EP0547116A1

EP0547116A1 - Thermosetting compositions based on cyanate ester compounds and polyimide compounds having diorganopolysiloxane grouping(s)

Info

Publication number: EP0547116A1
Application number: EP91916142A
Authority: EP
Inventors: Yves Camberlin
Original assignee: Ciba Geigy AG
Current assignee: Novartis AG
Priority date: 1990-09-07
Filing date: 1991-09-03
Publication date: 1993-06-23
Also published as: JPH06504071A; KR930702424A; IE912771A1; WO1992004395A1; CA2088672A1; MX174494B; AU8519691A; FR2666586A1; ZA915957B; PT98872A

Abstract

La présente invention se rapporte à des compositions thermodurcissables comprenant (A) au moins un composé cyanate ester consistant essentiellement dans un ester cyanique aromatique polyfonctionnel ayant au moins deux groupes cyanates (-O-C=N) liés à un noyau aromatique, dans un prépolymère dérivé dudit ester organique ou dans un coprépolymère dérivé dudit ester cyanique et d'une polyamine et (B) au moins un élastomère consistant essentiellement dans un N,N'-bis-maléimide à groupement diorganopolysiloxane, dans un prépolymère dérivé dudit bis-maléimide ou dans un coprépolymère dérivé dudit bis-maléimide et d'une diamine. Les compositions thermodurcissables conformes à la présente invention peuvent contenir en outre un catalyseur approprié et un ou plusieurs composé(s) additionnel(s) polymérisable(s) incluant notamment un bis-maléimide conventionnel, une résine époxy éventuellement halogénée, un réactif acrylate ou un alkénylphénol et elles peuvent être associées en plus à des charges de renforcement connues.The present invention relates to thermosetting compositions comprising (A) at least one cyanate ester compound consisting essentially of a polyfunctional aromatic cyanic ester having at least two cyanate groups (-OC = N) bonded to an aromatic nucleus, in a prepolymer derived from said. organic ester or in a coprepolymer derived from said cyanic ester and from a polyamine and (B) at least one elastomer consisting essentially of an N, N'-bis-maleimide containing a diorganopolysiloxane group, in a prepolymer derived from said bis-maleimide or in a coprepolymer derived from said bis-maleimide and a diamine. The thermosetting compositions in accordance with the present invention may further contain an appropriate catalyst and one or more additional polymerizable compound (s) including in particular a conventional bis-maleimide, an optionally halogenated epoxy resin, an acrylate reagent or an acrylate reagent. alkenylphenol and they can additionally be combined with known reinforcing fillers.

Description

THERMOSETTING COMPOSITIONS BASED ON CYANATE ESTER COMPOUNDS AND DIORGANOPOLYSILOXANE-BASED POLYIMIDE COMPOUNDS

The present invention relates to thermosetting compositions comprising (A) at least one cyanate ester compound consisting essentially of a polyfunctional aromatic cyanic ester having at least two cyanate groups (-0-CN) linked to an aromatic ring, in a prepolymer derived from said organic ester or in a co-polymer derived from said cyanic ester and from a polyamine and (B) at least one elastomer consisting essentially of a polyide compound comprising in its structure one or more diorganopol siane group (s).

It also relates to cured resins prepared from said thermosetting compositions. The thermosetting compositions in accordance with the present invention may also contain a suitable catalyst and one or more additional polymerizable compound (s) including in particular a conventional bismaleimide, an optionally halogenated epoxy resin, an acrylate reagent or an alkenylphenol and they can also be combined with known reinforcing charges.

Polyfunctional aromatic cyan esters are known products which are prepared by reaction between a cyanogen halide and a polyhydroxylated phenol (cf. US Pat. No. 3,553,244). These cyanic esters can lead to hardened resins by a cyclotrimerization reaction of the cyanate groups giving rise to substituted triazine rings which will organize themselves in a three-dimensional polycyanurate network.

Such polycyanurate resins, which have found many uses in several fields of application, have interesting electrical properties (in particular dielectric characteristics), but they have the defect of offering levels of properties which are still insufficient, particularly in terms of toughness. (the level of shock value CHARPY, 61C and K1C are to be improved) and adhesion on metallic substrates. In order to obtain stubborn resins, it has been proposed in the prior art to modify polycyanurate resins by adding to their preparation medium: plasticizers with a high boiling point containing ester groups (cf. US-A patent -4 094852); an acrylonitrile-butadiene copolymer (cf. US Pat. No. 3,649,714); an elastomer such as natural rubbers, polymers derived from conjugated dienes (such as butadiene and Tisoprene), polychloroprenes (cf. US Pat. No. 4,396,745); or an amorphous thermoplastic polymer such as a polysulfone, a polyarylate, a polyethersulfone (cf. application EP-A-0311 341). However, such polymer mixtures are likely to present a serious lack of thermostability of application temperatures as high as from 220 ^° C to 300 'C.

It has now been found that it is possible to obtain, starting from polyfunctional aromatic cyanic esters, resins having in the cured state an excellent compromise of properties, in particular as regards toughness, thermostability and adhesion, by using an agent. modification consisting essentially of a polyimide compound comprising in its structure one or more diorganopolysiloxane group (s). More specifically, the present invention relates to thermosetting compositions which comprise:

(A) - at least one cyanate ester compound chosen from the group formed by:

(1) - a polyfunctional aromatic cyanic ester, monomer, having the formula: R - (- 0-CN) _n (I)

in which: n is an integer ranging from 2 to 5 and R represents an aromatic organic radical of valence n, comprising from 6 to 30 carbon atoms in which the cyanate groups are linked to the aromatic nucleus (s) of R;

(2) - a prepolymer of (1), and

(3) - a coprepolymer of (1) and an aromatic primary polyamine;

(B) - at least one elastomeric compound; and optionally: (C) - a suitable catalyst; said compositions being characterized in that component (B) consists of at least one compound chosen from the group formed by:

(4) - an N, N'-bis-maleimide containing a diorganopolysiloxane group essentially corresponding to the general formula:

in which :

- X, which is in the ortho, meta or para position relative to the carbon atom of the benzene ring linked to nitrogen, represents a simple valential bond or an atom or a following group:

0 -; - S -; - S; - S -; 0 0

- Ri, R, R3, R4, R5, δ "R7" Rδ ", identical or different, each represent a monovalent hydrocarbon radical chosen from: alkyl radicals, linear or branched, having from 1 to 12 carbon atoms, these radicals being able to be substituted by one or more chlorine, bromine or fluorine atoms or by a -CN group; a phenyl radical optionally substituted by one or more alkyl and / or alkoxy radicals having from 1 to 4 carbon atoms or by one or more chlorine atoms; - the symbol x is an integer located in the range from 2 to 8;

- the symbols y and z represent numbers, identical or different, whole or fractional, the sum of which lies in the range from 0 to 100;

(5) - a prepolymer of (4), and

(6) - a coprepolymer of (4) and of an aromatic biprimary diamine.

