Organic compounds -- part of the class 532-570 series – Organic compounds – Cyanate esters
Reexamination Certificate
2001-01-31
2002-10-01
Geist, Gary (Department: 1623)
Organic compounds -- part of the class 532-570 series
Organic compounds
Cyanate esters
C528S097000, C528S099000, C528S119000, C528S120000, C528S211000, C528S271000, C528S363000, C528S422000
Reexamination Certificate
active
06458993
ABSTRACT:
This invention relates to novel aromatic cyanate ester compounds having at least two rings linked by an unsaturated group containing member, prepolymers and compositions thereof, and processes for making the same. The compounds can be employed in adhesives, composites, laminates and molding compositions. The compounds and compositions thereof have particular utility for use in molded articles requiring flame-resistance, low peak heat release rates, such as interiors for aircraft and other transportation vehicles, and low total heat release rates without generating significant amounts of smoke.
BACKGROUND OF THE INVENTION
Phenolic cyanate esters have been described extensively in the art. U.S. Pat. No. 5,360,887, for example, describes a flame resistant thermosetting composition containing a monocyanate ester and a dicyanate ester of the formula
wherein the bridging member A can be a direct bond, methylene or mono- or disubstituted methylene with alkyl and/or an aryl group, or a five or six membered cycolalkylene, sulfonyl, thio, oxyl, carbonyl or xylylene. The teachings in U.S. Pat. No. 5,109,078 represent one of many teachings of cyanato-group containing phenolic resins of the formula:
wherein X is a divalent organic radical, preferably a radical selected from the group consisting of: —CH2—, —CO—, —SO2—, (S)y,
There is a need in the transportation industry, particularly for aircraft interiors, for molded polymeric components that exhibit very low peak heat release rates. Many cyanate esters exhibit good dielectric properties, water absorption and flame retardancy. However, all of the currently known cyanate esters fail to have heat release rates below 35 Joule/g-° K, more preferably below 10 Joule/g-° K. Low peak heat release rates can be attained using other high performance polymers such as polyphenylsulfone, polyamineimides, polybenzoimadazoles and polybenzoxazoles. All of the currently available polymers having relatively low peak heat release rates suffer from one or more disadvantages such as high cost of manufacture or challenging processing requirements. The present invention produces molded articles having the desired low peak heat release rate using cyanate ester compounds and compositions thereof.
SUMMARY OF THE INVENTION
The present invention relates, in a first aspect, to a compound represented by formula (I):
wherein
Z is C
1
-C
4
alkylene group or a five or six membered cycolalkylene;
R
1
, R
5
, R
6
and R
10
, independently of one another, are unsubstituted or halogen- or C
1
-C
3
alkyl-substituted C
1
-C
4
alkyl that can be saturated or unsaturated, halogen, H, OCN, OH, C
1
-C
4
alkoxy, alkythio, mercaptan, nitro, —OCOR(C
1
-C
3
alkyl), —NCOR(C
1
-C
3
alkyl), —COR, —NO
2
, —NR′R″, wherein R, R′ and R″ are H or C
1
-C
3
alkyl;
R
2
, R
4
, R
7
and R
9
, independently of one another, are C
1
-C
4
alkyl, halogen, H, OCN, or OH, C
1
-C
4
alkoxy, alkythio, mercaptan, nitro, —OCOR(C
1
-C
3
alkyl), —NCOR(C
1
-C
3
alkyl), —COR, —NO
2
, —NR′R″, wherein R, R′ and R″ are H or C
1
-C
3
alkyl;
R
3
and R
8
, independently of one another, are C
1
-C
4
alkyl, halogen H, OCN or OH, C
1
-C
4
alkoxy, alkythio, mercaptan, nitro, —OCOR(C
1
-C
3
alkyl), —NCOR(C
1
-C
3
alkyl), —COR, —NO
2
, —NR′R″, wherein R, R′ and R″ are H or C
1
-C
3
alkyl; or
R
1
and R
2
together and/or R
2
and R
3
together, and/or R
9
and R
10
together, and/or R
8
and R
9
together, independently of one another, form one or more aromatic rings or five or six membered cycloalkylene that can each be substituted with C
1
-C
4
alkyl or halogen;
R
11
and R
12
, independently of one another are H, phenyl, C
1
-C
4
alkyl or halogen;
wherein at least one of aromatic rings A and B or at least one of the aromatic rings or the five or six membered ring formed by R
1
and R
2
and/or R
2
and R
3
and/or R
9
and R
10
and/or R
8
and R
9
is substituted by at least one cyanato group.
