Curable thermoset resin composition

A curable composition including a thermoset resin a curing agent component, an amount of a thermoplast component having reactive pendant and/or end groups, an organometallic curing catalyst component. The organometallic curing catalyst component is capable of forming cross-links with reactive pendant and/or end groups of the thermoset and thermoplast resins and comprises an organometallic complex compound of the formula I=M(R).sub.n, where M is selected from titanium, zirconium, hafnium, cerium, vanadium, niobium, R is selected from mono-, bi- and tri and/or tetra dentate organic ligands and n is four or six.

The present invention relates to improvements relating to resin
 compositions, in particular relating to curable thermoset resin
 compositions, such as epoxy resin compositions, by the provision of a
 suitable curing means, to the process for the preparation of such curable
 resin compositions and to the cured products thereof.
 Thermoset resins, or thermosets, are characterised by their temperature
 stability, induced in the curing stage by the onset of cross-linking. The
 resistance of this product to further application of heat (up to charring
 point) makes it eminently suitable for a wide number of applications,
 typically as structural plastics, laminates, surface coatings and
 adhesives. Additionally, the structural nature of these resins render them
 with excellent properties of mechanical and electrical strength and
 chemical resistance. The resins are additionally characterised by a low
 shrinkage on polymerisation.
 It is common practice to incorporate a certain amount of a thermoplastic
 component in curable thermoset resins to induce additional properties of
 toughness and ductility and solvent resistance which extends the useful
 range of these products.
 Conventional thermosets include the phenolics, aminoplastics, epoxys and
 some polyurethanes. Despite their wide range of usefulness, these resins
 are all characterised by a high processing cost, induced by the
 requirement for a high curing temperature in order to initiate the
 cross-linking stage of the curing process, commonly known as the
 post-curing stage. In European patent application no. EP-A-0 311 349 in
 the name of ICI Composites Inc are described epoxy resins requiring a
 curing temperature of the order of 180.degree. C. or more, with the
 inclusion of a catalyst, in particular, curable resin compositions
 comprising a thermoset resin component, together with a thermoplastic
 resin component for property modification, and a poly aryl sulphone curing
 agent. The curable resins typically pass through a glass transition
 temperature at 120.degree. C. but require elevated temperatures of
 180.degree. C. or more for post-curing, to raise the glass transition
 temperature (Tg). Typically curing is carried out at elevated pressure in
 the region of 3 to 7 bar, requiring the use of an autoclave or the like,
 increasing further both equipment and operation costs.
 Whilst it is true that a lower than optimum temperature may be employed,
 this requires increase in cure time and the possibility that cross-linking
 may nevertheless not be absolute or that properties may be otherwise
 compromised, and nevertheless delivers little or no economic saving due to
 maintaining the selected temperature for a prolonged period. In industrial
 application, this is moreover significant since the productivity would be
 significantly reduced were it necessary to cure thermoset products for up
 to 18 hours, moreover taking up valuable autoclave time.
 In certain applications thermoset resins are employed for the preparation
 of products which are to be produced in limited number as "designer"
 products, or intended for a small specialist market, or for the
 preparation of products which have a limited life cycle, not by virtue of
 their physical or mechanical integrity, but rather by virtue of changes in
 market demands and renewal of appearance or design. This is a severe
 limitation of the commercial potential of such products, since the high
 processing temperatures employed for their preparation necessitate the use
 of high temperature resistant moulds or tools where such products are made
 by means of moulding processes. It would be readily apparent that the most
 temperature resilient tools which are able to maintain their moulding
 integrity at the required temperatures in excess of 180.degree. C., are
 typically constructed of metals and as such are expensive to commission
 and will be required to pay back over a relatively long period of time.
 This is particularly the case for example, for the manufacture of panels
 such as for use in the specialist aerospace industry or in the
 construction of vehicle, caravan, mobile home or motorbike body shells or
 the like which are typically subject to fluctuating demands of fashion
 induced by severe competition, and of technology demanding changes in body
 shell shape for improved stream-lining, road holding, compatibility with
 other technical components, weight reduction and the like. Application to
 other products, for example for use in the construction of composite
 furniture such as household, office or garden items is also envisaged, for
 the above reasons.
 Accordingly, there is need for a curable thermoset resin which may be cured
 at a temperature which is less than that corresponding to the maximum
 temperature resistance of a suitable composite material which may be
 employed as a mould and which mould is required to serve for only a
 limited number of products and/or a limited lifetime. Moreover there is a
 need for such curable thermoset resin for the preparation of composite
 objects or products at low industrial processing cost. Moreover there is a
 need in some applications for such curable thermoset resin for the
 preparation of composite objects or products which are unmodified in
 respect of their mechanical and physical properties by virtue of the
 modified curable resin and accordingly are able to meet the demands to
 which the products will be subjected, for example for application in the
 manufacture of panels as hereinbefore described and in particular
 aerospace product, racing car, motor car and motorbike panels which must
 be able to perform to a high level of reliability in terms of mechanical
 and physical properties.