With regard to constituent (A), the symbol R of the cyanate ester of formula (I) can represent: (i) - a radical of valence n derived from an aromatic hydrocarbon containing from 6 to 16 carbon atoms such as for example the benzene, naphthalene, anthracene or pyrene: (2i) - a radical of valence n derived from a group comprising several aromatic rings linked together by a simple valential bond or by an inert atom or an inert divalent group such as for example the group of formula:

in which R 'represents: a simple valential bond or a divalent inert atom or group such as: -0-; -S-; a linear or branched alkylene radical having from 1 to 10 carbon atoms, optionally substituted by one or more chlorine, bromine or fluorine atoms and optionally interrupted by one or more oxygen atom (s); -CO-; -SO2-; -NR "- where R" represents a hydrogen atom, an alkyl radical having from 1 to 3 carbon atoms, phenyl or cyclohexyl; -C00-;

In addition, the various aromatic groups mentioned in paragraphs (i) and (2i) may be substituted by one or more linear or branched alkyl (s) or alkoxy radicals having from 1 to 4 carbon atoms or by one or more halogen atom (s).

Preferably, the cyanate esters (1) of formula (I) which are used consist of difunctional compounds which correspond to the formula:

in which: - R '"represents a simple valential link or an atom or the following grouping:

-0- -S- -CH2- -

the symbols R "", which are identical or different, each represent a substituent chosen from a chlorine, bromine or fluorine atom or a methyl, ethyl, propyl or isopropyl radical, two neighboring R "" on the same nucleus which can together represent a 6-membered aromatic nucleus;

- m is an integer equal to 0 or 1;

- a is an integer equal to 0, 1 or 2, the symbols a, when there are 2, can be identical or different between them. As specific examples of preferred difunctional cyanate esters (1) of formula (IV), there may be mentioned in particular:

. 1,3- and 1,4-diacyanatobenzene,

. 1,3-, 1,4-, 1,6-, 1,8-, 2,6- or 2,7-dicyanatonaphthalene,. 4,4'-dicyanatobiphenyl,

. bis (4-cyanatophenyl) methane,

. bis (3,5-dimethyl-4-cyanatophenyl) methane,

. 2,2-bis (4-cyanatophenyl) propane,

. 2,2-bis (4-cyanatophenyl) hexafluoropropane,. l, l-bis (4-cyanatophenyl) ethane,

. bis (4-cyanatophenyl) ether,

. bis (4-cyanatophenyl) thioether,

. bis (4-cyanatophenyl) sulfone,

. bis (4-cyanatophenyl) tetrahydrodicyclopentadiene. It is used very preferably, for the implementation

Work of the invention, bis (4-cyanatophenyl) methane, bis (3,5-dimethyl-4-cyanatophenyl) methane, 2,2-bis- (4-cyanatophenyl) propane or mixtures of these cyanates.

The cyanate esters (1) can also be used in the form of a prepolymer (2), comprising symmetrical triazine rings, which is preferred by partial cyclotimerization of the cyanate groups by heating the monomeric cyanate ester (1) to a temperature ranging from 130 ^* C at 220 ^* C for a time sufficient to cyclotimerize 5 to 75% of the total number of cyanate groups engaged, and preferably 15 to 50% of the functional cyanate groups. Such prepolymers (2) have a weight average molecular weight ranging from 400 to 12,000; they can be prepared in the presence of a catalyst, either acidic, for example a mineral protonic acid or a LEWIS acid, or basic, such as, for example, an alkali metal hydroxide, an alkali metal alcoholate or a tertiary amine.

The cyanate esters (1) can also be used in the form of a coprepolymer (3) derived from (1) and of an aromatic primary polyamine such as preferably an aromatic biprimary diamine chosen from the group formed by: * (3.1) - the species corresponding to the general formula: H2N - A - NH2 (V)

in which the symbol A represents a divalent radical chosen from the group consisting of radicals: cyclohexylenes; phenylenes; 4-methyl-1,3-phenylene; 2-methyl-1,3-phenylene; 5-methyl-1,3-phenylene; 2,5-diethyl-3-methyl-1,4-phenylene; and the radicals of formula:

in which B represents a simple valential link or a grouping

(3.2) - species corresponding to the general formula

in which :

. the symbols Rg, Rio _» R11 and R12, identical or different, each represent a methyl, ethyl, propyl or isopropyl radical; . the symbols T, which may be identical or different, each represent a hydrogen atom or a chlorine atom;

. the symbol E represents a divalent radical chosen from the group formed by the radicals:

* and (3.3) - species corresponding to the general formula

in which :

. the amino radicals are in meta or para position with respect to each other;

. the symbols Rι ₃ , identical or different, each represents a methyl, ethyl, propyl or isopropyl radical.

As specific examples of diamines (3.1) of formula (V), there may be mentioned in particular:

- paraphenylene diamine,

- methaphenylene diamine,

- 4,4 'diamino diphenylmethane,

- bis (4-amino phenyl) -2.2 propane,

- benzidine,

- bis- (4-amino phenyl) oxide,

- dimaine-4,4 'diphenylsulfone.

The diamino-4,4 'diphenylmethane is preferably used for the implementation of the present invention. As specific examples of hindered diamines (3.2) and (3.3) of formulas (VI) and (VII), there may be mentioned in particular:

- diamino-4,4 'tetramethyl-3,3', 5,5 '-diphenylmethane,

- diamino-4,4 'tetraethyl-3,3', 5,5'-diphenylmethane, - diamino-4,4 'dimethyl-3,5 diethyl-3', 5'-diphenylmethane,

- diamino-4,4 'diethyl-3,3' dimethyl -5,5'-diphenylmethane,

- diamino-4,4 'tetraisopropyl-3,3', 5,5'-diphenylmethane,

- diamino-4,4 'diisopropyl-3,3' dimethyl-5,5'- diphenylmethane, - bis (4-amino-dimethyl-3,5 α, α dimethylbenzyl) -1,4 benzene,

- bis (4-amino-3,5-dimethyla, dimethylbenzyl) -1,3 benzene,

- 1,3-diamino-2,4-diethyl-6-methyl-benzene,

- 1,3-diamino-2-methyl-4,6-diethyl benzene.

These hindered diamines can be prepared according to the methods described in English patent GB-A-852651 and American patent US-A-3 481 900. Diamino-4 is preferably used for the implementation of the present invention , 4 '3.3-tetramethyl, 5.5' - diphenylmethane, 4.4 'diamino' 3.3 'tetraethyl, 5.5'-diphenylmethane, 4.4' diamino-3.3 'diethyl '5,5-dimethyl' diphenylmethane and mixtures thereof. The coprepolymers (3) are obtained by reaction of the monomeric cyanate ester (1) and of the diamine by operating in a homogeneous liquid medium, optionally by using an appropriate solvent such as ketones, at a temperature ranging from 0 ^* C to 100 ^* C for a period ranging from 1 minute to 1 hour. The proportions of cyanate ester and of diamine are chosen so that the ratio number of cvanate groups - (- 0-C »N) number of NH2 groups is in the range from 1.1 / 1 to 10 / 1 and preferably ranging from 1.5 / 1 to 5/1. Use is made very especially preferably, for the implementation of the invention, of a constituent (A) consisting of a prepolymer (2) derived from the difunctional cyanate esters (1) of formula (IV). Component (B) of the curable compositions according to the present invention consists, as indicated above, in at least one compound chosen from the group formed by an N, N'-bis-maleimide siloxane (4), a prepolymer (5) derived from (4) and a coprepolymer (6) derived from (4) and an aromatic biprimary diamine.

Regarding the bis-maleimide siloxanes (4) of formula (II), when y and / or z are greater than 1, we are in the presence of a compound with a polymeric structure and we rarely have a single compound, but most often a mixture of compounds with the same chemical structure, which differ in the number of repeating units of their molecule; this leads to an average value of y and / or z which can be whole or fractional.

When the compositions according to the invention are prepared, according to the indications given below, in an organic diluent or solvent, any of the compounds (4) of formula (II) can be used.

