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
2001-06-28
2003-09-30
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...
C524S430000, C524S493000, C524S508000, C524S509000, C524S510000, C156S333000, C428S424700
Reexamination Certificate
active
06627691
ABSTRACT:
FIELD OF INVENTION
The present invention relates to a water based dispersed adhesive which contains a phenolic resin, chlorinated natural rubber and unexpectedly has improved pre-baked properties when precipitated silica is utilized.
BACKGROUND OF THE INVENTION
Heretofore, phenolic resin compositions have been utilized for bonding rubber to metal. While solvent based systems have generally had good pre-bake properties, apparently no known aqueous system exists which has good bonding of a rubber such as a nitrile to a metal as well as good pre-bake resistant properties. U.S. Pat. No. 5,093,203 relates to a rubber-metal adhesive system which contains a primer component and an overcoat component. The primer component includes a polychloroprene compound, a phenolic resin, and a metal oxide while the overcoat component preferably contains a nitroso compound, a halogenated polyolefin, and a metal oxide or salt. When applied between a metal surface and a rubber substrate under heat and pressure, the adhesive system provides a flexible rubber-metal bond which will withstand high temperature fluid environments.
U.S. Pat. No. 5,200,455 relates to a aqueous primer composition containing a polyvinyl alcohol-stabilized aqueous phenolic resin dispersion, a latex of a halogenated polyolefin, and a metal oxide. The phenolic resin dispersion is prepared by mixing (a) a pre-formed, solid substantially water-insoluble, phenolic resin; (b) water; (c) an organic coupling solvent; and (d) polyvinyl alcohol, at a temperature and for a period of time sufficient to form a dispersion of said phenolic resin in water. The aqueous primer composition substantially reduces the utilization of organic solvents, is resistant to pre-bake conditions, and provides for a robust adhesive bond which is flexible and resistant to adverse environments.
U.S. Pat. No. 5,354,805 relates to an aqueous adhesive composition for bonding nitrile rubber. The adhesive composition contains a chlorosulfonated polyethylene latex, a polyhydroxy phenolic resin copolymer, and a high molecular weight aldehyde polymer. The adhesive composition exhibits an unusual affinity for nitrile rubber and exhibits excellent adhesive performance as a single-coat formulation. The adhesive composition withstands high temperature bonding conditions and minimizes the utilization of volatile organic solvents.
U.S. Pat. No. 5,496,884 relates to an adhesive composition containing a polyvinyl alcohol-stabilized butadiene polymer latex and a methylene donor compound. The butadiene polymer latex is prepared by an emulsion polymerization in the presence of polyvinyl alcohol. The adhesive composition may also contain other optional ingredients such as a supplemental polymeric film-forming component, a nitroso compound crosslinker, a maleimide compound crosslinker, a vulcanizing agent, and an acid-scavenging compound. The polyvinyl alcohol-stabilized butadiene polymer latex and methylene donor compound combine to provide a tightly crosslinked, robust film which provides for excellent adhesion and environmental resistance.
SUMMARY OF INVENTION
An adhesive for bonding rubber such as acrylonitrile to metal comprises a phenolic resin, chlorinated natural rubber, a reactive filler such as zinc oxide, and the use of a precipitated silica which unexpectedly results in very good pre-baked resistance. Moreover, the adhesive composition is environmentally friendly in that it is water-based.
DETAILED DESCRIPTION OF THE INVENTION
The phenolic resin is desirably a novolac or a resole type which contains methylene bridge and/or alcohol groups. Such resins are known to the art and to the literature with suitable examples set forth in U.S. Pat. Nos. 5,200,455; 5,354,805; and 5,496,884, hereby fully incorporated by reference.