 We have now surprisingly found a resin composition and a process for the
 preparation thereof which meet the above mentioned requirements in
 admirable manner, specifically by means of incorporation of a certain
 class of compounds within a curable thermoset resin composition, which
 compounds enable the curing at reduced temperature.

There is therefore provided, in its broadest aspect, according to the
 present invention a curable composition comprising:
 (a) a thermoset resin component;
 (b) a curing agent component;
 (c) an amount of a thermoplast component; and
 (d) an organometallic curing catalyst component.
 Reference herein to components a), b), c) and/or d) is to the active
 monomer compound, partially cured resin precursor, oligomer or the like,
 to the functionally protected inactive equivalent or to any form commonly
 employed in the art. The properties of the invention may be evident in the
 curable composition but are normally evident only in the cured form
 thereof.
 It will be appreciated that Component a) may be suitably selected from the
 group consisting of an epoxy resin, an addition-polymerisation resin,
 especially a bis-maleimide resin, a formaldehyde condensate resin,
 especially a formaldehyde-phenol resin, a cyanate resin, an isocyanate
 resin and mixtures of two or more thereof, and is preferably an epoxy
 resin derived from the mono or poly-glycidyl derivative of one or more of
 the group of compounds consisting of aromatic diamines, aromatic
 monoprimary amines, aminophenols, polyhydric phenols, polyhydric alcohols,
 polycarboxylic acids and the like, or a mixture thereof. Examples of
 addition-polymerisation resins are acrylics, vinyls, bis-maleimides, and
 unsaturated polyesters. Examples of formaldehyde condensate resins are
 urea, melamine and phenols.
 More preferably the Component a) comprises at least one epoxy resin
 precursor, which is liquid at ambient temperature for example as disclosed
 in EP-A-0 311 349 or in PCT/GB/95/01303, selected from
 N,N,N'N'-tetraglycidyl diamino diphenylmethane (eg "MY 9663", "MY 720" or
 "MY 721" sold by Ciba-Geigy) viscosity 10-20 Pa s at 50.degree. C.; (MY
 721 is a lower viscosity version of MY720 and is designed for higher use
 temperatures);
 N,N,N',N'-tetraglycidyl-bis(4-aminophenyl)-1,4-diiso-propylbenzene (eg
 Epon 1071 sold by Shell Chemical Co) viscosity 18-22 Poise at 110.degree.
 C.;
 N,N,N',N'-tetraglycidyl-bis(4-amino-3,5-dimethylphenyl)-1,4-diisopropylben
 zene, (eg Epon 1072 sold by Shell Chemical Co) viscosity 30-40 Poise at
 110.degree. C.; triglycidyl ethers of p-aminophenol (eg "MY 0510" sold by
 Ciba-Geigy), viscosity 0.55-0.85 Pa s at 25.degree. C.; preferably of
 viscosity 8-20 Pa at 25.degree. C.; preferably this constitutes at least
 25% of the epoxy components used; diglycidyl ethers of bisphenol A based
 materials such as 2,2-bis(4,4'-dihydroxy phenyl) propane (eg "DE R 661"
 sold by Dow, or "Epikote 828" sold by Shell), and Novolak resins
 preferably of viscosity 8-20 Pa s at 25.degree. C.; glycidyl ethers of
 phenol Novolak resins (eg "DEN 431" or "DEN 438" sold by Dow), varieties
 in the low viscosity class of which are preferred in making compositions
 according to the invention; digylcidyl 1,2-phthalate, eg GLY CEL A-100;
 diglycidyl derivative of dihydroxy diphenyl methane (Bisphenol F) (eg "PY
 306" sold by Ciba Geigy) which is in the low viscosity class. Other epoxy
 resin precursors include cycloaliphatics such as
 3',4'-epoxycyclohexyl-3,-4-epoxycyclohexane carboxylate (eg "CY 179" sold
 by Ciba Geigy) and those in the "Bakelite" range of Union Carbide
 Corporation.
 The Component a) is suitably the product of at least partly curing a resin
 precursor using a curing agent and optionally a catalyst.