As suitable bis-maleimides, mention may be made of those which correspond to formula (II) in which:

1) X ^" - 0 -; Ri - R2 ^" R ₃ ^" R - R5 ^" Re" R7 ^" 8 * linear alkyl radical having 1 to 3 carbon atoms; x" 2, 3 or 4; y + z is in the range from 0 to 100 and preferably from 4 to 70.

2) X - - 0 -; Ri - R2 "R3" R4 - R7 - Rβ • linear alkyl radical having from 1 to 3 carbon atoms; R5 - R% "phenyl radical; x - 2, 3 or

4; y + z is in the range from 0 to 100 and preferably from 4 to 70. 3) X - - 0 -; Ri ^» R ^» R7 ^» β" linear alkyl radical having from 1 to

3 carbon atoms; R3 "R4" R5 - Re * phenyl radical; x »2, 3 or

4; y + z is in the range of 0 to 100 and preferably 4 to 70.

4) X ^” - 0 -; Ri ^" R ^" R3 ^" R5 ^" R7 "β" linear alkyl radical having from 1 to 3 carbon atoms; R4 "Rç - phenyl radical; x - 2, 3 or

4; y + z is in the range of 0 to 100 and preferably 4 to 70.

5) X - - 0 -; Ri "R3 - R5 - R7 - linear alkyl radical having from 1 to

3 carbon atoms; R2 - R4 - Re "β" phenyl radical; x - 2, 3 or 4; y + z is in the range of 0 to 100 and preferably 4 to 70. As specific examples of bis-maleimide siloxanes (4) which are suitable, mention will be made in particular of:

8)

When the preparation of the polymers according to the invention is carried out in bulk, preferably used as bis-maleimides (4) of formula (II) those in which the diorganopolysiloxane group contains a plurality of Si-phenyl or substituted Si-phenyl bonds. Bis-maleimides of this type which are particularly suitable are those belonging to the following groups, classified in ascending order of preference:

- bismaleimides ^No. 2, 3, 4 and 5,

- bismaleimides ^No. 7, 8 and 9.

The bis-maleimide siloxane of formula (II) are compounds which are obtained by reacting maleic anhydride, in the presence of a dehydrating agent, a tertiary amine, an organic diluent and a catalyst, on a diamine containing a diorganopolysiloxane group of formula:

in which X, Ri, R2, R3, R4. R5. 6 _> R7 _> β »x» y and z have the meanings given above for formula (II). For more details on these bis-maleimide siloxanes and on their preparation process, reference may be made in particular to the content of French patent application FR-A-2 611 728. The bis-maleimide siloxanes (4) can be also used in the form of a prepolymer (5) which is prepared by heating the bis-maleimide siloxane (4) by operating in bulk or in a liquid diluent, which may be a solvent, at a temperature ranging from 50 to 180 'C, preferably 80 to 170 ^° C, for a period ranging from 5 minutes to 2 hours or more, this period being much shorter than the adopted temperature is higher. The bis-maleimide siloxanes (4) can also be used in the form of a coprepolymer (6) derived from (4) and of an aromatic biprimary diamine chosen from the group formed by species (3.1), (3.2) and ( 3.3) which has been mentioned above with regard to the definition of the co-polymer (3) of the constituent (A). The coprepolymer (6) can be prepared by reacting the bis-maleimide siloxane (4) and the diamine by operating in bulk or in a liquid diluent, which may be a solvent, at a temperature ranging from 50 to 180 ^# C , preferably from 80 to 170 ° C, for a period ranging from 5 minutes to 2 hours or more so as to obtain a homogeneous liquid medium. The proportions of bis-imide and diamine are chosen so that the ratio number of moles of bis-imide number of moles of diamine is in the range from 1.2 / 1 to 10/1 and, from preferably ranging from 2/1 to 5/1.

Use is made, very especially preferably, for the implementation of the invention, of a constituent (B) consisting of a bis-maleimide siloxane (4) chosen from bis-maleimides n ^* 1 to 9.

The reactivity of the constituents of the curable compositions according to the invention can be increased and / or controlled, if necessary, by the addition of a catalyst (C) which can be chosen from the compounds accelerating and / or regulating the reactivity of the cyanate groups both during the cyclotrimerization reaction, only during the subsequent crosslinking reaction; as examples of compounds of this nature, there may be mentioned in particular:

- free hydrogen compounds such as, for example, alcohols, phenols, carboxylic acids and primary and secondary amines;

- compounds consisting of metal carboxylates, optionally dissolved in non-volatile functional liquids such as, for example, an alkylphenol or a monoalcohol (cf. US-A-4 604 452 and US-A-4 608434 the substance of which is introduced here as reference) ;

- Compounds consisting of chelates such as metallic acetylacetonates, optionally dissolved in an alkylphenol (cf. US-A-4,785,075, the substance of which is also introduced here for reference). The catalysts which are preferred consist of metallic acetylacetonates and, in particular, of zinc, copper, manganese or cobalt acetylacetonates.

In the thermosetting compositions which have just been defined, the quantities of the constituents (A) and (B) are chosen so as to have, by weight relative to the weight of the assembly (A) + (B):

- from 50 to 98% and, preferably, from 75 to 95% of constituent (A), and

- from 2 to 50% and, preferably, from 5 to 25% of elastomeric constituent (B). As regards the optional catalyst (C), according to its nature and according to the desired crosslinking speed at the implementation stage, it is used when it is needed at a rate ranging from 0.005 to 10% and preferably ranging from 0.01 to 5% relative to the weight of the overall composition including (A) + (B) + optionally the additional polymerizable compound (s) which will now be discussed later in this brief.

The compositions according to the invention may in fact comprise, in addition, an additive (D) consisting of one or more additional polymerizable compound (s) chosen from: (7) - an N, N '-bis maleimide of formula:

C0 co - c z

(VIII)

CO / 0 z

in which :

. the symbols Z, which are identical or different, each represent H, CH ₃ or Cl;

. the symbol 6 can represent one of the radicals represented by the symbol A in the formula (V) representing the species (3.1) of aromatic biprimary diamines;

(8) - a chlorinated or brominated epoxy resin;

(9) - a non-halogenated epoxy resin;

(10) - an alkenylphenol of formula:

in lacquer! :

. the symbol H represents a simple valential bond or divalent radical chosen from the group formed by radicals:

ÇH ₃

- CH2 -; - CH2 - CH2 -; - VS - ; - 0 -; - S -; - S0 -; and - SO2 -;

CH ₃

. the symbols R14, identical or different, each represent a hydrogen atom or a methyl radical;

. the symbols R15, identical or different, each represent a hydrogen atom or a linear or branched alkyl radical having from 1 to 6 carbon atoms or a phenyl radical; (11) - an acrylate of general formula:

(CH2 - CR16 - CO - 0 -) L (X)

P in which:. the symbol R15 represents a hydrogen atom or a methyl radical; . p represents an integer or fractional number at least equal to 1 and at most equal to 8;

. the symbol L represents an organic radical of valence p derived: from a saturated, linear or branched aliphatic residue, having from 1 to 30 carbon atoms and which may contain one or more oxygen bridge (s) and / or one or more function ( s) free hydroxyl (s); an aromatic residue (of aryl or arylaliphatic type) having from 6 to 150 carbon atoms constituted by a benzene ring, which may be substituted by one to three alkyl radicals having from 1 to 5 carbon atoms, or by several benzene rings, optionally substituted as indicated above, linked between them by a simple valential bond, an inert group or an alkylene radical having from 1 to 3 carbon atoms, said aromatic residue being able to contain at various places in its structure one or more oxygen bridge (s) and / or one or more function (s) free hydroxyl (s), the free valence (s) of the aromatic L radical which can be carried by a carbon atom of an aliphatic chain and / or by a carbon atom of a benzene nucleus.

