Method for preparation of a moulded composite from a bulk moulding compound

1. A bulk moulding compound comprising one or more cyanate ester, a catalyst, a filler and reinforcement fibres, wherein the one or more cyanate ester is independently selected from

a) a difunctional cyanate ester compound of formula (I)

wherein

R 1 through R 8 are independently selected from the group consisting of hydrogen, linear C 1-10 alkyl, halogenated linear C 1-10 alkyl, branched C 4-10 alkyl, halogenated branched C 4-10 alkyl, C 3-8 cycloalkyl, halogenated C 3-8 cycloalkyl, C 1-10 alkoxy, halogen, phenyl and phenoxy;

Z 1 indicates a direct bond or a divalent moiety selected from the group consisting of —O—, —S—, —S(═O)—, —S(═O) 2 —, —CH 2 —, —CH(CH 3 )—, —C(CH 3 ) 2 —, —CH(CF 3 )—, —C(CF 3 ) 2 —, —C(═O)—, —C(═CH 2 )—, —C(═CCl 2 )—, —Si(CH 3 ) 2 —, linear C 1-10 alkanediyl, branched C 4-10 alkanediyl, C 3-8 cycloalkanediyl, 1,2-phenylene, 1,3-phenylene, 1,4-phenylene, —N(R 13 )— wherein R 13 is selected from the group consisting of hydrogen, linear C 1-10 alkyl, halogenated linear C 1-10 alkyl, branched C 4-10 alkyl, halogenated branched C 4-10 alkyl, C 3-8 cycloalkyl, phenyl and phenoxy, and moieties of formulas

wherein X is independently selected from hydrogen and halogen;

and oligomers, polymers or mixtures thereof; and/or

b) a polyfunctional cyanate ester of formula (II)

wherein

n is an integer from 1 to 20; and

R 10 and R 11 are identical or different and independently from each other selected from the group consisting of hydrogen, linear C 1-10 alkyl and branched C 4-10 alkyl;

and oligomers, polymers or mixtures thereof,

and mixtures of cyanate esters of formula (I) and (II); and

wherein the catalyst is aluminum(III)acetylacetonate.

2. The bulk moulding compound according to claim 1 , wherein

(a) the difunctional cyanate ester of formula I is independently selected from the group consisting of

i) R 1 , R 2 , R 5 and R 6 are methyl, R 3 , R 4 , R 7 and R 8 are hydrogen and wherein Z 1 is methylene; and oligomers, polymers or mixtures thereof, or

ii) R 1 through R 8 are hydrogen and Z 1 is —C(CH 3 ) 2 — (Primaset® BADCy); and oligomers, polymers or mixtures thereof, or

iii) R 1 through R 8 are hydrogen and Z 1 is —S—; and oligomers, polymers or mixtures thereof, or

iv) R 1 through R 8 are hydrogen and Z 1 is —C(CF 3 ) 2 —; and oligomers, polymers or mixtures thereof, or

v) R 1 through R 8 are hydrogen and Z 1 is —C(═CCl 2 )—; and oligomers, polymers or mixtures thereof, or

vi) R 1 through R 8 are hydrogen and Z 1 is

and oligomers, polymers or mixtures thereof, or

vii) R 1 through R 8 are hydrogen and Z 1 is

and oligomers, polymers or mixtures thereof,

and oligomers, polymers or mixtures thereof;

and/or

(b) the polyfunctional cyanate ester of formula II is independently selected from the group consisting of compounds wherein n is an integer from 1 to 6; and

R 10 and R 11 are identical or different and independently selected from the group consisting of hydrogen, methyl, ethyl, propyl and butyl;

and oligomers, polymers or mixtures thereof;

and mixtures of cyanate esters of formula (I) and (II).

3. The bulk moulding compound according to claim 1 , wherein

(a) the difunctional cyanate ester of formula I is independently selected from the group consisting of compounds wherein

i) R 1 , R 2 , R 5 and R 6 are methyl, R 3 , R 4 , R 7 and R 8 are hydrogen and wherein Z 1 is methylene; and oligomers, polymers or mixtures thereof, or

ii) R 1 through R 8 are hydrogen and Z 1 is —C(CH 3 ) 2 — (Primaset® BADCy); and oligomers, polymers or mixtures thereof, or

iii) R 1 through R 8 are hydrogen and Z 1 is independently selected from the group consisting of

and oligomers, polymers or mixtures thereof, or

iv) R 1 through R 8 are hydrogen and Z 1 is

and oligomers, polymers or mixtures thereof;

and oligomers, polymers or mixtures thereof

and/or

(b) the polyfunctional cyanate ester is independently selected from the group consisting of compound of formula III, compound of formula IV, compound of formula V and compound of formula VI:

and mixtures of cyanate esters of formula (I) and (II).

4. The bulk moulding compound according to claim 1 , wherein the reinforcement fibres are selected from carbon fibres, glass fibres, aramid fibres, basalt fibres, natural fibres, fleeces, woven fabrics, and mixtures thereof.

5. The bulk moulding compound according to a claim 1 , wherein the reinforcement fibres are selected from chopped strand glass fibres, chopped strand carbon fibres, and mixtures thereof.

6. The bulk moulding compound according to claim 1 , wherein the filler is independently selected from the group consisting of CaCO 3 , coated CaCO 3 , kaolin clay, SiO 2 , talc, graphite, corundum (α-Al 2 O 3 ), SiC, glass microspheres, mica, calcium silicate (Ca 2 O 4 Si), wollastonite, MgO, anhydrous calcium sulfate (CaSO 4 or anhydrite), ceramic hollow microspheres, fused mullite (Al 2 O 3 —SiO 2 ), boron nitride (BN), vermiculite, basalt, and mixtures thereof.

7. A method for the preparation of a bulk moulding compound according to claim 1 , comprising the steps of

(i) providing a first mix by mixing the cyanate ester with the catalyst, and

(ii) mixing the first mix with the reinforcement fibres and the filler.

8. The method according to claim 7 , wherein

step (i) further comprises mixing the cyanate ester with the catalyst together with one or more further components selected from mould release agents, shrinkage modifiers, pigments and additives; and/or

the mixing step (ii) is performed at a temperature of below 100° C.

9. A method for the preparation of a moulded composite comprising the steps of:

(i) providing a bulk moulding compound as defined in claim 1 ;

(ii) pre-heating the bulk moulding compound;

(iii) transferring the bulk moulding compound into a mould;

(iv) curing the bulk moulding compound to obtain a moulded composite; and

(v) optionally heating the moulded composite.

10. The method according to claim 9 , wherein

step (i) comprises (i1) providing a first mixture by mixing the cyanate ester with the catalyst; and (i2) mixing the first mixture with the filler and the fibres to provide the bulk moulding compound; and/or

step (ii) is done at a temperature above room temperature but below the temperature where cyanate ester begins to polymerize; and/or

step (iv) is done at a temperature from 120 to 220° C.; and/or

step (iv) is done at a pressure of 50 kg/cm 3 or more; and/or

step (v) is done at a temperature from 100 to 300° C.

11. The method according to claim 9 , wherein the method for the preparation of the moulded composite is a compression moulding process or injection moulding process.

12. A moulded composite obtained by a process according to claim 9 .

13. The moulded composite according to claim 12 , the moulded composite having a glass transition temperature Tg (determined by Tan Delta measurement via DMTA) of more than 130° C.

14. Use of a bulk moulding compound as defined in claim 1 , for producing a moulded composite.