FILLED POLYMER COMPOSITIONS

Abstract: A fluid, highly filled curable composition comprising an organic liquid polymerisable to form a solid polymer, from 35 to 85 % by weight of a finely divided inorganic filler having specified particle size and surface area and a carboxylic acid ester or amide carrying a terminal acid group selected from sulphate, sulphonate, phosphate and phosphonate, and continuous fibre reinforcement with the proviso that the composition when cured contains at least 15 % by weight of repeat units derived from acrylate or methacrylate monomer. Compositions have attractive rheology characteristics enabling products to be readily fabricated, such products having excellent fire and smoke properties.

Description: FILLED POLYMER COMPOSITIONS This invention relates to curable compositions containing * high volume concentrations of finely divided particulate fillers having improved rheology characteristics, particularly when used <- 5 in combination with fibrous reinforcement. Interest in highly filled materials in which high concentrations of particulate and/or fibrous reinforcement are present within a polymeric matrix has grown rapidly over the past 10 to 15 years. In one aspect of these materials the matrix of 10 the material is obtained from a curable composition. The filled, curable composition can be cured in a mould to a desired shape. Alternatively, the curable compositions can be used in a continuous process, such as pultrusion, in which a curable composition is used to impregnate a continuous fibre structure, 15 such as a roving, the impregnated material subsequently being formed into profile of a desired shape and thereafter cured. In these processes the fabricator requires materials which can be used with a minimum of running problems (particularly in a continuous process), are easy to use and as a consequence give 20 high productivity. The materials themselves should give optimum properties at minimum expense. In addition, the resulting products must have desirable physical properties, such as mechanical strength and stiffness, excellent burning performance such as smoke emission and have good surface finish. 25 Compositions have now been developed which have attractive rheology characteristics enabling products to be readily fabricated, such products having excellent fire and smoke properties, good surface finish and high levels of mechanical properties. 30 According to the invention there is provided a fluid, highly filled, curable composition comprising r (A) an organic liquid which is polymerisable to form a solid polymer, (B) from 35 to 85Z by weight, preferably 50 to 80Z by 35 weight of a finely divided inorganic filler having a weight average particle size of between 0.5 and 7 microns, preferably between 3.0 and 5.0 microns, and a surface area measured by the BET nitrogen absorption method of less than 5m^/g and (C) a carboxylic acid ester or amide carrying a terminal acid group selected from sulphate, sulphonate, phosphate and phosphonate providing that when the composition has been cured the polymeric constituents contain at least 15Z by weight preferably at least 10 40Z by weight of the total polymeric content of repeat units of methacrylate or acrylate monomer. By "organic liquid which is polymerisable to form a solid polymer" is meant (a) a liquid monomer which can be polymerised to form a solid polymer in which the repeat units of the polymer 1 5 chain are linked through carbon-carbon bonds or by such bonds interrupted by hetero atoms, the polymerisation preferably taking place without the formation of an elimination product or (b) a mixture of liquid monomer as described in (a) and one or more polymers soluble in component (a) and either compatible or 2 incompatible with polymer produced from the polymerisation of component (a). With the proviso that at least 15Z by weight of the polymeric matrix of the cured products obtained from the curable composition should consist of repeat units derived from methyl 25 methacrylate, the liquid component (a) may be chosen from a wide variety of ethylenically unsaturated monomers. The esters of acrylic and methacrylic acids with alcohols containing 1 to 18 carbon atoms are preferred. It is advantageous if the final matrix polymer is a 30 cross-linked polymer or a polymer which is highly branched to the extent of being unprocessable by heat and/or pressure. This may be achieved by the inclusion in polymerisable liquid (A) of a proportion of a polyethylenically unsaturated