When a compound (D) (or a mixture of compounds D) is used for the preparation of the compositions according to the present invention, it represents by weight from 2 to 35%, preferably from 5 to 30%, of the overall composition ( A) + (B) + (D) + possibly (C).

As specific examples of bis-maleimides (7) of formula (VIII), there may be mentioned in particular:

- N, N'-metaphenylene-bis-maleimide, - N, N'-paraphenylene-bis-maleimide,

- N, N'-4,4'-diphenylmethane-bis-maleimide,

- N, N'-4-4'-diphenylether-bis-maleimide,

- N, N'-4,4'-diphenylsulphone-bis-maleimide,

- N, N'-cyclohexylene-1,4-bis-maleimide, - N, N'-4,4'-diphenyl-1,1-cyclohexane-bis maleimide,

- N, N'-4,4'-diphenyl-2,2-propane-bis-maleimide,

- N, N'-4,4'-triphenylmethane-bis-maleimide,

- N, N'-methyl-2 phenylene-1,3-bis-maleimide,

- N, N'-methyl-4 phenylene-1,3-bis-maleimide, - N, N '-_ 5-methyl-phenylene-1,3-bis-maleimide,

These bis-maleimides can be prepared according to the methods described in American patent US-A-3,018,290 and English patent GB-A-1,137,290. The N is preferably used for the implementation of the present invention , N'-4,4'-diphenylmethane-bis-maleimide taken alone or as a mixture with N, N'-methyl-2-phenylene-1,3, bis-maleimide, N, N'-methyl-4-phenylene- 1,3-bis-maleimide and / or N, N'-methyl-5-phenylene-1,3-bis-maleimide. It has been found that the amount of chlorine or bromine which can be added to the compositions according to the invention by the additive (8) is likely to influence certain properties of the cured compositions obtained, in particular the properties in terms of thermal stability and those in terms of adhesion of the compositions to metals such as for example copper. In this context, the best results are obtained when this quantity of chlorine or bromine provided by the additive (8), expressed by the percentage by weight of elemental chlorine or elemental bromine relative to the weight of the overall mixture (A) + (B) + optional compound (C) + optional compound (D), represents at most 8%; this amount of chlorine or bromine is preferably in the range from 1 to 6%. The amount of chlorine or bromine can easily be adjusted to the desired value by using, for example, epoxy resins (8) having a greater or lesser chlorine or bromine content or starting from mixtures of chlorinated or brominated epoxy resins (8) with non-halogenated epoxy resins (9).

The term “chlorinated or brominated epoxy resin” (8) is intended to define an epoxy resin which has an epoxy equivalent weight of between 200 and 2,000 and which consists of a glycidic ether obtained by reacting with chlorinated epichlorohydrin or bromine on the aromatic nucleus (s) derived from a polyphenol chosen from the group formed by: the family of bis (hydroxyphenyl) alkanes such as bis (4-hydroxyphenyl) -2.2 propane, bis (4-hydroxyphenyl) methane, bis (4-hydroxyphenyl) methyl -phenyl-methane, bis (4-hydroxyphenyl) tolyl-methanes; resorcinol; 1 hydroquinone; pyrocatechol; 4,4 'dihydroxy diphenyl; and the condensation products of the above-mentioned phenols with an aldehyde.

The expression "epoxy equivalent weight", which appears above, can be defined as being the resin weight (in grams) containing an epoxy function - C - C -. Preferably, a chlorinated or brominated epoxy resin having an epoxy equivalent weight of between 250 and 500 is chosen. An epoxy resin (8) consisting entirely of a resin belonging to the family of glycidic ethers of bis is most preferably used in the present invention. (hydroxyphenyl) alkanes, bromines on aromatic rings, which we discussed above in connection with the detailed definition of the resin (8).

By non-halogenated epoxy resin (9) is meant an epoxy resin which has an epoxy equivalent weight of between 100 and 1000 and which consists of a glycidic ether obtained by reacting with tepichlorhyrin a non-chlorinated or non-brominated polyphenol. on the aromatic nucleus (s) chosen from the group of phenols of which we have spoken above with regard to the detailed definition of the resin (8).

A non-halogenated epoxy resin having an epoxy equivalent weight of between 150 and 300 is preferably chosen. An epoxy resin (9) consisting very preferably of a resin belonging to the family of glycidic ethers of bis (hydroxyphenyl) alkanes is used, non-halogenated on aromatic rings, which we discussed above in connection with the detailed definition of the resin (8).

As specific examples of alkenylphenols (10) of formula (IX), there may be mentioned in particular:

- 4,4-dihydroxy '3,3-diallyl' bisphenyl,

- bis (4-hydroxy-3-allyl phenyl) methane,

- bis (4-hydroxy-3-allyl-phenyl) ether,

- bis (4-hydroxy-3-allyl-phenyl) -2.2 propane or 0.0'-diallyl-bisphenol A,

- Ethyl ether corresponding to one or other of the aforementioned alkenylphenols.

The al enylphenols are prepared, as is well known, by thermal transposition (Claisen) of the allyl ethers of phenols, which allyl ethers are obtained in a manner known per se by reacting for example phenols and allyl chloride in the presence an alkali metal hydroxide and solvents. As suitable acrylate reagent (11), there may be mentioned:

(11.1) - the mono (meth) acrylates corresponding to formula (X) in which:

. p - 1, and. L represents a monovalent organic radical of formula:

- (- CH ₂ CH ₂ 0} η Li (XI)

in which: Li represents an alkyl radical, linear or branched, having from 1 to 6 carbon atoms or a phenyl radical; and q is an integer of zero, 1, 2, 3, 4 or 5;

(11.2) - the di (meth) acrylates corresponding to formula (X) in which:

. p ≈ 2, and. L represents a divalent organic radical of formula:

-t-CH2CH2θ) τ ^L 2 tf ⁾ CH2CH2) s (XII)

in which: L2 represents a divalent alkylene radical, linear or branched, having from 2 to 9 carbon atoms and which can contain one or more oxygen bridge (s) or a radical of formula:

in which the symbol U represents an i in simplified value or a grouping:

CH3

-CH2-, -CH2-CH2-, -CH (CH ₃ ) CH2-, -C-, -0-, - | S-; r and s symbols,

CH ₃ 0 identical or different, each represents an integer equal to zero, 1, 2, 3, 4 or 5;

(11.3) - the tri- and tetra (meth) acrylates corresponding to formula (X) in which:. p * 3 or 4, and

. L represents a trivalent or tetravalent organic radical derived from a saturated, linear or branched aliphatic residue, having from 3 to

20 carbon atoms and which may contain one or more oxygen bridge (s) and / or one or more free hydroxyl function (s); (11-4) - the (meth) acrylates of novolak epoxy which, while corresponding to the formula (X), are represented here by the following formula:

(XIII)

in which :

. the symbol Rie has the meaning given above with respect to the formula (X);

. the symbol R17 represents a hydrogen atom or a methyl radical; - t is an integer or fractional number lying in the range from 0.1 to 7;

(11.5) - mixtures of several acrylates and / or methacrylates of the same type {(11.1), (11.2), (11.3) or (11.4)} between them or mixtures of one or more acylate (s) and / or methacrylate (s) of the same type with one or more acrylate (s) and / or methacrylate (s) of another type.

