Vinyl ester resin compositions

Abstract

The present invention relates to a vinyl ester resin composition for a cured-in-place pipe, the vinyl ester resin composition being thickenable using isocyanates and / or metal oxides and / or metal hydroxides, being curable by free radical polymerisation, and comprising: (a) a vinyl ester oligomer having a number average molecular weight of between 500 and 3000 as measured by gel permeation chromatography according to the method provided in the methods section; and (b) a reactive diluent monomer mixture; wherein the reactive diluent monomer mixture comprises a monofunctional reactive diluent monomer, a difunctional reactive diluent monomer and a trifunctional reactive diluent monomer. The invention also relates to a thickened vinyl ester resin composition, uses thereof for a cured-in-place pipe process, and cured products thereof.

Description

[0001] VINYL ESTER RESIN COMPOSITIONS

[0002] Field of the Invention

[0003] The present invention relates to a vinyl ester resin composition that is particularly suitable for use in a cured-in-place pipe, and particularly, although not exclusively, to a thickened vinyl ester resin composition, and cured products thereof.

[0004] Background

[0005] Cured-in-place pipe (CiPP) is a trenchless relining method of rehabilitating pipe systems. During the cured-in-place pipe process, a sleeve-shaped laminate, produced from fabric material such as felt, glass fibres, or a combination thereof, is impregnated with a vinyl ester resin or an unsaturated polyester resin containing one or more reactive diluent monomers. The laminate can then be installed into a damaged host pipe either by the inversion installation method, in which the laminate is inverted into a pipe system using air or hydrostatic pressure, or the pull-in method, in which the laminate is pulled into the line and inflated against the host pipe using air. In both cases, the resin is cured either by thermal or photoinitiated methods to repair the pipe system. Free radical initiators such as peroxides or UV initiators are typically used in the curing process. As the resin cures, it hardens and forms a solid, corrosion-resistant pipe within the host pipe.

[0006] Vinyl ester resin compositions are preferred resin compositions for cured-in-place pipe applications due to their exceptional chemical resistance, high mechanical strength and excellent adhesion properties. Vinyl ester resin compositions are typically derived from the reaction between epoxy resins with unsaturated carboxylic acids. The balance of toughness and chemical resistance makes these resin compositions particularly suitable for harsh environments and industrial applications where corrosion and chemical exposures are of concern.

[0007] Particularly important components that can be integrated into vinyl ester resin compositions for cured-in- place pipe applications are thickening agents. The thickening occurs by linking polymer or oligomer chains with each other to form chains of higher molecular weight, thereby increasing the viscosity of the resin composition. Typically, this is done by adding to the system a multifunctional compound which couples two or more vinyl ester oligomers together via their respective functional groups. Typically, vinyl ester oligomers contain more than two functional groups, and so the actual thickened composition comprises a complex network of interconnected polymer chains rather than discrete individual chains.

[0008] Thickening agents most commonly belong to one of two categories. The first type is (poly)isocyanates, which form covalent bonds between polymer chains. The second type is Group II metal oxides and hydroxides, with magnesium oxide being the most common agent of this type, which form hydrogen bonds between polymer chains.

[0009] US 4,197,390 describes thermosetting vinyl ester resin compositions with reactive carboxylic acid groups which can be rapidly thickened by adding a group II metal oxide or hydroxide and a catalytic amount of water to produce a firm, relatively non-tacky solid which can be easily handled before the final curing operation.

[0010] Similarly, US 3,466,259 describes chemically modified thickenable vinyl ester resins, prepared by the reaction between an ethy lenically unsaturated monocarboxylic acid with a polyepoxide in the presence of a small amount of a dicarboxylic acid and diluted with a copolymerisable monomer.

[0011] Other vinyl ester resin compositions are also known in the art, such as those disclosed in EP3755733, which use trifunctional materials to improve the cure of the resin, and those disclosed in EP2097369, which use a difunctional diluent and an optional monofunctional diluent to provide a low viscosity resin.

