AU679680B2 - Bismaleimide compounds - Google Patents

Description

OPI DATE 30/12/93 AOJP DATE 10/03/94 APPLN. ID 40542/93 PCT NUMBER PCT/AU93/00248 11111111 11111111111111111 11111111111111111 iii II IN I tKNA I UNAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT) (51) International Patent Classification 5 (11) International Publication Number: WO 93/24488 C07D 487/04, 403/14 C08G 73/10, C08L 79/08 Al (43) International Publication Date: 9 December 1993 (09.12.93) D06M 15/59 (21) Internationa ipplication Number: PCT/AU93/00248 (74) Agents: SLATTERY, John, Michael et al.; Davies Collison Cave, I Little Collins Street, Melbourne, VIC 3000 (22) International Filing Date: 27 May 1993 (27.05.93) (AU).

Priority data: (81) Designated States: AT, AU, BB, BG, BR, BY, CA, CH, PL 2658 28 May 1992(28.05.92) AU CZ, DE, DK, ES, FI, GB, HU, JP, KP, KR, KZ, LK, LU, MG, MN, MW, NL, NO, NZ, PL, PT, RO, RU, SD, SE, SK, UA, US, VN, European patent (AT, BE, (71) Applicant (for all designated States except US): COMMON- CH, DE, DK, ES, FR, GB, GR, IE, IT, LU, MC, NL, WEALTH SCIENTIFIC AND INDUSTRIAL RE- PT, SE), OAPI patent (BF, BJ, CF, CG, CI, CM, GA, SEARCH ORGANISATION [AU/AU]; Limestone GN, ML, MR, NE, SN, TD, TG).

Avenue, Campbell, ACT 2601 (AU).

(72) Inventors; and Published Inventors/Applicants (for US only) MORTON, Trevor, With international search report.

Charles [AU/AU]; 93 Orlando Street, Hampton, VIC 3188 HODGKIN, Jonathan, Howard [AU/AU]; 28 Celia Street, Burwood, VIC 3125 EIBL, Robert [AU/AU]; Old Melhourne Road, Little River, VIC 3211

(AU).

6796(54)Ti (54) Title: BISMALEIMIDE COMPOUNDS 0 0 0 0 I N-Ae-N Ar

N-A--N

o 0 0 0 (57) Abstract The invention relates to a bismaleimide compound of formula substantially free of oligomeric, amidic and uncyclized impurities, wherein Ar is an optionally substituted aromatic residue; and Ar' is an optionally substituted aromatic residue which provides either good conjugation between the nitrogen-containing groups shown in formula or steric or other restrictions capable of moderating the reactivity of an unreacted amine moiety attached to said residue, methods for their preparation and curable compositions containing them. The curable compositions may also be used in impregnated fibre reinforced materials and advanced composite materials.

WO 93/24488 PCT/AU93/00248 -1- BISMALEIMIDE COMPOUNDS This invention relates to bismaleimide compounds and polymers, particularly high temperature resistant polymers, prepared from them.

Bismaleimide derivatives of simple arydiamines can be used to prepare polyimides of good thermal stability. However, such bismaleimide derivatives are often difficult to process, and produce on curing, polymers with properties only marginally better than epoxy derived materials. Furthermore, such bismaleimides compounds have either been derivatives of relatively simple diamino compounds or ill defined products made from the co-reaction of a number of polyfunctional materials.

GB 1,137,592 and US 3,010,290 describe the preparation of bismaleimide compounds by reaction of maleic anhydride with some simple diarylamines. These products when converted to polymers with curing agents known in the art are generally more brittle than is desired for advanced composite use and as a result toughening agents are often necessary. This tends to lead to increased cost in processing and less reproducibility.

An alternative approach to improve toughness is to prepare thermally stable bi,,maleimide compounds of higher molecular weight so that on curing there will be greater molecular weight between crosslinks. However, it is a challenge to prepare relatively homogeneous materials and still retain some processibility and good thermal properties.

US 3,998,786 discloses a method of preparing maleimide terminated oligo-imide materials. This method involves a one pot reaction for preparing the curable resin of an arylimide type, relying solely on stoichiometry of the reactants (dianhydride, diamine and maleic anhydride) to determine the structure of the resulting maleimide.

WO 93/24488 PCT/AU93/00248 -2- US 3,998,786 suggests that a wide range of possible diamines and dianhydrides are suitable starting materials in synthesis, and as a consequence, some of the claimed products are alleged to have structures corresponding to those of the present application. However in our attempts to duplicate the method described in US 3,998,786 complex mixtures of chemicals, including considerable amounts of uncyclized and oligomeric material, were produced. This result is not unexpected, given the number of possible reactions, this type of synthesis would be expected to produce a complex mixture of different types of products which are very difficnl to separate. Although no data is provided in US 3,998,786, the resultant polyimides produced on curing such products could be inconsistent in properties from batch to batch including lower and variable Tg.

We have now found that substantially monomeric materials can be obtained by first preparing the monomeric diaminobisimides using the method disclosed in our International Patent Application No. PCT/AU91/00454.

According to one aspect of the present invention there is provided a bismaleimide compound of the formula substantially free of oligomeric, amidic and uncyclized impurities which may be converted into a high molecular weight polyimide polymer having improved properties: o o o o I I N-Ar-N) Ar ,N-Ar-N 0 0 0 0 WO 93/24488 PCr/AU9/00248 -3wherein: Ar is an aromatic residue; and Ar' is an optionally substituted aromatic residue which provides either good conjugation between the nitrogen-containing groups shown in formula or steric or other restrictions capable of moderating the reactivity of an unreacted amine moiety attached to said residue.