 The Component b) is suitably selected from any known curing agents, for
 example as disclosed in EP-A-0 311 349 or in PCT/GB95/01303, which are
 incorporated herein by reference, such as an amino compound having a
 molecular weight up to 500 per amino group, for example an aromatic amine
 or a guanidine derivative. Particular examples are 3,3'- and
 4-,4'-diaminodiphenylsulphone, (available as "DDS" from commercial
 sources), methylenedianiline,
 bis(4-amino-3,5-dimethylphenyl)-1,4-diisopropylbenzene (available as EPON
 1062 from Shell Chemical Co); bis(4-aminophenyl)-1,4-diisopropylbenzene
 (available as EPON 1061 from Shell Chemical Co);
 4-chlorophenyl-N,N-dimethyl-urea, eg Monuron;
 3,4-dichlorophenyl-N,N-dimethyl-urea, eg Diuron and dicyanodiamide
 (available as "Amicure CG 1200 from Pacific Anchor Chemical). Such amine
 curing agents are additional to the Component c) if such is an amine-ended
 thermoplast; thus the composition preferably contains epoxy-reactive
 amines of two types, one having a molecular weight up to 500 per amine
 group, the other having a molecular weight of at least 5000 per amine
 group and the total amine content being in the range 70-110% of the
 stoichiometric requirement of the epoxy resin precursor. Other standard
 epoxy curing agents such as aliphatic diamines, amides, carboxylic acid
 anhydrides, carboxylic acids and phenols can be used if desired.
 Conventionally, and as described in EP-A-0 311 349 or in PCT/GB95/01303, a
 catalyst for the epoxy resin component/curing agent reaction may also be
 used, typically a Lewis acid or a base. According to the present invention
 however it is convenient to dispense with such catalyst and in place
 thereof to employ a component d) as hereinbefore defined.
 The Component c) suitably comprises at least one thermoplastic polyaryl
 sulphone component, for example as defined in EP-A-0- 311 349, comprising
 at least one polyaryl sulphone comprising ether-linked repeating units,
 optionally additionally comprising thioether-linked repeating units, the
 units being selected from the group consisting of
EQU --(PhSO.sub.2 Ph).sub.n --
 and optionally additionally
EQU --(Ph).sub.a --
 wherein Ph is phenylene, n=1 to 2 and can be fractional, a=1 to 3 and can
 be fractional and when a exceeds 1, said phenylenes are linked linearly
 through a single chemical bond or a divalent group other than --SO.sub.2
 -- or are fused together, provided that the repeating unit --(PhSO.sub.2
 Ph).sub.n -- is always present in said at least one polyarylsulphone in
 such a proportion that on average at least two of said units --(PhSO.sub.2
 Ph).sub.n -- are in sequence in each polymer chain present, said at least
 one polyarylsulphone having reactive pendant and/or end groups of formula
 --A'--Y where A' is a divalent hydrocarbon group and Y is a group selected
 from groups providing active hydrogen, epoxy, cyanate, isocyanate, vinyl,
 allyl, ethynyl and maleimide functionality.
 Preferably the polyarylsulphone component comprises polyether sulphone,
 more preferably a combination of polyether sulphone and of polyether ether
 sulphone linked repeating units, in which the phenylene group is meta- or
 para- and is preferably para, and wherein the phenylenes are linked
 linearly through a single chemical bond or a divalent group other than
 sulphone, or are fused together. By "fractional" reference is made to the
 average value for a given polymer chain containing units having various
 values of n or a.
 Additionally, as also discussed, in said at least one polyarylsulphone, the
 relative proportions of the said repeating units is such that on average
 at least two units (PhSO.sub.2 Ph).sub.n are in immediate mutual
 succession in each polymer chain present and is preferably in the range
 1:99 to 99:1, especially 10:90 to 90:10, respectively. Typically the ratio
 is in the range 25-50 (Ph).sub.a, balance (Ph SO.sub.2 Ph).sub.n. In
 preferred polyarylsulphones the units are.
 1 X Ph SO.sub.2 Ph X Ph SO.sub.2 Ph ("PES") and
 11 X (Ph)a X Ph SO.sub.2 Ph ("PEES")
 where X is O or S and may differ from unit to unit; the ratio of 1 to 11
 (respectively) preferably between 10:90 and 80:20 especially between 10:90
 and 55:45.
 The preferred relative proportions of the repeating units of the
 polyarylsulphone may be expressed in terms of the weight percent SO.sub.2
 content, defined as 100 times (weight of SO.sub.2)/(weight of average
 repeat unit). The preferred SO.sub.2 content is at least 22, preferably 23
 to 25%. When a=1 this corresponds to PES/PEES ratios of at least 20:80,
 preferably in the range 35:65 to 65:35.
 The above proportions refer only to the units mentioned. In addition to
 such units the polyarylsulphone may contain up to 50 especially up to 25%
 molar of other repeating units: the preferred SO.sub.2 content ranges (if
 used) then apply to the whole polymer. Such units may be for example of
 the formula.
 ##STR1##
 in which A is a direct link, oxygen, sulphur, --CO-- or a divalent
 hydrocarbon radical. When the polyarylsulphone is the product of
 nucleophilic synthesis, its units may have been derived for example from
 one or more bisphenols and/or corresponding bisthiols or phenol-thiols
 selected from hydroquinone, 4,4'-dihydroxybiphenyl, resorcinol,
 dihydroxynaphthalene (2,6 and other isomers), 4,4'-dihydroxybenzophenone,
 2,2'-di(4-hydroxyphenyl) propane and -methane.