[0012] Consequently, there remains a need within the art for improvements in the thickening profile of resins which are suitable for cured-in-place pipe applications, in particular so that a lower amount of a standard thickening agent may be used to achieve the same increase in viscosity of the resin composition.

[0013] The present invention has been devised in light of the above considerations.

[0014] Summary of the Invention

[0015] A first aspect of the invention is a vinyl ester resin composition for a cured-in-place pipe, the vinyl ester resin composition being thickenable using isocyanates and / or metal oxides and / or metal hydroxides, being curable by free radical polymerisation, and comprising a vinyl ester oligomer having a number average molecular weight of between 500 and 3000, as measured by gel permeation chromatography according to the method provided in the methods section, and a reactive diluent monomer mixture comprising: a monofunctional reactive diluent monomer, a difunctional reactive diluent monomer and a trifunctional reactive diluent monomer.

[0016] Surprisingly, the present inventors have found that the use of the combination of a vinyl ester oligomer having a number average molecular weight of between 500 and 3000, as measured by gel permeation chromatography according to the method provided in the methods section, with a reactive diluent monomer mixture comprising a monofunctional reactive diluent monomer, a difunctional reactive diluent monomer and a trifunctional reactive diluent monomer, can lead to an improved thickening profile of the vinyl ester resin composition.

[0017] In particular, the improved vinyl ester resin compositions are evidenced by the use of an equivalent amount of a thickening agent, such as a (poly)isocyanate compound or magnesium oxide, which produces a greater increase in the viscosity of the vinyl ester resin composition when compared against commercially available vinyl ester resin compositions and those described in the prior art. Conversely, the same increase in viscosity may be achieved with the present vinyl ester resin composition when a lower amount of thickening agent is used. Furthermore, the higher viscosity plateau may also be achieved at a faster rate. An improved thickening profile is particularly advantageous for cured-in-place pipe applications. Advantageously, the present inventors have found that the use of a reactive diluent monomer mixture comprising a monofunctional reactive diluent monomer, a difunctional reactive diluent monomer and a trifunctional reactive diluent monomer in combination with a vinyl ester oligomer having a number average molecular weight Mn of between 500 and 3000, as measured by gel permeation chromatography according to the method provided in the methods section, has the desirable effect of reducing production times and material costs for resin manufacturers without compromising on the UV reactivity of the vinyl ester resin composition which is required in industrial processes.

[0018] Suitably, the vinyl ester resin composition according to the first aspect can undergo a thickening process in which its viscosity increases. A thickening agent can initiate the thickening process. In some embodiments, the vinyl ester resin composition is supplied together with a thickening agent in a kit - that is to say, the thickening agent is not pre-added to the composition.

[0019] Thus, in a second aspect of the invention, there is provided a kit comprising the vinyl ester resin composition according to the first aspect and a thickening agent for use in thickening the vinyl ester resin composition to produce a thickened vinyl ester resin composition. Suitably, the thickening agent may be a (poly)isocyanate-based thickening agent, or an inorganic thickening agent such as those comprising a basic or alkaline metal oxide or a basic or alkaline metal hydroxide.

[0020] Thus, in a third aspect of the invention, there is provided a thickened vinyl ester resin composition. The thickened vinyl ester resin composition is derived from the vinyl ester resin composition according to the first aspect and which has a higher viscosity relative to the vinyl ester resin composition according to the first aspect due to addition of the thickening agent.

[0021] Surprisingly, the thickened vinyl ester resin composition of the third aspect, or a thickened vinyl ester resin composition obtained from the kit of the second aspect, has a viscosity which achieved at a faster rate than the viscosity of vinyl ester resin compositions which are commercially available and described in the prior art.

[0022] In a fourth aspect of the invention, there is provided a method for preparing the vinyl ester resin composition according to the first aspect.

[0023] In a fifth aspect of the invention, there is provided a method for preparing the thickened vinyl ester resin composition according to the third aspect.