As used herein the term "good conjugation" means that during formation of the diaminobisimide precursor from a diamine of formula (II):

H

2 N-Ar'-NH2

(II)

substitution of an electron-withdrawing group on one of the nitrogen atoms suppresses the reactivity of the other nitrogen atom during the reaction as disclosed in International Patent Application No. PCT/AU91/00454.

Suitable Ar groups include aryl, bridged or bonded di- or poly-aryl or heteroaryl groups. The Ar group may be substituted with one or more alkyl, haloalkyl, alkoxy, alkylthio, aryl, heteroaryl, aryloxy, carboxy, alkylamino, dialkylamino, amino, nitro, cyano or halo groups.

"Aryl" means an aromatic carbocyclic group, such as phenyl, naphthyl, and the like.

"Bridged or bonded di- or poly- aryl" ir-" l ns a group consisting of two or more aromatic carbocyclic ring systems, such L nenyl, naphthyl or the like joined by a bond, such as in biphenyl, or a bridging group, such as in sulphonyldiphenyl. A preferred bridged di-aryl group is 2,2-bis(phenyleneoxyphenyl) propane.

WO 93/24488 PC/AU93/00248

B

-4- "Bridging group" includes for example SO 2 CO and O such as in compounds of the formula (IIIa)

R

2 (IIIa) wherein R 2 is a divalent radical such as SO 2 CO and 0.

Generally the group Ar' may be selected from the groups listed above for Ar.

However, because of the constraints imposed by the requirement of "good conjugation" or "steric or other restrictions capable of moderating reactivity of the unreacted amine moiety" (as defined above) some bridged di- or poly-aryl groups may not be suitable.

Thus for Ar', it is desirable for the briding group (if present) to provide good conjugation between the amino groups of the diamine moiety For example, there is insufficient conjugation in the group of the formula (IIIb)

H

2 N NH 2 I Rb) (Illb) WO 93/24488 PCT/AU93/00248 wherein R, is CH- 2 o~r when the diamine is 3,3'-sulphonyldianiline and oligomeric diaminoimides are present in the precursor diaminoimides. In contrast, benzidine and 4,4'-sulphonyldianilines have sufficient conjulyation and give the desired predominantly monomeric diaminobisimide compound and hence a substantially monomeric bismaleimide.

Preferably the aromatic diamine "if the formula (II) is sterically hindered, such as in compounds of the formulae and (V)

R

3 R

H

2 N

NH

2

H

2 N R R4 R6 R5NH 2 is RS wherein R 3

R

4

R

5 and R 6 are the same or different and each may be a substituent selected from the group consisting of alkyl, alkyithio, haloalkyl, aryl, heteroaryl, nitro, and halogen groups.

"Heteroaryl" means aromatic monocyclic or polycyclic groups containing at least one hetero atom such as nitrogen, oxygen or sulfur. Examples of suitable "heteroaryl" groups are: 3- to 8-membered, more preferably 5- or 6-membered, heteromonocydlic groups containing 1 to 4-nitrogen atom(s), for example, pyrrolyl, iniidazolyL, pyrazolyl, pyridyl, pyrimidyl, pyrazinyl, pyridazinyl, triazinyl; condensed heterocyclic groups' containing 1 to 5 nitrogeni atom(s), for example, indolyl, isoindolyl, indolizinyl, benzimidazolyl, quinolyl, is, inolyl, indazolyL, benzotriazolyl, etc.; 3 to 8-membered heteromonocydic groups containing 1 or 2 sulfur atom(s) and 1 to 3 nitrogen atom(s), for example, thiazolyl, isothiazolyl thiadiazolyl, etc.; 3 to 8membered heteromonocyclic groups containing 1 or 2 sulfur atom(s), for example WO 93/24488 PCT/AU93/00248 -6condensed heterocyclic groups containing 1 or 2 sulfur atom(s) and 1 to 3 nitrogen atom(s), for example, benzothiazolyl; benzothiadiazolyl, etc.; 4 to 8-membered heteromonocyclic groups containing an oxygen atom, for example, furyl, etc.; condensed heterocyclic groups containing 1 to 2 sulfur atom(s), for example, benzothienyl, etc.; and condensed heterocyclic groups containing 1 or 2 oxygen atom(s), for example, benzofuranyl, etc.

"Alkyl" groups may be straight chain or branched and contain 1 to 20 carbon atoms.

Suitable alkyl groups are methyl, ethyl, propyl, iso-propyl, n-butyl, iso-butyl, tertbutyl, n-pentyl, iso-pentyl, neo-pentyl, n-octyl, iso-octyl, decyl, cetyl, stearyl, and the like.

"Alkoxy" and "alkylthio" mean such groups in which the alkyl moiety is a branched or unbranched saturated hydrocarbon group containing from 1 to 8 carbon atoms, such as methyl, ethyl, propyl, iso-propyl, n-butyl, i-o-butyl, tert-butyl and the like.

The bismaleimide compounds of the formula as shown above wherein: Ar is an optionally substituted aromatic residue; and Ar' is phenylene substituted with one or more methyl, ethyl, methylthio or ethylthio groups; or Ar' is phenylene substituted with one or more methylthio or ethylthio groups and one or more methyl or ethyl groups;.

or Ar' is diphenylmethane substituted with one or more methyl or ethyl groups; or Ar' is a benzidine substituted with one or more methyl or ethyl groups, are novel per se and form another aspect of the present invention.

WO 93/244888 PCT/AU93/00248 -7- According to a further aspect of the present invention there is provided a method for the preparation of a bismaleimide compound as defined above, comprising reacting the appropriate diaminobisimide with maleic anhydride and cyclizing the resulting amidic acid.