 If a bis-thiol is used, it may be formed in situ, that is, a dihalide as
 described for example below may be reacted with an alkali sulphide or
 polysulphide or thiosulphate.
 Other examples of such additional units are of the formula
 ##STR2##
 in which Q and Q', which may be the same or different, are CO or SO2; Ar is
 a divalent aromatic radical; and n is 0, 1, 2, or 3, provided that n is
 not zero where Q is SO2. Ar is preferably at least one divalent aromatic
 radical selected from phenylene, biphenylene or terphenylene. Particular
 units have the formula.
 ##STR3##
 where m is 1, 2 or 3. When the polymer is the product of nucleophilic
 synthesis, such units may have been derived from one or more dihalides,
 for example selected from 4,4'-dihalobenzophenone, 4,4'
 bis(4-chlorophenylsulphonyl)biphenyl, 1,4 bis(4-halobenzoyl)benzene and
 4,4'-bis(4-halobenzoyl)biphenyl.
 They may of course have been derived partly from the corresponding
 bisphenols.
 The polyarylsulphone may be the product of nucleophilic synthesis from
 halophenols and/or halothiophenols. In any nucleophilic synthesis the
 halogen if chlorine or bromine may be activated by the presence of a
 copper catalyst. Such activation is often unnecessary if the halogen is
 activated by an electron withdrawing group. In any event fluoride is
 usually more active than chloride. Any nucleophilic synthesis of the
 polyarylsulphone is carried out preferably in the presence of one or more
 alkali metal carbonates in up to 10% molar excess over the stoichiometric
 and of an aromatic sulphone solvent, at a temperature in the range
 150-350.degree. C.
 If desired, the polyarylsulphone may be the product of electrophilic
 synthesis.
 As previously mentioned, said at least one polyarylsulphone contains end
 groups and/or pendant groups of formula --A'--Y where A' is a divalent
 hydrocarbon group, preferably aromatic, and Y is a group reactive with
 epoxide groups or with a curing agent or with like groups on other polymer
 molecules. Examples of Y are groups providing active hydrogen especially
 OH, NH.sub.2, NHR or --SH, where R is a hydrocarbon group containing up to
 8 carbon atoms, or providing other cross-linking reactivity especially
 epoxy, cyanate, isocyanate, acetylene or ethylene, as in vinyl, allyl or
 maleimide.
 The number average molecular weight of the polyarylsulphone is suitably in
 the range 2000 to 60000. Preferably it is over 9000 especially over 10000
 for example 11000 to 25000 and structurally as well as by chemical
 interaction increases toughness by comparison with that of the thermoset
 resin alone by providing zones of the tough thermoplast between
 cross-linked thermoset zones. Another useful sub-range is 3000-11000,
 especially 3000-9000 in which it acts more as chain-extender for the
 thermoset resin, separating and diluting local cross-links and thus
 toughening the structure. Within the above definition of the
 polyarylsulphone those are preferably chosen which are miscible with
 suitable epoxy resin precursors, have high modulus and Tg and are tough.
 The weight proportion of thermoplast component in the composition is
 typically in the range 5 to 90%, especially 20 to 50, for example 25 to
 40%.
 The Component d) is suitably selected from organometallic compositions or
 compounds which are capable of forming cross-links with reactive pendant
 and/or end groups, such as the epoxy or hydroxy groups of the thermoset
 resins and the groups A'Y of the thermoplast resins, and suitably are of
 reactivity adapted for the advancement of the resin composition of the
 invention only when subjected to the desired conditions of elevated
 temperature. Preferably the Component d) comprises a class of
 organometallic complex compounds represented by the formula I:
EQU M(R).sub.n (I)
 wherein M is any suitable metal able to support organic ligands, R is
 selected from known mono-, bi- and tridentate organic ligands and n is the
 coordination number of the metal, and active intermediates or combination
 products thereof. Suitably M is selected from the transition elements and
 the lanthanides, preferably from titanium, zirconium, hafnium, cerium,
 vanadium, niobium, more preferably from titanium and zirconium, whereby n
 is four or six.
 Suitably R is selected from organic ligands comprising one or more
 nucleophilic units or moieties, for example selected from straight or
 branched, short or long chain alcohols, amines, acids, esters, phosphates,
 ketones, anhydrides or the like which may optionally be additionally
 functionalised, and combinations thereof in the form or mono, bi, tri
 and/or tetradentate ligands, suitably of a combination of monodentate
 ligands with one or more bi, tri or tetradentate ligands, which
 multidentate or chelate ligands for example are suitably selected from
 glycols, alkanolamines, alpha-hydroxy acids, .beta.-keto-esters and acid
 phosphates and combinations thereof. In a preferred embodiment the
 Component d) comprises an organo titanate wherein two of the organic
 ligands comprise monodentate ligands such as alcohols and a further two
 comprise bidentate chelate ligands as hereinbefore defined, however the
 ligands may be present in any combination of multiplicity and type.