monomer or oligomer copolymerisable with liquid component (a). Of particular 35 interest are final matrix polymers derived from oligourethane acrylates or methacrylates, optionally containing a reactive diluent such as methyl methacrylate, providing that at least 50Z by weight of the cured product consists of repeat units of an acrylate or methacrylate monomer. Cross-linked polymers derived from monomeric or oligomeric components of unsaturated polyesters are also suitable providing they have been polymerised in the presence of components which result in a final product containing at least 15Z of repeat units of an acrylate or methacrylate monomer. A preferred polymerisable liquid comprises (i) an ethylenically unsaturated urethane composition comprising at least one ethylenically unsaturated urethane compound having an average double bond functionality of greater than 1.0, or the precursors for such a urethane composition, and . (ϋ) at least one ethylenically unsaturated monomer which is a vehicle for, and is copolymerisable with, the unsaturated urethane composition which is either present as a preformed species or is formed by reaction of the precursors therefor in the at least one ethylenically unsaturated monomer. Preferably, the unsaturated urethane composition is the product obtained from the reaction of a reactant mixture containing at least one hydroxyl containing vinyl monomer, at least one organic polyisocyanate or isocyanate functional derivative thereof having an average isocyanate functionality of at least 2.0, and optionally at least one saturated compound containing a plurality of isocyanate reactive groups. In a preferred embodiment, the unsaturated urethane composition is a polyurethane polyacrylate and/or polymethacrylate composition which is the reaction product off (i) at least one hydroxyalkyl acrylate and/or hydroxyalkyl methacrylate compound; (2) at least one polyisocyanate or isocyanate functional derivative thereof having an average isocyanate functionality of at least 2.0 and preferably greater than 2.0; and (3) optionally at least one saturated polyol. It is preferred that the viscosity of component A is less than 1000 centipoise and preferably less than 200 centipoise measured at ambient temperature. Component (B) is a particulate inorganic filler having a mean particle size by weight of between 0.5 and 7 microns, preferably between 3 and 5 microns. Suitable filler materials include forms of alumina, particularly alumina trihydrate, forms of silica such as quartz, cristobalite and tridymite, kaolin and its calcination products, magnesium hydroxides, dolomite, gypsum and other metal silicates, aluminates, aluminosilicates, phosphates, sulphates, carbonates and oxides. The filler will be chosen with a view to the properties required of the final composite, for example, products with a high level of fire retardancy will include an appropriate filler such as alumina trihydrate, magnesium hydroxides, dimagnesium phosphate trihydrate, trimagnesium phosphate octahydrate, magnesium hydroxide, hydrated magnesium carbonates and sulphates and other fillers which show an endothermic decomposition. In general the particles in a given filler cannot be regarded as spherical in shape. The particle sizes quoted in this specification take this into account, averaging the dimensions of a given particle as seen through a microscope ot taken from a photographic record. The filler particle size distribution, surface area and other surface chemistry/morphology aspects have a profound effect on the processability of the described compositions. This is particularly in evidence when high levels of particulate filler are used in the composition, typically 50 to 80Z by weight, in order to achieve good fire and smoke properties. The particle size distribution of the filler must be carefully chosen such that less than 25Z by wt but most preferably less than 10Z by wt of the particles have an average diameter of greater than 10 μ . The presence of higher concentrations of particles greater than 10 μm in average diameter can result in poor processability when used in resin transfer moulding (RTM), cold press moulding (CP) and pultrusion. The surface area (BET method) of the filler must also be carefully controlled to enable a composition of suitable viscosity to be achieved. The surface area should be less than 5 m 2 g _1 but preferred fillers have surface areas of less than 3 m-^g" 1 and in particular less than 2 m^g -1 . In order to achieve such low