine curable polymer or prepolymer.

It is yet another aspect of the present in-vention to provide a repaired rubber elastomer, asabove, wherein said amine curable polyumer or pre-polymer is a urethane polymer or prepolymer, andwherein said treating agent is trichloroisocyanuricacid (trichloro-s-triazinetrione).

These and other aspects of the present in-vention will become apparent from the followingdescription of the invention.

In general, one aspect of the invention is arepaired, reinforced elastomer article, comprising: (a) the elastomer article, said elastomerhaving unsaturated groups therein, said article beingcured and having a hollow therein; (b) an elastomer patch, said patch beingcured and located juxtaposition to said hollow; (c) a treating agent, said treating agentcoating said hollow and said article in said patchjuxtaposition area, said treating agent selected fromthe group consisting of N־halohydantoins, N-halo-amides, N־haloimides, and combinations thereof; (d) an amine curable polymer or prepolymer,said amine curable polymer or prepolymer substan-tially filling said hollow, said amine curable poly-mer or prepolymer also located between said patch andsaid article in said juxtaposition area; (e) said amine curable polymer or prepoly-mer bonded to said patch and said hollow at ambienttemperature.

In general, one aspect of the invention is arepaired, reinforced elastomer article, comprising: (a) the elastomer article, said elatomerhaving unsaturated groups therein, said article beingcured and having a hollow therein; (b) a cured patch, said patch located jux-taposition to said hollow; (c) a treating agent, said treating agentcoating said hollow and said article in said patchjuxtaposition area, said treating agent selected fromthe group consisting of N-halohydantoins, N-halo-amides, N-haloimides, and combinations thereof; (d) an amine curable polymer or prepolymer,said amine curable polymer or prepolymer substan-tially filling said hollow, said amine curable poly-mer or prepolymer also located between said patch andsaid article in said juxtaposition area, said aminecurable polymer or prepolymer filling said hollowhaving a rubber filler therein; (e) said amine curable polymer or prepoly-mer bonded to said patch and said hollow at ambienttemperature.

Another aspect is achieved by: a repairedelastomer article, comprising: the elastomer article,said article having a hollow therein; a cured gumrubber disposed within said hollow; a treating agentapplied to the inner surface of said article immed-lately surrounding said filled aperture, said treat-ing agent selected from the group consisting of:N־halohydantoins, N-haloamides, N-haloimides, andcombinations thereof; an amine curable polymer orprepolymer applied over the treated surface of saidarticle; and a patch positioned over said polymer orprepolymer; wherein said polymer or prepolymer iscured in situ at room temperature; and wherein saidelastomer article is cured and unsaturated. -·« 5

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BRIEF DESCRIPTION OF DRAWINGS

Fig. 1 relates to a cross-sectional viewshowing the repair of a reinforced elastomeric arti-cle having an aperture extending therethrough,according to the present invention; and

Fig. 2 relates to a cross-sectional viewshowing the repair of a reinforced elastomer articlehaving a cavity extending into the cord area, accord-ing to the present invention.

Fig. 3 relates to a cross-sectional viewshowing the repair of a reinforced, elastomeric arti-cle having an aperture therethrough, according to thepresent invention utilizing a rubber filler therein;

Fig. 4 relates to a cross-sectional viewshowing the repair of an elastomer article having acut therein, according to the present invention uti-lizing a rubber filler therein;

Fig. 5 relates to a cross-sectional viewshowing the repair of a reinforced elastomer articlehaving a cavity therein, according to the presentinvention utilizing a rubber filler therein;

Fig. 6 relates to a cross-sectional viewshowing the repair of a reinforced elastomeric arti-cle having a hollow extending completely there-through, according to the present invention; and

Fig. 7 is a cross-sectional view showing therepair of a similar reinforced׳elastomeric articlewherein the hollow extends only partiallytherethrough. 5 10 15 20 25 30 4* )! 35 -8-

PREFERRED EMBODIMENTS

According to the concepts of the presentinvention, a reinforced elastomer article having ahollow therein is repaired in association with acured rubber patch. The hollow, that is the recessor void exists in the article and extends at leastinto the reinforced area such that some of the cords,that is at least approximately 25 percent, aredamaged, broken, or severed. When the hollow extendsonly into the cord area, a cavity is formed in thearticle. When the article extends entirely throughthe article, an aperture is formed. In either case,an amine curable polymer or prepolymer is applied tothe hollow and to a space between the rubber elasto-mer and cured rubber patch. Cure occurs at ambienttemperature.

SUBSTRATE ELASTOMERS

According to the embodiment of Fig. 1, arti-cle 10 has hollow 12 in the form of an aperture, orthe like and extends clearly therethrough. The arti-cle to be repaired, or substrate, is a cured rubberor elastomer, having unsaturated groups therein. Thesubstrate typically has cords 14 therein. The sub-strate can be any conventional elastomer or rubberknown to those skilled in the art. For example, itcan be made from conjugated dienes having from 4 to12 carbon atoms such as butadiene, isoprene, and thelike. It can also be made from natural rubber, thatis from a substance which is obtained from varioustrees and plants which grow in the tropics or desertportions of the world. Such natural rubber generallyhas in excess of 90 and usually in excess of 95 per-cent of cis-1,4-polyisoprene content. The substrate 35 t

V i -9- may also be various elastomeric copolymers such asthose made from monomers of conjugated dienes havingfrom 4 to 12 carbon atoms as set forth above, andvinyl substituted aromatic compounds having from 8 to15 carbon atoms. Examples of such vinyl substitutedaromatic compounds include styrene, alpha-methyl-styrene, and the like. An example of a specific co-polymer is styrene-butadiene rubber.

Naturally, other types of rubber compoundscan be utilized such as the so-called butyl rubbers,neoprene, that is polychloroprene, and the like, aswell as blends of said above rubbers.

ELASTOMER PREPARATION 5 10 4•"״ד י 15 The preparation of such above noted various elastomers is well known to the art. The article tobe repaired is often in the form of a tire, especial-ly an off-the-road tire, a conveyor belt, or any rub-ber article having a hollow therein. Regardless of20 the type or nature of the article in which the elas- tomer exists as a cured form, it is desirable toclean the surface to which the amine curable polymeris to be applied. Cleaning can take place as througha physical treatment of the area to be repaired, for25 example, as through buffing or through skiving, that is cutting and removing a portion of the surface.Another method involves the use of any conventionalorganic solvent to remove dirt and residue. Typicalsolvents include acetone, or ethyl acetate. As ap-30 parent from the drawing, the area which is typical- ly cleaned involves aperture 12, the area adjacentto patch 20 and the patch as well. Thus, the aper-ture may be difficult to clean by physical means, canbe cleaned by utilizing a solvent whereas the bottom 35 ־10־ portion of the article can be buffed. To ensureremoval of all loose rubber, the buffed portion canthen be cleaned with a solvent.