 The component d) may comprise at least in part, an amount of compound of
 formula I as hereinbefore defined which has been pre-reacted to form
 multinuclear complex, oligomeric or combination products.
 Organo titanates are known, and commercially available for example from
 Tioxides Specialities Limited, and are used in a number of applications in
 the manufacture and modification of synthetic and natural products. The
 wide range of application of such compounds is however coupled with a wide
 range of effects, whereby it is not possible to predict the nature or
 effect thereof on specific systems without resorting to detailed
 experimentation. According to the present invention it has surprisingly
 been found that the incorporation of component d) in suitable manner, and
 in particular comprising an organotitanate as hereinbefore defined may
 enable the curing of the hereinbefore defined thermoset resin composition
 at significantly lowered temperature, and advantageously in a preferred
 aspect with no deleterious effect on the mechanical and physical
 properties thereof. In a particularly preferred aspect of the invention
 certain organotitanates enable the preparation of a thermoset resin as
 hereinbefore defined having morphologies superior to the corresponding
 resin which is prepared in absence of the organotitanate.
 In a particularly advantageous aspect of the present invention the
 organometallic component d) may be selected for its specific application,
 either by virtue of the nature of Components a), b) and c) as hereinbefore
 defined or by virtue of the required processing temperature, processing
 time, mechanical or physical properties or the like which are desired.
 Preferably therefore there is provided according to the present invention a
 thermoset resin composition as hereinbefore defined comprising the
 components a), b) and c) as hereinbefore defined and a component d)
 wherein component d) comprises one or more organotitanates represented by
 the formula II:
EQU Ti(R').sub.4 (II)
 wherein R' is selected from organic ligands as hereinbefore defined with
 reference to R, and suitably is selected from ligands comprising primary,
 secondary and tertiary C.sub.2 -C.sub.18 moieties, for example comprising
 n- or i-propyl, n-, i- or t- butyl, pentyl, hexyl, heptyl or octyl
 moieties, and active intermediates or combination products thereof.
 In a particularly preferred aspect of the invention, the compound of
 formula II as hereinbefore defined comprises one or more monodentate
 ligands selected from alcohols and amines as hereinbefore defined
 optionally in combination with one or more bidentate ligands selected from
 glycols, alcohol amines, alphahydroxy acids, .beta.-ketone esters and acid
 phosphates as hereinbefore defined. Preferably any ligand comprises a
 suitable carbon chain link of the order C.sub.2 -C.sub.18 as hereinbefore
 defined which is compatible with the other components of the composition
 and the desired rigidity of cross-linking.
 Preferably the component d) is present, calculated as the active resin
 without any added solvent or the like, in an amount of up to 15 parts by
 weight, preferably in excess of 0.5 parts by weight, for example in the
 range of 1 to 12 parts by weight, and most preferably in the range of 3 to
 10 parts by weight with respect to the total weight of the components a)
 to c). The amount of component d) will be determined by the nature of the
 components a), b) and c) with which it may cross-link and by the
 particular component d), for example an organo titanate being employed.
 In a particularly advantageous aspect of the invention thermoset resins
 comprising an amount of thermoplast component as taught in EP-A-0 311 349
 having excellent morphological properties, typically comprising a fine
 co-continuous morphology, are also obtained with the use of certain
 components d) as hereinbefore defined.
 Moreover other properties such as the glass transition temperature, and
 mechanical properties of yield stress, modulus, ductility and the like may
 be advantageously enhanced according to the present invention. In
 particular it has been found that the composition comprising component d)
 as hereinbefore defined wherein at least one and preferably two of the
 groups R comprise a strongly nucleophilic chelate ligand, and most
 specifically comprise two or more ligands selected from chelates alcohol
 amine, .beta.-keto-acids, -esters and -ketones and the like, provide cured
 products having excellent mechanical and physical properties.
 The components a) to d) as hereinbefore defined are commercially available,
 or the preparation of components a) to c) is taught in hereinbefore
 mentioned EP-A-0 311 349 and or in PCT/GB95/01303.
 The component d) as hereinbefore defined is suitably obtained for example
 from the commercially available tetrachloro compound, by means of the
 substitution reaction with an alcohol and substituting further as
 appropriate. In fact the compounds n-propyl, isopropyl and n-butyl
 titanate are industrially manufactured, whereby the preparation of the
 desired component d) is suitably performed by means of the following
 reaction:
EQU Ti(O--iC.sub.3 H.sub.7).sub.4 +4ROH.fwdarw.Ti(OR).sub.4 +4iC.sub.3 H.sub.7
 OH
 wherein R is as hereinbefore defined with reference to component d).