In one embodiment, the appropriate diaminobisimide compound is placed in a suitable solvent such as acetone, dichloromethane or DMF and then reacted dropwise with a solution of maleic anhydride. The temperature of the reaction is usually maintained in the range of about 5 to about 70 "C and bismaleiamic acid formation is usually complete after about 2 to about 24h. The bismaleimide compound is then formed by cyclization of the bismaleiamic acid preferably by adding acetic anhydride and a base such as sodium acetate, triethylamine or K 2

CO

3 to the reaction mixture and raising the temperature for a few hours. In handling very insoluble diaminobisimide compounds, we have found that excess molten maleic anhydride is advantageously used as a solvent. The maleiamic acid produced may be freed of excess maleic anhydride by washing with dichloromethane.

According to a still further aspect of the present invention there is provided a method for the preparation of a bismaleimide compound as defined above, comprising reacting a diimine of the appropriate diaminobisimide with maleic anhydride.

The bismaleimide compound is preferably prepared by direct reaction of the diimine of the appropriate diaminobisimide and maleic anhydride by refluxing in a hydrocarbon solvent or phenolic solvent. However, pure imines of aryldiamines are only readily available from diamines with substituents on all positions ortho to the amine groups.

The bismaleimide compounds of the invention can be polymerized thermally with or without an appropriate catalyst and with or without a co-reactant.

WO 93/24488 PCT/AU93/00248 -8- The bismaleimides compounds may be reacted with curing agents to form polyimide polymers which are useful for a variety of applications including adhesives, bars, films, electronic encapsulation, moulded components and composites including composite tooling. The molecular architecture of the polyimide p'oduct can be controllably varied because of the range of starting diaminobisimide monomers that can be prepared.

Thus, the present invention also provides a curable bismaleimide composition comprising a bismaleimide compound as defined above and one or more curing agents.

Examples of curing agents include diamine, olefin, allyl ether, diene and cyanate compounds. Di-and poly- allylethers of phenols including hydroxynapthalene derivatives are particularly suitable for use in curing the bismaleimide compound of the present invention.

Another useful curing agent for bismaleimide compounds known in the art is ortho substituted propenyl (usually allyl) bisphenol A (see e.g. DE 2,627,045). EP 253 600 also describes the curing of some simple bismaleimides with bisphenol A diallyl ether.

The curable composition may also include one or more additives, such as, for example toughening polymers, inhibitors or catalysts and/or a further bismaleimide compound which is not of the formula as defined above. A small amount of hydroquinone or other additives may be added to the curable composition during the production of voidless resin bars so as to prevent "skinning" and hence entrapment of residual volatiles during the early stages of cure.

WO 93/24488 PCT/AU93/00248 -9- In a particularly preferred embodiment, the curing agent is an ether compound of the formula (VI): R'O O R4

R

2

R

3 n

(VI)

wherein n is an integer less than 9;

R

1 is hydrogen or an alkenyl group; and

R

2 and R 3 may be the same or different and is selected from one or more of alkyl, alkenyl, aryl, alkylaryl or haloalkyl groups; or

R

2 and R 3 together form part of a macrocyclic ring structure or an oxidized derivative thereof when n is 3 or greater; and

R

4 is hydrogen or alkenyl; or

R

3 and R 4 together form part of an optionally substituted heterocyclic or reduced heterocyclic ring.

In the compound of formula the alkenyl group includes allyl, 2-propenyl or crotonyl. The heterocyclic or reduced hetercyclic ring may be substituted with alkyl, branched alkyl, haloalkyl, alkenyl, branched alkenyl, alkynyl, branched alkynyl, aryl, alkylaryl, O-substituted aryl or heterocyclic groups. The macrocyclic ring structure may be a calixarene or an oxidised derivative thereof.

WO 93/24488 PCT/AU93/00248 When n is 2 and R 3 and R 4 form part of a heterocyclic or reduced heterocyclic ring in the compound of formula one carbon atom of each such ring may be common so as to form a spiro compound.

The curable bismaleimide compositions of the invention may be cured to provide composite materials at temperatures in the range of up to about 350 "C.

Thus, the present invention further provides a cured bismaleimide composition which is produced by heating the curable bismaleimide composition defined above at a temperature of up to about 350"C.

The curable compositers are also capable of complete or partial cure at temperatures in the range of about 50 °C to about 120 C if an aliphatic polyamine of the type used for low temperature epoxy resin curing is used or at higher temperatures if a mono-, di- or poly-alkenylether compound, more preferably a mono-, di- or polyallylether derivative of a phenol or naphthol is used.

The curable compositions of the present invention may also be used in the manufacture of fibre reinforced composite materials. For example, the curable compositions may be applied to reinforcing cloth such as uni-directional or woven carbon fibre either from solution (preferably a lower aliphatic ketone or halogenated hydrocarbon solvent), from a hot melt, or by powder. Application may be manual or by a machine process including those involving transfer from a precoated transfer medium.

According to the present invention there is also provided an impregnated fibre reinforced material (commonly known as a "prepreg") comprising fibre reinforcements impregnated with a curable bismaleimide composition defined above.

The impregnated fibre materials can be laid down by any suitable known method for producing composite materials such as, for example, vacuum bagging on a caul plate or an appropriate tool. The impregnated fibre reinforced materials are also suitable

I

WO 93/24488 PCT/AU93/00248 -11 for use in the production of advanced composite materials.

According to the present invention there is further provided an advanced composite material comprising an assembly of reinforcing fibres in a matrix of cured bismaleimide composition as defined above.

