Organic compounds -- part of the class 532-570 series – Organic compounds – Silicon containing
Patent
1996-06-05
1999-06-15
Shaver, Paul F.
Organic compounds -- part of the class 532-570 series
Organic compounds
Silicon containing
556417, 560301, C07F 710
Patent
active
059123770
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to novel aromatic cyanate ester silanes which contain aromatic cyanate ester groups and hydrolyzable silyl groups. Curable compositions comprising a cyanate ester resins and the aromatic cyanate ester silane as a coupling agent provide adhesives and protective coatings.
BACKGROUND OF THE INVENTION
Cyanate ester resins have utility in a variety of composite, adhesive, and coating applications, such as circuit board laminates, conductive adhesives, structural adhesives, protective coatings, aerospace structures, filled molded parts, structural composites, and semiconductor encapsulants, where adhesion between the cyanate ester resin and a surface is of critical importance.
Adhesion of polymers to substrates has long been a problem in adhesive and coating chemistry and in making of polymer composites. One solution has been the use of silane coupling agents as described, for example, by Plueddemann in the book "Silane Coupling Agents," published in 1982 by Plenum (New York), pp. 1-28. Typically, silane coupling agents have the structure X--Y--SiZ.sub.3 where X is a functional group capable of interacting, or preferably, reacting, with the polymeric resin, Y is an organic linkage, and at least one Z is a reactive or hydrolyzable group capable of reacting with hydroxyl groups on the surface of the substrate. The X group bonds with the polymer network and the SiZ.sub.3 group bonds to the substrate. This provides a chemical link (covalent bonds) from the polymer to the substrate through the organic group Y and thereby improves the adhesion of the polymer to the substrate. Numerous silane coupling agents have been developed for a variety of polymeric resins, but it is believed a silane coupling agent has never been developed specifically for cyanate ester resins.
Existing silane coupling agents have been used with cyanate ester resins. For example, U.S. Pat. Nos. 5,143,785 and 5,330,684 describe cyanate ester based conductive adhesives which may incorporate silane coupling agents where the X group, shown above, is mercapto, epoxy, acrylyl, or amino. A preferred coupling agent may be 3-glycidoxypropyltrimethoxysilane which was used exclusively in the examples of U.S. Pat. No. 5,143,785. Mercapto, hydroxy, and amino groups are known to react with cyanate esters but may produce undesirable side reactions and thermally or hydrolytically unstable bonds. Additionally, amino groups react too rapidly with cyanate esters to be of practical value and are catalysts for cyanate ester cure which leads to reduced shelf life for the adhesive. The '684 patent requires that an epoxy resin be present in conductive adhesive composition. Numerous patents, see U.S. Pat. No. 4,797,454, for example, have reported that epoxy groups couple with cyanate ester groups by the formation of oxazoline groups. However, recent research results reported by Fyfe and coworkers (Journal of Polymer Science: Part A: Polymer Chemistry, Vol. 32, 1994, pp. 2203-2221) show that the reaction of cyanate esters with epoxy compounds is very complex and does not produce oxazoline structures. These researchers report that the direct reaction of cyanate esters and epoxies provides oxazolidinone structures and that this is a minor reaction pathway. This type of complex and inefficient chemistry is undesirable for a coupling agent.
SUMMARY OF THE INVENTION
Briefly, a composition of matter comprises an aromatic cyanate ester silane comprising at least one aromatic cyanate ester and at least one hydrolyzable silyl groups. When present in admixture with a cyanate ester resin, the aromatic cyanate ester silane is a coupling agent for the resin.
In a further aspect, methods for preparing the composition of the present invention are described. The aromatic cyanate ester silane compounds are novel and are prepared from aromatic hydroxyl compounds which contain at least one olefinic double bond, which preferably is an aliphatic or cycloaliphatic carbon-to-carbon double bond, by a combination of hydrosilation and cyanation
REFERENCES:
patent: 3190762 (1965-06-01), Carlson et al.
patent: 4797454 (1989-01-01), Ryang
patent: 4845257 (1989-07-01), Naito et al.
patent: 5143785 (1992-09-01), Pujol et al.
patent: 5210247 (1993-05-01), Haberle et al.
patent: 5214176 (1993-05-01), Soula et al.
patent: 5260398 (1993-11-01), Liao et al.
patent: 5330684 (1994-07-01), Emori et al.
"Silane Coupling Agents" (1982), publishing by Plenum (NY), pp. 1-28.
Fyfe et al., Journal of Polymer Science: Part A: Polymer Chemistry, vol. 32, 1994, pp. 2203-2221. JP,A,05 086214, abstract. & JP,A,04 192489, abstract. JP,A,02 089634, abstract.
Hall Joyce B.
McCormick Fred B.
Vogel Kim M.
Yamaguchi Hiroyaki
Dahl Philip Y.
Minnesota Mining and Manufacturing Company
Shaver Paul F.
Sherman Lorraine R.
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