 In a further aspect of the invention there is provided a composition for
 use in the curing of thermoset resins as hereinbefore defined with
 reference to components a), b) and c) comprising an organometallic
 compound as hereinbefore defined with reference to component d).
 In a further aspect of the invention there is provided the use of compound
 of formula I as hereinbefore defined, in the preparation of a component d)
 as hereinbefore defined for the curing of thermoplast-modified thermoset
 resins as hereinbefore defined.
 In a further aspect there is provided according to the invention the use of
 a precursor or intermediate in the preparation of a compound of the
 formula I as hereinbefore defined for the preparation of a compound d) as
 hereinbefore defined for the curing of thermoplast-modified thermoset
 resins compositions as hereinbefore defined.
 The composition is particularly suitable for fabrication of structures,
 including load-bearing or impact resisting structures. For this purpose it
 may contain a reinforcing agent such as fibres. Fibres can be added short
 or chopped typically of mean fibre length not more than 2 cm, for example
 about 6 mm. Alternatively, and preferably, the fibres are continuous and
 may, for example, be unidirectionally-disposed fibres or a woven fabric,
 ie the composite material comprises a prepreg. Combinations of both short
 and/or chopped fibres and continuous fibres may be utilised. The fibres
 may be sized or unsized. Fibres can be added typically at a concentration
 of 5 to 35, preferably at least 20%, by weight. For structural
 applications, it is preferred to use continuous fibre for example glass or
 carbon, especially at 30 to 70, more especially 50 to 70% by volume.
 The fibre can be organic, especially of stiff polymers such as poly
 paraphenylene terephthalamide, or inorganic. Among inorganic fibres glass
 fibres such as "E" or "S" can be used, or alumina, zirconia, silicon
 carbide, other compound ceramics or metals. A very suitable reinforcing
 fibre is carbon, especially as graphite. Graphite fibres which have been
 found to be especially useful in the invention are those supplied by Amoco
 under the trade designations T650-35, T650-42 and T300; those supplied by
 Toray under the trade designation T800-HB; and those supplied by Hercules
 under the trade designations AS4, AU4, IM 8 and IM 7.
 Organic or carbon fibre is preferably unsized or is sized with a material
 that is compatible with the composition according to the invention, in the
 sense of being soluble in the liquid precursor composition without adverse
 reaction or of bonding both to the fibre and to the
 thermoset/thermoplastic composition according to the invention. In
 particular carbon or graphite fibres that are unsized or are sized with
 epoxy resin precursor or thermoplast such as polyarylsulphone are
 preferred. Inorganic fibre preferably is sized with a material that bonds
 both to the fibre and to the polymer composition; examples are the
 organo-silane coupling agents applied to glass fibre.
 The composition may contain for example conventional toughening agents such
 as liquid rubbers having reactive groups, aggregates such as glass beads,
 rubber particles and rubber-coated glass beads, filler such as
 polytetrafluorethylene, silica, graphite, boron nitride, mica, talc and
 vermiculite, pigments, nucleating agents, and stabilisers such as
 phosphates. The total of such materials and any fibrous reinforcing agent
 in the composition should be at least 20% by volume, as a percentage of
 the total volume of the polysulphone/thermoset mixture. The percentages of
 fibres and such other materials are calculated on the total composition
 after curing at the hereinbelow defined temperatures.
 The first composition precursor is made by mixing the polysulphone,
 thermoset precursor and (at some stage) any fibrous reinforcing agent and
 other materials. A solvent may be present. The solvent and the proportion
 thereof are chosen so that the mixture of polymer and resin precursor form
 at least a stable emulsion, preferably a stable apparently single-phase
 solution. The ratio of solvent to polysulphone is suitably in the range
 5:1 to 20:1 by weight. Preferably a mixture of solvents is used, for
 example of a halogenated hydrocarbon and an alcohol, in a ratio suitably
 in the range 99:1 to 85:15. Conveniently the solvents in such a mixture
 should boil at under 100.degree. C. at 1 atm pressure and should be
 mutually miscible in the proportions used. Alternatively the polysulphone
 and thermoset or precursor can be brought together by hot melting and/or
 high shear mixing.
 The mixture is stirred until sufficiently homogeneous. Thereafter any
 solvent is removed by evaporation to give a concentrated first composition
 precursor. Evaporation is suitably at 50-200.degree. C. and, at least in
 its final stages, can be at subatmospheric pressure, for example in the
 range 13.33 Pa to 1333 Pa (0.1 to 10 mm Hg). The concentrated first
 composition precursor preferably contains up to 5% w/w of volatile
 solvent, to assist flow when used to impregnate fibres. This residual
 solvent will be removed in contact with the hot rollers of the
 impregnating machine.