TREATING AGENTS

To the cleaned surfaces are applied a coat-ing of various treating agents 30 which have beenfound to improve adhesion between the substrate andthe amine curable polymer or prepolymer 40. Suitabletreating agents include the various N־halohydantoins,the various N-haloamides, the various N-haloimides,and combinations thereof. Examples of various de-sirable N־halohydantoins include 1,3-dichloro5,5־-dimethyl hydantoin; 1,3- dibromo-5,5-dimethyl hydan-toin; 1,3-dichloro-5-methyl-5-isobutyl hydantoin; and1,3-dichloro-5-methyl~5~hexyl hydantoin. Examples ofN-haloamides include N-bromoacetamide and tetra-chloroglycoluril. Examples of N-haloimides includeN־bromosuccinimide and the various chloro substituteds-triazinetriones, commonly known as mono־, di־, andtrichloroisocyanuric acids. A preferred treatingcomposition for use in the practice of the presentinvention are the various mono-, di-, or trichloro-isocyanuric acids, or combinations thereof. Tri-chloroisocyanuric acid is especially preferred.

APPLICATION OF TREATING AGENTS

The treating agents usually exist in solidform. They are readily soluble in solvents such asacetone and the like and thus can be applied inliquid form. Application of the treating agent gen-erally occurs at ambient temperatures. Applicationcan occur through any conventional manner as through 35 -11- brushing, spraying, and the like. The amount appliedis such that the rubber substrate surface is coated.Preferably, two or more coats of the treating agentor adhesive compound is used to ensure that all thecured rubber substrate surface has been coated.

TYPICAL AMOUNTS OF TREATING AGENTS A typical amount of the treating agent inthe suitable solvent, for example ethyl acetate oracetone is generally from about 0.1 to about 10 per-cent by weight based upon the total weight of saidtreating agent and solvent, and preferably from about0.5 percent to about 5 percent. Of course, higher orlower concentrations can be utilized. This solventsystem has been found to dry within a matter ofminutes so that the amine curable polymer or prepoly-mer can be bonded thereto. It is thought that theadhesive treating system adds halogen groups, forexample, chlorine to the cured rubber which activatesthe cured rubber surface allowing the amine curablepolymer or polymer system to adhere strongly to thecured rubber surface.

AMINE CURABLE POLYMERS OR PREPOLYMERS

Of the various amine curable polymers orprepolymers, the urethanes are preferred. Other pre-polymers or polymers which can be cured with theamine curing agent include the compounds set forth inU. S. Patent No. 3,755,261 which is hereby fully in-corporated by reference. Briefly, such compounds arethe various epoxy resins such as those disclosed inthe "Encyclopedia of Polymer Science and Technology"Interscience Publishers, New York (1967), Volume 6, 35 ־12־ pages 212221־; halogen-containing hydrocarbon poly-mers such as chloroprene polymers, chlorinated butylrubber, and chlorinated polyethylene and polypropyl־ene; chlorosulfonated polymers such as those de-scribed in U. S. Patent No. 2,723,257; polymers con-taining acid halide groups such as 0 -C — Cl and halo- formate groups such as 0

H -0—C—Cl; polymers containing anhydride groups which on reaction with diaminesyield amide-acid linkages, and organo-polysiloxanesas described in U. S. Patent No. 2,938,010.

TYPICAL URETHANE POLYMERS OR PREPOLYMERS

The urethane prepolymers or polymers, thatis those which contain isocyanate groups, are gener-ally formed by first reacting a polyether polyol or apolyester polyol with a molar excess of a diiso-cyanate to form a prepolymer having terminal iso-cyanate groups. The polymer is then cured to in-crease its molecular weight from less than about3,000 upwards to over 10,000. Examples of such poly-mers are set forth in U. S. Patent Nos. 2,620,516;2,777,831; 2,843,568; 2,866,774; 2,900,368; 2,929,-800; 2,948,691; 2,948,707; and 3,114,735, all ofwhich are hereby fully incorporated by reference.Typical specific examples of such polyurethanes in-elude Adiprene L-367, polytetramethylene ether glycolcontaining approximately 6.4 percent isocyanate endgroups by weight, manufactured by DuPont; AdipreneL-42, polytetramethylene ether glycol containingapproximately 2.8 percent isocyanate end groups byweight, manufactured by DuPont; and Cyanaprene A-7, apolyester-based coating polymer with approximately 35 -13- 2.4 percent isocyanate end groups, manufactured byAmerican Cyanamid. Blends of these polyurethanes canalso be utilized. Moreover, it has been found, par-ticularly with repair or application of the aminecurable polymer to the patch area, that is the areabetween patch 20 and cured substrate 11, better ad-hesion is often obtained by utilizing two differenttypes of urethane. For example, a urethane contain-ing a high amount by weight of isocyanate end groupssuch as Adiprene L-367 can be blended with a urethanecontaining a low amount by weight of isocyanate endgroups such as Adiprene L-42. The amount of one ure-thane to the other can range from about 1 to about 99percent and desirably from about 30 to about 70 per-cent by weight.

AMINE CURING AGENTS 5 10 15 m. 4^־

To the amine curable prepolymer or polymercompound is added a conventional amine curing agent,known to those skilled in the art. Generally, anyconventional or known amine curing agent can be usedand, thus, only a few specific examples will begiven. Thus, the curing agent can be MOCA, that is4,4'-methylene bis(2-chloroaniline) or, desirably a25 complex of 4,4'-methylene dianiline and a salt, or a complex of racemic 2,3-di-(4-aminophenyl) butane anda salt, as set forth in U. S. Patent No. 3,755,261 toVanGulick which is hereby fully incorporated by ref-erence. The latter two complexes are preferred. The30 methods for preparing the complexes are set forth in U. S. Patent No. 3,755,261. A preferred salt uti-lized with the 4,4 *-methylene dianiline compound issodium chloride or lithium chloride. Due generallyto availability and costs, the complexes or salts 20

Vv / 35 ־14־ derived from 4,4'־methylene dianiline are highly pre-ferred. Another class of amine curing agents whichcan be utili2ed are the various Versamides, that isthe condensation products of polyamines and dibasicacids obtained when certain unsaturated fatty acidsare polymerized, and are manufactured by HenkelChemical Company.

EQUIVALENT WEIGHT OF AMINE CURING AGENTS

Equivalent weight of the curing agent uti־lized with regard to the curable prepolymer or poly-mer, including the amine curing agent, generallyranges from about 85 percent to 115 percent with fromabout 95 to 105 percent being preferred.

Often to facilitate processing, the curingagent, and especially an amine curing agent such asthe complex of 4,4’-methylene dianiline and a salt isutilized with a plasticizer such as dioctylphthalateon a 50 percent weight basis, or Flexol 4-GO, tetra-ethylene glycol bis(2־ethyl hexanoate) manufacturedby Union Carbide Corporation on a 50 percent weightbasis. The amount of plasticizer can range fromabout 20 percent to about 60 weight percent.

