Process for continuous preparation of a prepolymer based on phenolic resins, oxazolines and epoxides
View Patent ↗Process for the continuous preparation of prepolymers based on phenolic resin, an oxazoline component and an epoxide in the presence of a catalyst, including supplying the phenolic resin and the oxazoline component to an extruder in a stream A; a Lewis adduct of boron trifluoride or of aluminum trichloride, or arylsulphonic acids or alkylsulphonic acids, or latent arylsulphonic acids or latent alkylsulphonic acids, in a stream B, and the epoxide in a stream C, the infeed of stream A being situated, as seen in extrusion direction, before the infeed of stream C, these reactants are mixed at a reaction temperature of 120 to 200° C. with a residence time in the extruder of 3 seconds to 15 minutes, and then the product discharge of the extruder is cooled to a temperature of less than 45° C. within from 30 to 60 seconds.
1. A process for the continuous preparation of a prepolymer composition wherein the prepolymers are based on a phenolic resin component, an oxazoline component and an epoxide component, comprising:
combining the phenolic resin component, the oxazoline component and the epoxide component, in the presence of a catalyst, in an extruder,
wherein the phenolic resin component and the oxazoline component are supplied to the extruder in a stream A, and
at least one catalyst selected from the group consisting of a Lewis adduct of boron trifluoride, a Lewis acid adduct of aluminium trichloride, an arylsulphonic acid, an alkylsulphonic acid, a latent arylsulphonic acid, and a latent alkylsulphonic acid, as catalyst, are supplied to the extruder as stream B, and
the epoxide component is supplied to the extruder in a stream C,
wherein an infeed of the stream A, relative to an extrusion direction, is before an infeed of the stream C,
wherein the streams A, B and C are combined at a reaction temperature of 120 to 200° C. with a residence time in the extruder of 3 seconds to 15 minutes to form a product, and then the product is discharged from the extruder and cooled to a temperature of less than 45° C. within from 30 to 60 seconds.
2. The process according to claim 1 , wherein the extruder is a multi-barrel extruder.
3. The process according to claim 2 , wherein the barrels of the multi-barrel extruder are at different temperatures during the combining.
4. The process according to claim 3 , wherein the multi-barrel extruder comprises a first barrel for the stream A, a second barrel subsequent to the first barrel, in an extrusion direction, one or more additional barrels subsequent to the second barrel, and a third barrel subsequent to the additional barrels and before a product discharge location, wherein the first barrel, the second barrel and the third barrel have a temperature below the temperature in the additional barrels in which the streams A, B and C are combined.
5. The process according to claim 4 , comprising supplying the streams B and C in a fourth barrel which is located, in an extrusion direction, between the first barrel in which the stream A is supplied and the product discharge location at which the product is discharged.
6. The process according to claim 4 , wherein streams A and B are supplied together into the extruder.
7. The process according to claim 1 , wherein the epoxide component comprises at least one of:
a monoepoxide of the structure
where R 8 =hydrogen, C 1-3 alkyl group,
a diepoxide of the structure (4)
where R 9 and R 10 =hydrogen and C 1-3 alkyl group, it being possible for R 9 and R 10 to be identical or different,
a polyfunctional epoxide of the structure (5), and a polyepoxide of structure (6)
where R 11 =hydrogen, C 1-3 alkyl group or
where R 12 =hydrogen or C 1-3 alkyl group.
8. The process according to claim 1 , wherein the total amount of the epoxide component combined with the oxazoline component and the phenolic resin component is from 1 to 10% by weight based on the total weight of components supplied to the extruder.
9. The process according to claim 1 , further comprising:
supplying one or more hindered amine light stabilizers to the extruder.
10. The process according to claim 1 , further comprising:
supplying one or more sterically hindered phenolic antioxidants to the extruder.
11. The process according to claim 1 , further comprising:
supplying from 1% to 15% by weight of at least one impact modifier to the extruder based on the total weight of the streams supplied to the extruder.
12. The process according to claim 1 , further comprising:
supplying from 1% to 10% by weight of at least one of a halogenated flame retardant and a nonhalogenated flame retardant is supplied to the extruder based on the total weight of the streams supplied to the extruder.
13. A prepolymer obtained by the process according to claim 1 .
14. A composition comprising the prepolymer of claim 13 .
15. A powder for producing prepregs, comprising: the prepolymer of claim 13 and one or more additional components.
16. A process comprising:
dissolving the prepolymer of claim 13 in 2-butanone and impregnating at least one reinforcing fiber selected from the group consisting of a glass fibre and a carbon fibre with the dissolved prepolymer, and
curing the impregnated reinforcing fiber.