[0024] In a sixth aspect of the invention, there is provided a use of the thickened vinyl ester resin composition according to the third aspect, or a kit according to the second aspect, for a cured-in-place pipe process. Thus, according to the sixth aspect, the vinyl ester resin composition and the thickened vinyl ester resin composition is used in a cured-in-place pipe process.

[0025] In a seventh aspect of the invention, there is provided a cured product of the thickened vinyl ester resin composition according to the third aspect.

[0026] In an eighth aspect of the invention, there is provided a cured-in-place pipe comprising the cured product according to the seventh aspect. The invention includes the combination of the aspects and preferred features described except where such a combination is clearly impermissible or expressly avoided.

[0027] Preferred embodiments of the invention may also include any one or more of the following preferred features. Preferred features mentioned in relation to the first aspect of the invention may apply equally to the other aspects.

[0028] Detailed Description of the Invention

[0029] Aspects and embodiments of the present invention will now be discussed with reference to the accompanying figures. Further aspects and embodiments will be apparent to those skilled in the art. All documents mentioned in this text are incorporated herein by reference.

[0030] As used herein, the term “(meth)acrylate” refers to both or any one of “acrylate” and “methacrylate”.

[0031] As used herein, the term “monomer” refers to a small molecule that may chemically react and become chemically bonded with itself or with other monomers to form a polymer.

[0032] As used herein, the term “vinyl ester oligomer” refers to an oligomer obtained from the esterification of an epoxy resin with (meth)acrylates. An oligomer is a low molecular weight polymer obtained by reaction of molecules having lower molecular weights. The oligomer may in some instances contain a small number of repeating sequences of the lower molecular weight molecules, for example two repeating sequences, three repeating sequences or four repeating sequences.

[0033] In some embodiments, the vinyl ester oligomer is derived from, or is the reaction product of:

[0034] (i) an epoxy compound comprising at least two epoxy groups;

[0035] (ii) a chain-extending reagent; and

[0036] (iii) a compound selected from an a,p-unsaturated monocarboxylic acid, a (meth)acrylate ester or a (meth)acrylate anhydride.

[0037] In some embodiments, the epoxy group of the epoxy compound is capable of reacting with a suitable functional group of the chain-extending reagent, such as a hydroxyl group or a carboxylic acid group, via an epoxide ring-opening reaction.

[0038] In some embodiments, the epoxy group is bisphenol A diglycidyl ether.

[0039] In some embodiments, the chain-extending reagent is an aromatic chain-extending reagent.

[0040] In some embodiments, the chain-extending reagent comprises at least two hydroxyl groups or at least two carboxylic acid groups.

[0041] In some embodiments, the chain-extending reagent is bisphenol A. In some embodiments, the a,p-unsaturated monocarboxylic acid is methacrylic acid.

[0042] In some embodiments, the (meth)acrylate ester is a methacrylate ester, such as glycidyl methacrylate.

[0043] In some embodiments, the (meth)acrylate anhydride is a methacrylic anhydride.

[0044] Thus, for example the vinyl ester oligomer may be prepared by reacting two moles of an epoxy compound, such as bisphenol A diglycidyl ether, with one mole of a chain-extending reagent, such as bisphenol A, to form a vinyl ester pre-polymer. The resulting vinyl ester pre-polymer could then be reacted with two moles of a compound which acts as an end-capping reagent, such as (meth)acrylic acid, to give a vinyl ester oligomer, which would have a theoretical structure A-(X-Y-X)n-A, in which A is the end-capping reagent, X is the epoxy compound, Y is the chain-extending reagent and n is an integer representing the number of X-Y-X sequences. For example, n is selected from 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10 or more.

[0045] As is well understood by those skilled in the art, the preparation of products of this nature inevitably results in a mixture of molecular structures with differing molecular weights, having a variety of values of n. The relative proportions of epoxy compound (X) and chain-extending reagent (Y) determines the average value of n for what is in practice, a mixture of similar oligomer structures.

[0046] Examples of suitable vinyl ester oligomers typically have a number average molecular weight Mn of at least 500, such as least 600, such as at least 700, such as at least 800, such as at least 900, such as at least 1000, as measured by gel permeation chromatography according to the method provided in the methods section.