BLENDING OF CURING AGENTS WITH POLAR SOLVENT

The curing agent is blended with the pre-polymer or polymers in various mixers such as doughmixers, high speed impellers, paddle-type mixers, andthe like. Small batches can be mixed by stirringwith a spatula. Usually, the prepolymer or polymeris a liquid. If not, when mixed with the polar sol-vent, a liquid mixture results. However, even if asolid curing agent is used, when added to the pre- 5 10 15 20 25 30 35 &amp;amp; -15- polymer or the polymer, and to a solvent system, aliquid system results even though the curing agent(e.g., amine) can be in the form of a dispersion.Thus, even though the system may contain solidstherein, the solids exist in the form of a dispersionso that a liquid system is produced.

AMOUNT OF POLAR SOLVENTS

The curing agent and the amine curable poly-mers or prepolymers form the curable polymer systemwhich is mixed with a polar solvent so that a liquidsystem is obtained which cures at ambient or roomtemperature, that is, the prevailing temperature asfrom about 10°C to about 50°C. Often the ambienttemperature will range from about 15°C to about 35°Cor 40°C. The polar solvents which can be utilized,especially with the amine curing agent and the aminepolymers or prepolymers are, for example, set forthin U. S. Patent No. 3,888,831 to Kogon which is here-by fully incorporated by reference. Generally, theamount of solvent utilized per 100 parts by weight ofthe curable prepolymer or polymer ranges from about 2to about 40, desirably from about 2 to about 20, andpreferably from about 5 to about 15 parts by weight.Specific examples of preferred solvents include di-methylformamide, tetrahydrofuran, cyclohexanone,ethyl acetate, nitromethane, nitroethane, nitropro-pane, methyl ethyl ketone, and acetone. Acetone andmethyl ethyl ketone are highly preferred. The amountof curing agent, based upon said polymer or prepoly-mer, ranges from about 0.85 to about 1.15 equiva-lents. 5 tl . ! 1 ־ ־ 10 15 20 25 30 35 ־16-

PATCH CONSTRUCTION

Considering patch 20, it can generally be ofany desired size so long as it is greater in surfacearea than the aperture adjacent thereto. Typically, 5 the surface area of the patch is at least twice as great as the aperture. Generally, an appropriatepatch size will be known to one skilled in the art ofpatch construction and/or patch application. Thepatch is made of rubber and is generally fully cured.10 Although cured natural rubber or a composition con- taining at least 80 percent by weight of natural rub-ber is often preferred, any conventional type ofcured rubber compound can be utilized. Thus, thepatch can be made substantially from a conjugated15 diene having from 4 to 12 carbon atoms, copolymers made from conjugated dienes having from 4 to 12 car-bon atoms with vinyl substituted aromatics havingfrom 8 to 15 carbon atoms, for example styrene- buta-diene rubber, and the like. In essence, the patch20 can be made out of the same type of rubber as the substrate. Often, the patch will have a cushionedlayer thereon to alleviate stresses formed betweenthe tire carcass and tire patch.

Since in the preferred embodiment of the25 present invention the substrate has cords therein, desirably the patch also has cords therein. Althoughthe number of the cords can range from a small numberto a very large number, the strength of the cords inthe patch is generally at least equal to the strength30 of the preinjured damaged cords contained in the sub- strate. More specifically, whenever approximately 25percent to about 50 percent of the cords are damaged,severed, broken, etc., the strength of the cords inthe patch is approximately equal to the strength of 5־־־

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'4 35 -17- said cords before being damaged, etc. However,should approximately 50 percent to 100 percent of allthe cords be damaged, severed, or otherwise injured,the strength of the cords in the patch is equal tothe strength of the total cords in the article beforeany injury thereto. Should the number of damagedcords in the article be less than approximately 25percent, then, the strength of the remaining cords isusually adequate such that a reinforced patch neednot be utilized. The cords in the patch can be madeof polyester, nylon, steel, rayon, and the like, withnylon being preferred. It has been found that ac-cording to the present invention, large aperturesextending through a cured rubber substate can berepaired up to approximately eight inches in diame-ter.

Generally, any rubber article having anaperture therethrough can usually be repaired by thepresent invention. Specific examples include con-veyor belts, tires, especially off-the-road tiressuch as those utilized for front-end loaders, miningequipment machines, and the like. A repaired article having a hollow in theform of an aperture is shown in Fig. 2. An aminecured polymer or prepolymer, as for example a ure-thane cured polymer 40, fills the aperture. It alsoforms a good adhesive bond with treating agent 30which in turn coats the aperture 12 of substrate 10,patch 20, and the adjacent article area. The aminecured urethane extends through the aperture and intothe patch area, that is the area juxtaposition to thepatch or located between the patch and the substrate.In this area, a good bond is also formed such thatthe patch reinforces the substrate. When the rubberarticle is a tire, usually the patch area is buffed ־18־ sufficiently to remove surface contamination. Theinner liner should at least be buffed and in somecases removed to the tie-gum layer in order to obtaina fresh surface. Occasionally, it is desirable toeven remove one or two of the cord plies in order toensure a fresh surface for bonding. Reinforcing patch20 can contain a plurality of cords therein, general-ly approximately equal in strength to the total num-ber of cords in the tire to be repaired. The patch iscoated with the treating agent and then coated withthe amine curable polymer or prepolymer. The patchis then taped into place over the aperture area. Thepatch is also held in place by inflating a curingtube located inside the tire. With the aperture ofthe tire located in the uppermost verticle position,the amine curable polymer or prepolymer is pouredinto the aperture until it is filled. Of course, theaperture has previously been coated with the treatingagent. The top of the aperture is then taped and theamine curable polymer in the patch area and in theaperture is allowed to cure at ambient temperature.Taping of the aperture area retains the polar solventsuch as acetone which promotes curing of the poly-mer. In a variation of this procedure, the aminecurable polymer is applied to the patch area and thenthe patch applied thereto. The patch is taped intoplace and the polymer is allowed to cure. Next, theamine curable polymer is separately added to theaperture so that it is filled and then taped there-over. The aperture portion of the repair is thenseparately cured at ambient temperatures. The endresult by either method is a repaired article havingmuch better strength and durability than that re-paired according to heretofore conventional methodsthat are performed on site. ' 1 צ 10 15 20 25 &gt;

S 30 35 ' · · ' -19־

In the embodiment of Fig. 2, the hollow isin the form of a cavity wherein some cords of thereinforced article have been damaged, severed, or thelike. Usually, at least 25 percent of the cords havebeen broken, damaged, etc., and the article is re-paired utilizing a patch. Either the cavity can befilled or the patch applied first. In repair ofcavity 112, treating agent 130 is applied to all sur-faces thereof. Then, the cavity is filled with aminecurable polymer 140, generally to the level of thesubstrate. Naturally, in this operation, the cavityis located in the uppermost vertical position of thearticle. As before, the tape is then applied overthe filled cavity to promote curing of the polymer.Cure occurs at ambient temperature.