The bismaleimide compounds of the invention can be used in an appropriate resin composition for resin transfer moulding or for the manufacture of sheet moulded material. Another possible application is in pultrusion.

The invention is illustrated by the following non-limiting Examples. These Examples are not to be construed as limiting the invention in any way.

In the Examples, the systematic names are based on Chemical Abstracts names of related compounds. However, because of the difficulty of systematically naming these chemical structures, names given are not to be taken as limiting the chemical structure of the materials.

Erample 1 2,6-bis[3-(2,5-dihydro-2,-dioxo-lH-pyrrol-1-yl)-methyl-diethylphenylene]benzo[1,2-c:4,5-c']-dipyrrole-1,3 ,,7(1H,6H)tetomne.

(Formnua I, Ar C6H 2 Ar'= (methyl-dieth-l1,3-phenylene) Asolutionof2,6-bis(3-amino(methyl-diethyl)phenylene)-benzo[1,2-c:4,5-c ]dipyrrole- 1,3,5,7(1H,6H)-tetrone prepared as described in our Patent Application No.

PCT/AU91/00454 (5.38g, 0.01 mole) dissolved in acetone (20ml) and clarified by filtering was added slowly with stirring to a solution of maleic anhydride (1.97g, 0.02 mole) in dry acetone (5 ml) at room temperature. A few drops of triethylamine were added and the mixture was stirred at room temperature overnight. A small amount of insoluble material which had formed was filtered off with the aid of diatomaceous earth and then the filtrate was evaporated to dryness to give the crude amidic acid (7.53g). 1 H n.m.r (CDC1 3

/CD

3 0D) 1.14,m, 12H, 4xCH 3 1.98, 2.15, s, 6H, CH 3 of regioisomers; 2.44, m, 4xCH 3

CH

2 bs exchangeable, COOH; 6.36, d (J12Hz), WO 93/24488 PCT/AU93/00248 -12- 2H, CH CH; 6.64, d (J12Hz), 2H, CH CH; 7.02, 7.18, s, 2H, arom; 8.50, bs, 2H, arom.

The crude amidic acid (7.40g, 0.01 mole) was mixed with acetic anhydride (2.84ml, 0.03 mole) and anhydrous sodium acetate (0.246g, 0.003 mole) and heated on an oil bath at 90 "C for 15 min. After cooling ice/water was added and the mixture stirred for a while and then neutralized with NaHC0 3 (pH 56). The product was extracted with dichloromethane (2x50ml) and the combined extracts were washed with dilute brine, dried over Na 2

SO

4 filtered and evaporated to dryness to give the crude bismaleimide (6.85g, Purification yielded the pure bismaleimide as a yellow microcrystalline powder (0.46g, 30%) m.p 231-242 *C whose structure was confirmed by 1H and 13C nmr as well as mass spectrometry and FTIR.

Curing Properties The purified bismaleimide (16.7mg, 0.0239 mmole) and the hardener, Matrimid® 5292B (6.4mg, 0.0208 mmole) were both dissolved in dichloromethane and then the solution was evaporated to dryness. The resulting powder (5mg) was examined by DSC and a broad curing exotherm (109 dk/mole of bismaleimide) observed at 293 C. This compares to the exotherm observed with 4,4'-bismaleimidodiphenylmethane (Matrimid® 5J2A) peaking at 255 "C (136 kJ/mole).

Matrimids is a Registered Trade Mark of Ciba-Geigy Method 2 All operations were done under argon. 2,6-bis(3-amino(methyl-diethyl)phenylene)benzo[ 1,2-c -dipyrrolel,3,5,7(1H,6H)-tetrone (215.2g, 0.4 mole) in dry DMF (molecular sieve) (350ml) was cooled in ice/water until the temperature of the solution was <15 The maleic anhydride (78.44g, 0.8 mole) dissolved in dry DMF (150 ml) was added dropwise and the solution temperature kept below 15 The cooling was removed after the addition and the stirring continued for 2h at room temperature. After this time anhydrous sodium acetate (26.2g, 0.32 mole) and acetic anhydride (110 ml) were added and the mixture was heated with stirring up to 55 *C and held there for Ih before standard workup. The bismaleimidewas then recovered WO 93/24488 PCTr/AU93/00248 -13by filtration, as an off-white powder, (270.6g, 97%).

Method 3 2,6-Bis(3-amino-methyl-diethylphenylene)-benzo[1,2-c:4,5-c']-dipyrrole-1,3,5,7- (1H,6H)-tetrone (510g, CG.95 mole) and maleic anhvdride (202g, 2.06 mole) were dissolved in acetone (900 ml). The acetone solution was then evaporated to dryness and the residue heated to 1500C with stirring. The melt was kept at 150 C for min during which time water of reaction was distilled off. After cooling to 700C, ethanol (1000 ml) was added and the reaction mix stirred for 30 min. At the end of this time the product was filtered off, washed with ethanol and then dried to give the bismaleimide as an off-white solid (667g, Method 4 2,6-Bis(3-amino-methyl-diethylphenylene)-benzo[1 ,2-c:4,5-c']-dipyrrole-1,3,5,7- (1H,6H)-tetrone was reacted with methyl ethyl ketone in a mixture of toluene and acetic acid under Dean and Stark conditions to give the diimine. The diimine plus a stoichiometric amount of maleic anhydride was refluxed in m-cresol for two hours to give on workup (precipitation in ethanol and subsequent washing) the product as a fawn powder. Spectral properties were consistent with this consisting of mainly the expected bimaleimide, with some higher molecular weight material. This was confirmed by h.p.l.c.

Erample 2 2,6-bis[3-(2,5-dihydO-2,5-diao-1H-pyrrol--yi.)-(teth-phentene]benzo[1,-c:4,5-dc']-dipyrrole-1,3,5,7(1H,6H)-tetrone.