surface areas with particle size distributions as previously described, it is preferred that the particle shape is approximately spherical and that the particle size distribution is such that optimum particle packing can occur. Component (C) is a carboxylic acid ester or amide carrying a terminal acid group. Compounds of this general type are disclosed in published European Patent Application No. 164817. A preferred compound which can be used as component (C) is one having the general formula: A - (0 - B - C0) m - D I wherein A and D are end groups, one of which is or carries a terminal acid group selected from sulphate, sulphonate, phosphate and phosphonate and the other is a terminal group which does not render the compound hydrophilic; B is a divalent hydrocarbon group; and m is from 1 to 100. In the compound of Formula I, when D carries the acid group, A is preferably the residue (A-—CO-) of an esterifiable carboxylic acid of the formula A 1 -COOH, in which A-^- is H, a hydrocarbon or a substituted hydrocarbon. Although A 1 is conveniently an optionally substituted alkyl, alkenyl, cycloalkyl or polycycloalkyl group containing up to 50, more preferably up to 35, carbon atoms, it can be any convenient monovalent group. In this case D preferably includes a polyvalent, more preferably di- or tri-valent, bridging group which links the acid group to the ester chain, AlC0(0-B-C0) m -, for example a group such as D- 2 defined hereafter. Where D has a valency greater than 2 it may link two or more acid groups to a single ester or two or more esters chain to a single acid group. Where the acid group has more than one valency it may be linked to two more more esters through two bridging groups. In the compound of Formula I, when A carries the acid group, D is preferably the residue of an alcohol, a thiol or a primary or secondary amine, D-*—XH, in which D-*- is an aliphatic or alicyclic group as described for A 1 ; X is -0-, -S- or -NR-; and R is H, alkyl, alkenyl, cycloalkyl, or phenyl, in which the alkyl and alkenyl groups contain up to 20 carbon atoms and the cycloalkyl groups from 4 to 8 carbon atoms. In this case A is preferably the acid group itself and where the acid group has more than one valency it may be linked to two or more polyester chains, although A may also include a polyvalent linking group, like D above, which links the acid group to the polyester chain. The hydrocarbon group represented by B, which is preferably an optionally substituted divalent alkyl, alkenyl, cycloalkyl or polycycloalkyl group, preferably contains up to 50, more preferably from 3 to 24, carbon atoms, with at least 3 carbon atoms separating the -0- and -CO- groups. Optional substituents for A , Dl and B include halo, especially chloro, hydroxy, amino, alkoxy and other non-ionic species in so far as they do not make the ester/amide chain hydrophilic in character. It is preferred that m is from 2 to 75, more preferably 3 to 30, so that the compound of Formula I is an oligo- or poly-ester. Where i = 1 it is preferred that the group represented by A or D which is remote from the acid group contains at least 6 carbon atoms and that the surfactant contains at least 12 carbon atoms and more preferably at least 20 carbon atoms. It is also generally preferred that B is a pentamethylene group. One preferred compound which can be used as component (C) is a compound conforming to the formula: [A 1 - CO -(0 - Bl - C0) m - D 2 ] k - L M II wherein A---C0 is the residue of an esterifiable carboxylic acid of the formula, A-^-COOH; B 1 is selected from alkylene, alkenylene, cycloalkylene, polycycloalkylene and halo derivatives thereof; D 2 is a bridging group of the formula - X - G - Y - wherein X is -0-, -S- or -NR- and Y is -0-, -NR- or a direct link, in which each R independently is as hereinbefore defined or, where X and Y are both -NR-, the two groups, R, may form a single alkylene or alkenylene group linking the two nitrogens to which they are attached, and G is alkylene, alkenylene, cycloalkylene or arylene; L is phosphonate or sulphonate; M is a cation; k is 1 or 2; and m is as hereinbefore defined. An especially preferred compound which can be used as component (c) is a compound conforming to the formula: [D 1 - X -(CO - B 1 - 0 m ]k - L M III wherein Ω~ is an aliphatic or alicyclic group and B^, L, M, X, m and k are all as hereinbefore defined. The residue of the esterifiable carboxylic acid represented by A-J-CO in Formula II may be any convenient terminal hydrophobic group