The patch area is prepared as before bycleaning and even buffing down to the tie-gum layerand even to the cord ply layer. Treating agent 130is applied to the patch area of substrate 110 as wellas to one side of patch 120. Amine curable polymeror prepolymer 140 is then applied to the treated sideof the patch, with the patch in turn being applied tothe treated portion of substate 110. The ends of thepatch can be taped to the substrate or held in placewith a curing tube located inside the tire. The num-ber of cords of the patch is as previously set forth.That is, if less than 25 percent of the cords aredamaged, the use of the patch having cords therein isoptional. When approximately 25 to about 50 percentof the cords are damaged, severed, etc., the strengthof the cords in the patch is at least equal to thestrength of such cords before being damaged. Whenapproximately 50 percent or more of the cords aredamaged, injured, broken, etc., the strength of thecords in the patch is equal to the strength of the 5 10 15 20 25 30

I נ 35 -20- total number of cords in the substrate before anyinjury thereto. The repair is then cured at ambienttemperature.

In forming the amine curable polymer system,generally the amine curable polymer or prepolymer ismixed with the polar solvent and then the curingagent is added last. During cure, an effective andstrong bond is formed between the prepolymer or poly-mer system and the treated elastomer substrate.

Since the present invention relates to an ambienttemperature, repair of large and cumbersome articlessuch as off-the-road tires, conveyor belts, and thelike, can be made in situ. In other words, the re-pair can be made at the job site. The only accessorywhich may be required is a tire bladder, although asand bag can be used. In such a situation, the re-pair can be made at the local tire repair shop.

Since the cure is ambient, no steam chambers, orother vulcanizable tire repair equipment are re-quired. This, of course, also results in an energysavings.

It is to be understood that various conven-tional additives in typical amounts can be added tothe amine curing agent and prepolymer system such ascolorants, softeners, fillers, antioxidants, plasti-cizers, and the like.

The invention will be better understood byreference to the following representative examples. צ 10 15 20 25 m

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'·* I EXAMPLE 1 A damaged off-the-road tire, having the in-jury through the innerliner, was repaired as follows.The damaged area was skived out, making sure to re-move all of the damaged area, body plies, and lug 30 A * 35 -21- areas. The repair area was then buffed to an RMA #3or #4 buff rating. The innerliner was also buffed.

In most cases, the innerliner must be at least re-moved to the tie-gum. In some cases, removal of oneor two of the body plies was necessary in order to5 get a good fresh surface for bonding of the rein- forced patch. Once both areas have been buffed, theywere thoroughly washed with a solvent, normally ace-tone on a piece of Rymplecloth. The acetone wasallowed to dry thoroughly. Application of several10 coats of a 3 percent trichloro-s-triazinetrione in ethyl acetate follows the washing procedure. Thislikewise was allowed to dry thoroughly. Installationof the reinforcing patch was preferably done first.This was accomplished by mixing a polyurethane repair13 kit comprised of the following two components. _COMPONENT A__COMPONENT B_

Adiprene L-42 150 grams Caytur 21 72 grams

Adiprene L-367 150 grams20 Flexol 4G0 30 grams

Acetone 30 grams

The thoroughly mixed polyurethane was thencoated onto a reinforcing patch that was fully curedand contained no uncured gum layer. The patch was25 buffed, washed and primed with the 3 percent tri- chloro-s-triazinetrione prior to the application ofthe polyurethane. After the patch was coated, thebuffed portion of the innerliner was also coated.

The polyurethane was allowed to thicken to a non-30 flowing material before installation of the patch to the innerliner was carried out. The patch was tapedin place and then held permanently in place by in-flating a curing tube inside the tire. After thepatch was secured, the tire was rotated 180° so that

<img img-format="tif" img-content="drawing" file="IL71284AD00231.tif" id="idf0004" />

! 35 -22- the aperture was at the top of the tire. Additionalpolyurethane repair material was poured into theaperture until completely full. The surface of therepair was covered with tape in order to keep thefluid material in place and allow the acetone to re-main in the formulation long enough to fully cure thesystem. After standing 24 hours at ambient tempera-ture, the tape was removed from the aperture and thecuring tube and tape were removed from the innerlinerposition of the tire. The tire was ready to beplaced back into service.

The above procedure was performed on a 37.25x 35 scrapper tire. The size of the injury was a 4inch inside diameter on the innerliner and 10 1/2inch outside diameter on the exterior (tread) sur-face. The injury was located in the crown area. AROCO #7 patch was used (Rocson, Inc.׳ Copley, Ohio).The patch was fully cured. After the tire was pre-pared, it was placed back into service. The repairedtire lasted 342 hours before a small air leakoccurred.

RUBBER FILLERS

According to other concepts of the presentinvention, an elastomer article having a deformitytherein is substantially filled with an amine curablepolymer or prepolymer. If the deformity is a cut,the amine curable polymer or prepolymer has a rubberfiller therein. If the deformity is a hollow such asa cavity or an aperture, a cured elastomer patch isutilized in association with the repair and is 10-cated juxtaposition to said aperture. See Figs. 3, 4and 5. The amine curable polymer or prepolymer inthe hollow area will have a rubber filler therein. -23-

However, such polymer or prepolymer when utilized inthe patch area will have no such filler. In eithersituation, cure of the amine curable polymer occursat ambient temperature.

Generally, the article to be repaired hascords or reinforcement therein. When the article hasa hollow therein, that is a recess or void, such hoi-low extends at least 25 percent into the reinforce-ment area such that some of the cords are broken,severed, damaged, or the like. When the hollow soextends only into the cord area, a cavity is formedin the article. When the hollow extends entirelythrough the article, an aperture is formed.

Considering an elastomer article having anaperture therethrough, as shown in Fig. 3, the arti-cle is generally indicated by the numeral 100. Thearticle or substrate can be an elastomer of the typeset forth above. Aperture 120 extends entirelythrough the article. The article to be repaired, orsubstrate is a cured rubber or elastomer havingunsaturated groups therein. The article typicallyhas cords 140 therein. In the embodiment of Fig. 4,a cured rubber article having unsaturated groupstherein is generally indicated by the number 1000.

The cut area 1120 has a treating agent 1300 thereon.The cut is substantially filled with said amine cur-able polymer or prepolymer. In the embodiment ofFig. 5, cavity 2120 extends into the reinforcementportion of the article, generally indicated by thenumber 2000. Article 2000 also has unsaturatedgroups therein. Regardless of the nature of theopening, the substrate can be any conventional elas-tomer or rubber known to those skilled in the art andas set forth herein above. 5 10 15 20 25 30 1?־ 1. י*.

F

V 35 -24-

The article such as a tire is cleaned in amanner as set forth above, which is hereby fully in-corporated by reference, that is through physicaltreatment, use of convention organic solvents and thelike.

To the cleaned surfaces are applied a coat-ing of various treating agents 30, 130 or 230 whichhave been found to improve adhesion betwen the sub-strate and the rubber filled amine curable polymer orprepolymer 40, 140, or 240, respectively.

Suitable treating agents include the variousN-halohydantoins, the various N-haloamides, the vari-ous N-haloimides, and combinations thereof. Examp les of such treating agents are also set forth aboveand thus will not be repeated at this point. Appli-cation thereof is in any conventional manner and atambient temperature, as set forth above.

The amount of the treating agent is gener-ally from about 0.1 to about 10 percent by weightbased upon the total weight of said treating agentand solvent, with the preferred amount being as setforth above.