As specific examples of acrylate reagent (11.1) which are very suitable, mention may be made in particular of: methyl mono (meth) acrylates; mono (meth) acrylates of (mono-oxyethylated) phenol; my (meth) acrylates of (di-oxyethylated) phenol.

As specific examples of acrylate reagent (11.2) which are very suitable, there may be mentioned: ethylene glycol di (meth) acrylates; 1,4-butanediol di (meth) acrylates; di (meth) acrylates of 1,6-hexanediol; tripropylene glycol di (meth) acrylates; the di (meth) acrylates of diphenols, di (mono- or poly-oxyethylated) or not, the following: dihydroxy-4,4'-diphenylmethane, bisphenol A, dihydroxy-4,4'-diphenylether and in particular the di (meth) acrylates of bisphenol A di (mono-oxyethylated) or di (meth) acrylates of bisphenol A di (di-oxyethylated) {cf. formula (XII) in which L2 represents the radical:

and r - s * 1 or 2}.

As specific examples of acrylate reagent (11.3) which are very suitable, mention may be made in particular of: tri (meth) acrylates of 1,2,4,4-butanetriol; tri (meth) acrylates of hexanetriol-1,2,6; trimethylolpropane tri (meth) acrylates; pentaerythritol tri (meth) acrylates; pentaerythritol tetra (eth) acrylates.

Novolak epoxy (meth) acrylates (11.4) are known products, some of which are commercially available. They can be prepared by reacting (meth) acrylic acids with a resin novolak type epoxy, the latter being the reaction product of epichlorohydrin and phenol / formaldehyde polycondensates {in formula (XIII) given above R \ 7 is then a hydrogen atom} or cresol / formaldehyde polycondensates { in the formula R17 is then a methyl radical}. These oligomeric polyacrylates (11.4) and a process for preparing them are described for example in American patent US-A-3,535,403.

As specific examples of acrylate reagent (11.4) which are very suitable, mention may in particular be made of novolak epoxy acrylates of formula (XIII) in which R15 and R17 represent a hydrogen atom and t is an integer or fractional in the range 0.1 to 5.

As specific examples of acrylate reagent (11.5) which are very suitable, mention may be made of mixtures of (meth) acrylates of novolak epoxy (11.4) with at most 30% by weight, relative to the weight of the mixture (11.4) + (11.3), a triacrylate and / or a trimethacrylate corresponding to the definitions given above with regard to the acrylate reagent (11.3) and in particular the mixtures of novolak epoxy acrylates which are well suited, just mentioned above , with at most 25% by weight, relative to the weight of the mixture, of a triacrylate and / or of a suitable trimethacrylate well chosen from those just mentioned above.

The acrylate reagent (11) which is very preferably used is taken from the group formed by: the di (meth) acrylates of bisphenol A di (mono-oxyethylated); di (meth) acrylates of bisphenol A di (di-oxyethylated); novolak epoxy acrylates of formula (XIII) in which R \ s and R17 represent a hydrogen atom and t is an integer or fractional number ranging from 0.1 to 5, these compounds being taken alone or as a mixture with at most 25% by weight, relative to the weight of the mixture, of triethyl acrylate triacrylate. Various adjuvants can also be incorporated into the compositions according to the invention. These adjuvants, usually used and well known to those skilled in the art, can be, for example, stabilizers or degradation inhibitors, lubricants or release agents, dyes or pigments, pulverulent fillers or particles like silicates, carbonates, kaolin, chalk, powdered quartz, mica or glass microbeads. It is also possible to incorporate adjuvants which modify the physical structure of the product obtained, such as, for example, blowing agents or fibrous reinforcing agents such as in particular carbon, polyimide, aromatic polyamide fibrils, whiskers.

The curable compositions of the invention may be the result of a simple direct mixing at room temperature (23 ^° C) of component (A), component (B) and optionally the additive (D), if necessary with the catalyst (C).

But preferably, the curable compositions according to the invention are the result of a preliminary reaction, concerning the various constituents used, obtained by heating and leading to a homogeneous liquid material. The curable compositions according to the invention thus obtained will be defined in the following paragraphs by the expression: "preferred compositions".

More specifically, said preferred compositions can be prepared by direct heating of component (A), of component (B) and optionally of additive (D), with the catalyst (C) if necessary, for a sufficient time to obtain a mixture homogeneous liquid; the temperature may vary depending on the physical state of the compounds in the presence, but it is between 40 and 120 ^° C and preferably between 50 and 100 ° C; the duration is of the order of 5 minutes to 1 hour or more.

According to one advantageous procedure, used to prepare the preferred compositions, is brought in a first step the cyanate ester component (A) at a temperature between 40 and 120 ^° C and preferably between 50 and 100 ° C, to which it is in a homogeneous liquid state, operating in the absence of any catalyst (C). Then, in a second step is added in the liquid medium which is stirred and maintained at a temperature identical to or different from wil implemented in the previous step, also between 40 and 120 ^° C and preferably between 50 and 100 ° C., the polyimide siloxane component (B), the stirring and the temperature being maintained for a sufficient time to obtain a homogeneous liquid medium (duration of the order from 5 minutes to 1 hour or more). In the case where it is chosen to use the optional catalyst (C), it is introduced in the second step, preferably in the form of a solution in the constituent (B) charged. In the case where one chooses to use the additive (D), it can be introduced at any chosen time either during the first stage or during the second stage.

The viscosity in the molten state of the preferred compositions thus obtained, measured at 80 ^° C, can be easily adjusted to the desired value, between 0.1 Pa.s and 50 Pa.s, especially by playing on the nature and respective proportions of the constituents used as well as on the temperature and the duration of the heating.

The operations which have just been described can be carried out not only in the melt, but also in the presence of variable quantities of a polar liquid such as for example: cresol, dimethylformamide, N-methylpyrrolidone, dimethylaceta ide, methyl ethyl ketone, dioxane, cyclohexanone .

In the homogeneous liquid state, the preferred compositions can be used directly, for example either for the impregnation of conductors, or for molding by simple hot casting or by injection, or even for making adhesives. It is also possible, after cooling and grinding, to use these compositions in the form of powders, for example for obtaining compression molded objects, optionally in association with fibrous or pulverulent fillers. The preferred compositions can also be used in solution for the preparation of coatings, collages, laminated materials, the backbone of which can be in the form of woven or nonwoven webs, unidirectional elements or natural or synthetic cut fibers such as for example. filaments or fibers of earth, boron, carbon, tungsten, silicon, polya ide-imide or aromatic polyamide.

The preferred compositions are of particular interest for obtaining intermediate prepregs without solvent. The impregnation of the fibrous material can be carried out by application of the usual techniques such as immersion, coating with doctor blade or curtain or impregnation by transfer. The transferable film and the prepregs can be used directly or stored for later use; they remarkably retain their properties during cold storage between 0 and 10 ° C. The preferred compositions used for this application preferably have a melt viscosity of between 2 Pa.s and 50 Pa.s.