for the ester chain, -(0 - B--- - C0) m , although it is preferably an optionally substituted alkyl, alkenyl, cycloalkyl or polycycloalkyl group containing up to 50 carbon atoms and more preferably from 1 to 35 carbon atoms. The optional substituents are preferably selected from hydroxy, aπiino, halogen and alkoxy provided A-*-- does not render the compound hydrophilic in character. The aliphatic or alicyclic group represented by D 1 in Formula III is preferably an optionally substituted alkyl, alkenyl, cycloalkyl or polycycloalkyl group containing up to 35 carbon atoms, the optional substituents being preferably selected from halogen, tertiary amino and alkoxy. The alkylene, alkenylene, cycloalkylene and polycycloalkylene groups represented by B-^- preferably contain from 3 to 35 carbon atoms, more preferably from 4 to 20 carbon atoms, with at least 3 and more preferably at least 4 carbon atoms separating the -0- and -CO- groups, and are preferably unsubstituted. It is especially preferred that H~ is a pentamethylene group. The alkylene and alkenylene groups represented by G preferably contain up to 10 carbon atoms and more preferably from 2 to 6 carbon atoms. The cycloalkylene group represented by G preferably contains from 4 to 8 carbon, atoms and especially preferably is 1,4-cyclohexylene. The arylene group represented by G is preferably monocyclic and especially 1,4-phenylene. The alkyl and alkenyl groups represented by R may contain up to 25 carbon atoms and preferably contain up to 5 carbon atoms. Where two groups, R, form a single group this preferably contains up to 10 carbon atoms. In the compound of Formula II, when Y is -0-, the acid group, L, is attached to the ester/amide chain through an oxygen atom so that phosphonate and -0- form phosphate and sulphonate and -0- form sulphate. Similarly, in the compound of Formula II, when Y is -NR-, phosphonate and -NR- form phosphoramide and sulphonate and -NR- form sulphonamide. In the compound of Formula III, the group L is attached to the ester chain through an oxygen atom and the phosphonate and sulphonate groups then * , form phosphate and sulphate groups respectively. The cation represented by M is preferably H + , a metal ion, an ammonium ion or a substituted ammonium ion and examples of suitable cations are Na + , + , Ca 2+ , NBV 1" , NH(CH2CH2θH) 3 + , NH(CH 3 ) 3 + and N(CH 3 )4+. Specific examples of the bridging group represented by D 2 are - NHC2H -, - OC2H4 -, - OC2H4O -, - OC2H4NH -, - NH(CH2)n NH - wherein n is from 2 to 5, piperazin-l,4-ylene and phen-l,4-ylene- diamino. Examples of the groups represented by A-*- and A 2 are methyl, ethyl, CH 3 ( CH 2 )4 -. CH 3 (CH 2 )io -, CH 3 (CH 2 )l4 -. CH 3 (CH 2 )i6 -. H0 ( CH 2 ) 5 -, CH 3 ( CH 2 ) 7CH=CH(CH 2 ) 7 -. CH 3 )CH 2 ) 2 8 -, CH 3 (CH2)5CH(OH) ( CH 2 )lθ - . CH3(CH2)4CH=CHCH 2 CH=CH(CH2)7 -, CH 3 (CH2)5CH(0H)CH2CH-=CH(CH2)7 - and CH 3 0CH 2 -. Examples of the group represented by D 1 are methyl, ethyl, CH 3 (CH 2 )9 -. CH 3 (CH 2 )n -, CH 3 (CH 2 )ι 5 -, CH 3 (CH 2 )ι 7 -, CH 3 (CH2>29 -. CH 3 (CH2)7CH=CH(CH2)7 -, CH 3 0CH - and CH 3 (CH2)4CH=CHCH 2 CH=CH(CH 2 )7 -. Examples of the groups represented by B and B-- are: -CH-(CH 2 )lθ- -CH-(CH 2 )8- -CH-(CH 2 )7- -CH-CH2CH-=CH(CH2.'7- ι i i I I I (CH 2 ) 5 . (CH 2 ) 7 , (CH 2 )8 . (CH 2 ) 5 CH 3 CH 3 CH 3 CH 3 and preferably - (CH2>5 -• Component C may be present at a concentration of between 0.5 and 5.0Z by weight of the filler component (B), and is preferably used within the range 1.5 to 2.5Z by weight. The compositions of the invention find particular use when used in conjunction with continuous fibre reinforcement, particularly glass fibre. By 'continuous fibre' is meant fibre of length at least 20 mm, although the fibre is preferably continuous through the major dimensions of the article formed by curing the compositions. This enhances impact and stiffness properties resulting in a high strength to weight ratio article. The compositions can be used to impregnate fibre structures such as mats prepared from woven fibre or random fibres at least 20 mm long, or continuous fibre filament in the form of rovings. The compositions are particularly appropriate for impregnating fibre reinforcement using the processing technologies of resin transfer moulding (RTM), cold pressing moulding (CP) and pultrusion. The concentration of fibre reinforcement present in the final article will depend on the properties required. With higher levels of fibre, the mechanical properties are greater. Fire