With regard to the various amine curablepolymers or prepolymers, they are the same as setforth above. Similarly, the amine curing agents havealso previously been set forth as has the equivalentratio as the use of a plasticizer. The blending ofthe amine curing agent as well as the ambient curingtemperature range has also been described. Alongwith the amount of the solvent.

An important aspect of the present inventionrelates to the use of a rubber filler 500 in theamine curable polymer or prepolymer to repair aper-ture 120. As previously noted, the patch area pre-ferably does not have any rubber fillers therein 5 10 15 20 25 30 'pj * % 35 -25- since such fillers' will appreicably weaken the adhe-sive bond of the amine curable polymer or prepolymer.

Moreover, cut 1120 and cavity 2120 do have a rubberfiller in the amine curable polymer or prepolymer.Filler 500, 1500, or 2500 is preferably a cured rub-ber and is in the form of particles. Desirably, theparticle size can range from about 10 millimeters toabout 0.01 (dust size) and preferably from about 1.0millimeter to about 0.01 millimeter (dust size).Generally, any type of synthetic rubber can be uti-lized as the particle filler so long as it is an un-saturated rubber. A class of suitable rubber com-pounds include the same types of rubbers as thatutilized in the article or substrate 100 or 1000.

That is, conjugated dienes having from 4 to 12 carbonatoms, natural rubber, typically containing in excessof 90 to 95 percent cis־l, 4-׳polyisoprene, copolymersmade from dienes having from 4 to 12 carbon atoms andvinyl substituted aromatics having from 8 to 15 car-bon atoms, for example, styrene-butadiene rubber, thevarious types of nitrile rubber, polychloroprene, andthe like. Although saturated type rubbers can alsobe utilized, the unsaturated types give better adhe-sion and thus are preferred.

The cured rubber source can be any conven-tional or common source such as ground tire scrap,ground rubber scrap, ground tire tread, and the like.

The rubber source can also be in the form of a pow-der such as that obtained by buffing a tire. Asshoud be apparent, such sources are very economicaland will generally include specific rubbers such aspolybutadiene, natural rubber, styrene-butadiene rub-ber, synthetic polyisoprene, and combinations there-of. 35 -26־

The amount of rubber utilized in the amine curable polymer or prepolymer ranges from about 10 to about 75 percent by weight, and preferably from about 40 to about 50 percent by weight, with an optimum amount being approximately 43 percent by weight based 5 upon the total amount of said amine curable polymer or prepolymer and said cured rubber parti- cles. Generally, the addition of the rubber parti- cles to the amine curable polymer or prepolymer will make such polymer softer as well as reduce its 10 modulus. The hardness of the amine cured polymer or prepolymer 400, 1400, or 2400 containing rubber par- tides therein in aperture 120, cut 1120, or cavity 2120, respectively, can thus be varied by the type of rubber utilizied as well as the amount thereof. 15 Depending upon the repaired article, a desired hard- ness of the cured rubber-amine cured polymer or pre- polymer mixture will vary. It is desirable that the hardness of the rubber particle-amine cured polymer or prepolymer mixture is generally similar or equal 20 to that of substrate 100, 1000, or 2000. With regard to a tire, such hardness generally ranges from about 40 to about 90 on the Rockwell Shore A hardness scale, and preferably from about 60 to about 70. The 2 low strain (lbs./in. ) modulus will generally range25 from about 25 to about 500, and preferably from aobut 50 to about 75. Not only does such rubber par-ticle-amine cured polymer or prepolymer mixtureresult in improved performance with regard to arepaired article, but the material costs of the30 filled aperture is reduced.

The cured rubber particles can be added tothe amine curable prepolymer or polymer system at anystage and blended or mixed therewith utilizing anyconventional mixing device as for example a spatula,35 a mixer, and the like. :1 1

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-27-

The construction of the patch is as setforth above which is hereby fully incorporated.

Thus, the patch can have any number of cords thereinand the like.

Generally, any rubber article having a cut,cavity, or an aperture therethrough can usually berepaired by the present invention. Specific examplesinclude tires, especially off-the-road tires such asthose utilized for front-end loaders, mining equip-ment machines, and the like. Repaired articles areshown in the drawings. Fig. 3 relates to a tire hav-ing an aperture therethrough and is repaired utili-zing patch 200. Patch 200 will have cords therein,not shown. Fig. 4 relates to an opening in the formof a cut as in a tire. The opening can be on thetread area or the sidewall. Fig. 5 relates to acavity extending into cords 2140 of a tire.

When the rubber article is a tire and thedeformity is an aperture, as in Fig. 3, usually thepatch area is buffed sufficiently to remove surfacecontamination. The inner liner should at least bebuffed and in some cases removed to the tie-gum layerin order to obtain a fresh surface. Occasionally, attimes, it is desirable to even remove one or two ofthe cord plies in order to ensure a fresh surface forbonding. Reinforcing patch 200 can contain a plura-lity of cords therein (not shown), generally approxi-mately in strength to the cords in the tire to berepaired. The patch is coated with treating agent300 and then coated with amine curable polymer orprepolymer 400 having no rubber filler therein. Thepatch is then taped into place over the aperturearea. The patch is also held in place by inflating acuring tube located on the inside of the tire. Withthe aperture of the tire located in the uppermost 35 ־28־ vertical position, the amine curable polymer or pre-polymer having rubber filler 500 therein is pouredinto the aperture until it is filled. Of couse, theaperture has previously been coated with treatingagent 300. The top of the aperture is then taped andthe amine curable polymer in the patch area and inthe aperture is allowed to cure at ambient tempera-ture. Taping of the aperture area retains the polarsolvent such as acetone which promotes curing of thepolymer. In a variation of this procedure, the aminecurable polymer is applied to the patch area and thenthe patch applied thereto. The patch is taped intoplace and the polymer is allowed to cure. Next, theamine curable polymer 400 having filler 500 thereinis separately added to the aperture so that it isfilled and then taped thereover. The aperture por-tion of the repair is then separately cured at am-bient temperature.

With regard to the embodiment of Fig. 4,article 1000 is rotated until the cut is located inthe uppermost portion and then filled. The aminecurable polymer 1400 having rubber fillers 1500therein is preferably covered, as by tape, andallowed to cure at ambient temperature.

Considering the embodiment of Fig. 5, it issimilar to Fig. 3 in that the hollow, in the form ofa cavity, is filled in association with a patch.

More specifically, whenever approximately 25 to about50 percent of cords 2140 are severed, broken, orotherwise damaged, the strength of the cords in patch2200 (not shown) is approximately equal to the pre-injury strength of the damaged cords. However,should the number of damaged, severed, or brokencords be approximately 50 percent to 100 percent, the 35 -29- total strength of the cords in the patch is approx-imately equal to at least the total strength of thecords in the article. The repair of an article hav-ing a cavity therein, such as in Fig. 5, generallyproceeds in the same manner as in the embodiment ofFig. 3. That is, article 2000 is buffed or otherwisecleaned such that one or two of the cords areexposed. The patch area located juxtaposition tocavity 2120 is coated with treating agent 2300 as ispatch 2200. Then, an amine curable polymer or pre-polymer is applied to the patch and the patch thenapplied to the article and held in place as by tap-ing. The size of the patch is that as discussedabove. As in the embodiment of Fig. 3, the articleis then rotated until the cavity is in the uppermostposition and then the amine curable polymer havingfiller 2500 therein is applied to the cavity whichhas previously been treated with treating agent 2300.