(Formula I, Ar= C6H 2 Ar'= (timeth)-1,3-phenylene) 2,6-Bis[3-amino(trimethyl)phenylene]-benzo[,2-c:4,5-c]-dipyrrole-1,3,5,7(1H,6H)tetrone as previously prepared by the method of PCTIAU91/00454. (4.82g, 0.01 mole) dissolved in dry CH 2 C1 2 (20ml) was added slowly to a solution of maleic anhydride (1.97g, 0.02 mole in CH 2 C1 2 cetone, 3:2v/v, a few drops of triethylamine were added and the solution was stirred at room temperature for 16h. The amidic acid was then filtered off as a fine solid, washed and dried (4.9g, 1H n.m.r.

WO 93/24488 WO 9324488PCI7/AU93/00248 14 (d 6 -acetone) was consistent with this being the amidic acid (AB system: 6.40, di (J12H-z); 6.90, d (J12Hz); 10.1, bs, NH).

The crude amidic acid (4.8g) was cyclized as in Example 1 and after similar workup and purification yielded bisinaleimide 3.9g). Recrystallization/reprecipitation from CHCI3/toluene yielded the bismaleimide as a light brown powder, m.p>315 0

C

Structure was confirmed by 1H- nmr, mass spectrometry and FTIR.

Curing Properties The purified bismaleimide (74.5mg, 0.116 rnmole) and the hardener, Matrimid®v 5292B (30.8 mg, O.hnmole) were both dissolved in dichioromethane and then the solution was evaporated to dryness. The resulting powder (5mg) was examined by DSC and a broad curing exotherm (155 Id/mole of bismaleimide) was observed at 276 OC. This compares to the exotherni observed with 4,4'-bismaleimidodiphenylinethane (MatrimidO 5292A) peaking at 255 0 C (136 Id/mole). A further experiment showed that a substantial amount of bismaleimide remained uncured after heating the mixture above for lh at 140 0 C and lb at 180 0 C (DSC still shows an exotherm of 82 Ud/mole of bismaleimide on this sample). After lb at 140 C, lb at 180 0 C, and 4h at 220 0 C curing was complete (as evidenced by the absence of the usual exotherm) Exrample 3 (Maleic anhydride solvent method) Preparation NN-bW~(2,S-dihydro-2,5dix-Hpn)-ype~npoopey-, crobs-13dhdo13dx-H isoindole].

(Formula 1, Ar carbonybisphen~Tene, A'phenyisulphony~pheri) The very low solubility of the starting DABI, N,N'-bis[4-aminophenylsulphonyl- [1 ,3-dihydro-1,3-dioxo-2H-isoindole] necessitated a different approach to synthesis of this bisma3timide. Maleic anhydride (20.49g, 0.209 mole) in a flask fitted with mechanical sthtTing was melted by heating in an oil bath at 90 a C. The starting DAB! (16.34g, 0.0209 mole) was added in portions to the molten maleic anhydride with stirring. At first a paste was formed but as reaction proceeded the whole mass of material solidified (about 2h). The product was allowed to cool WO 93/24488 PCT/AU93/00248 and freed of maleic anhydride by extensive washing with dichloromethane. After drying, the amidic acid was obtained as a yellow solid. This material was used as obtained in a cyclization procedure similar to that described in the examples above.

After standard workup the bismaleimide was obtained as a yellow powder. (12g, The extreme insolubility of this product precluded further purification but 'H nmr (d 7 -DMF), and ETIR confirmed its structure.

Example 4 Preparation N,N'-bis[(2,5-dihydro-2,5-dioxo-lH-pyrrol--y)-3- [1,3-dihydro-1,3-dioxo-2H-isoindole] (Formula I Ar= carbonybis(phenyene), Ar' 3-methy-diethyphenylene) This material was prepared by a method similar to that described in Example 1, Method 2. The bismaleimide was obtained as a brown powder, 300 "C Its structure was confirmed by spectral data.

Erample 5 Preparation 2,2-bis[4-[N-(2,-dihydm-2,5-dioxo-lH-pyrrol--l-1,4phenyene)-13-dihydr-1,3-dxo-2H-soindoyxypheni]propane (Bismaleimide of DABI produced from reaction of p-phenyiene diamine and ultem anhydride.

(Formula I, Ar =2,2-bis[3 and 4-phenyieneoxypheny propane, Ar' =1,4-phenylene) The precursor DABI amine (8.4g, 0.012 mole) in dry DMF (20ml) was cooled to 0 C under a blanket of argon and treated with a solution of maleic anhydride (2.4g, 0.024 mole) in dry DMF (5ml) over a few minutes keeping the temperature below 0 C. The mixture was stirred at 15 0 C for 4h. Anhydrous sodium acetate (0.79g, 0.0096 mole) and acetic anhydride (4.2 mil) were then added and the mixture stirred at 15 OC for 1h.

The reaction mixture was poured into ethanol to precipitate the product, stirred for min and then filtered. The product was washed again by stirring in ethanol, filtered and dried to give a the bismaleimide as a yellow solid (9.3g, m.p. 172- 177 0

C

Erxampe 6 Preparation 2,2-bis[4-[N-(2,5-di)dro-2,-di1x H-Pfrpygl-yi)-1,3- WO 93/24488 PCT/AU93/00248 -16- (methyl-diethylphenylene)-1,3-dihydro-l,3-dioxo-2H-isoindoyloxy]phenyl]propane (Bismaleimide of DABI produced from reaction of Ethacure*100 and ultem anhydride) (Formula I, Ar 2,-bis[3 and 4-pheenyeoxyphenyI]propane, Ar' methyl-diethyl-13phenylene) Synthesis using an adaption of method 2 in Example 1 yielded the bismaleimide as a buff coloured powder, m.p. 199-210 0

C.

