Coating processes – With post-treatment of coating or coating material – Heating or drying
Reexamination Certificate
1999-04-05
2001-04-17
Cameron, Erma (Department: 1762)
Coating processes
With post-treatment of coating or coating material
Heating or drying
C428S447000, C556S415000, C560S301000
Reexamination Certificate
active
06217943
ABSTRACT:
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
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
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, acryloyl, 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 reactions.
In yet a further aspect, a method of coupling a cyanate ester resin to a substrate by means of the aromatic cyanate ester silane coupling agent of the invention is described.
In a still further aspect, an adhesive film which optionally can include conductive particles, and which includes the curable composition of matter of the present invention comprises a cyanate ester resin and an aromatic cyanate ester coupling agent as well as a thermoplastic polymer.
In this application:
“cyanate ester” means a derivative of cyanic acid (HOCN) in which the H is replaced by an organic group, preferably an aromatic group;
“silane” means a silicon containing compound having at least one single bond between the silicon atom and a carbon atom of an organic group; and
“hydrolyzable silyl group” means a silicon atom and its substituents, whereby at least one and up to three of the substituents may be cleaved by water or alcohol to produce one to three OH groups attached to the silicon.
The novel coupling agents of the present invention provide a means by which cyanate ester resins can have improved adhesion to inorganic or organic surfaces. The resulting curable compositions can have utility in reinforced composites and in a variety of adhesive and coating applications, such as circuit board laminates, conductive adhesives, structural adhesives, structural composites, protective coatings, aerospace structures, filled molded articles, and semiconductor encapsulants. In these applications adhesion between the cyanate ester resin and an substrate is of critical importance.
It has now been discovered that silane coupling agents incorporating aromatic cyanate ester groups and hydrolyzable silyl groups can be prepared and that they improve the adhesion of cyanate ester resins to substrates.
REFERENCES:
patent: 3190762 (1965-06-01), Carlson et al.
patent: 4797454 (1989-01-01), Ryang
patent: 4845257 (1989-07-01), Naito et al.
patent: 4983644 (1991-01-01), Mukai et al.
patent: 5143785 (1992-09-01), Pujoi et al.
patent: 5210247 (1993-05-01), Haberle et al.
patent: 5214176 (1993-05-01), Soula et al.
patent: 5215860 (1993-06-01), McCormick et al.
patent: 5260398 (1993-11-01), Liao et al.
patent: 5330684 (1994-07-01), Emori et al.
patent: 6005047 (1999-12-01), Shaffer et al.
patent: 7-179839 (1995-07-01), None
patent: WO 93/17860 (1993-09-01), None
“Silane Coupling Agents”(1982), published by Plenum (NY), pp. 1-28.
Fyfe et al.,Journal of Polymer Science: Part A; Polymer Chemistry, vol. 32, 1994, pp. 2203-2221.
Patent Abstracts of Japan, vol. 17, no. 420 ( C-1093) [6049], 5 Aug. 1993 & JP,A,05 086214, abstract.
Patent Abstracts of Japan, vol. 16, no. 513 (E-1283) [5556], 22 Oct. 1992 & JP,A,04 192489, abstract.
Patent Abstracts of Japan, vol. 14, no. 287 (M-988) [4230], 21 Jun. 1990 & JP, A,02 089634, abstract.
Hall Joyce B.
McCormick Fred B.
Vogel Kim M.
Yamaguchi Hiroyaki
3M Innovative Properties Company
Cameron Erma
Dahl Philip Y.
LandOfFree
Aromatic cyanate ester silane coupling agents does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Aromatic cyanate ester silane coupling agents, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Aromatic cyanate ester silane coupling agents will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2520087