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
1995-12-04
2001-07-31
Reddick, Judy M (Department: 1713)
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...
C523S408000, C524S399000, C524S408000, C524S413000, C524S414000, C524S417000, C524S424000, C524S430000, C524S432000, C524S433000, C524S459000, C524S500000, C524S501000, C524S503000
Reexamination Certificate
active
06268422
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to compositions of matter useful for bonding various substrates such as elastomeric materials. More specifically, the present invention relates to environmentally resistant aqueous adhesive compositions based on polyvinyl alcohol-stablized butadiene polymer latices and methbylene donor compounds.
BACKGROUND OF THE INVENTION
In light of the increasing awareness for environmental protection and workplace safety, a current major thrust of the adhesives industry is to develop an adhesive composition which avoids the use of highly volatile organic solvents which can cause damage to the environment and potentially affect the health of workers exposed to the solvent. It has thus far been relatively difficult to develop an aqueous adhesive which performs at a level equal to traditional solvent-based adhesives. One major problem associated with bonds formed from aqueous adhesives is the relative susceptibility of the bonds to high temperature fluids and corrosive materials. In applications involving the bonding of elastomeric substrates to surfaces such as metal surfaces, an aqueous 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 aqueous 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/vinvlidene 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 polymaleimide compound which is a polymer of a bismaleimide.
Many of the previously developed aqueous adhesive compositions such as those described above do not provide adhesive performance at the same level as traditional solvent-based adhesive compositions. A need currently exists for an aqueous adhesive composition that will exhibit substantial affinity for an elastomeric substrate as well as produce a bond that will withstand harsh environmental conditions such as those caused by high temperature fluids and corrosive materials.
SUMMARY OF THE INVENTION
The present invention is an aqueous adhesive composition that exhibits substantial affinity for an elastomeric substrate and that produces an environmentally resistant adhesive bond. The adhesive composition of the present invention comprises a polyvinyl alcohol-stabilized butadiene polymer latex in combination with a methylene donor compound. The latices utilized in the present invention can be prepared by the emulsion polymerization of butadiene monomers, or a combination of butadiene monomers and additional copolymerizable monomers in the presence of polyvinyl alcohol. More specifically, the latices of the present invention are prepared by initiating and maintaining free radical polymerization of the appropriate monomers in an aqueous suspension of polyvinyl alcohol. A butadiene homopolymer may be prepared by utilizing a butadiene monomer such as 2,3-dichloro-1,3-butadiene, or a copolymer or terpolymer of polybutadiene monomers may be produced by copolymerizing a combination of butadiene monomers or by copolymerizing one or more butadiene monomers with other copolymerizable monomers. Examples of other copolymerizable monomers include &agr;-haloacrylonitrile, acrylic acid, methacrylic acid, and styrene sulfonic acid.
It has presently been discovered that the combination of the methylene donor compound and the polyvinyl alcohol-stabilized butadiene polymer latex results in an adhesive composition which exhibits an unexpected improvement in bonding performance, particularly with respect to resistance to high temperature fluids and corrosive materials. It is believed that the methylene donor compound synergistically reacts with the hydroxyl groups inherent in the polyvinyl alcohol network of the stabilized latex to produce a tightly crosslinked, robust film which provides for excellent adhesion and environmental resistance.
DETAILED DESCRIPTION OF THE INVENTION
The butadiene latices of the present invention can be prepared by polymerizing appropriate monomers in an aqueous solution of polyvinyl alcohol. The butadiene polymer of the present invention can be prepared from butadiene monomers alone or from a combination of butadiene monomers and other copolymerizable monomers described in more detail below. “Butadiene polymer,” therefore, herein refers to butadiene homopolymers, butadiene copolymers, butadiene terpolymers and higher polymers.
The butadiene monomers useful for preparing the butadiene polymer of the latex of the present invention can essentially be any monomer containing conjugated unsaturation. Typical monomers include 2,3-dichloro-1,3-butadiene; 1,3-butadiene; 2,3-dibromo-1,3-butadiene; isoprene; 2,3-dimethylbutadiene; chloroprene; bromoprene; 2,3-dibromo-1,3-butadiene; 1,1,2-trichlorobutadiene; cyanoprene; hexachlorobutadiene and combinations thereof. It is particularly preferred to use 2,3-dichloro-1,3-butadiene as the butadiene monomer of the present invention since butadiene homopolymers derived from 2,3-dichloro-1,3-butadiene or butadiene copolymers wherein a major portion of the polymer contains 2,3-dichloro-1,3-butadiene monomer units have been found to be particularly useful in adhesive applications due to the excellent bonding ability and barrier properties of the 2,3-dichloro-1,3-butadiene-based polymers. “Copolymerizable monomers” herein refers to monomers which are capable of undergoing copolymerization with the butadiene monomers described above. Typical copolymerizable monomers useful in the present invention include &agr;-haloacrylonitriles such as &agr;-bromoacrylonitrile and &agr;-chloroacrylonitrile; &agr;,&bgr;-unsaturated carboxylic acids such as acrylic, methacrylic, 2-ethylacrylic, 2-propylacrylic, 2-butylacrylic and itaconic acids; alkyl-2-haloacrylates such as ethyl-2-chloroacrylate and ethyl-2-bromoacrylate; styrene; styrene sulfonic acid; a-halostyrenes; chlorostyrene; &agr;-methylstyrene; &agr;-bromovinylketone; vinylidene chloride; vinyl toluenes; vinylnaphthalenes; vinyl ethers, esters, and ketones such as methyl vinyl ether, vinyl acetate, and methyl vinyl ketone; esters, amides, and nitriles of acrylic and methacrylic acids such as ethyl acrylate, methyl methacrylate, glycidyl acrylate, methacrylamide, and acrylonitrile; and combinations of such monomers.
The copolymerizable monomers, if utilized, are preferably &agr;-haloacrylonitrile and/or &agr;,&bgr;-unsaturated carboxylic acid monomers. The copolymerizable monomers are utilized in an amount ranging from about 0.1 to 30, percent by weight of the total monomers utilized to form the butadiene polymer.
Two butadiene polymers which have been found to be particularly useful in adhesive applications
Kucera Helmut W.
Mowrey Douglas H.
Warren Patrick A.
Weih Mark A.
Dearth Miles B.
Lord Corporation
Reddick Judy M
Rupert Wayne W.
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