and smoke properties are also improved if the overall resin content of the article is reduced by incorporation of high fibre levels. The fibre content may range from 10 to 70Z by volume of the final article. For RTM and CP processing methods, it is preferred that the fibre content is 15 to 40Z by volume. For pultrusion processing, it is preferred that the fibre content 5 .is 25 to 50Z by volume. The particulate filled, compositions of the invention are ideally suited for preparing reinforced articles in which a fibrous structure such as a chopped fibre mat or woven fibre mat is impregnated with the composition and subsequently cured. For RTM and CP processes the mat is normally located in a mould prior to filling the mould with the curable composition and curing in the mould. Prior art compositions which have a suitably low viscosity have a marked tendency for the filler to be at least partially filtered out by the fibre mat. The low viscosity of the compositions provided by the combination of low viscosity resin, particular filler surface area and dispersant enables the mould to be filled quickly and with even distribution of filler and resin throughout the glass reinforcement. For RTM processing, compositions of viscosity less than 25 Poise, preferably less than 15 Poise (measured on a Brookfield viscometer) are preferred to enable quick mould filling. For CP processing, compositions of viscosity less than 100 Poise, preferably less than 60 Poise, are preferred. The excellent processability of the compositions of the invention make them ideally suited for use in continuous pultrusion processes in which continuous fibres are impregnated with a material for example by pulling the fibres through a bath of material, and subsequently curing the composite. For pultrusion processing compositions having a viscosity of less than 100 Poise, preferably less than 60 Poise are preferred. The low viscosity and good rheological properties enable the fibres to be impregnated easily, even though the rate of pull through of the fibre roving is high. The ease of impregnation provides a uniformity of filler and resin distribution which gives a continuously running process which is seldom interrupted by breakages caused by build up of fluid material filtered out on the surface of the impregnated roving, which are particularly prone to occur as the roving passes into the profiling die to produce a profiled article. Pultrusion processes give rise to products of very high strength and stiffness because parallel alignment of fibres enables a very high volume of fibres to be incorporated in an article through close packing of the parallel fibres. The resin content may consequently be reduced to the minimum necessary to wet the fibres and the dispersed filler and fill the interstices between the parallel fibres. Provided that the matrix resin is well bonded to the fibres, very high levels of mechanical properties can be achieved through these high fibre levels. Although the bonding between the inorganic materials and the matrix resin may be sufficient for most purposes, the particulate filled compositions of the invention may also include coupling additives to ensure that the inorganic materials are even more strongly bonded to the matrix polymer after curing. Coupling agents fulfilling this function are well known in the art. Fibres are normally provided by the fibre manufacturer with a size to enable the fibre to withstand the fibre manufacturing process without undue damage to the fibre surface. In the case of glass fibres the size normally includes a silane coupling agent to help achieve optimum properties in the application for which the glass fibre is intended to be used. Glass fibre manufacturers will normally be able to recommend a fibre carrying a coupling agent most suited to the application. The strength properties contributed by the continuous fibres dominate the strength of the cured composite. Shaped articles formed from the compositions of the invention, whether fibre reinforced or not, exhibit remarkably good burning performance in respect of both fire retardancy and smoke emission. The invention is further illustrated by reference to the following examples. EXAMPLE 1 170g of a dispersing additive prepared as hereinafter described was stirred into 5 kg of Modar 826HT resin of viscosity 135 centipoise. Modar 826HT is a low profile resin suitable for pultrusion containing 40Z by weight of methyl methacrylate, 55Z by weight of an oligourethane chain extended cross