[0047] Examples of suitable vinyl ester oligomers typically have a number average molecular weight Mn of at most 5000, such as at most 4500, such as at most 4000, such as at most 3500, such as at most 3000, as measured by gel permeation chromatography according to the method provided in the methods section.

[0048] Examples of suitable vinyl ester oligomers typically have a number average molecular weight Mn of between 500 to 5000, such as between 600 to 5000, such as between 700 to 4500, such as between 800 to 4000, such as between 900 to 3500, such as between 1000 to 3000, as measured by gel permeation chromatography according to the method provided in the methods section.

[0049] In some embodiments, the vinyl ester oligomer is present, based on the total weight of the vinyl ester resin composition, in an amount of at least 20 wt%, such as at least 25 wt%, such as at least 30 wt%, such as at least 35 wt%, such as at least 40 wt%.

[0050] In some embodiments, the vinyl ester oligomer is present, based on the total weight of the vinyl ester resin composition, in an amount of at most 70 wt%, such as at most 65 wt%, such as at most 60 wt%, such as at most 55 wt%, such as at most 50 wt%.

[0051] In some embodiments, the vinyl ester oligomer is present, based on the total weight of the vinyl ester resin composition, in an amount from 20 to 70 wt%, such as from 25 to 65 wt%, such as from 30 to 60 wt%, such as from 35 to 55 wt%, such as from 40 to 50 wt%. Reactive diluent monomer

[0052] The reactive diluent monomer mixture of the present invention comprises a monofunctional reactive diluent monomer, a difunctional reactive diluent monomer and a trifunctional reactive diluent monomer.

[0053] As used herein, the term “reactive diluent monomer” refers to any reactive monomer which is capable of reducing the viscosity of a resin, the reactive monomer being in liquid form at room temperature and being curable with the vinyl ester oligomer. As used herein, the term “reactive diluent monomer mixture” refers to a mixture of the reactive diluent monomers.

[0054] By “monofunctional”, it is meant that the monomer has a functionality of about 1 , i.e. one bonding site. By “difunctional”, it is meant that the monomer has a functionality of about 2, i.e. two bonding sites. By “trifunctional”, it is meant that the monomer has a functionality of about 3, i.e. three bonding sites. An example of a bonding site is a (meth)acrylate functional group.

[0055] The vinyl ester resin composition of the present invention may not be limited to only monofunctional reactive diluent monomers, difunctional reactive diluent monomers and trifunctional reactive diluent monomers. In some embodiments, the vinyl ester resin composition further comprises other polyfunctional reactive diluent monomers, such as tetrafunctional reactive diluent monomers. Suitable examples of tetrafunctional reactive diluent monomers include penta erythritol tetra(meth)acrylate, ethoxy modified products of pentaerythritol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, ethoxy modified products of ditrimethylolpropane tetra(meth)acrylate, and condensation reaction products of trimethylolethane, acrylic acid and succinic anhydride.

[0056] In some embodiments, the vinyl ester resin composition comprises only one monofunctional reactive diluent monomer, only one difunctional reactive diluent monomer and only one trifunctional reactive diluent monomer. That is, in some embodiments, the vinyl ester resin composition comprises at most one of each type of the reactive diluent monomers which constitutes the reactive diluent monomer mixture.

[0057] In some embodiments, the vinyl ester resin composition does not comprise reactive diluent monomers which are not monofunctional, difunctional or trifunctional. That is, in some embodiments, the vinyl ester resin composition does not comprise reactive diluent monomers having a functionality of over 3, such as over 4.

[0058] Preferably, the monofunctional reactive diluent monomer is a (meth)acrylate. Preferably, the difunctional reactive diluent monomer is a di(meth)acrylate. Preferably, the trifunctional reactive diluent monomer is a tri(meth)acrylate. Preferably, at least one of the reactive diluent monomers, such as all of the reactive diluent monomers, present in the vinyl ester resin composition is a (meth)acrylate.