The prepreg materials can be used for the production of parts having various shapes and functions in many industries such as for example in aeronautics. These parts which may be parts of revolution are obtained by plating several layers of prepregs on a form or a support. One can also use prepregs as reinforcements or means of repairing deteriorated parts. But it is also possible to design parts according to the technique of filament winding with or without support, intended for the production of parts of revolution, a technique used in particular for making parts relating to the automotive and aeronautical industries. The preferred compositions used in this technique preferably have a viscosity in the molten state of between 0.1 Pa.s and 2 Pa.s. Curable compositions according to the invention can be cured (or crosslinked) by heating at temperatures between 100 and 250 ^° C, for 10 minutes to 25 hours, optionally under pressure. Before crosslinking, in the case of the preparation of the preferred compositions, the latter are in the form of a prepolymer consisting of a single phase; the products derived from the polyimide siloxane component (B) and optionally from the additive (D) are indeed soluble in the product derived from the polyfunctional cyanate ester component (A). In the course of crosslinking, as the reactions relating to the groups - (- 0-CN) still free, a phase separation phenomenon develops and finally a hardened composition is recovered having a biphasic structure consisting a continuous phase rich in product from the starting cyanate ester and a discontinuous phase, formed of particles of the order of 0.01 to 1 μi, rich in product from the starting elastomer component (B). The examples which follow illustrate in a nonlimiting manner how the present invention can be put into practice.

In these examples, a number of checks are carried out. Likewise, various properties are measured. The procedures and / or standards according to which these checks and measurements are carried out are indicated below.

- VISCOSITY IN THE MELT CONDITION OF THE CURABLE COMPOSITION:

The viscosity in the molten state which is spoken of in the present specification is the dynamic viscosity of the composition obtained at the time of casting at the end of the preparation process carried out in bulk by heating the constituents; it is measured at 80 ^° C +/- 0.1 ^° C with a viscometer Rheomat 30 of Contraves Company equipped with a rotor rotating in a gradient of 13 s'; its value is given in Pa.s.

- SOFTENING POINT OF THE CURABLE COMPOSITION:

The approximate temperature at which a 6 mm diameter glass rod can easily sink a few mm into the material is called a softening point.

- GLASS TRANSITION TEMPERATURE OF THE HARDENED COMPOSITION t

The glass transition temperature (Tg) corresponds to the sudden drop in the modulus of elasticity as a function of temperature. It can be determined on the graph representing the variations in the modulus of elasticity (E) as a function of the temperature, variations measured by dynamic mechanical analysis, using a DMA DUPONT model 982 device, at a rate of rise in temperature of 3 ^* C / minute. The test pieces are conditioned to EHO (Zero Hygrometric State), that is to say they are placed in a desiccator on silica gel and dried for 24 hours at room temperature under 0.66-1.33.102 Pa before carrying out the measurements. - TENACITY OF THE HARDENED COMPOSITION:

The CHARPY impact resistance is determined at 20 ° C. on bar type test pieces of 80 × 10 × 4 mm not comprising a notch, conditioned to EHO, according to standard ASTM D 256. The energy of crack propagation G1C and the critical stress concentration coefficient K1C are determined on CT specimens (CT ≈ Compact Tension) according to standard ASTM E 399.

- TEST OF ADHESION OF THE HARDENED COMPOSITION ON STAINLESS STEEL: It is carried out in simple shear according to standard ASTM D

1002. The curable composition is deposited in the form of a film of 200 μ thick on the metal substrate, then it is crosslinked under pressure. The value of the shear breaking stress (6R) is measured.

- EXAMPLE 1:

1. - Example of implementation of the invention: 100 g of a 2,2-bis (4-cyanatophenyl) propane prepolymer are introduced at room temperature into a glass reactor fitted with an anchor-type stirrer. in which 30% of the functional cyanate groups have been cyclotrimerized; this product is that marketed by the company HI-TEK POLYMERS under the name AR0CY B30.

Step 1: the reactor is immersed in an oil bath preheated to 80 ^° C and its contents is stirred until complete melting of the constituent charged and a homogeneous liquid mass. The duration of this step is 5 minutes and degassing is then carried out under reduced pressure.

Step 2: the liquid mass obtained is cooled to 60 ^° C and is introduced 18 g of the siloxane bismaleimide that is described in paragraph 2 below and 0.025 g of copper acetylacetonate Cu {(CsH7θ) 2 previously dissolved in bis-maleimide siloxane. The reaction mass is maintained at 60 ° C. with stirring until a homogeneous liquid medium is obtained. The duration of this stage is 10 minutes. Then poured the reaction mixture liquid obtained in a mold preheated to 170 ^° C.

The thermosetting composition thus obtained is flexible and tacky at room temperature (20 ^° C). It has a point of neighbor softening 0 ^° C. Its viscosity at 80 ^° C is 1 Pa · s and its gel time at 170 ^° C is 8 minutes.

With this composition, the HOT-MELT type impregnation (with molten material without solvent) of fibrous materials, based for example on woven sheets of carbon fibers, to make prepreg intermediate articles, is possible in the temperature range from from 50 to 100 'C.

By immediately pouring the thermosetting composition into a mold as indicated above, plates of dimensions 140 x 100 x 4 mm can be prepared which will undergo the following cooking cycle:. 60 minutes at 170 ^* C,

. 55 minutes between 170 and 225 ^* C,. 4 p.m. at 225 ^* C,. and 2 hours between 225 and 25 ^* C.

After demolding, the plates based on hardened composition are cut to obtain test pieces of appropriate dimensions on which we measure: the glass transition temperature (Tg), the elastic modulus (E), the impact resistance CHARPY (Rc) not cut and the values of GIC and K1C.

The values found are as follows:. Tg: 235 ^* C

. E: * at 20 'C: 3.0 GPa * at 200 ^* C: 1.75 GPa . GIC: 160 J / m2. K1C: 0.66 Mpa VϋT

By way of comparison, the operations described above have been reproduced, but without using bis-maleimide siloxane. The Rc and GIC values are reduced by 50%; the moduli of elasticity E at 20 and 200 ′ C are increased by 10%. Adhesion tests on stainless steel were also carried out. The curable composition according to the example is crosslinked under a pressure of 10 ^ Pa, according to the above-mentioned cooking cycle. The values found for the shear breaking stress (6R) are as follows:

. 6R: * at 20 ^* C: 16 Mpa * at 200 ^* C: 18 MPa

These values are substantially unchanged after subjecting the samples tested aging 1000 hours at 180 ^° C. In the absence of siloxane bismaleimide, strain values of the shear breaking are 10 MPa at 20 ^° C and from 12 MPa to 200 "C.

2. Description of the process for the preparation of bis-maleimide with diorganopolysiloxane groups used in the example:

This bis-maleimide has the following formula:

2.1. - Preparation of the diamine containing a diorganopolysiloxane group from which this bis-maleimide is derived:

369 g (0.46 mole) of alpha is charged into a glass reactor fitted with a central stirrer, a dropping funnel and an ascending cooler in which a slight overpressure of dry nitrogen is established. , omega-bis (hydrogen) diorganopolysiloxane of formula:

having a reaction mass of the order of 802 g.

The reactor is then introduced into an oil bath preheated to 55 ° C., then the catalyst is added. The latter is the catalyst for KARSTED (complex based on elementary platinum and 1,3-divinyl tetramethyl-1,1,3,3 disiloxane ligands): it is in solution in toluene (concentration of 3.5% by weight ) and 1.49 cm ³ of this catalyst solution are introduced with a syringe; the ratio (weight of elementary platinum engaged / weight of the reaction mass) is equal to 91.10 " ⁶ .