Erample 7 Preparation of Cured Neat Resin Bars A mixture of the product from Example 1 (27g) and the bismaleimide of Ethacure®208 18.2g) was ground together and preheated in an oil bath at 200 *C under vacuum to remove any solvent traces. On cooling, Matrimid® 5292B (21 7g, equivalent to 1:1 stoichiometry) was added and the mixture reheated to 190 *C with stirring until the whole mass became a homogeneous liquid (approx 20 min). This mixture was degassed under vacuum (1-2mm) for 3 min and then hydroquinone (1.24g) was added and blended in rapidly. After further degassing for 3 min the resin mixture was poured into preheated moulds.

Curing was carried out at 200 *C for 3h followed by 250 *C for 5h. By this means cured samples free of voids were obtained. Tg and modulus data obtained by DMTA are listed in Table 1.

The product from Example 4 above (10.6g) and the bismaleimide of Ethacure 0 208 (6.22g) were preheated for lh at 200"C to ensure that all solvents were removed. The latter compound was combined with Matrimid® 5292B (8.2g) and heated in an oil bath at 180 C. The product from Example 4 was then added in portions to the melt to achieve a near homogeneo's melt. After degassing for 8 min a near perfectly homogeneous melt had been obtained and this was poured into a pre-heated flat Teflon® mold. The mold wais sealed and N 2 at 10psig was aprlied to the Teflon® membrane covering the resin throughout the cure. Curing was carried out at 180 0 C for Ih, 200 "C for 2h and 250 "C for 6h. The cured neat resin bar was WbO 93/24488 PCT/AU93/00248 -17dark brown in colour and virtually void free Tg and modulus data obtained by DMTA are listed in Table 1.

The same procedure as in was followed except the Matrimid® 5292B was replaced by a mixture of the diallyl ether of bisphenol A and the mono ether The same procedure as in was followed except the Matrimid® 5292B was replaced by the diallyl ether of 7,7'-dihydroxy-4,4,4',4'-tetramethyl-2,2'spirobi(chroman). Tg and modulus data obtained by DMTA are listed in Table 1.

Exanple 8 Preparation of Laminates Prepreg was made by dissolving the uncured resin mixtures in either MEK or dichloromethane and adjusting the volume to achieve a suitable viscosity for prepregging and the applied to cloth (usually Fiberite® W.322.42 or equivalent) at a rate of l.lg of resin/g of cloth. The prepregs were dried in warm air for 60 min and staged if necessary at temperatures ranging from 60-200 *C for short periods.

Ethacure@ is a Registered Trade Mark of Ethyl Corp.

Fiberite® is a Registered Trade Mark of ICI America.

A 10xOcm coupon for DMTA use was typically made by aligning 5 plies of prepreg in the warp direction and hot pressing between caul plates under a pressure of 200 psi fr Ih at 180 2h at 200 *C and 3h at 250 Table 2 lists Tg and modulus data obtained by DMTA.

WO 93/24488 WO 934488PAU93/00248 18 Table 1 Glass transition (Tan 6 curve at 1Hz) and modulus at 50 OC for various individual neat resin cures Bismaleimide Additives Curing ITg (tan 5) Modulus used Conditions (1Hz) 50 SC E'GPa Compound of EthacureeD 200 C,3h; 286 OC 1.8GPa Example 1 208BMI 250 Matritnid B ___________Hydroquinone Compound of Ethacure,320 200 11C,2h; 2820C 1.8GPa Example 1 8 250

BMI

Diallyl ether of

BPA

___________Hydroquinone Compound of Ethacuree20 200 "C,3h; 307 *C 2.4GPa Example 2 8 250

BMI

Diallyl ether of BPA Compound of Ethacure' Under N 2 261 OC Example 4 208 180 aC,1h; BMI 200 0 CA2; B 250 a C,6h WO 93/24488 WO 9324488PCT/AU93/00248 19 Table 2 Glass transition (Tan 8 curve at 1Hz) and modulus at 0 C for various individual laminates Bismaleimide Additives Conditions Tg (tan 6) Loss Mod.

used in laminate Compound of MatrimidO B 180 -C,lh 317 0 C 25.4GPa Example 1 200 250 0 C,6h Compound of Ethacure208 180 -Clh 308 oC 35.7GPa Example 2 BMI 200 C,2h MatrimidO B 250 0 C,6h Compound of Matrimids B 180 -Clh 183 OC 33.5GPa Example 3 1-Methyl-2- 200 -C,2h pyrrolidinone 250 a C,3h Compov- d of Ethacure(&208 180 C,1h 285 OC 25.4GPa Example 4 BMI 200 C,2h Diallyl ether of 250 OC,6h

BPA

Hydroquinone______ Compound of Ethacure0208 180 0 Clh 256COC 30.8GPa Example 5 BMI 200 C,2h Matrimids B 250 -C,6h -Hydroquinone- Compound of Ethacure6208 180 0 C,lh 2640C 31.6GPa Example 6 BMI 200 -C,2h Matrimid' B 250 C,6h Hydroquinone Some water uptake and thermal weight loss data obtained from laminates made from prepregs produced from these materials is shown in Table 3.