[0059] Suitable examples of monofunctional reactive diluent monomers include, but are not limited to, hydroxyl ethyl (meth)acrylate, hydroxyl propyl (meth)acrylate, butyl (meth)acrylate, vinyl toluene, hexyl (meth)acrylate and cyclohexyl (meth)acrylate, phenoxyethyl (meth)acrylate, tetrahydro furfuryl, (meth)acrylate, allyl (meth)acrylate, tetrahydro furfuryl (meth)acrylate, hydroxyl ethyl (meth)acrylate, hydroxyl propyl (meth)acrylate, tert butyl cyclohexyl (meth)acrylate and benzyl (meth)acrylate. In some embodiments, the monofunctional reactive diluent monomer is selected from the group consisting of benzyl (meth)acrylate (BzMA), cyclohexyl (meth)acrylate (CHMA) and tert butyl cyclohexyl (meth)acrylate (TBCHMA).

[0060] Suitable examples of difunctional reactive diluent monomers include, but are not limited to, PEG200 di(meth)acrylate, 1 ,4-butanediol di(meth)acrylate, 1 ,3-butanediol di(meth)acrylate, 2,3-butanediol di(meth)acrylate, 1 ,6-hexanediol di(meth)acrylate and its isomers, diethyleneglycol di(meth)acrylate, triethyleneglycol di(meth)acrylate, glycerol di(meth)acrylate, trimethylolpropane di(meth)acrylate, neopentyl glycol di(meth)acrylate, dipropyleneglycol di(meth)acrylate, tripropyleneglycol di(meth)acrylate, PPG250 di(meth)acrylate, tricyclodecane dimethylol di(meth)acrylate, 1 ,10-decanediol di(meth)acrylate and / or tetraethylene glycol dimethacrylate.

[0061] In some embodiments, the difunctional reactive diluent monomer is selected from the group of commercially available monomers consisting of SR238 HDDA, SR259 PEG200DA, SR306 TPGDA, SR341 MPDDA, SR349 ethoxylated BPADA, SR508 DPGDA, SR601 E EO(4)BPADA, SR833S TCDDMDA, SR205H TEGDMA, SR206H EGDMA, SR214 BDDMA, SR231 DEGDMA, SR239 HDDMA, SR348 EO(3)BPADMA, SR540 EO(4)BPADMA, SR480 EO(10)BPADMA, DPGDMA and TPGDMA.

[0062] Suitable examples of trifunctional reactive diluent monomers include, but are not limited to, trimethylolpropane tri(meth)acrylate, ethoxylated trimethylolpropane tri(meth)acrylate, propoxylated glycerine tri(meth)acrylate, pentaerythritol tri(meth)acrylate, propoxylated trimethylolpropane tri(meth)acrylate, and tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate.

[0063] In some embodiments, the trifunctional reactive diluent monomer is selected from the group of commercially available monomers consisting of SR351 TMPTA, SR444D PETIA, SR499 EO(6)TMPTA, SR502 EO(9)TMPTA, SR9020 PP(3)GPTA, SR9035 EO(15)TMPTA and SR350D TMPTMA.

[0064] In some embodiments, the monofunctional reactive diluent has a molecular weight Mw of between 100 to 200, such as between 110 to 190, such as between 120 to 180.

[0065] In some embodiments, the difunctional reactive diluent has a molecular weight Mw of between 200 to 500, such as between 225 to 475, such as between 250 to 450.

[0066] In some embodiments, the trifunctional reactive diluent has a molecular weight Mw of between 400 to 700, such as between 450 to 650, such as between 500 to 600.

[0067] The composition and characteristics of the vinyl ester resin composition may be modified by adjusting the relative amount of each reactive diluent monomer.