linker and 5Z by weight of a low profiling additive. (Modar 826HT is available from ICI Chemicals and Polymers Ltd.) The stirring was conducted at 45°C to 50°C until solution was complete. The solution was cooled to room temperature and 8.5 kg of precipitated alumina trihydrate (Grade C305B, supplied by Sumitomo Chemical Company and having a weight average particle size of 4.8 μm; a surface area by the BET nitrogen absorption method of 1.6m 2 /g; and containing between 5 and 10Z by weight of particles having an average diameter of greater than 10 μ . The particles being approximately spherical in shape.) was stirred in manually over a period of 15 minutes. The mixture was rolled in a drum for a further 30 minutes. The viscosity of the dispersion was 40 Poise (measured on a Brookfield viscometer at 23°C using Spindle No. 3 at 6 rpm). \ The dispersing additive used in this Example had been prepared as follows. mixture of 500g of epsilon-caprolactone, 67g of dodecanol and O.lg of tetrabutyl titanate was stirred at 160-180°C under a stream of nitrogen for 19 hours. The reaction mass was then discharged and allowed to solidify to a waxy solid. 105g of this solid was stirred at 60-65°C and 5g of phosphorus pentoxide was then added gradually over 30 minutes. The temperature was then raised to 90°C, and the reaction mass stirred for a further 16 hours at this temperature. It was then discharged and allowed to solidify to give a waxy solid. Thermally active initiators were added to the dispersion previously described by dissolving the initiators listed below at room temperature in the dispersion using a hand-held stirrer. 2.0 parts per 100 of resin of Triganox C (tert-butyl perbenzoate). 0.2 parts per 100 of resin of 'Perkadox' 16 (bis-4-tert-butyl cyclohexyl peroxydicarbonate) .- The activated dispersion was used to impregnate continuous glass fibre rovings in a pultrusion process according to the following method. Using a Pultrex 500 pultrusion machine fitted with a 75 mm x 4 mm flat die of chromed steel, with the die heated to between 120 and 140°C, 48 glass rovings of 4800 tex were pulled through a bath containing the dispersion and the heated die at a rate of 0.5m/min. Continuous filament mats of density 450g/m 2 were fed through the dispersion bath and the die to provide a cured composite material emerging from the die having a total glass content of 39Z by volume. The product had an excellent surface finish. The process was run continuously for an hour without problems arising. The pulling force, monitored by a load cell, remained substantially steady at 220 kg. The resulting product was very stiff and had a good combination of fire retardancy and smoke emission properties. Comparative Example A The procedure of Example 1 was repeated except in that the filler used was a grade of precipitated alumina trihydrate obtained from Sumitomo Chemical Company as C308. This has a weight average particle size of 8 urn and a surface area of 0.9m 2 /g. About 35 to 40Z by weight of the total filler had an average diameter greater than 10 μm. The viscosity of the dispersion obtained was 35 Poise, marginally less than Example 1 but when the dispersion was used in the pultrusion process of Example 1 the profile rapidly jammed in the die as the pulling force rose to over 500 kg. Comparative Example B The procedure of Example 1 was repeated using an alumina hydrate grade obtained from BA Chemicals Ltd designated BA FRF 85. This has a weight average particle size of 5.5 μm and a surface area of 6m- 2 /g (measured by the BET nitrogen absorption method). The weight content of particles having an average particle size greater than 10 μm was between 1 and 5Z. The particles are platey in shape having been produced by milling and grinding. The resulting dispersion was very poorly wetted giving a viscosity which was too high to be measured using Spindle No. 3 of the Brookfield viscometer (>250 Poise). In an attempted pultrusion experiment according to the procedure of Example 1 the profile jammed in the die shortly after start up. EXAMPLE 2 The procedure of Example 1 was repeated using a grade of precipitated alumina trihydrate obtained from Sumitomo Chemical Co as CL303. This has an average particle size of 3 μm and a surface area of 2m 2 /g. The weight content of particles of average diameter greater than 10 μ is between 1 and 5Z. A dispersion viscosity of 31 Poise was obtained. When used in the pultrusion process of Example 1 the material ran smoothly with an indicated pulling