The cavity portion is then taped and allowed to curewith the patch portion. Alternatively, the patch canbe separately applied and cured as can the aminecurable polymer or prepolymer-filler mixture appliedto the cavity. As noted above, when generally about25 to about 50 percent of the cords are broken ordamaged, the strength of the cords in patch 2200 isapproximately equal to the initial strength of thebroken cords. However, when approximately 50 percentor greater of the cords are broken, the strength ofthe cords of the patch is substantially equal to orgreater than the total strength of cords 2140 inarticle 2000.

The end result is a repaired article beingprepared by an easier method and having equivalent orbetter strength and durability than that repairedaccording to heretofore conventional methods that are 5 1'־:• 15 20 25 30 35 ־30־ performed on site. Moreover, the hardness and/ormodulus of the repair is similar to the substrate andthus results in improved performance.

In forming the amine curable polymer system,generally the amine curable polymer or prepolymer ismixed with the polar solvent and then the curingagent is added last. As previously noted, the rubberparticles can be added at any stage. During cure, aneffective and strong bond is formed between the pre-polymer or polymer system with the treated elastomersubstrate and the previously cured rubber particles.Since the present invention relates to an ambienttemperature, repair of large and cumbersome articlessuch as off־the-road tires, and the like, can be madein situ. In other words, the repair can be made atthe job site. The only accessory which may be re-quired is a tire bladder, although a sand bag can beused. In such a situation, the repair can be made atthe local tire repair shop. Since the cure is am-bient, no steam chambers, or other vulcanizable tirerepair equipment are required. This, of course, alsoresults in an energy savings.

It is to be understood that various conven-tional additives in typical amounts can be added tothe amine curing agent and prepolymer system such ascolorants, softeners, fillers, antioxidants, plas-ticizers, and the like.

This aspect of the invention will be betterunderstood by reference to the followingrepresentative examples. 5 10 15 20 25 30 r

Vs

I *r ז ) f &gt; 35 ־31-

EXAMPLE II

An exterior cut in a tire 36.00 x 51 haulertire (OTR, off-the-road) was repaired in the follow-ing manner using the composite type urethane repair.The cut (commonly known as a spot repair) was buffedthoroughly, making sure the injury was free of anyloose rubber particles or cuts or gouges. It wasbuffed to an RMA #3 or #4 buff rating. The cut waswashed thoroughly with acetone on a piece ofRymplecloth. The acetone was allowed to dry com-pletely. The surface was then coated with severalcoats of a 3 percent trichloro-s-triazinetrione inethyl acetate allowing each coat to dry before thenext coat was applied. After the last coat haddried, a composite kit was mixed and poured or placedinto the cut. The composite kit consisted of threecomponents.

COMPONENT C

Treated Rubber(100 gm)

COMPONENT B

Caytur 21(14.3 gm)

COMPONENT A

Adiprene L-42(100 gm)

Flexol 4G0 (10 gm)Acetone (lOgm)

The treated rubber was tread rubber frompassenger and truck tires (both natural and syntheticrubber) that was graded to remove large chunks ofrubber and then washed with acetone (slurried), driedand treated with a dilute solution of trichloro-s-triazinetrione in ethyl acetate (slurried). The rub-ber was separated from the primer and dried overnightat room temperature and then at 100°C for one hour. -32-

The mixing procedure consisted of mixingcomponet C with component A, thoroughly; then mixingcomponent B with the mixture of A and C. The mixedmaterial was then added to the cut by means of aspatula. The surface was taped in order to promotethe ambient cure by containing the acetone. Therepair was allowed to cure for 24 hours at ambienttemperature. After the required time of cure, thetape was removed and the tire was ready for service.

After 973 hours of testing, the repair wasbetter than a control.

EXAMPLE III

A 10.00 x 20 Load Range F, 8־ply, Transport1 Truck tire having a 3/4 ,inch injury in the crownarea and extending into the cord area was repaired asfollows: The injury was buffed to an RMA #3 or H buff rating using a tungsten-carbide tip tool. Theinnerliner was then buffed down to the top body plyin the same manner. The innerliner was buffed outonly as large as the patch to be used. The patch wasused as a template and was also buffed on the side tobe adhered to the tire. All buffed areas were thenwashed thoroughly using acetone on a piece ofRymplecloth. The solvent was allowed to drythoroughly (10-15 minutes). The buffed and cleansurfaces were next treated with two coats of 3 per-cent trichloro-s-triazinetrione in ethyl acetate,allowing the first coat to dry before the second coatwas added. The patch was also coated with two coatsof the 3 percent trichloro-s-triazinetrione. The 30 ־33- was installed first. A standard 50/50 kit wasIt contained the following ingredients: 75 gm. 75 gm. 15 gm. A-Side 15 gm. 36 gm. B-Side patchused.

Adiprene L-42Adiprene L-367Flexol 4GOAcetone

Caytur 21

The two sides, A and B, were thoroughlymixed and then allowed to thicken to a nearlynon-flowable state. At this point, the material wascoated onto the patch (Rocson Patch ROCO 8-4) andonto the innerliner area. The patch was put in placeand held in position with tape. A tube was insertedand inflated to hold the patch in position and toapply pressure on it. The tire was then rotated sothat the injury was located at the top. A compositesystem was mixed. It had the following formulation:

Adiprene L-42 25 gm. Acetone 2.5 gm. 4 GO 2. gm. Ground Scrap Rubber Treated 25 gm Caytur 21 3.6 gm. *

The ground scrap rubber was graded to a No.20 mesh, slurried with acetone, drained and dried.

It was then treated briefly with a 0.25 percent tri-choro-s-triazinetrione in ethyl acetate solution,drained, and dried at 100°C for 10 minutes. It wasstored in a jar and kept capped until used.

The composite formulation was mixedthoroughly and placed into the injured area. Therepaired area was covered with tape and allowed to 5 10 15 20 25 30 35 -34- cure for 24 hours at room temperature. After the 24hour cure period, the tape and tube were removed fromthe tire. Both the patch and spot looked excellent.The tire was tested on a crown break test (a stepwiseincrease in speed under a loaded condition). Thetire ran 1,245 miles. It was removed at a durationof 3 hours at 70 mph. This was considered an excel-lent result for this type of severe test on arepaired tire.

GUM RUBBER

The instant invention is also useful inrepairing reinforced elastomer articles with gum rub־־ber wherein damage has been manifested as achunk-out, leaving a hollow area in the article. Theinjury may extend completely through the article oronly through a portion thereof, but reinforcement,that is cords, belts, or the like, contained in thearticle will have been partially or completelysevered thereby providing a weakened area.

