Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
2001-11-16
2003-01-28
Niland, Patrick D. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S493000, C524S506000, C524S507000, C524S508000, C524S509000, C524S519000
Reexamination Certificate
active
06512039
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a solvent or aqueous adhesive composition for bonding a peroxide-cured elastomer to a substrate where the bonding takes place during the vulcanization of the elastomer. More specifically, the present invention relates to aqueous or solvent-based adhesive composition comprising a maleimide curing agent, film former, acid scavenger and a silicate.
BACKGROUND OF THE INVENTION
In applications involving the bonding of elastomeric substrates to surfaces such as metal surfaces, an adhesive must exhibit an affinity for the elastomeric substrate as well as possess the ability to withstand degradation by high temperature fluids or corrosive materials.
Various solvent-based and aqueous-based adhesives for bonding elastomeric materials have been developed in a continuing effort to obtain the ultimate aqueous adhesive for bonding elastomeric substrates. For example, U.S. Pat. No. 4,167,500 describes an aqueous adhesive composition that contains a water dispersible novolak phenolic resin, a methylene donor such as an acetal homopolymer or acetal copolymer, and water. The phenolic resins described are primarily derived from resorcinol and alkylphenols such as p-nonylphenol although various other polyhydroxy phenols are mentioned, such as phloroglucinol and pyrogallol.
U.S. Pat. No. 4,483,962 describes a terpolymer latex of an emulsion-polymerized terpolymer of at least one 2,3-dihalo-1,3-butadiene monomer, at least one monoalkenyl aromatic alkylhalide monomer, and at least one olefinically unsaturated monomer. The terpolymer latex utilizes a surfactant such as an anionic surfactant or a mixture of an anionic surfactant and a non-anionic surfactant.
U.S. Pat. No. 4,988,753 describes an aqueous bonding composition containing (1) a mixture of chlorosulfonated polyethylene and vinyl chloride/vinylidene chloride/acrylic acid copolymer, (2) an organic polynitroso compound, and (3) a coreactive compound selected from diallyl acrylamide and phenylene bis-maleic acid imide. The adhesive composition may also optionally contain adhesion promoters, fillers, and processing aids.
U.S. Pat. No. 5,036,122 describes an aqueous adhesive composition which is a blend of a latex of a polymerized conjugated diene, a poly-C-nitroso compound, and a maleimide compound, e.g., a bismaleimide.
For example, U.S. Pat. No. 3,258,388, discusses the incorporation of poly-C-nitroso aromatic compounds into conventional rubber-to-metal adhesives to improve bonding. The conventional adhesives into which these compounds may be incorporated include compositions containing thermo-setting condensation polymers; polymers and copolymers of polar, ethylenically unsaturated materials; halogenated rubbers; and polyisocyanates.
U.S. Pat. No. 3,282,883 discloses an adhesive composition that includes dinitrosobenzene, chlorosulfonated polyethylene, and an orthoalkoxy aryl diisocyanate. This composition is produced by dissolving and/or dispersing the components in an organic solvent. The composition is for bonding natural and synthetic rubbers, such as ethylene-propylene-nonconjugated diene terpolymers, neoprene, styrene-butadiene rubber, butyl rubber, halobutyl rubber, butadiene-acrylonitrile, halosulfonated polyethylene rubber, polyurethane rubber, and polyacrylate rubber. The rubbers may be bonded to themselves or to other substrates, such as metals.
U.S. Pat. No. 3,824,217 discloses combining an oxime compound with an excess of a polyisocyanate compound, so that all oxime groups are reacted with isocyanate. The resulting compound may be used in compositions for bonding rubbers to primed metal substrates.
U.S. Pat. No. 3,830,784 discloses an adhesive composition that includes a poly-C-nitroso aromatic compound, a polyisocyanate that is reactive at room temperature or greater, and an acidic halogen-containing polymer. The composition is produced by dissolving the acidic halogen-containing polymer and the aromatic polyisocyanate in an organic solvent, and the poly-C-nitroso aromatic compound is dispersed in the resulting solution. The resultant composition is shelf-stable and forms a strong adhesive bond between the substrate and the elastomer during vulcanization thereof.
U.S. Pat. No. 4,581,092 discloses a cold-vulcanizable adhesive system for bonding vulcanized rubbers. The system is of particular use in creating durable seams between rubber strips or sheets. The adhesive compositions include butyl rubber, a polyisocyanate compound, and at least one of a nitroso compound and an oxime compound, with the oxime compound requiring the additional presence of an oxidizing agent. DE 22 28 544 describes a binder for the production of composites by vulcanization of rubber mixtures onto metals or other stable substrates. In addition to chlorosulfonated polyethylene, chlorinated rubber, polyisocyanates and a phenolic resin, this binder also contains dinitrosobenzene in the form of a suspension in solvents.
The prior art adhesive compositions for bonding sulfur-cured vulcanizable elastomers where bonding takes place during vulcanization suggest as an essential component one or more of a dinitroso compound, an oxime compound, a polyisocyanate compound, and an oxidizing agent. The toxicity of these ingredients poses handling and safety problems. When bonding peroxide-cured elastomers, it has been found that dinitroso compounds (e.g. poly-C nitroso), particularly poly(p-dinitrosobenzene, (poly DNB) or p-dinitrosobenzene (DNB) sublime at temperatures encountered in vulcanizing the elastomers.
U.S. Pat. No. 6,132,870 discloses a reinforced composite including an elastomer of low unsaturation, a reinforcing fiber, an adhesive composition that bonds the elastomer to the coated reinforcing fiber including a halogenated polyolefin, a nitroso compound, a maleimide, the maleimide present in an amount of at least 50% by weight of the halogenated polyolefin.
Thus, there remains a need for new adhesive compositions that are simple, safe, stable, and effective for the bonding of peroxide-cured elastomers to substrates, particularly metal and glass substrates. Effective adhesives will have high rubber retention under conventional peel tests, and good pre-bake resistance.
SUMMARY OF THE INVENTION
The present invention is an aqueous adhesive composition that is poor in bonding sulfur-cured elastomers, but is especially advantageous for bonding peroxide-cured elastomers, in that the bonded peroxide-cured elastomer using the adhesives according to the present invention exhibits durable, rubber-tearing bonds between the vulcanized rubber and substrates. Durability means the adhesive produces a high degree of rubber retention in bond failure, high peel strength, and an environmentally resistant adhesive bond. The peroxide-bonding elastomer according to the invention resides in an adhesive, substantially absent a nitrso compound, and consisting essentially of a diluent, a film forming polymer, a maleimide compound, a optional precipitated silicate, and an optional metal scavenger.
The present invention is further directed to a method of bonding a peroxide-curable elastomer to a metallic surface comprising coating the substrate with the above adhesive composition, drying the adhesive composition, applying a peroxide-cured elastomer to the adhesive composition coating, and curing the assembly with heat and/or pressure.
The present invention is also directed to adhesive composition, and composite article of manufacture comprising a peroxide-cured elastomer bonded to a substrate with the adhesive composition.
DESCRIPTION OF THE PREFERED EMBODIMENTS
The peroxide-curable rubber substrates bonded by the invention are the conventional vulcanizable rubbers that must contain a peroxide as the curing agent. Although in a few special instances, both a sulfur-curing component and a peroxide curing component can both be present, there must be a peroxide curing agent present in the elastomers bonded according to the invention. The adhesive compositions of the present invention have been found to have surprising strong bonding cha
Dearth Miles B.
Lord Corporation
Niland Patrick D.
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