force of 280 kg. The resulting profile was similar in appearance and properties to that of Example 1. EXAMPLE 3 The procedure of Example 1 was repeated using 10 kg of the same filler, but using 200g of the dispersing additive and 5 kg of a resin designated Modar 865 (obtainable from ICI Chemicals and Polymers Ltd). Modar 865 contains approximately 50Z by weight of methyl methacrylate and 50Z by weight of an oligourethane chain extended cross linker. The resin has a viscosity of 130 centipoise. A dispersion viscosity of 45 Poise was obtained (Brookfield Spindle 3). The dispersion was activated using a mixture of 2.0 phr 'Irganox C* and 1.0 phr *Perkadox 16' . In a pultrusion experiment (using 40 rovings instead of the 48 used in Example 1) the pulling rate was initially set at 0.5 m/min. A very low pulling force was registered on the load cell. The speed was increased by 50Z with the pulling force just registering on the load cell at 100 to 200 kg. A pultruded profile having an overall glass content of 35Z by volume and of similar appearance and properties to that of Example 1 was obtained. EXAMPLE 4 The procedure of Example 3 was repeated using 11.35 kg of the C305B filler, 250g of the dispersing additive and 5 kg of a resin designated Modar 865/1 (obtainable from ICI Chemicals and Polymers Ltd). Modar 865/1 contains approximately 45Z by weight of methyl methacrylate, 45Z by weight of oligourethane chain extended cross-linker and 10Z by weight of methacrylic acid. The dispersion had a viscosity of 45 Poise (Brookfield, Spindle 3) . The dispersion was evaluated in the pultrusion process of Example 1, behaving as the dispersion of Example 3. The pultruded product was similar in appearance and properties to that of Example 3. EXAMPLE 5 A dispersion was made up using the procedure of Example 1 to give a composition containing 10 kg C305B filler, 200g of the dispersing additive of Example 1 and 5kg parts of a resin designated as Modar 835S. Modar 835S is obtainable from ICI Chemicals and Polymers Ltd and is a mixture of approximately 40Z by weight methyl methacrylate, 20Z by weight oligourethane chain extended cross linker and 20Z by weight of a polyester resin. Modar 835S has a viscosity of 60 centipoise. The dispersion had a viscosity of 15 Poise and was sufficiently low to be evaluated in resin transfer moulding RTM. In the evaluation 1.5 phr benzoyl peroxide and 0.3 phr dimethylaniline were mixed into the dispersion using a mixing. head. The activated dispersion was then pumped into a closed plate mould having a cavity 3 mm thick containing 3 glass fibre mats of density 450g/m 2 , the glass content being such as to give a concentration on the total composition of 18Z by volume. After curing for 30 minutes and cooling below 50°C the cured article was removed from the mould. The article was free from air entrapments. The glass fibre had been evenly wetted with no sign of filler filtration by the fibre mat. EXAMPLE 6 Samples having the compositions set out in Table 1 (prepared by the procedure of Example 1 using C305B filler, 2.0Z by weight of filler of dispersing additive and Modar 865 as the resin) were cured to shaped articles by pouring the sample dispersions into a mould containing 18Z by volume of a glass fibre mat.Initiators had previously been added to the dispersion (1.5 phr benzoyl peroxide and 0.3 phr dimethylaniline). The compositions were cured without applying external heat. Curing occurred within 30 minutes. After conditioning at room temperature for 24 hours the samples were evaluated in burning tests using the following recognised standard tests: ISO 5657 (30 kw) Epiradiateur NP 92-501 BS 6401 : Part 3 (Flaming) These tests show that substantial benefits in resistance to ignition (ISO 5657, Epiradiateur) are achieved by increasing the alumina trihydrate content. Classifications of Epiradiateur NFP 92-501 to Ml or M2 are desirable for applications in public transport and buildings. A reduction in smoke is also observed when using higher loadings of alumina trihydrate (BS 6401 : Part 3). Table 1 BS6401 Part 3 Filler Resin Dispersion IS05657(30kw) Epiradiateur (Flaming) Amount Amount Viscosity Time to Ignition(secs) NFP92-501 D max (parts) (parts) 150 100 20P 300 M3 223 200 100 45P 400 M2 169 250 100 75P 600 M2/M1

