WO2011085443A1 - Curable composition - Google Patents

Abstract

The present invention relates to a two-part curable composition, methods for preparing the two-part curable composition and its use as a polymeric material for lining and reinforcement. The two-part curable composition comprises a first part which is a prepolymer composition comprising an unsaturated polyester, a vinyl-functional monomer and an accelerator; and a second part which is a promoter composition comprising a promoter and a vinyl-functional monomer. In use, the promoter composition of the second part promotes curing of the curable composition when the first and second parts are combined.

Description

CURABLE COMPOSITION

TECHNICAL FIELD

The present invention relates to a two-part curable composition, methods for preparing the two-part curable composition and its use as a polymeric material for lining and reinforcement. The two-part curable composition may find application in the reinforcement of underground mine roofs, tunnels, rockface stabilisation and roadway embankments, blast proofing, pipe remediation, waterproofing, building repair, structural strengthening and repair of bridges, buildings, marine structures and asbestos remediation.

BACKGROUND

Polymeric skin reinforcement materials can be made using polyester systems and have numerous industrial applications. In preparing such materials, current polyester systems use a resin component, which is mixed with a very small percentage of accelerator component. For example, commonly used ratios of prepolymer mixture to accelerator would be around 50:1. The resin and accelerator components of the polyester system are therefore used in vastly different volume ratios, which makes obtaining an accurate composition in a batch process difficult. There are also problems associated with mixing small and large volumes, and in the application and handling of polyester systems, particularly those which are not uniformly mixed or accurately prepared. This problem is currently overcome by preparing polyester systems having longer cure times. However, longer cure times also limit the potential uses of these polyester systems. There is therefore a need for a system which allows for improved mixing and application of the polymer. Such an improved composition would, among other applications, also be suitable for use in underground mine roof support.

Currently skin reinforcement and confinement in longwall coal mine roadways is achieved using steel mesh. The current method of installation is slow and manual, and places mine personnel conducting the installation in a dangerous position under unsupported roof.

Ground support practices presently range from a single rib bolt per metre and no mesh to three or more rib bolts and complete ceiling to floor meshing, depending on the structural soundness of the rib coal and the degree of ground movement experienced. In most cases, however, skin reinforcement of the roof is full width and continuous. Roadway development practices range from cut-and-flit to bolting and meshing directly behind the continuous miner cutting head, depending on the stability of the strata.

There is a need for a new system for skin reinforcement and confinement for underground mine roof support applications which is virtually odourless, has a low toxicity and may be rapidly and safely installed, preferably using an automated method. This would increase the rate of roadway advancement and remove personnel from the immediate face area.

In some mines, gas drainage is an issue. Other mines have problems with mine water at low and/or high pH. Any new material would preferably be able to be successfully applied, and provide the requisite level of long-term support under these widely varying conditions. Polymeric skin reinforcement materials are preferably capable of being spray- applied for successful used in underground coal mines ahead of the bolters, and be sufficiently cured by the time the bolts were inserted.

There is therefore a need for an improved polyester system which may be more easily mixed and applied, and is therefore suitable for a wide range of applications. SUMMARY

In a first aspect there is provided a two-part curable composition comprising:

(i) a first part which is a prepolymer composition comprising an unsaturated polyester, a vinyl-functional monomer and an accelerator; and

(ii) a second part which is a promoter composition comprising a promoter and a vinyl-functional monomer,

the second part being capable of promoting curing of the curable composition when the first and second parts are combined.

The unsaturated polyester of the prepolymer composition is preferably a condensation product of:

(i) a diacid and/or anhydride, preferably an alpha, beta-ethylenically unsaturated diacid and/or anhydride such as maleic anhydride and a non-polymerisable diacid and/or anhydride such as phthalic anhydride or adipic acid or both; and

(ii) an organic diol, preferably a polyhydric alcohol which may be selected from the group consisting of 1 ,2-propanediol, 1 ,6-hexanediol, 1 ,4-butanediol, and combinations thereof.

Suitable vinyl-functional crosslinking monomers include any desired vinyl-functional monomer that is able to crosslink with the polyester under the influence of the accelerator and the promoter. Preferably, the vinyl-functional monomer may be chosen so that the two- part composition may be safely used in a confined environment. This may be achieved by using a vinyl-functional monomer having a vapour pressure which is less than styrene at 20°C. Suitable vinyl-functional monomers may include divinyl monomers such as divinyl ether monomers, particularly glycol divinyl ether monomers. Examples include triethylene glycol divinyl ether (TEGDVE), diethylene glycol divinyl ether (DEGDVE) and ethylene glycol divinyl ether (EDVE). Preferably the monomer is TEGDVE, which has a vapour pressure below about 0.012 mmHg at 20°C. The prepolymer composition may also contain an inhibitor to impart increased shelf life and to control cure time.

The promoter composition of the second part may also contain a co-accelerator.

The promoter composition of the second part may also contain one or more additives such as a filler, inhibitor, flame retardant or antistatic agent.

In a second aspect there is provided a promoter composition comprising a promoter and a vinyl-functional monomer. Preferably, the promoter composition also contains a co- accelerator.

The prepolymer composition of the first part and the promoter composition of the second part may be combined to form a curable composition which is sprayable.

In a third aspect there is provided a kit comprising:

(i) the prepolymer composition of the first part according to claim 1 ; and

(ii) the promoter composition of the second part according to claim 1 ,

the second part being capable of promoting curing of the curable composition when the first and second parts are combined.

In a fourth aspect there is provided a process for preparing a curable composition, comprising the step of:

a. combining the prepolymer composition of the first part as defined in claim 1 and the promoter composition of the second part as defined in claim 1 , the second part promoting curing of the curable composition.

The prepolymer composition of the first part may be prepared by combining the unsaturated polyester or the constituents thereof such as a diacid and/or anhydride and an organic diol, the vinyl-functional monomer and the accelerator.

The promoter composition of the second part may be prepared by combining the promoter and the vinyl-functional monomer. Preferably, the promoter composition may be prepared by combining the promoter, a co-accelerator and the vinyl-functional monomer.

In a fifth aspect there is provided a process for preparing a cured composition comprising curing the curable composition defined above. The process for preparing a cured composition, comprises the steps of:

a. combining the prepolymer composition of the first part as defined in claim 1 and the promoter composition of the second part as defined in claim 1 , the second part promoting curing of the curable composition; and

b. curing the curable composition.

In a sixth aspect there is provided a cured composition prepared by the process as defined above. The cured composition as defined above may be used as a polymeric material for lining or reinforcing a surface. This may include applications in reinforcing the roof of underground mines, tunnels, rockface stabilisation and roadway embankments, blast proofing, pipe remediation, waterproofing, building repair, structural strengthening and repair of bridges, buildings, marine structures and asbestos remediation.

In a seventh aspect there is provided use of the two-part curable composition as defined above in the manufacture of a polymeric material such as a polymeric skin or liner.

In one embodiment, there is provided use of the prepolymer composition of the first part as defined above and the promoter composition of the second part in the manufacture of a polymeric material such as a polymeric skin or liner.

In an eighth aspect of the invention there is provided use of a promoter composition as defined above to promote curing of a curable composition.

In a ninth aspect of the invention there is provided a process for reinforcing a surface comprising the steps of:

a. combining the prepolymer composition of the first part according to claim 1 and the promoter composition of the second part according to claim 1 to form a curable composition;

b. applying the curable composition to a surface; and

c. allowing the curable composition to cure on the surface to form a polymeric skin or liner.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described, by way of an example only, with reference to the accompanying drawings in which:

Fig. 1 is a graph showing variation in cure time with varying prepolymer composition;

Fig. 2 is a graph showing variation in tensile modulus with varying prepolymer composition;

Fig. 3 is a graph showing variation in tensile strength with varying prepolymer composition;

Fig. 4 is a graph showing variation in elongation at break with varying prepolymer composition;

Fig. 5 is a graph showing variation in flexural modulus with varying prepolymer composition;

Fig. 6 is a graph showing variation in flexural strength with varying prepolymer composition; Fig. 7 is a graph showing variation in flexural failure with varying prepolymer composition;

DETAILED DESCRIPTION

The present invention relates to a prepolymer composition of the first part comprising an unsaturated polyester, a vinyl-functional monomer and an accelerator. The prepolymer composition is capable of curing when combined with a promoter composition of the second part comprising a promoter and a vinyl-functional monomer to form a polymeric material on a surface.

The ratio of the first part and the second part may be in the range of 1 :1 to 10:1 , preferably 3:1 to 6:1 , more preferably 4:1 to 5:1. As the volumes of the first and second parts are similar, this makes combination of the parts and therefore curing more straightforward.

Prepolymer Composition of the first part

Unsaturated Polyester

The unsaturated polyester may be a condensation product of at least one diacid and/or anhydride and at least one organic diol. The polyester comprises copolymerisable carbon-carbon double bonds which may be provided by either the diacid, anhydride and/or diol. Since the condensation of the diacid and/or anhydride with the diol results in an alternating copolymer polyester, it follows that the mole ratio between units derived from the diacid and/or anhydride and the diol is about 1 :1. If the prepolymer has hydroxyl end groups, then the ratio will be slightly greater than 1 :1. If the prepolymer has carboxylic acid end groups, then the ratio will be slightly less than 1 :1.

The diacid and/or anhydride may be an aromatic or aliphatic diacid and/or anhydride. Examples include:

aliphatic anhydrides such as maleic anhydride, succinic anhydride and glutaric anhydride;

aromatic anhydrides such as phthalic anhydride and 1 ,8-naphthalic anhydride; cyclic anhydrides or diacids having 5 to 10 atoms in the ring (e.g. 5, 6, 7, 8, 9 or 10 atoms in the ring) such as cyclopentanedicarboxylic acid and cyclohexanedicarboxylic anhydride;

aliphatic diacids (e.g. α,ω-diacids) where the two acid groups are joined by 1 to 10 carbon atoms, 1 to 5 carbon atoms, 2 to 10 carbon atoms or 2 to 6 carbon atoms (e.g. 1 , 2, 3, 4, 5, 6, 7, 8, 9 or 10 carbon atoms) such as succinic acid, glutaric acid and adipic acid; and

aromatic diacids such as phthalic acid, isophthalic acid and 1 ,8-naphthalenedioic acid. In a preferred embodiment, the diacid and/or anhydride is a combination of an alpha, beta-ethylenically unsaturated diacid and/or anhydride and a non-polymerisable diacid and/or anhydride, preferably an alpha, beta-ethylenically unsaturated anhydride such as maleic anhydride and a non-polymerisable diacid and/or anhydride such as phthalic anhydride or adipic acid or both. When maleic anhydride and phthalic anhydride are used they may be present in a ratio of 1 :1 to 10:1.

In the event that a mixture of acids and anhydrides is used, an acid and anhydride having a copolymerisable double bond may be present in the mixture at between about 25 to 75% on a molar basis; or about 25 to 50, 50 to 75, 30 to 70, 40 to 60 or 45 to 55%; or about 25, 30, 35, 40, 45, 50, 55, 60, 65, 70 or 75%.

The organic diol may be a saturated or unsaturated aliphatic diol which may be optionally interrupted by a cyclic group or an ether group. The diol may be a linear or branched alkyl diol (e.g. an α,ω-diol) having 2 to 10 carbon atoms linking the two alcohol groups or 2 to 8, 2 to 6 or 2 to 4 carbon atoms. The carbon atoms linking the two alcohol groups may form a cyclic group such as a C_4-8cyclic group for example a cyclopentane or cyclohexane ring. The diol may be an ether diol such as diethylene glycol or triethylene glycol. One or more diols (e.g. 2, 3 or 4) may be used. Suitable diols include 1 ,2-ethanediol (also known as ethylene glycol), 1 ,2-propanediol, 1 ,6-hexanediol, diethylene glycol, 1 ,3- propanediol, 2-methyl-1 ,3-propanediol, 1 ,4-cyclohexanedimethanol, 1 ,4-butanediol and 1 ,5- pentandiol or combinations thereof.

The polyester is preferably a condensation product of maleic anhydride; phthalic anhydride or adipic acid or both, more preferably phthalic anhydride; and a polyhydric alcohol which may be selected from the group consisting of 1 ,2-ethanediol, 1 ,2-propanediol, 1 ,6-hexanediol, diethylene glycol, 1 ,3-propanediol, 2-methyl-1 ,3-propanediol, 1 ,4-butanediol, 1 ,5-pentanediol and 1 ,4-cyclohexanedimethanol and combinations thereof, more preferably 1 ,2-propane diol, 1 ,6-hexanediol or 1 ,4-butandiol.

It will be understood that more than one polyester may be present in the compositions of the invention. A preferred blend of polyesters comprises condensation products of maleic anhydride, phthalic anhydride and 1 ,2-propanediol; maleic anhydride, phthalic anhydride and 1 ,6-hexanediol; and/or maleic anhydride, phthalic anhydride and 1 ,4- butanediol.

Monomer

The vinyl-functional monomer may be any desired vinyl-functional monomer that is able to crosslink with the polyester under the influence of the accelerator and the promoter. Suitable vinyl-functional monomers include styrene and its alkyl derivatives such as a- methyl styrene, 4-methyl styrene, 4-t-butyl styrene, 4-t-butoxy styrene and 4-acetoxy styrene; acrylates such as hydroxyethyl acrylate and butyl acrylate; methacrylates such as methyl methacrylate, butyl methacrylate, benzyl methacrylate and hyroxyethyl methacrylate; allyl benzene; N-vinyl pyrrolidone and vinyl toluene. Suitable monomers also include difunctional monomers such as divinyl benzene, diallyl phthalate, hexanediol diacrylate and divinyl ether monomers, particularly glycol divinyl ether monomers. Examples include triethylene glycol divinyl ether (TEGDVE), diethylene glycol divinyl ether (DEGDVE) and ethylene glycol divinyl ether (EDVE). Poly-functional monomers such as trimethylolpropane triacrylate may also be used.

In a preferred embodiment, the vinyl-functional monomer may be chosen so that the two-part composition may be safely used in a confined environment. The vinyl-functional monomer may also be chosen so that the prepolymer composition is capable of rapid cure at ambient temperatures when combined with the promoter composition. This is achieved by use of a monomer having a vapour pressure which is less than that of styrene at 20°C. Preferably, the vapour pressure is significantly less than that of styrene at 20°C. The vapour pressure is preferably less than about 2mmHg; less than about 1.5, 1 , 0.5, 0.2 or 0.1 ; about 0.01 to 2, 0.01 to 1 , 0.01 to 0.5, 0.01 to 0.1 , 0.01 to 0.05, 0.05 to 2, 0.1 to 2, 0.5 to 2, 1 to 2, 0.1 to 1 , 0.05 to 0.5 or 0.05 to 0.2, or about 0.01 , 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1 , 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.6, 0.7, 0.8, 0.9, 1 , 1.1 , 1.2, 1 .3, 1 .4, 1 .5, 1.6, 1 .7, 1.8, 1.9 or 2mmHg at 20°C.

Vinyl-functional monomers suitable for use in a confined environment include, but are not restricted to, divinyl monomers such as divinyl ether monomers, particularly glycol divinyl ether monomers. Examples include triethylene glycol divinyl ether (TEGDVE), diethylene glycol divinyl ether (DEGDVE) and ethylene glycol divinyl ether (EDVE). Preferably the monomer is TEGDVE which has a vapour pressure below about 0.012 mmHg at 20°C. Other advantages of using TEGDVE are that it has a low odour and is non toxic. For use in confined environments such as mining applications, it is preferable that the monomer is non-flammable, non-combustible, non-irritant and/or non-toxic. The monomer also functions to crosslink with the polyester under the influence of the accelerator and the promoter.

The vinyl-functional monomer may be present in the prepolymer composition in an amount of about 20 to about 50% by weight; about 20 to 40, 20 to 30, 30 to 50, 40 to 50 or 30 to 40%; or about 20, 25, 30, 31 , 32, 33, 34, 35, 40, 45 or 50% by weight.

The same monomer is also used in the promoter composition. In a preferred embodiment, where a co-accelerator is present in the promoter composition, the co- accelerator may be dissolved in the monomer. The vinyl-functional monomer may be present in the promoter composition in an amount of about 60 to about 95% by weight. Accelerator

The accelerator (sometimes referred to as the "catalyst") may be a transition metal salt such as a cobalt, iron, copper, manganese, tin or vanadium salt, for example a cobalt (II) salt. Suitable accelerators include transition metal salts of an organic acid such as transition metal salts of a carboxylic acid. Examples include cobalt naphthenate, cobalt octanoate, cobalt 2-ethylhexanoate, cobalt hexanoate, iron naphthenate, copper naphthenate, manganese octanoate, tin octanoate, vanadyl acetyl octanoate and vanadium acetyl acetonate, preferably cobalt naphthenate. The accelerator may be provided neat, but is more commonly obtained as a 6% solution in a suitable inert solvent such as white spirit.

The accelerator may be present in the prepolymer composition at a level of between about 0.1 and about 3% by weight of the prepolymer composition when a 6% solution of the accelerator is used; about 0.1 to 2, 0.1 to 1 , 0.1 to 0.5, 0.1 to 0.2, 0.2 to 1 , 0.5 to 1 , 0.5 to 3, 1 to 3, 2 to 3, 0.5 to 2, 1 to 2 or 0.3 to 0.8%; or about 0.1 , 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1 , 1.5, 2, 2.5 or 3% by weight.

An inhibitor may also be present in the prepolymer composition to provide storage stability and to control the gel time. Suitable inhibitors include quinones such as hydroquinone or naphthoquinone. Typically such inhibitors may be added at a concentration in the range of between 50 and 200 parts per million.

Promoter Composition of the second part

Promoter

Suitable promoters in the promoter composition include organic peroxides. Examples include the following:

1. Diacyl peroxides such as benzoyl peroxide, dilauryoyl peroxide, acetyl peroxide, caprylyl peroxide, p-chlorobenzoyl peroxide, decanoyl peroxide, 2,4- dichlorobenzoyl peroxide, pelargonoyl peroxide or propionyl peroxide;

2. Ketone peroxides usually transition such as monomeric or dimeric methyl ethyl ketone peroxide (MEKP), acetyl acetone peroxide or cyclohexanone peroxide;

3. Peroxy esters such as t-butyl peroxybenzoate, t-butyl peroxyacetate, t-butyl peroxy(2-ethylhexanoate), t-butyl peroxyisobutyrate, t-butyl peroxyisopropylcarbonate, t- Butyl peroxypivalate, 2,5-dimethylhexyl-2,5-di(peroxybenzoate), 2,5-dimethylhexyl-2,5- di(peroxy(2-ethylhexanoate)), di-t-butyl diperoxyphthalate or 1 ,1 ,3,3-tetramethylbutyl peroxy- 2-ethylhexanoate;

4. Alkyl peroxides such as di-t-butyl peroxide, dicumyl peroxide, n-butyl-4,4- bis(t-butyl peroxy)valerate, 2,5-dimethyl-2,5-bis(t-butyl peroxy)hexane, 2,5-dimethyl-2,5- bis(t-butyl peroxy)hexyne-3, 1 , 1 -di-t-butyl peroxyl cyclohexane or 1 , 1 -di-t-butyl peroxyl-3,5,5- trimethylcyclohexane; and 5. Hydroperoxides such as cumene hydroperoxide, t-butyl hydroperoxide or 2,5- dimethylhexane-2,5-dihydroperoxide.

The ketone peroxides of group 2 generally require the use of a transition metal salt as an accelerator with a tertiary amine as an optional co-accelerator. Groups 1 , 3, 4 and 5 may be used with a tertiary amine accelerator such as dimethylaniline or dimethyltoluidine either in the absence or presence of a transition metal salt.

Preferably the promoter is a ketone peroxide such as MEKP.

The promoter may be provided neat or in solution. The solvent for the solution may be an inert solvent. Suitable solvents include mineral oil, dibutyl phthalate, benzene, high boiling organic solvents and mineral spirits.

The promoter is generally present in the promoter composition in an amount of about 5% to about 20%, depending upon the desired concentration in the final cured composition.

Co-accelerator

The promoter composition may optionally comprise a co-accelerator (sometimes referred to as the "co-catalyst"). The co-accelerator may be a tertiary amine such as a tertiary aromatic amine, for example, a dialkylaniline derivative. The alkyl groups of the dialkylaniline derivative may be Ci_-6alkyl groups such as methyl, ethyl or propyl groups. Suitable co-accelerators include Ν,Ν-dimethyl p-toluidine (DMPT) or Ν,Ν-dimethylaniline or derivatives thereof.

The co-accelerator may be present in the promoter composition in an amount of about 0.5% to 5%, depending upon the desired concentration in the final cured composition. Additives

It will be appreciated that the promoter composition or the curable or cured composition may include additives. Examples include one or more fillers, inhibitors, antistatic agents or flame retardants.

The filler may be a fibrous filler, for example a reinforcing filler. Examples include short glass fibres which may have a mean fibre length of less than about 10cm; less than about 5, 2 or 1 cm; about 0.1 to 10, 0.1 to 5, 0.1 to 2, 0.1 to 1 , 0.1 to 0.5, 0.5 to 10, 1 to 10, 2 to 10, 5 to 10, 0.5 to 5, 0.5 to 2 or 1 to 5cm; or about 0.1 , 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1 , 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 6, 7, 8, 9 or 10cm.

The filler may be pretreated so as to improve its adhesion to the polymeric material when formed. Suitable pretreatments include treatment with silane coupling agents for example vinylfunctional silanes such as methacryloyloxypropyltrimethoxysilane.

The filler may be present in the promoter composition or the curable or cured composition at about 5 to about 50% by weight or volume; about 5 to 20, 5 to 10, 10 to 50, 20 to 50, 10 to 30, 20 to 40 or 15 to 25%; or about 5, 10, 15, 20, 25, 30, 35, 40, 45 or 50% by weight or by volume.

An inhibitor may be present in the promoter composition to provide storage stability and to control the gel time. Suitable inhibitors include quinones such as hydroquinone or naphthoquinone, typically added at a concentration of between 50 and 200 parts per million.

One major application of the compositions of the present invention is for use in mine tunnels. Static electricity is generated underground by the movement of dry air over susceptible surfaces, and by other mechanisms. This poses a danger as it is a potential spark source which can lead to a fire. Steel mesh, which is presently used as a reinforcement material, is able to conduct static electricity away to be earthed through the rock bolts, thereby reducing the risk due to static electricity. Most polymers (including polyesters) are intrinsically electrically insulating, and so static electricity can build up on polymer surfaces. Therefore, if it is desired to replace steel mesh with a polymer-based alternative, some degree of electrical conductivity in the polymer may be desirable.

Anti-static additives for polymers generally fall into two categories. The first category is ionic organic compounds that migrate to the surface of the polymer and reduce static by attracting atmospheric water which condenses on the surface. These compounds eventually wash off and are replaced by more of the additive migrating to the surface. Ultimately, however, the reservoir of additive in the bulk of the polymer is exhausted and the anti-static activity ceases. An additional problem with this type of agent in the underground environment is that static electricity is typically generated by the passage of ventilation air that contains very little moisture, so the anti-static action may never "switch on".

The second category of anti-static agents is the so-called "permanent anti-stats". These additives are generally metals or semiconductors, and operate by providing electrical connectivity. In order to be effective, however, they generally need to be added in relatively high amounts.

One possibility for suppressing static electricity in the compositions of the present invention is to apply an anti-static powder to the surface as the polyester is curing, thereby confining all of the anti-static activity to the surface. In this way much less of the anti-static material would be required. A second option is to incorporate an additive that migrates to the surface during cure (known as "self-stratifying" additives).

In underground coal mines there is always a risk of fire. Coal itself is combustible, and often flammable methane gas is associated with the coal. A major advantage of steel mesh over many polymeric alternatives is that it is non-combustible. If an alternative to steel mesh is to be used, it is preferable that it be less combustible than the coal to which it is attached. There are several approaches to the endowment of polymeric materials with flame retardancy. One approach is to make the polymer from flame-retardant monomers, thus making the resultant polymer inherently flame-retardant. Halogen-functional monomers (those containing chlorine or bromine) are mostly used in this context. An alternative, and possibly more cost-effective, approach is to use flame-retardant additives, of which there are 3 types:

• substances that disrupt free radical propagation in the flame;

• substances that decompose when heated to produce a flame-suppressant gas such as C0₂; and

• substances that char and swell when heated and thereby remove the seat of the flame from the fuel source.

Additives in the third category are known as "intumescent" flame retardants. Typically two or more types are used in conjunction to produce an effective flame-retardant system.

Suitable additives include mixtures of silica gel and potassium carbonate, which enhance char formation. Such mixtures have been used to provide effective flame retardancy to a range of polymers (both inherently char-forming and non-char-forming) at total additive levels up to 10%. Silica gel and potassium carbonate are both inexpensive and readily available. An advantage of this system for use underground is that CO formation during combustion was not significantly increased by the presence of the additives.

Thus the promoter composition, the curable composition and the cured composition described herein may all comprise either an antistatic agent or a flame retardant or both. The antistatic agent, if present, may be distributed in the cured composition either throughout the cured composition or on the surface thereof. Thus the process for preparing promoter or curable composition may comprise the additional step of mixing an effective amount of an antistatic agent or of a flame retardant or both with the composition once formed, or with one or more of the components prior to mixing them to form said composition. Alternatively or additionally, the process for forming the cured composition may comprise applying (e.g. spraying) an antistatic agent onto the surface of the curable composition after it has been located in the desired location and before it has gelled, or before the surface of the curable composition has become tack-free. In this context, "tack- free" refers to a state in which the antistatic agent fails to adhere to the surface.

In one embodiment, the monomer is at least partially halogenated (e.g. chlorinated or brominated). This may serve to provide intrinsic flame retardancy to the compositions incorporating them without the need for separate added flame retardants. Thus the monomer may be at least partially halogenated, or the diacid, anhydride or diol (or more than one, optionally all, of these) used in making the polyester forming part of the prepolymer composition may be at least partially halogenated. Suitable polyesters may be made using (or may have monomer units derived from) halogenated anhydrides such as dibromophthalic anhydride, dichlorophthalic anhydride etc.

Suitable antistatic agents that may be added to the compositions of the present invention, include carbon black, fullerenes, carbon nanotubes, graphene, tetrapod zinc oxide, electrolytic nickel powder, intrinsically-conducting polymers such as BTATZ (bis(aminotetrazolyl)tetrazine), polyacetylene and polyparaphenylene sulphide.

Suitable flame retardants that may be added to the compositions of the present invention, include combinations of silica gel and a metal carbonate such as potassium carbonate. Metal hydroxides, for example aluminium hydroxide, magnesium hydroxide etc. may also be used.

Curable composition

The invention also provides a curable composition comprising the prepolymer composition defined above and the promoter composition also defined above, which is capable of causing the prepolymer composition to cure when it is combined with the prepolymer composition. The curable composition may also be provided as a kit. The curable composition will spontaneously cure once formed due to crosslinking of the polyester with the monomer under the influence of the promoter and the accelerator.

When the prepolymer composition and the promoter composition are combined, solidification of the curable composition occurs as the monomer partially polymerises, and co-polymerises with the polyester, to form a crosslinked solid material. The accelerator and optionally the co-accelerator cause the decomposition of the promoter into "free radicals", which then react with the double bonds in the unsaturated polyester and the monomer causing chemical linkages, as shown in Scheme 1 below.

DMT

Promoter R-O' (Free Radical)

R— O' + X=CH₂ Y=Y— Y=Y— Y=Y— Y=Y

(Crosslinking\ Unsaturated

Monomer / , Polyester

Scheme 1 This process occurs in two stages known as "gelation" and "vitrification". Gelation involves localised crosslinking as shown in Scheme 1 , leading to a dimensionally-stable but soft material (a "gel"). Vitrification involves the linking up of the individual gel domains into a continuous solid material and leads to the development of full strength. This is accompanied by a temperature increase known as the "Trommsdorff Effect".

An advantage of the curable composition of the present invention is that there are no small molecule by-products of the polymerisation process. As most of the polymerisation takes place during gelation, there are substantially no volatile materials present when the exotherm occurs.

The prepolymer and promoter compositions are preferably capable of formulation into a sprayable curable composition. The co-accelerator is preferably present in the promoter composition when the prepolymer and promoter compositions are formulated into a sprayable curable composition.

Suitable sprayable curable compositions have a short gel time of under about 1 minute, preferably under 45 seconds, under 30 seconds, 10 to 60 seconds, 10 to 45 seconds, 10 to 30 seconds, 10 to 20 seconds, 20 to 45 seconds, 30 to 45 seconds or 15 to 30 seconds or about 10, 15, 20, 25, 30, 35, 40, 45, 50, 55 or 60 seconds.

The term "gel time" as used herein refers to the time following combination of the prepolymer composition and the promoter composition until the resulting mixture has gelled as estimated visually. In the present specification the phrase "gel time" or "initial cure" "at room temperature" indicates that the composition is initially mixed at room temperature (e.g. at about 20 to 25°C; or 20, 21 , 22, 23, 24 or 25°C) and that no external heating or cooling is applied thereafter until the composition gels. It will be understood that the actual temperature of the curing mixture will vary due to heat evolved during the curing process.

The requirement for a short gel time is particularly important when the composition is used for reinforcing surfaces in confined environments such as the ceiling, walls and/or floor of a tunnel. Thus rapid cure is required firstly in order to ensure that the formulation does not flow away from its initial location prior to gelation, secondly to enable the cured composition to be bolted in place without excessive delay, and thirdly to minimise the time required to reinforce the tunnel so as to achieve a safe working environment for workers in the tunnel.

The cured composition may be bolted in place when used to reinforce mining tunnels. Bolts are typically made of mild steel. They may be up to 1.8m long and are typically about 2.5cm diameter. They may be ribbed for most of their length and may have a screw thread on the bottom end. The bolts may be self-drilling bolts. Self-drilling bolts commonly have a hardened steel drill tip and are hollow (and therefore wider than other types of bolts) to allow the chemical anchor resin through to the annulus between the hole and the bolt. Thus commonly in use of such bolts, a chemical anchor resin flows up through the hollow core and into the annular space between the hole and the bolt, thereby anchoring the bolt when set. The chemical anchor resin may be the same as the curable composition described herein, or may be a different curable resin.

The requirement for sprayability of the composition may be met when both the prepolymer composition and the promoter composition are liquids. They should each have a viscosity such that when combined the resulting composition has a viscosity such that it is sprayable. The viscosity of the prepolymer and promoter compositions may be the same or different. They may each independently be between about 200 and 1000 cP; about 200 to 700, 200 to 500, 400 to 1000, 500 to 1000, 300 to 600 or 400 to 500cP; or about 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950 or l OOOcP. These values are as measured at 25°C using a Brookfield viscometer. Suitable conditions for the Brookfield viscometer are spindle LV1 at 6rpm. The viscosity may be varied as required by addition of a suitable diluent, for example the vinyl-functional monomer, in small quantities. Processes

There is also provided a process for preparing the prepolymer composition. This process involves combining the components of the prepolymer composition, i.e. the unsaturated polyester, the vinyl-functional monomer and the accelerator. These may be combined in any desired order, as no chemical reaction is desired at this stage. Thus the components may all be added and then combined, or the polyester may be combined with the monomer and the resulting mixture mixed with the accelerator, or some other order may be used.

There is further provided a process for preparing the promoter composition. This process involves combining the components of the promoter composition, i.e., the promoter and the vinyl-functional monomer. These may be combined in any desired order, as no chemical reaction is desired at this stage. Thus the components may all be added and then combined or the monomer may be added to the promoter or some other order may be used.

In a preferred embodiment, the promoter composition includes a co-accelerator. When the co-accelerator is present, the process for preparing the promoter composition involves combining the components of the promoter composition, i.e., the promoter, the co- accelerator and the vinyl-functional monomer. These may be combined in any desired order, as no chemical reaction is desired at this stage. Thus the components may all be added and then combined or the co-accelerator may be dissolved in the monomer and added to the promoter or some other order may be used. If a filler, inhibitor, flame retardant, anti-static agent and/or other additives are included, they may be added at any stage of the process for making the promoter composition, added when the prepolymer composition and the promoter composition are combined or added after the prepolymer composition and the promoter composition are combined. The components of the prepolymer and promoter composition may be combined using any suitable known apparatus such as a batch reactor.

The invention also provides a process for making the curable composition. This process comprises combining the prepolymer composition with the promoter composition whereby the promoter composition is capable of causing the prepolymer to cure. If a filler, inhibitor, flame retardant, anti-static agent and/or other additives are included, they may be combined at any stage of the process for making the curable composition. In one embodiment, the process involves combining the filler with the promoter composition or with the combined prepolymer and promoter compositions. In one example of the process, the filler is combined with the promoter composition to produce the curable composition which is then sprayed onto the desired surface (e.g. the wall, ceiling and/or floor of a mine tunnel) where it cures in situ. In another embodiment of the process the filler is located on the desired surface, for example as a bed of filler. Separately the prepolymer and promoter compositions are combined and then sprayed onto the filler. The prepolymer composition then combines with the filler by penetrating into and/or through the filler to form the curable composition where it cures in situ.

It will be appreciated that once the prepolymer and promoter compositions are combined, the curable composition cures without further stimulus. In a preferred embodiment, where the promoter composition contains a co-accelerator, the curable composition will cure rapidly when the prepolymer and promoter compositions are combined. It is therefore desirable to apply the curable composition to the surface as rapidly as possible. It is also preferable to combine the prepolymer and promoter compositions as rapidly as possible. These objectives may be met using any suitable apparatus such as automated systems, for example spray heads which combine the two parts and spray them onto a desired location. Other mixing/dispensing devices may also be used to combine and apply the curable composition.

Cured Composition

The cured composition may be used as a polymeric material for reinforcing a surface.

The surface may be a floor, a wall or a ceiling. It may be in a confined space such as a mine or in a house or in a dwelling or in some other location. The cured composition may be used for the purpose of reinforcing, protecting or substantially preventing matter from detaching from the surface so as to avoid danger to humans and/or animals.

The cured composition may at least partially adhere to the surface. It is preferably applied to the surface by spraying. In mining applications, the at least partially cured composition may additionally be bolted to the surface. The spacings between the bolts spacing are commonly specified by geotechnical engineers based on strata stability and may vary considerably based on local conditions.

As the cured composition of the present invention is impermeable to liquid water, there is the potential for water to build up behind the composition as water seeps through the wall and/or ceiling of the mine tunnel. This water build-up may be alleviated by perforating the cured composition at regular intervals in order to allow the water to penetrate the composition. Thus the process may additionally comprise the step of perforating the cured composition following application to the surface of the mine tunnel.

Properties

The mechanical properties of the polymeric material of the present invention are similar to or superior to the steel mesh which is presently used to reinforce the surfaces of tunnels in mines.

The typical mechanical and physical properties of the polymer material of the present invention are as follows:

Applications

The compositions of the present invention have use in many applications. These include, but are not limited to, the following:

1. Reinforcement In Confined Applications

As discussed above, the composition of the present invention, with a reinforcing filler such as glass fibre, is capable of forming a polymeric skin and/or liner which may be used to reinforce the surface in hard rock mines, underground roadways in longwall mines and provide stabilisation of road and corridor excavators. They can also provide bord and pillar coal mine strata support, and temporary arrest of fretting and spalling of longwall faces in mines.

2. Lining For An Aged Reinforced Concrete Water Supply And/Or Drainage Conduit The composition may be used to waterproof water vessels such as tanks, pipes and underground concrete sewer pipes. These structures frequently develop cracks as they age, due to deterioration or embrittlement of the construction materials or to movement in substrates. Coating these structures with a polymeric material described herein can provide a waterproofing treatment which is capable of absorbing minor movements in the substrate without failure.

3. Residential And Commercial Buildings

Sprayed with a suitable reinforcing filler such as glass fibre onto surfaces such as floors, ceilings or walls, the composition may be used as a building material. This may find application for example in Japan. Typhoons and torrential rainstorms repeatedly hit Japan every year. Residences commonly need to be reinforced against storms using designs that ensure the strength and waterproofing of buildings. In addition, as a precaution against ignition and spread of fires, which is of great importance in neighbourhoods with houses arranged close together. Fireproof materials such as those of the present invention are also desirable so as to achieve fire-retardant performance. The compositions may also be used to cover dangerous and difficult to remove building products for example to remediate old asbestos containing buildings.

Issues of importance in the Japanese housing market include:

• formaldehyde concentration;

• toluene and xylene concentration;

• floor sound insulation performance;

• air sealing performance;

• thermal insulation performance;

• earthquake resistance for the plan.

The present invention may assist in addressing at least some of these issues.

4. Unsupported Rock Failures In Undergrounds Mining

Tenaciously adhering, deformable polymeric materials such as those of the present invention have an ability to substantially mitigate damage often seen to result when catastrophic unsupported rock failure occurs. Shotcrete support, while demonstrating significant capacity to restrain rock heave and fragment ejection, has been noted to suffer generally greater layer damage and potential breakup than any of the spray-on polymeric materials. Rockbolts and bolt-and-mesh support media provided least effective support restraint in terms of reducing fragment ejection, restriction of the extent of the damage zone formed and prevention of damage to support materials.

5. Spray On Truck Bed Liners

These are generally comprised of a variety of materials such as polyethylene, polypropylene or polyvinylchloride. These liners are generally vacuum formed to fit a particular configuration of a vehicle bed and then stored in inventory. Once a molded liner is purchased, it is dropped into the vehicle bed and may be attached to the bed to act as a protective liner. The disadvantages of a molded liner are numerous. Molded drop-in-place liners may require drilling or bolting to the vehicle body, which exposes the vehicle bed to rust and corrosion. Further, molded vehicle bed liners may warp, crack, tear or vibrate loose. Additionally, no matter how closely the bed liner models that of the vehicle to be lined, the molded liner will leave gaps between the liner and the vehicle bed. The gaps may become filled with dirt, moisture or other materials that create the environment for accelerated corrosion of the vehicle bed beneath the liner. Also, worn out portions of molded liners cannot readily be replaced or repaired. Thus, the entire molded liner must be replaced after a portion of the liner is worn through, regardless of the condition of the remainder of the liner. A spray on polymeric material such as provided by the present invention may be readily applied to line any truck bed without the need to be customer manufactured.

EXAMPLES

Unsaturated Polyester Synthesis

In a typical polyesterification synthesis, the reactants and 0.1 % by weight of a polyesterification catalyst such as butyl stannoic acid are introduced into a spherical reaction flask (usually with a slight stoichiometric excess of diol) equipped with a stirrer, a Dean-Stark trap and condenser (for collection of product water), a temperature controller probe, and a source of nitrogen gas (to avoid oxidation during the synthesis). The contents are slowly heated with stirring until a homogeneous mixture is achieved, and then the mixture is heated at up to 230°C for about 24h. The final stage of the synthesis involves removal of the last traces of water, if necessary, by azeotropic distillation with xylene, followed by xylene removal before decanting the finished polyester.

Twelve polyester prepolymers were synthesised using the above general procedure. The table below shows the diacid and diol components. In all cases, the diacid was a combination of phthalic anhydride and maleic anhydride, which were present in the mole ratio specified in the Table 1 below. Table 1

Raw Materials for ln-house Unsaturated Polyesters and Masses of Reactants Used to Prepare 500g

In the following example, the concentration of TEGDVE in the final cured composition was 30% by mass. For different TEGDVE concentrations in the final cured product, actual masses of TEGDVE, cobalt naphthenate solution and MEKP solution would vary in order to achieve the final concentrations described above. Consequently, the relative amounts of prepolymer composition and promoter composition would also vary to give the desired composition of the final cured product.

Prepolymer Composition Synthesis

The prepolymer composition was prepared by combining 500g unsaturated polyester with 125g triethylene glycol divinyl ether and stirring with heating until a clear viscous liquid resulted. The mixture was cooled and 3.6g of cobalt naphthenate accelerator (6% solution in white spirit) stirred in, resulting in a magenta liquid, which is referred to as the prepolymer composition.

Promoter Composition Synthesis

The promoter composition was prepared by combining 14.3g MEKP promoter with 90g triethylene glycol divinyl ether.

In all of the examples described below, the concentration of cobalt naphthenate accelerator solution (6% in white spirit) was 0.5% by mass, and the concentration of MEKP promoter solution (35% in 2,2,4-trimethyl-1 ,3-pentanediol diisobutyrate, trade name Luperox DDM-9) was 2% by weight. In these examples, a co-accelerator was not used. Curable Composition Synthesis for Measurement of Unreinforced Tensile Properties

The prepolymer composition (25.6g) and the promoter composition (4.4g) were combined with vigorous stirring, and this mixture was poured into a dogbone mould. Gel times of 3 - 33 minutes were recorded, depending on actual composition (see Table 1 ). After cure the sample was removed from the mould. The cured dogbone sample was approximately 5mm thick with a central test section approximately 13mm wide and a gauge length of approximately 100mm.

Curable Composition Synthesis for Measurement of Reinforced Flexural Properties

The prepolymer composition (341.3g) and the promoter composition (58.7g) were combined with vigorous stirring, and this mixture was poured into a rectangular mould. Chopped strand mat (5 layers, approximately 100g) was dispersed in the liquid composition using a lay-up roller. Gel times of 3 - 33 minutes were recorded, depending on actual composition (see Table 1 ). After cure, the solid plate (approximately 5mm thick) was removed from the mould and cut into coupons 100mm long and 20mm wide.

Cure and Mechanical Properties of Polyester Prepolymers Crosslinked with Triethylene Glycol Divinyl Ether

The mechanical properties of the prepolymer composition were measured when crosslinked with TEGDVE (i.e. the cured composition).

Cure time was measured as the time to gel for the unreinforced dogbone samples. The unreinforced dogbone samples were subjected to tensile testing to determine the tensile modulus (Youngs modulus, a measure of stiffness), tensile strength and elongation at break.

The reinforced coupons were subjected to 3-point-bend testing with a lower support distance of 80mm to determine the flexural modulus, flexural strength and flexural failure. All twelve cured polyesters, dissolved in 20%, 30% or 40% TEGDVE, were tested (36 formulations in all) and the test results are shown in Tables 2 to 8 below.

Table 2

Cure Time (minutes) of Polyesters Crosslinked

with Triethylene Glycol Divinyl Ether, measured as Time to Gel

It can be seen from Table 2 that the cured composition having polyesters 5, 6 and 7 with 20% triethylene glycol divinyl ether and polyester 10 with 40% triethylene glycol divinyl ether gave the fastest cure time for producing the cured product, with a cure time of about 2 minutes. Polyesters 1 to 4 gave cure times of about 30 minutes irrespective of TEGDVE concentration used.

Table 3

Tensile Modulus (MPa) of Unreinforced Polyesters Crosslinked

with Triethylene Glycol Divinyl Ether

Polyesters 1 to 4, irrespective of TEGDVE concentration, generally gave low tensile modulus values. In general, 30% TEGDVE samples had superior tensile modulus values compared to 20% and 40% for any given polyester. Polyester 12 with 30% TEGDVE produced the sample with the highest tensile modulus.

Table 4:

Tensile Strength (MPa) of Unreinforced Polyesters Crosslinked

with Triethylene Glycol Divinyl Ether

The cured composition including polyester 10 and 20% triethylene glycol divinyl ether gave a product with the highest tensile strength.

Table 5

Elongation at Break (%) of Unreinforced Polyesters Crosslinked

with Triethylene Glycol Divinyl Ether

Elongation at break was typically in the range 3 - 7%. Some samples failed prematurely, largely due to the presence of air bubbles and other anomalies. Polyester 9 crosslinked with 20% TEGDVE gave an unusually high elongation at break.

Table 6

Flexural Modulus (MPa) of Glass-reinforced Polyesters Crosslinked

with Triethylene Glycol Divinyl Ether

In general, polyester formulations containing higher maleic anhydride:phthalic anhydride ratios and 30% TEGDVE gave superior flexural moduli.

Table 7

Flexural Strength (MPa) of Glass-reinforced Polyesters Crosslinked

with Triethylene Glycol Divinyl Ether

In general, higher flexural strength characteristics were exhibited by polyesters of higher maleic anhydride:phthalic anhydride ratios crosslinked with 30% TEGDVE.

Table 8

Flexural Failure (mm) of Glass-reinforced Polyesters Crosslinked

with Triethylene Glycol Divinyl Ether

Formulations crosslinked with 20% TEGDVE generally gave more flexible flexural behaviour.

Of the curable compositions thus far investigated, polyester 7 crosslinked with 30% triethylene glycol divinyl ether appears to be the most promising. This selection is based on appropriate cure behaviour with minimal shrinkage and no cracking, adequate unreinforced tensile properties and superior reinforced flexural properties, however several formulations would appear to be suitable for the desired application.

In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.

Claims

CLAIMS:

1. A two-part curable composition comprising:

(i) a first part which is a prepolymer composition comprising an unsaturated polyester, a vinyl-functional monomer and an accelerator; and

(ii) a second part which is a promoter composition comprising a promoter and a vinyl-functional monomer,

the second part being capable of promoting curing of the curable composition when the first and second parts are combined.

2. The two-part curable composition according to claim 1 , wherein the unsaturated polyester of the prepolymer composition is a condensation product of at least one diacid and/or anhydride and at least one organic diol.

3. The two-part curable composition according to claim 2, wherein the diacid and/or anhydride is an aromatic diacid and/or anhydride; an aliphatic diacid and/or anhydride; and/or a cyclic diacid and/or anhydride having 5 to 10 atoms in the ring.

4. The two-part curable composition according to claim 3, wherein the aromatic diacid is selected from the group consisting of phthalic acid, isophthalic acid and 1 ,8- naphthalenedioic acid.

5. The two-part curable composition according to claim 3, wherein the aromatic anhydride is selected from the group consisting of phthalic anhydride and 1 ,8-naphthalic anhydride.

6. The two-part curable composition according to claim 3, wherein the aliphatic diacid is selected from the group consisting of succinic acid, glutaric acid and adipic acid.

7. The two-part curable composition according to claim 3, wherein the aliphatic anhydride is selected from the group consisting of maleic anhydride, succinic anhydride and glutaric anhydride.

8. The two-part curable composition according to claim 3, wherein the cyclic diacid and/or anhydride is selected from the group consisting of cyclopentanedicarboxylic acid and cyclohexanedicarboxylic anhydride.

9. The two-part curable composition according to claim 2, wherein the diacid and/or anhydride is a combination of an alpha, beta-ethylenically unsaturated diacid and/or anhydride and a non-polymerisable diacid and/or anhydride.

10. The two-part curable composition according to claim 9, wherein the combination of an alpha, beta-ethylenically unsaturated diacid and/or anhydride and a non-polymerisable iacid and/or anhydride is a combination of maleic anhydride and phthalic anhydride, adipic acid and maleic anhydride, or maleic anhydride, phthalic anhydride and adipic acid.

1 1 . The two-part curable composition according to claim 2, wherein the organic diol is a saturated or unsaturated aliphatic diol, optionally interrupted by a cyclic group or an ether group.

12. The two-part curable composition according to claim 2, wherein the organic diol is a linear or branched diol having 2 to 10 carbon atoms linking the two alcohol groups.

13. The two-part curable composition according to claim 2, wherein the organic diol comprises one or more diols selected from the group consisting of diethylene glycol, triethylene glycol, 1 ,2-ethanediol, 1 ,2-propanediol, 1 ,6-hexanediol, 1 ,3-propanediol, 2- methyl-1 ,3-propanediol, 1 ,4-butanediol, 1 ,5-pentanediol, 1 ,4-cyclohexanedimethanol and combinations thereof.

14. The two-part curable composition according to claim 1 , wherein the vinyl-functional monomer of the prepolymer composition or the promoter composition is selected from the group consisting of styrene, alkyl derivatives of styrene, acrylates, methacrylates, allyl benzene, N-vinyl pyrrolidone, vinyl toluene, divinyl benzene, diallyl phthalate, hexanediol diacrylate, divinyl ether, glycol divinyl ether and trimethylolpropane triacrylate.

15. The two-part curable composition according to claim 14, wherein the divinyl ether monomer and the glycol divinyl ether monomer is selected from the group consisting of triethylene glycol divinyl ether (TEGDVE), diethylene glycol divinyl ether (DEGDVE) and ethylene glycol divinyl ether (EDVE).

16. The two-part curable composition according to claim 1 , wherein the accelerator is a transition metal salt.

17. The two-part curable composition according to claim 16, wherein the transition metal salt is selected from the group consisting of a cobalt salt, an iron salt, a copper salt, a manganese salt, a tin salt and a vanadium salt.

18. The two-part curable composition according to claim 17, wherein the transition metal salt is selected from the group consisting of cobalt naphthenate, cobalt octanoate, cobalt 2- ethylhexanoate, cobalt hexanoate, iron naphthenate, copper naphthenate, manganese octanoate, tin octanoate, vanadyl acetyl octanoate and vanadium acetyl acetonate.

19. The two-part curable composition according to claim 1 , wherein the promotor is an organic peroxide.

20. The two-part curable composition according to claim 19, wherein the organic peroxide is selected from the group consisting of diacyl peroxides, ketone peroxides, peroxy esters, alkyl peroxides and hydroperoxides.

21 . The two-part curable composition according to claim 1 , wherein the composition further comprises a co-accelerator.

22. The two-part curable composition according to claim 21 , wherein the co-accelerator is a tertiary amine.

23. The two-part curable composition according to claim 1 , wherein the prepolymer composition comprises an inhibitor to impart increased shelf life.

24. The two-part curable composition according to claim 1 , wherein the composition is sprayable.

25. A promoter composition comprising a promoter and a vinyl-functional monomer.

26. A promoter composition comprising a promoter, a co-accelerator and a vinyl- functional monomer.

27. A promoter composition according to claim 25 or 26, further comprising an additive selected from the group consisting of a filler, inhibitor, flame retardant and antistatic agent.

28. A kit comprising:

(i) the prepolymer composition of the first part according to claim 1 ; and

(ii) the promoter composition of the second part according to claim 1 , the second part being capable of promoting curing of the curable composition when the first and second parts are combined.

29. A process for preparing a curable composition, comprising the step of:

a. combining the prepolymer composition of the first part as defined in claim 1 and the promoter composition of the second part as defined in claim 1 , the second part promoting curing of the curable composition.

30. A process for preparing a cured composition, comprising the steps of:

a. combining the prepolymer composition of the first part as defined in claim 1 and the promoter composition of the second part as defined in claim 1 , the second part promoting curing of the curable composition; and

b. curing the curable composition.

31 . A cured composition prepared by the process according to claim 30.

33. Use of the curable composition as defined in claim 1 in the manufacture of a polymeric material.

34. Use of a promoter composition as defined in claim 25 or 26 to promote curing of a curable composition.

35. A process for reinforcing a surface comprising the steps of:

a. combining the prepolymer composition of the first part according to claim 1 and the promoter composition of the second part according to claim 1 to form a curable composition;

b. applying the curable composition to a surface; and c. allowing the curable composition to cure on the surface to form a polymeric skin or liner.