A desired phenolic novolac resin is set forth in U.S. Pat. No. 5,354,805 and is a polyhydroxy phenolic resin copolymer which comprises a phenolic resin prepared from certain multihydroxy aromatic compounds and a formaldehyde source. Specifically, the phenolic resin copolymer of the present invention is prepared by combining a monohydroxy and/or a dihydroxy aromatic compound, as a first phenolic component, with a trihydroxy aromatic compound, as a second phenolic component, and a formaldehyde source under reaction conditions sufficient to create a phenolic resin copolymer.
The monohydroxy, dihydroxy and trihydroxy aromatic compounds of the present invention can be essentially any aromatic compound having one, two and three hydroxy substituents, respectively. The aromatic compound is preferably benzene, and the other non-hydroxy substituents on the benzene ring or other aromatic compound may be hydrogen, alkyl, aryl, alkylaryl, arylalkyl carboxy, alkoxy, amide, imide, halogen or the like. The non-hydroxy substituents are most preferably hydrogen and, if alkyl, are preferably lower alkyls having from 1 to 10 carbon atoms including methyl, ethyl, propyl, amyl, and nonyl. Representative monohydroxy compounds include phenol, p-t-butyl phenol, p-phenylphenol, p-chloro-phenol, p-alkoxyphenol, O-cresol, m-cresol, o-chlorophenol, m-bromo-phenol, 2-ethylphenol, amyl phenol, and nonyl phenol, with phenol, p-t-butyl phenol and nonyl phenol. being preferred. Representative dihydroxy compounds include resorcinol, hydroquinone and catechol with resorcinol being the preferred dihydroxy aromatic compound. The monohydroxy aromatic compound, dihydroxy aromatic compound or combination thereof comprises the first phenolic component and is utilized in the invention in an amount from about 1 to about 97, preferably from about 75 to about 95 percent by weight of the ingredients (excluding solvent) utilized to prepare the phenolic resin copolymer.
Representative trihydroxy compounds include pyrogallol, gallates such as propyl gallate, robinerin, baptigenin and anthragallol, with pyrogallol being the preferred trihydroxy aromatic compound. The trihydroxy aromatic compound comprises the second phenolic component and is utilized in the invention in an amount from about 1 to about 97, preferably from about 2 to about 25 percent by weight of the ingredients (excluding solvent) utilized to prepare the phenolic resin copolymer.
It should be noted that it is believed that the effectiveness of the present phenolic resin copolymer is based on the presence of the trihydroxy aromatic compound (the second phenolic component) in the copolymer, and therefore, the trihydroxy aromatic compound is an essential component of the copolymer. The first phenolic component of the copolymer may be a monohydroxy aromatic compound, a dihydroxy aromatic compound, or a combination thereof. However, the use of at least one dihydroxy aromatic compound in the first phenolic component of the invention has been shown to exhibit exceptional bonding ability (possibly due to the numerous hydroxy groups present in the resulting copolymer), and a dihydroxy aromatic compound is therefore particularly preferred for use in the first phenolic component of the invention.
The present phenolic resin copolymer requires a formaldehyde source in order to react with the multihydroxy aromatic compounds to form a novolak phenolic resin copolymer. The formaldehyde source can essentially be any type of formaldehyde known to react with hydroxy aromatic compounds to form novolak phenolic resins. Typical compounds useful as a formaldehyde source in the present invention include formaldehyde and aqueous solutions of formaldehyde, such as formalin; acetaldehyde; propionaldehyde; isobutyraldehyde; 2-ethylbutyraldehyde; 2-methylpentaldehyde; 2-ethylhexaldehyde; benzaldehyde; as well as compounds which decompose to formaldehyde, such as paraformaldehyde, trioxane, furfural, hexamethylenetetramine; acetals which liberate formaldehyde on heating; and the like. The formaldehyde source is utilized in an amount ranging from about 1 to about 25, preferably from about 5 to about 20 percent by weight of the ingredients utilized to prepare the phenolic resin copolymer. When utilizing an aqueous solution of formaldehyde such as formalin, the percent by
Cowles Rebecca S.
Mowrey Douglas H.
Dearth Miles B.
Lord Corporation
Niland Patrick D.
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