 The stable emulsion may be stored as appropriate. For further processing
 thereof, the emulsion must be destabilised to a desired extent, typically
 by addition of the curing agent in suitable nature and amount, and/or
 changing temperature and adding or removing solvent. The curing catalyst
 component d) is then added. The solution is stirred to ensure uniform
 distribution of both components and may be cooled and stored as a stable
 emulsion.
 It is an advantage of the present invention that the component d) is
 typically in the liquid form at or close to room temperature.
 The composition of the invention may be cured in known manner. Suitably the
 composition in form of a resin solution is transferred onto a suitable
 mould or tool for preparation of a panel, prepreg or the like, the mould
 or tool having been preheated to a desired degassing temperature.
 The stable emulsion is combined with any reinforcing, toughening, filling,
 nucleating materials or agents or the like, and the temperature is raised
 to initiate curing thereof. Suitably curing is carried out at elevated
 temperature up to 150.degree. C., preferably in the range of 100 to
 130.degree. C., more preferably at about 120-125.degree. C., and with use
 of elevated pressure to restrain deforming effects of escaping gases, or
 to restrain void formation, suitably at pressure of up to 10 bar,
 preferably in the range of 3 to 7 bar abs. Suitably the cure temperature
 is attained by heating at up to 5.degree. C./min, for example 2.degree. C.
 to 3.degree. C./min and is maintained for the required period of up to 9
 hours, preferably up to 6 hours, for example 3 to 4 hours. Pressure is
 released throughout and temperature reduced by cooling at up to 5.degree.
 C./min, for example up to 3.degree. C./min. Post-curing at temperatures in
 the range of 150.degree. C. to 180.degree. C. may be performed, at
 atmospheric pressure, employing suitable heating rates to improve the
 glass transition temperature of the product or otherwise.
 The concentrated first composition precursor, possibly containing some
 volatile solvent already present or newly added, can be used for example
 as an adhesive or for coating surfaces or for making solid structures by
 casting possibly in a foamed state. Short fibre reinforcement may be
 incorporated with composition precursor prior to curing thereof.
 Preferably a fibre-reinforced composition is made by passing essentially
 continuous fibre into contact with such precursor composition. The
 resulting impregnated fibrous reinforcing agent may be used alone or
 together with other materials, for example a further quantity of the same
 or a different polymer or resin precursor or mixture, to form a shaped
 article. This technique is described in more detail in EP-A-56703, 102158
 and 102159.
 A further procedure comprises forming incompletely cured composition into
 film by for example compression moulding, extrusion, melt-casting or
 belt-casting, laminating such films to fibrous reinforcing agent in the
 form of for example a non-woven mat of relatively short fibres, a woven
 cloth or essentially continuous fibre in conditions of temperature and
 pressure sufficient to cause the mixture to flow and impregnate the fibres
 and curing the resulting laminate.
 Plies of impregnated fibrous reinforcing agent, especially as made by the
 procedure of one or more of EP-A 56703, 102158, 102159, can be laminated
 together by heat and pressure, for example by autoclave, vacuum or
 compression moulding or by heated rollers, at a temperature above the
 curing temperature of the thermosetting resin or, if curing has already
 taken place, above the glass transition temperature of the mixture,
 conveniently at least 120.degree. C. and typically up to 150.degree. C.,
 and at a pressure in particular in excess of 1 bar, preferably in the
 range of 1-10 bar.
 The resulting multi-ply laminate may be anisotropic in which the fibres are
 continuous and unidirectional, orientated essentially parallel to one
 another, or quasi-isotropic in each ply of which the fibres are orientated
 at an angle, conveniently 45.degree. as in most quasi-isotropic laminates
 but possibly for example 30.degree. or 60.degree. or 90.degree. or
 intermediately, to those in the plies above and below. Orientations
 intermediate between anisotropic and quasi-isotropic, and combination
 laminates, may be used. Suitable laminates contain at least 4 preferably
 at least 8, plies. The number of plies is dependent on the application for
 the laminate, for example the strength required, and laminates containing
 32 or even more, for example several hundred, plies may be desirable.
 There may be aggregates, as mentioned above in interlaminar regions. Woven
 fabrics are an example of quasi-isotropic or intermediate between
 anisotropic and quasi-isotropic.
 The stable emulsions obtained in the process may have a shelf life long
 enough to be handled in commerce.
 Accordingly there is provided in accordance with the present invention a
 process for the preparation of a curable resin composition comprising
 combining components a) and c) in suitable manner, thereafter
 incorporating component b) in suitable manner, followed by incorporating
 component d), with use of appropriate solvents, diluents, application of
 heat and the like as appropriate. Optionally reinforcing or strengthening
 agents, fillers and the like may be incorporated in suitable manner.