Claims: CLAIM 1. A fluid, highly filled, curable composition comprising (A) an organic liquid which is polymerisable to form a solid polymer; (B) from 35 to 85Z by weight of a finely divided inorganic filler having a weight average particle size of between 0.5 and 7 microns and a surface area measured by the BET nitrogen absorption method of less than 5m 2 /g; (C) a carboxylic acid ester or amide carrying a terminal acid group selected from sulphate, sulphonate, phosphate and phosphonate; and, optionally (D) continuous fibre reinforcement providing that when the composition has been cured the polymeric constituents contain at least 15Z by weight of the total polymeric content of repeat units of methacrylate or acrylate monomer. 2. A curable composition as claimed in claim 1 wherein the polymerisable liquid (A) comprises (i) an ethylenically unsaturated urethane composition comprising at least one ethylenically unsaturated urethane compound having an average double bond functionality of greater than 1.0, or the precursors for such a urethane composition, and (ii) at least one ethylenically unsaturated monomer which is a vehicle for, and is copolymerisable with, the unsaturated urethane composition which is either present as a preformed species or is formed by reaction of the precursors therefor in the at least one ethylenically unsaturated monomer. 3. A curable composition as claimed in claim 2 wherein the unsaturated urethane composition is a polyurethane polyacrylate and/or polymethacrylate composition which is the reaction product of: (1) at least one hydroxyalkyl acrylate and/or hydroxyalkyl methacrylate compound; (2) at least one polyisocyanate or isocyanate functional derivative thereof having an average isocyanate functionality of at least 2.0 and preferably greater than 2.0; and (3) optionally at least one sa rated polyol. 4. A curable composition as claimed in any one of claims 1 to 3 wherein the viscosity of the polymerisable liquid (A) is less than 1000 centipoise. 5. A curable composition as claimed in any one of claims 1 to 4 comprising from 50 to 80Z by weight of a finely divided inorganic filler having a weight average particle size of between 0.5 and 7 microns. 6. A curable composition as claimed in any one of claims 1 to 5 wherein the finely divided inorganic filler has a weight average particle size of between preferably between 3.0 and 5.0 microns. 7. A curable composition as claimed in any one of claims 1 to 6 wherein the finely divided inorganic filler is one which shows an endothermic decomposition. 8. A curable composition as claimed in any one of claims 1 to 7 wherein component (C) is one having the general formula: A - (0 - B - C0) m - D I wherein A and D are end groups, one of which is or carries a terminal acid group selected from sulphate, sulphonate, phosphate and phosphonate and the other is a terminal group which does not render the compound hydrophilic; B is a divalent hydrocarbon group; and m is from 1 to 100. 9. A curable composition as claimed in any one of claims 1 to 7 wherein component (C) is one having the general formula: [A 1 - CO -(0 - B 3 - - C0) m - D 2 ]k - L M II wherein A 1 -CO is the residue of an esterifiable carboxylic acid of the formula, A-^-COOH; B 1 is selected from alkylene, alkenylene, cycloalkylene, polycycloalkylene and halo derivatives thereof; D 2 is a bridging group of the formula - X - G - Y - wherein X is -0-, -S- or -NR- and Y is -0-, -NR- or a direct link, in which each R independently is as hereinbefore defined or, where X and Y are both -NR-, the two groups, R, may form a single alkylene or alkenylene group linking the two nitrogens to which they are attached, and G is alkylene, alkenylene, cycloalkylene or arylene; L is phosphonate or sulphonate; M is a cation; k is 1 or 2; and m is from 1 to 100. 10. A curable composition as claimed in any one of claims 1 to 7 wherein component (C) is one having the general formula: [D 1 - X -(CO - B 1 - 0) m ] k - L M III wherein D 1 is an aliphatic or alicyclic group and B-**- is selected from alkylene, alkenylene, cycloalkylene, polycycloalkylene and halo derivatives thereof; L is phosphonate or sulphonate; M is a cation; k is 1 or 2; and m is from 1 to 100. 11. A curable composition as claimed in any one of claims 1 to 10 comprising continuous fibre reinforcement formed from glass fibre. 12. A shaped article formed by curing a curable composition as claimed in any one of claims 1 to 11.

Inventors: MOORMAN GERALDINE ANNE, MOORMAN, GERALDINE, ANNE
Applicants: ICI PLC, MOORMAN GERALDINE ANNE, IMPERIAL CHEMICAL INDUSTRIES PLC
Application year: 1993
Main classification: C08K13
IPC codes: C08F2, C08F20, C08F290, C08F299, C08G18, C08J5, C08K7, C08K13, C08L33, C08L75, C08L101