WO 93/24488 WO 9324488PCT'/AU93/00248 Table 3 Water uptake at 71 OC and thermal weight loss in air at 250 C for cured laminates Thermal Loss BMI system Additives Water uptake I day 7 days at 250 11C 1 day 7 days Compound of Matrimid B 1.50 1.67 0.52 3.37 Example 1 Compound of Ethacure 208 1.58 2.34 0.35 425 Example 2 BM[ Matrimid, B Compound of Ethacure 208 1.47 2.93 0.41 3.98 Example 4 BMI Matrimid B Compound of Ethacure 208 1.89 4.01 0.41 2.39 Example 4 BMI Diallyl ether of

BPA

Compound of Matrimid B 1.39 1.80 0.59 5.99 -Example 4 Compound of Ethacure 208 1.91 3.44 0.31 1.84 Example 5 BMI Matrimid B Compound of Matrimid B 0.71 1.13 0.41 Example 5 Compound of Ethacure 208 1.02 1.16 0.33 1.41 Example 6 BMI Matrimid B Davies Coillson Cave 24-04-97 16i:27 Throughout this spcification and the claims which follow, unless the context requires otherwise, the word "comprise", or variations such as "comprises" or "comprising", wAIl be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of anly other integer or group of integers.

Claims (8)

1. 21- THfr CLAIMS )DEF[NfNG THE INVENTION ARE AS FOLLOWS: 1. A bisrnaleimide compound of the formula substantially free of oligonmeric, amnicic and unqcyed impurities:- 0 0 0 0 I N-ArN Ar N-Ar-N 0 0 0 0 %:S .hri 0. Soo:2. bisalcmid comoun acordig t Clam 1 whreinAr(s a Go: 2 5 eri Ar is an o,-ptionall substcuyed proan gresup, 2. A bismaleimide compound according to aim one ofhepreeArin noptionally substituted aryl o an optionally substitute rdgdo one i o oy ay ranotonlysusiutdhcroaryl group. WO 93/24488 PCT/AU93/00248 -22- S. A bismaleimide compound according to any one of the preceding claims, wherein Ar and/or Ar' are substituted with one or more alkyl, haloalkyl, alkoxy, alkylthio, aryl, heteroaryl, aryloxy, carboxy, alkylamino, dialkylamino, amino, nitro, cyano or halo groups. 6. A bismaleimide compound of the formula as shown in Claim 1 wherein Ar is an optionally substituted aromatic residue and Ar' is phenylene substituted with one or more methyl, ethyl, methylthio or ethylthio groups. 7. A bismaleimide compound of the formula as shown in Claim 1 wherein Ar is an optionally substituted aromatic residue and Ar' is phenylene substituted with one or more methylthio or ethylthio groups and one or more methyl or ethyl groups. 8. A bismaleimide compound of the formula as shown in Claim 1 wherein Ar is an optionally substituted aromatic residue and Ar' is diphenylmethane substituted with one or more methyl or ethyl groups. 9. A bismaleimide compound of the formula as shown in Claim 1 wherein Ar is an optionally substituted aromatic residue and Ar' is a benzidine substituted with one or more methyl or ethyl groups. A method for the preparation of a bismaleimide compound according to any one of the preceding claims comprising reacting the appropriate diaminobisimide with maleic anhydride and cyclizing the resulting amidic acid. 11. A method for the preparation of a bismaleimide compound according to any one of Claims 1 to 9 comprising reacting a diimine of the appropriate diaminobisimide with maleic anhydride. WO 93/24488 PCT/A U93/00248 -23- 12. A curable bismaleimide composition comprising a bismaleimide compound according to any one of Claims 1 to 9 and one or more curing agents. 13. A curable bismaleimide composition according to Claim 12, wherein the curing agent is selected from diamine, olefin, allyl ether, diene and cyanate compounds. 14. A curable bismaleimide composition according to Claim 12 or Claim 13, wherein the curing agent is a mono-, di- or poly- allylether compound. A curable bismaleimide composition according to Claim 12 or Claim 13 wherein the curing agent is derived from a mono-, di- or poly- alkenylether compound. 1.6. A curable bismaleimide composition according to any one of Claims 12 to 15, wherein the curing agent is bisphenol A diallyl ether. 17. A curable bismaleimide composition according to any one of Claims 12 to 16, wherein the curing agent is a mono-, di- or poly- alkenylether derivative of a phenol or hydroxynapththalene compound. 18. A curable bismaleimide composition according to any one of Claims 12 to 17, wherein the curing agent is an ether compound of the formula (VI) R3O OR 4 R2 R3 n (VI) WO 93/24488 PCT/AU93/00248 -24- wherein n is an integer less than 9; R 1 is hydrogen or an alkenyl group; and R 2 and R 3 may be the same or different and is selected from one or more of alkyl, alkenyl, aryl, alkylaryl or haloalkyl groups; or R 2 and R 3 together form part of a macrocyclic ring structure or an oxidized derivative thereof when n is 3 or greater; and R4 is hydrogen or alkenyl; or R 3 and R 4 together form part of an optionally substituted heterocyclic or reduced he6erocyclic ring. 19. A curable bismaleimide composition according to Claim 18, wherein the alkenyl group is an allyl, 2-propenyl or crotonyl group. A curable bismaleimide composition according to Claim 18 or Claim 19, wherein R 3 and R 4 together form part of a heterocyclic or reduced heterocyclic ring substituted with one or more alkyl, branched alkyl, haloalkyl, alkenyl, branched alkyl, haloalkyl, alkenyl, branched alkenyl, alkynyl, branched alkynyl, aryl, alkylaryl, 0-substituted aryl or heterocyclic groups. 21. A curable bismaleimide composition according to any one of Claims 18 to 20, wherein n is 2 and R 3 and R 4 form part of a heterocyclic or reduced heterocyclic ring in which one carbon atom of each ring is common so as to form a spiro compound.