A preferred compound is characterized according to formula (I) above wherein Z is C
1
-C
2
alkylene; R
1
and R
10
are H; R
2
, R
4
, R
7
and R
9
, independently of one another, are halogen, H, OCN, or OH; R
3
, R
5
, R
6
and R
8
, independently of one another, are H, OCN or OH; R
11
, and R
12
are halogen; and at least one of aromatic rings A and B is substituted by at least one cyanato group.
A particularly preferred compound is characterized according to formula (I) above wherein Z is C
1
-C
2
alkylene; R
1
, R
5
, R
6
and R
10
are H; R
2
, R
4
, R
7
and R
9
, independently of one another, are halogen or H; R
11
and R
12
are halogen; and R
3
and R
8
are OCN. More preferably, R
11
and R
12
are chlorine or bromine. Most preferably, R
11
and R
12
are chlorine.
A further preferred compound is characterized according to formula (I) above wherein Z is methylene; R
1
, R
2
, R
4
, R
5
, R
6
, R
7
, R
9
and R
10
are H; R
3
and R
8
are OCN; and R
11
and R
12
are chlorine.
The present invention relates, in a second aspect, to a prepolymer mixture containing a cyclotrimerized reaction product of cyanate esters wherein at least one of said cyanate esters is the compound according to formula (I) above. Preferably, up to about 60% of the cyanato groups in the overall mixture are trimerized as a part of the cyclotrimerized reaction product. More particularly, about 10 to 40%, preferably, about 20 to 30% of the cyanato groups in the overall composition are trimerized as a part of the cyclotrimerized reaction product.
The present invention relates, in a further aspect, to a composition containing a) a compound according to formula (I) above or a cyclotrimerized reaction product thereof and b) a solvent or c) a monocyanate ester different from component a). Preferably, component c) is at least one halogen-substituted or unsubstituted aromatic monocyanate ester selected from naphthol cyanate, phenylphenol, chloronaphthol cyanate, chlorophenylphenol, dichloronaphthol cyanate, dichlorophenylphenol, bromonaphthol cyanate, bromophenylphenol, dibromonaphthol cyanate, dibromophenylphenol and mixtures thereof.
The present invention, in a further aspect, relates to a composition containing a) a compound according to formula (I) above or a cyclotrimerized reaction product thereof and b) a thermally curable monomer or oligomer other than a cyanate ester. Preferably, the thermally curable or reactive monomer or oligomer is selected from an epoxy, bismaleimide, polyimide, polyester, epoxy-acrylate, urethane-acrylate, diallyl phthalate, spiropyrane, phenolic resin and mixtures thereof.
The present invention, in a further aspect, relates to a composition containing a) at least 15%, preferably about 50 to 100%, more preferably about 60 to 99%, by weight of the overall composition of a compound according to formula (I) or a cyclotrimerized reaction product thereof with the balance of the composition optionally being at least one of components b) to g): b) solvent; c) additional mono- and polycyanato-group containing compounds; d) thermal curable or reactive compounds other than cyanate esters; e) cure accelerators; f) tougheners; and g) customary additives and fillers.
The present relates, in a still further aspect, to a process for preparing a cyanate ester comprising:
a) reacting at least one aromatic compound with a halogen substituted aldehyde, hemiacetal or acetal, in the presence of an acid to produce an aromatic compound having at least two rings according to formula (A)
wherein
Z is C
1
-C
4
alkylene group or a five or six membered cycolalkylene;
R
1
, R
5
, R
6
and R
10
, independently of one another, are unsubstituted or halogen- or C
1
-C
3
alkyl-substituted C
1
-C
4
alkyl that can be saturated or unsaturated, halogen, H, OCN, OH, C
1
-C
4
alkoxy, alkythio, mercaptan, nitro, —OCOR(C
1
-C
3
alkyl), —NCOR(C
1
-C
3
alkyl), —COR, —NO
2
, —NR′R″, wherein R, R′ and R″ are H or C
1
-C
3
alkyl;
R
2
, R
4
, R
7
and R
9
, independently of one another, are C
1
-C
4
alkyl, halogen, H, OCN, or OH, C
1
-C
4
alkoxy, alkythio, mercapta
Amone Michael James
Lin Bor-Sheng
Geist Gary
Neuman Kristin H.
Oh Taylor V
Shalek James H.
Vantico Inc.
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