This aspect of the invention can be seenwith reference to the figures. As is readilyapparent, the salient features in each are identicalexcept that the hollow 4120 in Fig. 7 does not extendcompletely through the substrate. For the sake ofsimplicity, all references to Figure 6 shall haveequal reference to Figure 7, except for thedimensions of the hollow, as above. Referring thento Fig. 6, the article is generally indicated by thenumber 410, comprising a substrate 413 havingembedded therein a plurality of reinforcement cordsor belts 414, and a hollow 412. 35 -35-

The substrate 413 can be any conventionalelastomer or rubber known to those skilled in the artand having unsaturated groups therein. For example,it can be made from various dienes, vinyl substitutedaromatic compounds, etc. as set forth above which ishereby fully incorporated by reference as is the pre-paration of such elastomers. . The next step in utilizing this portion ofthe packing of a quantity of uncured gum rubber 422into the hollow 412, most preferably from the outersurface defined as that surface of the substrateopposite where a patch 420 is later positioned. Thegum rubber is then cured in placed using conventionalmeans such as a pair of heated plates, otherwiseknown as spotters, one applied to the outer surface424 and one to the inner surface of the substrate.

The types of gum rubber which can be usedare well known in the art, being generally composedof compounds of natural rubber or rubber blends andtypically having other compounding ingredients suchas sulfur, carbon black, accelerators, and the like. A variety of all purpose repair gums, readily avail-able commercially, can be used. Alternatively, oneskilled in the art can readily devise a suitable gumrubber recipe without undue experimentation.·

Once the gum rubber has been cured in place,the innerside is buffed around the now filled aper-ture and a treating agent 416 applied both to thesubstrate and the cured gum rubber surfaces, whichshould of course be first cleaned as outlined above.An amine curable polymer 418 is then applied to theinner surface after having been first allowed tothicken or partially "set up", resulting in anincrease in viscosity to several thousand centipoise. -36-

This results in a toothpaste-like consistency help-ing hold the polymer in place while the patch isapplied.

The patch, after being buffed and havingreceived a coating of treating agent 416, is thenapplied to the polymer surface. It is thereaftertemporarily taped into place and held by some form ofapplied pressure, such as, in the case of a tire, acuring tube or a plurality of sand bags. The repairis allowed to set in this position for approximately424 hours. The end result is a repaired article hav-ing much better strength and durability than onerepaired according to heretofore known methods.

In the embodiment of Fig. 7, the hollow 4120in the article 4100 is in the form of a cavitywherein some cords 4140 of the reinforced articlehave been damaged, severed, or the like. Usually atleast 25 percent of the cords have been broken ordamaged and the article is repaired utilizing apatch. Either the cavity can be filled or the patchapplied first. In repair of cavity 4120, the surfaceis first cleaned. The cavity is then filled with agum rubber 4220, generally to the level of the sub-strate 4130. Naturally, in this operation, the cav״ity is located in the upper most vertical position ofthe article.

The area to be patched is prepared as beforeby cleaning and even buffing, in which, in eitherembodiment, the tie-gum layer or the cord ply layercan be exposed. Treating layer 4160 is applied tothe patch area of substrate 4130 as well as to oneside of the patch 4200. The amine curable polymer ofprepolymer 4180 is then applied to the treated sideof the patch, with the patch in turn being applied tothe treated portion of substrate 4130. The ends of 5 10 15 20 25 30 '%י' ־/_־ ·if

<img img-format="tif" img-content="drawing" file="IL71284AD00381.tif" id="idf0006" />

Wt S' i 1 35 ־37- the patch can be taped to the substrate or held inplace with a curing tube located inside the tire.

The number of cords in the patch is as previously setforth. That is, if less than 25 percent of the cordsare damaged, the use of the patch having cords there-in is optional in that a solid rubber patch providesadequate reinforcement. When approximately 25 to 50percent of the cords are damaged, severed or thelike, the strength of the cords in the patch is atleast equal to the strength of such cords beforebeing damaged. When approximately 50 percent or moreof the cords are damaged, the strength of the cordsand the patch is equal to the strength of the totalnumber of cords in the substrate before any injurythereto. The repair is then cured at ambient temper-ature.

The type of suitable treating agents used,and typical amounts thereof are in accordance as setforth above and hereby fully incorporated. Simi-larly, the type of various amine curable polymers orprepolymers, typical urethane polymers or prepoly-mers, amine curing agents, and the equivalent weightof amine curing agents is also set forth above. Theabove portion of the specification also sets forththe blending of the curing agents, i.e., polar sol-vents as well as the amount of solvent. Thus, oncethe bottom of the gum rubber is treated with thetreating agent, the amine curable polymer orprepolymer is blended with a suitable amount of aminecuring agent and a polar solvent is applied. Thetreating agent is also applied to the patch which isapplied to the amine curable polymer layer. Theentire patch amine curable polymer layer is thencured at ambient temperature. 35

Considering patch 420, it can generally beof any desired size so long as it is greater in sur-face area than the hollow it seals. Typically, thesurface area of the patch is at least twice as greatas the hollow. Generally, an appropriate patch sizewill be known to one skilled in the art of patch con-struction and/or patch application. The patch ismade of rubber and is generally fully cured. Al-though cured natural rubber or a composition con-taining at least 80% by weight of natural rubber isoften preferred, any conventional type of cured rub-ber compound can be utilized. Thus, the patch can bemade from a conjugated diene having from 4 to 12 car-bon atoms, copolymers made from conjugated dieneshaving from 4 to 12 carbon atoms with vinyl substi-tuted aromatics having from 8 to 15 carbon atoms, forexample styrene-butadiene rubber, and the like. Inessence, the patch can be made from the same type ofrubber as the substrate. Often, the patch will havea cushioned layer thereon to alleviate stressesformed between the tire carcass and the patch.

Because the patch must provide structuralreinforcement to the repaired article, it generallyutilizes cords in the same manner as the article.Although the number of cords can range from a smallnumber to a very large number, as above, they gen-erally equal in strength the cords damaged in thesubstrate. Such a provision provides an adequatereinforcement for the article. The cords can be madeof polyester, nylon, steel, rayon, or the like withnylon being preferred. It has been found thataccording to the present invention, large hollows canbe repaired up to approximately 8 inches in diameter. 10 15 20 25 S' 30 35 -39-

In preparing the amine curable polymer sys-tem, generally the amine curable polymer or pre-polymer is mixed with the polar solvent and there-after the curing agent. During cure, an effectiveand strong bond is formed between the prepolymer orpolymer system and the treated elastomer substrate.Since the present invention relates to an ambienttemperature cure, repair of large and cumbersomearticles such as off the road tires, conveyor belts,and the like can be made in situ. In other words,the repair can be made at the job site. The onlyaccessory which may be required is some means forholding the patch in place while the polymer cures.

As above, this can be an inflatable bladder or one ormore sand bags. Since the cure is ambient, no steamchambers or other vulcanizing tire repair equipmentis required other than that necessary to cure the gumrubber. This of course also results in energy sav-ings.