 It should be appreciated that the process may be performed in any desired
 sequence, suited to the component and the desired result. For example it
 may be desired to pre-react any two or more components prior to
 cross-linking with the remaining component(s). However optimum results are
 obtained by the employing the sequence as hereinbefore defined.
 In a further aspect of the invention there is provided a composition
 comprising components b) and d) as hereinbefore defined for incorporation
 with a composition comprising components a) and c) as hereinbefore
 defined, and any additional materials or agents and initiating the curing
 thereof.
 Suitably the process as hereinbefore defined is characterised by obtaining
 a curable resin composition which is adapted to be cured at a temperature
 below that which would be required for the corresponding composition
 comprising only components a), b) and c) over an equivalent period of
 time, preferably is adapted to be cured at a temperature of less than that
 at which the material constituting the mould or tool on or in which it is
 intended to cure the resin composition becomes heat sensitive in any way,
 and more preferably at a temperature of less than or equal to 150.degree.
 C. at elevated pressure, most preferably at a temperature of less than or
 equal to 135.degree. C. at a pressure in the range of 3 to 7 bar. Suitably
 the composition is adapted to be cured over a period of less than or equal
 6 hours, preferably less than or equal to 4 hours, most preferably of the
 order of less than or equal to 3 hours.
 In a further aspect of the invention there is provided a process for the
 preparation of a cured thermoset resin comprising obtaining the curable
 resin composition in a suitable mould or tool, or equivalent state in
 which it is to be cured subjecting the composition to a desired cure
 temperature at suitable pressure, for example at atmospheric pressure and
 maintaining the temperature for a required period. Preferably the cure
 temperature is selected as hereinbefore defined, with reference to the
 temperature sensitivity of a mould or the like which is being employed or
 otherwise, more preferably is less than or equal to 150.degree. C. at
 elevated pressure. Preferably the curing time is determined as
 hereinbefore defined.
 In a further aspect of the invention there is provided the use of a
 composite mould or tool to contain or support a composition according to
 the invention as hereinbefore defined during the curing thereof.
 Preferably such composite tool is constructed of any suitable unsaturated
 polyester or thermoset resin such as epoxy or bis-maleinides having a heat
 resistance in excess of the curing temperature to be employed.
 Reinforcement is suitably provided in the form of glass fibres. Composite
 moulds may be prepared in conventional manner for use according to the
 present invention.
 In a further aspect of the invention there is provided a prepreg comprising
 a composition as hereinbefore defined and obtained by a process as
 hereinbefore defined.
 In a further aspect of the invention there is provided a
 thermoplast-modified thermoset resin shaped product which is obtained by
 the method as hereinbefore defined. Preferably such product is selected
 from a car, motorbike, caravan or a mobile home panel as hereinbefore
 defined or from a furniture component as hereinbefore defined, which is to
 be made in limited number or for a limited period only. More preferably
 such object is a vehicle body shell, for example, a racing car body shell.
 The invention is now illustrated in non limiting manner with reference to
 the following examples.
 EXAMPLE 1
 Preparation of a Neat Resin Composition of the Invention
 A neat resin composition was made in the following manner wherein parts are
 by weight. 24.8 parts and 25.8 parts respectively of epoxy resin
 components MY0510 and PY306 were weighed into a 500 cm.sup.3 tin and
 warmed to about 40.degree. C. Upon dissolution, 30 parts of thermoplast
 resin component comprising polyarylsulphone of 40:60 PES:PEES ratio, RV
 0.26 and --NH.sub.2 ends, made according to the procedure given below,
 pre-dissolved in dichloromethane, was added to the two blended epoxies.
 The solution was then heated to facilitate the dissolution of precipitated
 polymer. 19.6 parts of catalyst component DDS was then added with some
 additional solvent to aid dispersion. The volume of solvent was reduced
 and 5 parts of titanate curing component (active weight) was incorporated
 at this stage in the preparation of the resin solution.
 The polyarylsulphone used in this example was synthesised by reacting
 together the appropriate aromatic dihalo-compounds and dihydric phenols
 exemplified by 4,4'-dichlorodiphenyl sulphone (DCDPS) (50 molar parts)
 with hydroquinone (10 to 40 molar parts) and
 4,4'-dihydroxydiphenylsulphone (40-10 molar parts) in presence of
 potassium carbonate optionally with sodium carbonate, and diphenyl
 sulphone (DPS) solvent at a temperature rising to 280.degree. C. The
 synthesis used excess DCDPS and the product thereof was reacted further
 with m-aminophenol to give amino end groups. The polyarylsulphone was
 characterised by a 40:60 PES : PEES ratio, an RV of 0.26 and amino end
 groups.
 Compositions were obtained according to the procedure of Example 1 with the
 use of the following organotitanates as the curing component of Example 1,
 each in an active amount of 5 parts by weight together with additional
 solvent as required, as follows: