Halogen-free benzoxazine based curable compositions for high TG applications
The present invention provides a halogen-free curable composition including a benzoxazine monomer, at least one epoxy resin, a catalyst, a toughening agent and a solvent. The halogen-free curable composition is especially suited for use in automobile and aerospace applications since the composition, upon curing, produces a composite having a high glass transition temperature.
1. A halogen-free curable composition comprising:
(a) a benzoxazine monomer of the formula (I)
wherein each R is, independently from one another, allyl, unsubstituted or substituted phenyl, unsubstituted or substituted C 1 -C 8 alkyl or unsubstituted or substituted C 3 -C 8 cycloalkyl;
(b) at least one epoxy resin;
(c) 5.7-10 parts by weight of a catalyst selected from tetraphenolethane;
(d) 5.7-10 parts by weigh of a toughening agent of the formula (II)
wherein m is 1 or 2, n is 2 to 6, R 0 is an n-valent radical of an elastomeric prepolymer after the removal of the terminal isocyanate, amino or hydroxyl groups, the elastomeric prepolymer being soluble or dispersible in epoxy resin, X and Y independently of one another are —O— or —NR 3 —, at least one X or Y being —NR 3 —, R 2 is an m+1-valent radical of polyphenol or aminophenol after the removal of the phenolic hydroxyl group(s) and optionally of the amino group, and R 3 is hydrogen, C 1 -C 6 alkyl or phenol; and
(e) a solvent
where the parts by weight are per 100 parts by weight of the composition.
2. The halogen-free curable composition according to claim 1 wherein R is phenyl.
3. The halogen-free curable composition according to claim 1 wherein the solvent is selected from the group consisting of methylethylketone, acetone, N-methyl-2-pyrrolidone, N,N-dimethyl formamide, pentanol, butanol, dioxolane, isopropanol, methoxy propanol, methoxy propanol acetate, dimethylformamide, glycol, glycol acetate, toluene, xylene and mixtures thereof.
4. A halogen-free curable composition comprising:
(a) 10-90 parts by weight of a benzoxazine monomer of the formula (I)
wherein each R is, independently from one another, allyl, unsubstituted or substituted phenyl, unsubstituted or substituted C 1 -C 8 -alkyl or unsubstituted or substituted C 3 -C 8 cycloalkyl;
(b) 2-60 parts by weight of at least one epoxy resin;
(c) 5.7-10 parts by weight of a catalyst selected from tetraphenolethane;
(d) 5.7-10 parts by weight of a toughening agent of the formula (II)
wherein m is 1 or 2, n is 2 to 6, R 0 is an n-valent radical of an elastomeric prepolymer after the removal of the terminal isocyanate, amino or hydroxyl groups, the elastomeric prepolymer being soluble or dispersible in epoxy resin, X and Y independently of one another are —O— or —NR 3 —, at least one X or Y being —NR 3 —, R 2 is an m+1-valent radical of polyphenol or aminophenol after the removal of the phenolic hydroxyl group(s) and optionally of the amino group, and R 3 is hydrogen, C 1 -C 6 alkyl or phenol; and
(e) 1-50 parts by weight of a solvent,
per 100 parts by weight of the halogen-free curable composition wherein the halogen-free curable composition, upon curing, has a glass transition temperature greater than 160° C.
5. The halogen-free curable composition according to claim 4 , wherein the glass transition temperature is greater than 200° C.
6. The halogen-free curable composition according to claim 4 , wherein the glass transition temperature is greater than 230° C.