137 g (0.92 mole) of etaallyloxyaniline are then gradually poured into the reactor, over a period of 60 minutes, so as to control the exothermicity of the reaction. Thirty minutes after the end of the pouring, it returns to room temperature. The product obtained, weighing 506 g, is a limpid viscous oil, of orange-brown color, having an NMR spectrum of the proton in agreement with the structure:

The molecular mass is about 1100 g. Under these conditions, the conversion rate of the reagents used is 100% (by NMR and infrared analysis, neither amine nor hydrogenated siloxane oligomer is detected) and the desired yield by weight of diamine is 100 %.

2.2. - Preparation of bis-maleimide diorgano¬ polysiloxane: In a glass reactor provided with central stirring, and an ascending cooler in which a slight overpressure of dry nitrogen is established and which is placed in a preheated oil bath at 55 "C, simultaneously introduced, in 10 minutes, using 2 dropping funnels:

- 20 cm3 of a solution in acetone of 28 g (0.025 mole and 0.02 NH2 function) of the dimaine siloxane prepared in paragraph 2.1,

- 15 cm3 of a solution in acetone of 6.4 g (0.055 mole) of maleic anhydride.

When the flows are finished, each vial is rinsed with 5 c of acetone, which are then added to the reaction mass, kept stirring for another 15 minutes.

6.1 g (0.06 mole) of acetic anhydride are loaded into the dropping funnel which has contained maleic anhydride and, into the other funnel, o charged 1.67 g (0.0165 mole) of triethylamine. These two compounds are then poured into the reactor, then 0.3 cm ³ of an aqueous solution containing 0.0528 mole of nickel acetate is added per 100 cm ³ of solution.

The reaction mixture is maintained at reflux with stirring for 2 hours 30 minutes. The temperature is then lowered to 20 ° C.

The reaction mixture is diluted with 80 cm ³ of ice water (5 ° C.) with vigorous stirring and the oily product present is then extracted with 80 cm ³ of ethyl acetate. The organic phase obtained is washed with three times 80 cm ³ of water to arrive at pH 6 in the washing waters, then dried for 2 hours over anhydrous sodium sulfate. After filtration, the ethyl acetate is evaporated off from the organic phase, completing this operation under reduced pressure (around 70 Pa) at 60 ° C. and 30.3 g are collected (ie a yield by weight of 96% by theory) of a viscous, orange-brown product, the NMR spectrum of which is in agreement with the structure of the desired bis-maleimide which was defined at the beginning of this example. The molecular mass is of the order of 1,260 g.

- EXAMPLE 2:

The operation is carried out exactly as indicated in example 1, but without loading a catalyst (copper acetylacetonate) in step 2.

At the end of step 2, the liquid reaction mass flowing into a mold preheated to 200 ^° C.

The thermosetting composition thus obtained is flexible and tacky at room temperature (20 ^# C). It has a softening point close to 0 ^* C. Its viscosity at 80 ^* C is 1 Pa.s and its gel time at 200 ^* C is 35 minutes.

With this composition, the HOT-MELT type impregnation (with molten material without solvent) of fibrous materials, based for example on woven sheets of carbon fibers, to make prepreg intermediate articles, is possible in the temperature range from from 50 to 100 ^* C.

By immediately pouring the thermosetting composition into a mold, plates of dimensions 140 x 100 x 4 mm can be prepared which will undergo the following cooking cycle: . 60 minutes at 200 'C,. 50 minutes between 200 and 250 ^* C ^,. 5 hours at 250 'C,. and 2 hours between 250 and 25 'C. After demolding, the plates based on a hardened composition are cut to obtain test pieces of appropriate dimensions on which we measure: the glass transition product (Tg), the elastic modulus (E), the impact resistance CHARPY (Rc ) not cut and the values of GIC and 1C. The values found are as follows:

- EXAMPLE 3:

In a glass reactor fitted with an anchor-type stirrer, 75 g of a prepolymer of

2,2-bis (4-cyanatophenyl) propane in which 30% of the functional cyanate groups have been cyclotimerized; this product is that marketed by the company HI-TEK POLYMERS under the name AROCY B30.

Stage 1: the reactor is immersed in an oil bath preheated to 80 ° C. and its contents are stirred until complete melting of the charged component and obtaining a homogeneous liquid mass. The duration of this step is 5 minutes and degassing is then carried out under reduced pressure.

Step 2: the liquid mass obtained is cooled to 60 ^° C and is introduced 18 g of the siloxane bismaleimide that is described in Example 1, 0.025 g of copper acetylacetonate previously dissolved in the siloxane bismaleimide and 25 g of bisphenol A di (di-oxyethylated) diacrylate {product available commercially under the registered trademark EBECRYL 150 from the company UCB}. The reaction mass is maintained at 60 ° C. with stirring until a homogeneous liquid medium is obtained. The duration of this stage is 10 minutes. The liquid reaction mass obtained is then poured into a mold preheated to 170 ° C. The thermosetting composition thus obtained is flexible and tacky at room temperature (20 ^° C). It has a point of neighbor softening -10 ^° C. Its viscosity at 80 ^° C is 0,5Pa.s and gel time at 170 ^° C is 10 minutes.

By immediately pouring the thermosetting composition into a mold, plates of dimensions 140 x 100 x 4 mm can be prepared which will undergo the following cooking cycle:. 60 minutes at 170 ^* C,. 55 minutes between 170 and 225 * C,. 4 p.m. at 225 ^* C,. and 2 hours between 225 and 25 ^* C. After demolding, the plates based on hardened composition are cut to obtain test pieces of appropriate dimensions on which we measure: the glass transition temperature (Tg), the elasticity modulus (E ), the impact resistance CHARPY (Rc) not cut and the values of GIC and K1C. The values found are as follows:

. Tg: 210 ^* C

. E: * at 20 'C: 3.0 GPa * at 200 ^# C: 1.0 GPa. Rc: 26 kJ / m2

. 1C: 0.79 Mpa VF

Claims

1. - Thermosetting compositions which include:

(A) - at least one cyanate ester compound chosen from the group formed by:

(1) - a polyfunctional aromatic cyanic ester, monomer, having the formula:

R - (- 0-CN) _n (I) in which: n is an integer ranging from 2 to 5 and R represents an aromatic organic radical of valence n, comprising from 6 to 30 carbon atoms where the cyanate groups are linked to the aromatic nucleus (s) of R;

(2) - a prepolymer of (1), and

(3) - a coprepolymer of (1) and an aromatic primary polyamine;

(B) - at least one elastomeric compound; and eventually :

(C) - a suitable catalyst; said compositions being characterized in that component (B) consists of at least one compound chosen from the group formed by:

in which :

- X, which is in the ortho, eta or para position with respect to the carbon atom of the benzene ring linked to nitrogen, represents a simple valential bond or an atom or a following group:

0

'I

- 0 -; - S -; - S -; - S -;

It II 0 0

- Ri, R2, R3, R4, R5, 6 _> R7 "R8", identical or different, each represent a monovalent hydrocarbon radical chosen from: alkyl radicals, linear or branched, having from 1 to 12 carbon atoms, these radicals possibly be substituted by one or more chlorine, bromine or fluorine atoms or by a -CN group; a phenyl radical optionally substituted by one or more alkyl and / or alkoxy radicals having from 1 to 4 carbon atoms or by one or more chlorine atoms;

- the symbol x is an integer located in the range from 2 to 8; - the symbols y and z represent numbers, identical or different, whole or fractional, the sum of which lies in the range from 0 to 100;

(5) - a prepolymer of (4), and

(6) - a coprepolymer of (4) and of an aromatic biprimary diamine.