2. 22. A curable bismaleimide composition according to Claim 19 or Claim wherein the oxidized macrocyclic ring structure is a calixarene or a derivative thereof. Davies CoIllson Cave E)~vlee oilson ave2-04-97 16:28 CBS]J Nof
3. 23. A cuirable bisrnaleimidc comrposition accoirding to Claim 12, wherein the curing agent is a allphatic poiyarine of the type. used for low temperature epoxy resin curing.
4. 24. A curable bismaleimide composicion according to any one of Claims 12 to 23 which further comprises one or more additives selected from toughening polymners, inhibitors and catalysts. A curable bismaleimide composition viccording to any one of Claims 12 to 24 which comprises a further bismaleimide compound which is not of the formula as defined in Claim 1.
5. 26. A cured or partiaVhy cured bismaleimide composition which is produced by heating the curable bismaleimide composition according to any one of Claims 12 to 25 at a temperature Of Up to about 350'C.
6. 27. An impregnated fibre reinforced material comprising fibre reinforcements which are coated with a cur~able bismaleiM.Ide composition according to any one of Claims 12 to
7. 028. An advanced composite material comprising an assembly of reinforcing fibres in a mauix of a cured bismaleiraide composition according to Claim 26,
8. 29. A bfsirialelmide conipowic1 accurding to claim I substantially as herehlbefore dcs5cribcd withi reference to any onie of the Exwnples. A rnethod accordiig tu claimii substantially as licreinhblre described with reIlerencc to any onc of the Excamples, DATED this 241h day of April 1997 Couwizweultz Scientific aund Industrial Re.varcx Orgaisation Hly DAVIES COLLISON CAVE Ile -I 7 Patent Attorneys Ior the Applicant INTERNATIONAL SEARCH REPORT International Application No. PCTIAU93/00248 A. CLASSIFICATION OF SUBJECT MVATTER Int. C1. 5 C07D 487/04, 403/14 CO8G 73/10, C08L 79/08, D06M 15/59 According to International Patent Classification (WPC) or to both national classification and [PC B. FIELDS SEARCHED Minimum documentation searched (classification system followed by classification symbols) IPC C07D 487,VO4, 403/14 Documentation searched other than mjinum documentation to the extent that such documents are included in the fields searched AU: IPC as above Electronic data base consulted during the international search (name of data base, and where practicable, search terms used) DERWENT tetrone and pyrrol: JAPIO tetrone and pyrrol: C. DOCUMENTS CONSIDERED TO BE RELEVANT Citegory" Citation of document, with Indication, where appropriate, of the relevant passages Relevant to Claim No. A AUA 86280/91 (Commonwealth Scieatfic and Industrial Research Organisation) 1-11 16 April 1992 (16.04.92) page 21 line 9 to page 24 line 24 A AU,B, 50572/72 (462823) (FUJI PHOTO FILM CO. LTD.) 1-11 4 July 1974 (04.07.74) page 44 line I A AU,B, 2862S/57 (220290) Du Pont De Nemnours and Company) 1-11 19 December 1957 (19.12.57) column 2 lines 13-25 A US,A, 3998786 (University of Notre Dame du Lac) 1-11,26 21 December 1976 (21.12.76) column 3 lines 43 54 I] Further documents are listed [J See patent family annex. in the continuation of Box C. F Special categories of cited documents: later document pub~lished after the international ocuent efiin he ecra stae o th artwliclifiling date or priority date and not in conflict "Auoumn einn ar staev h dwihi with the application but cited to understand the not considered to o p ati peac rinciple or t nhcngth nvnto earlier document but pulse n or after the "Xx dlocument of particular relevance; the claimed international filing dat invention cannot be considered novel or cannot be document which may throw doubts on priority claim~s codered toivlea netvUtpweh o r which is cited to establish the publication date of dcnerdt involven anlonentv we h anter citation or other special reason (as specified) docunment of particular relevance; t claimed document referring to an oral disclosure, use, invention cannot be considered to involve an exhibition or other means inventive step when the document is combined document published prior to the international filing date with one or more other such documents, such but later than the priority date claimed combination being obvious to a person skilled in the ant document member of the same. patent: family Date of the actual completion of the international search Date of mailing of the international search report June 1993 (2S.06.93) 30 dUjAV 1qq3 (do 0 06 q3) Name and mailing address of the ISA/AU Authorized officer AUSTRALIAN PATENT OFFICE PO BOX 200 WODEN ACT 2606 AUSTRALIA 511. IDRUS Facsimil No. 06 2853929 Telephne No. (06) 283253 Form PcT/ISA/210 (continuation of first sheet (July 1992) coplco INTERNATIONAL B ARCH REPORT f liforination on parent nly mcmt Intc"nmdonal applicadn No. PCT/AU93100248 This Annex lists the known publication level patent family members relating to the patent documents cited in the above-mentioned international search report. The Australian Patent Office is in no way liable for these particulars which are merely given for the purpose of information. Patent Document Cited in Search Patent Family Member Report AU 86280/91 NZ 240089 WO 9206078 AU 50572/72 BE 793446 BR 7209220 CA 1041343 CH 561436 DE 2263875 FR 2169879 GB 1421123 GB 1421126 IT 974398 JP 48073147 NL 7217721 US 4269936 US 3998786 DE 2425163 FR 2230675 JP 50022091 NL 7407022 US 4055543 US 4075171 DE 2425164 FR 2230676 JP 50027883 NL 7407023 US 3897395 US 4026833 US 4026871 US 4058505 US 4060515 US 4197397 US 4537947 END OF ANNEX Form PCT/ISA/210(patent family annex)(July 1992) copke