It is to be understood that various conven-tional additives in typical amounts can be added tothe ·amine curing agent and prepolymer system such ascolorants, softeners, fillers, antioxidants, plast.i-cizers, and the like.

This aspect of the invention will be betterunderstood by reference to the followingrepresentative examples: EXAMPLE IV - Sidewall Section Repair

An 11.00 R 24.5 steel radial truck tire con-taining two injuries in the sidewall was repaired asfollows: injury number 1 was 3/8 inches wide by 4 inches long after buffing with a tungsten-carbide tiptool. The buffed area was cleaned with a rubber sol- -40- vent. The innerliner was then marked with an outlineof the patch and likewise buffed with the tungsten-carbide tool. Only the innerliner was buffed. Thebuffed areas were cleaned again with a rubber solventand allowed to dry thoroughly. A coat of Firestone'sSup-R-Tac rubber cement was applied to the buffedareas. It also was allowed to dry thoroughly. Anuncured patch was stitched into place (Rocson 5314-6,Rocson, Inc., Copley, Ohio). Uncured all-purpose gumrubber (Roscon regular cure AP repair gum) was thenstitched into the external injury. The repair wascured in a Vulcan split-rim mold.

Injury number 2 was 3/8 inch wide by 3 1/2inches long after buffing with a tungsten-carbide tiptool. The cut was cleaned thoroughly with a rubbersolvent and allowed to dry. A cover patch was ·cemen-ted and stitched to the innerliner in order to holdthe gum rubber in the external injury. The coverpatch, made from the all purpose gum rubber, wasabout 1/2 inch larger in all directions than the in-jury and about 1/8 inch thick. One coat of Fire-stone's Sup-R-Tac rubber cement was applied to theinjured area and allowed to dry. Uncured all-purposegum rubber (Roscon regular cure AP repair gum) wasstitched into the external injury and cured in aVulcan split-rim mold. The reinforced patch was theninstalled as follows: the innerliner was buffed tothe patch size, making sure to remove the cover stripadded earlier. The patch was also buffed. Thebuffed areas, patch and innerliner, were cleaned withacetone on a piece of Rymplecloth and allowed to dry.

Two coats of a 3 percent trichloro-s-triazinetrionein ethyle acetate were applied to the buffed inner- -41- liner and patch. After the primer system had dried,a standard 50/50 kit was mixed. The composition wasas follows:

Adiprene L 42 150 grm. Adiprene L 367 150 grm. Flexol 4GO 30 grm. Acetone 30 grm. A־Side Caytur 21 72 grm. Black MB* 2 grm. B-Side * 15 parts of carbon black in Dioctylphthalate base.

The thoroughly mixed material was allowed tothicken to a nearly non-pourable stage and thenapplied to the patch and innerliner area. The patchwas placed in position and held there with tape. Atube was then inserted and inflated to hold the patchin position and to apply pressure on it. The patchwas cured for 24 hours at room temperature. Afterthe 24 hour cure period, the tape and tube wereremoved. The repair had good appearance. The tirewas tested on a radial truck tire endurance testknown as a C-2 test, which loads the tire 40 percentover the rated load and runs 22 mph until failure.

The tire failed at 4455 miles yielding very good per-formance for a repaired tire. As a comparison, newtires are expected to run 7000 miles and a used tireover 3000 miles. The failure occured on the oppositeside of the tire, away from the two repairs. Theuncured patch had fallen off the innerliner. ־42- κ

V t EXAMPLE V - Full Section (Crown) Repair

An 18.00 x 25,28 ply rated, off-the-road(OTR) tire containing a 1 x 2 1/2 inch injury com-pletely through the tire in the crown area wasrepaired as follows: the injury was buffed clean toan RMA #3 or #4 buff rating using a tungsten carbidetool. The innerliner was lightly buffed 1/2 to 1inches wider than the injury. The buffed areas werecleaned with a rubber solvent and allowed to dry. Acoat of Firestone's Sup-R-Tac rubber cement wasapplied to the buffed surface and allowed to dry. Acover patch made from uncured all purpose gum rubber(1/8 inch thick Crocson Patch Company, Copley, Ohio)was stitched onto the innerliner. The external in-jury was then filled with the same rubber bystitching small amounts in at a time. The spot wasthen cured using a Vulcan mold. After the tire hadcooled, the patch was positioned over the internalinjury and outlined. The temporary cover patch, in-nerliner, tie-gum and two body plys were removed fromthe tire, tapering the edges of the innerliner sothat the patch made a close fit with it. The patch,a Roco No. 4, was also buffed. All buffed areas werecleaned using acetone and Rymplecloth. After thesurface had dried, several coats of a 3 percent tri-chloro-s-triazinetrione in ethylacetate were appliedto the innerliner area and the patch. The primer wasallowed to dry thoroughly. A standard 50/50 kitdescribed in Example IV was mixed thoroughly andallowed to thicken nearly to a non-pourable stage.

The material was then applied to the patch and theinnerliner areas. The patch was installed and tapedin place. A tube was inflated behind the patch tohold the patch in position and to apply pressure to si*

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S*J f' 30 35 ' « t ♦ t -43- it. The patch was cured 24 hours at room temperatureafter which teh tube and tape were removed. The re-pair looked excellent. The tire was recapped andsent back into service. The tire has not beenreturned after seven months, indicating that no fail-ure has occured. EXAMPLE VI - Reinforce (Crown) Repair A 33.5 x 33,44 ply rated, OTR tire requiringa reinforce patch was repaired as follows: theweaken area of the tire was located on teh insdie ofthe tire and marked. A template of the size of thepatch to be added was centered over the injured areaand outlined. The area was buffed with a tungstencarbide tool down to the top or first body ply(removed innerliner and tie-gum layers). The buffedarea was washed thoroughly with acetone on a piece ofRymplecloth. Both the patch and innerliner were thentreated with several coats of a 3 percent tri-chloro-s־triazinetrione in ethyl acetate. The primerwas allowed to dry thoroughly. A standard 50/50 kitdescribed in Example III was mixed thoroughly andallowed to thicken nearly to a non-pourable stage.

The material was then applied to the patch and inner-liner areas. The patch was installed and taped inplace. A tube was inflated behind the patch to holdthe patch in position and to apply pressure to it.

The patch was cured 24 hours at room temperature.After the 24 hours had elapsed, the tube and tapewere removed. The repair looked very good and wastightly bound to the innerliner. The tire was re-capped, the external spot being repaired at the timeof recapping. The tire was sent back into service.The tire has not been returned after seven months,indicating continued use. 5 10 15 20 25 30 35

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f &lt; c h.' # * v“ t♦ -44-

Generally, any rubber article having a hoi-low therein can usually be repaired by the presentinvention. Specific examples include conveyor beltsand tires, especially off the road tires such asthose utilized for front-end loaders, mining equip-5 ment machines and the like.

While various preferred embodiments of thepresent invention, as well as the best mode thereofhave been described in detail, in accordance with thePatent Statutes, it is to be understood that the in-10 vention is measured by the attached claims. -h,

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i I 15 20 25 ־!ד 30 35