2. - Thermosetting compositions according to claim 1, characterized in that with regard to the constituent (A), the symbol R of the cyanate ester of formula (I) can represent:

(i) - a radical of valence n derived from an aromatic hydrocarbon containing from 6 to 16 carbon atoms such as, for example, benzene, naphthalene, anthracene or pyrene; (2i) - a radical of valence n derived from a group comprising several aromatic rings linked together by a simple valential bond or by an inert atom or an inert divalent group such as for example the group of formula: in which R 'represents: a simple valential bond or a divalent inert atom or group such as: -0-; -S-; a linear or branched alkylene radical having from 1 to 10 carbon atoms, optionally substituted by one or more chlorine, bromine or fluorine atoms and optionally interrupted by one or more oxygen atom (s); -C0-; -SO2-; -NR "- where R" represents a hydrogen atom, an alkyl radical having from 1 to 3 carbon atoms, phenyl or cyclohexyl; -C00-;

the various aromatic groups mentioned in paragraphs (i) and (2i) may be substituted by one or more alkyl (s) or alkoxy radicals, linear or branched, containing from 1 to 4 carbon atoms or by one or more atom (s) ) halogen.

3. - Thermosetting compositions according to claim 2, characterized in that the cyanate esters (1) of formula (I) which are used consist of difunctional compounds which correspond to the formula:

in which - R '"represents a simple valential link or an atom or the following grouping:

- m is an integer equal to 0 or 1; - a is an integer equal to 0, 1 or 2, the symbols a, when there are 2, can be identical or different between them.

4. - thermosetting compositions according to any one of claims 1 to 3, characterized in that, with regard to the constituent (B), the bis-maleimide siloxane (4) is taken from the group formed by the bis-maleimides siloxane of formula (II) in which:

1) X - - 0 -; Ri - R2 - R ₃ - R4 - R5 ^" Rβ * 7 ^• Rβ" linear alkyl radical having 1 to 3 carbon atoms; x - 2, 3 or 4; y + z is in the range from 0 to 100 and preferably from 4 to 70. 2) X - - 0 -; Ri - R2 - R3 - R4 - R7 "β • linear alkyl radical having from 1 to 3 carbon atoms; R5 - Rβ - phenyl radical; x - 2, 3 or 4; y + z is in the range of 0 to 100 and preferably 4 to 70. 3) X - - 0 -; Ri - R2 - R7 - Rδ * linear alkyl radical having from 1 to

3 carbon atoms; R ₃ »R4 - R5 * Rζ - phenyl radical; x - 2, 3 or

4; y + z is in the range from 0 to 100 and preferably from 4 to 70. 4) X = - 0 -; Ri - R2 - R3 ^" R5 * R7 - Rβ * linear alkyl radical having from 1 to 3 carbon atoms; R4 "Rβ - phenyl radical; x »2, 3 or 4; y + z is in the range from 0 to 100 and preferably from 4 to 70. 5) X "- 0 -; Ri - R ₃ - R5 * R7 - linear alkyl radical having from 1 to 3 carbon atoms; R2 ^» R4 - Rô * β * phenyl radical; x ^» 2, 3 or 4; y + z is in the range of 0 to 100 and preferably 4 to 70.

5. - Thermosetting compositions according to any one of claims 1 to 4, characterized in that the catalyst (C), when one is used, is taken from the group formed by:

- compounds with labile hydrogen consisting of alcohols, phenols, carboxylic acids and primary or secondary amines,

- compounds consisting of metal carboxylates, optionally dissolved in an alkylphenol or a monoalcohol,

- compounds consisting of metal acetylacetonates, optionally dissolved in an alkylphenol.

6. • thermosetting compositions according to any one of claims 1 to 5, characterized in that the quantities of the constituents (A) and (B) are chosen so as to have, by weight relative to the weight of the assembly ( A) + (B):

- from 50 to 98% and, preferably, from 75 to 95% of constituent (A), and

- from 2 to 50% and, preferably, from 5 to 25% of elastomeric constituent (B).

7. - Thermosetting compositions according to one of claims 1 to 6, characterized in that they additionally comprise an additive (D) consisting of one or more additional compound (s) polymerizable (s) chosen from : (7) - an N, N'-bis maleimide of formula:

C - CO, C0 Z

N - G - N (VIII)

Z - C - CO CO Z

in which :

. the symbol G represents a divalent radical chosen from the group consisting of radicals: cyclohexylenes; phenylenes; 4-methyl-1,3-phenylene; 2-methyl-1,3-phenylene; 5-methyl-1,3-phenylene; 2,5-diethyl-3-methyl-1,4-phenylene; and the radicals of formula:

in which B represents a simple valential link or a grouping

(8) - a chlorinated or broached epoxy resin;

(9) - a non-halogenated epoxy resin;

(10) - an alkenylphenol of formula:

in which :

ÇH ₃

- CH2 - î - CH2 - CH2 - - 0 - S - S0 -; and - S02

CH ₃

(CH2 - CRiβ - CO - 0 - L (X)

P in which:

. the symbol Rie represents a hydrogen atom or a methyl radical; . p represents an integer or fractional number at least equal to 1 and at most equal to 8; . the symbol L represents an organic radical of valence p derived: from a saturated, linear or branched aliphatic residue, having from 1 to 30 carbon atoms and which may contain one or more oxygen bridge (s) and / or one or more function ( s) free hydroxyl (s); an aromatic residue (of aryl or arylaliphatic type) having from 6 to 150 carbon atoms constituted by a benzene ring, which may be substituted by one to three alkyl radicals having from 1 to 5 carbon atoms, or by several benzene rings, optionally substituted as indicated above, linked together by a simple valential bond, an inert group or an alkylene radical having from 1 to 3 carbon atoms, said aromatic residue being able to contain at various places in its structure one or more bridge (s ) oxygen and / or one or more free hydroxyl function (s), the free valence (s) of the aromatic L radical being able to be carried by a carbon atom d 'an aliphatic chain and / or by a carbon atom of a benzene nucleus.

8. - Thermosetting compositions according to any one of claims 1 to 7, characterized in that the catalyst (C), when one is used, is used at a rate ranging from 0.005 to 10% and, from preferably, ranging from 0.01 to 5% relative to the weight of the overall composition including (A) + (B) + optionally the (or) additional compound (s) polymerizable (s) (D).

9. - Process for the preparation of thermosetting compositions according to any one of Claims 1 to 8, characterized in that:

- is brought in a first step the cyanate ester component (A) at a temperature between 40 and 120 ^° C and preferably between 50 and 100 ° C, at which it is in a homogeneous liquid state, by operating in absence of any catalyst (C); - then, in a second step is added in the liquid medium which is stirred and maintained at a temperature identical to or different from that used in the previous step, also between 40 and 120 ^° C and, preferably, between 50 and 100 ^° C, the polyimide siloxane component (B), the stirring and the temperature being maintained for a sufficient time to obtain a homogeneous liquid medium;

- ensuring that if Ton chooses to use the optional catalyst (C), the latter is introduced in the second step, preferably in the form of a solution in the constituent (B) charged.

10. - Application of the thermosetting compositions according to any one of claims 1 to 8, in the manufacture:

- adhesives;

- structural parts according to the technique of either molding by simple hot casting or injection, or of the filament winding;

- intermediate articles pre-impregnated according to the technique of solvent-free impregnation of various fibrous materials.