[0068] In some embodiments, the monofunctional reactive diluent monomer is present, based on the total weight of the reactive diluent monomer mixture, in an amount of at least 50 wt%, such as at least 55 wt%, such as at least 60 wt%, such as at least 65 wt%, such as at least 70 wt%, such as at least 75 wt%, such as at least 80 wt%, such as at least 85 wt%, such as at least 90 wt%. In some embodiments, the monofunctional reactive diluent monomer is present, based on the total weight of the reactive diluent monomer mixture, in an amount of at most 90 wt%, such as at most 85 wt%, such as at most 80 wt%, such as at most 75 wt%, such as at most 70 wt%, such as at most 65 wt%.

[0069] In some embodiments, the monofunctional reactive diluent monomer is present, based on the total weight of the reactive diluent monomer mixture, in an amount from 10 to 90 wt%, such as from 15 to 90 wt%, such as from 15 to 85 wt%, such as from 20 to 85 wt%, such as from 25 to 85 wt%, such as from 25 to 80 wt%, such as from 30 to 80 wt%, such as from 35 to 80 wt%, such as from 40 to 80 wt%, such as from 40 to 75 wt%, such as from 45 to 75 wt%, such as from 50 to 75 wt%, such as from 50 to 70 wt%, such as from 55 to 70 wt%, such as from 55 to 65 wt%.

[0070] In some embodiments, the difunctional reactive diluent monomer is present, based on the total weight of the reactive diluent monomer mixture, in an amount of at least 10 wt%, such as at least 12 wt%, such as at least 14 wt%, such as at least 16 wt%, such as at least 18 wt%.

[0071] In some embodiments, the difunctional reactive diluent monomer is present, based on the total weight of the reactive diluent monomer mixture, in an amount of at most 30 wt%, such as at most 28 wt%, such as at most 26 wt%, such as at most 24 wt%, such as at most 22 wt%.

[0072] In some embodiments, the difunctional reactive diluent monomer is present, based on the total weight of the reactive diluent monomer mixture, in an amount from 10 to 30 wt%, such as from 12 to 28 wt%, such as from 14 to 26 wt%, %, such as from 16 to 24 wt%, such as from 18 to 22 wt%.

[0073] In some embodiments, the trifunctional reactive diluent monomer is present, based on the total weight of the reactive diluent monomer mixture, in an amount of at least 10 wt%, such as at least 12 wt%, such as at least 14 wt%, such as at least 16 wt%, such as at least 18 wt%.

[0074] In some embodiments, the trifunctional reactive diluent monomer is present, based on the total weight of the reactive diluent monomer mixture, in an amount of at most 30 wt%, such as at most 28 wt%, such as at most 26 wt%, such as at most 24 wt%, such as at most 22 wt%.

[0075] In some embodiments, the trifunctional reactive diluent monomer is present, based on the total weight of the reactive diluent monomer mixture, in an amount from 10 to 30 wt%, such as from 12 to 28 wt%, such as from 14 to 26 wt%, such as from 16 to 24 wt%, such as from 18 to 22 wt%.

[0076] Preferably, the monofunctional reactive diluent monomer is present, based on the total weight of the vinyl ester resin composition, in an amount which is greater than the amount of the difunctional reactive diluent monomer or the amount of the trifunctional reactive diluent monomer.

[0077] Preferably, the monofunctional reactive diluent monomer is present, based on the total weight of the vinyl ester resin composition, in an amount which is greater than the sum of the amounts of all other reactive diluent monomers, such as at least 1.2 times the sum of the amounts of all other reactive diluent monomers, such as at least 1 .5 times the sum of the amounts of all other reactive diluent monomers, such as at least 1 .8 times the sum of the amounts of all other reactive diluent monomers, such as at least 2 times the sum of the amounts of all other reactive diluent monomers. In this context, the all other reactive diluent monomers includes the difunctional reactive diluent monomer and the trifunctional reactive diluent monomer, and optionally any polyfunctional reactive diluent monomers.

[0078] Preferably, the monofunctional reactive diluent monomer is present, based on the total weight of the vinyl ester resin composition, in an amount which is at least 1 .2 times the amount of the difunctional reactive diluent monomer, such as at least 1 .5 times the amount of the difunctional reactive diluent monomer, such as at least 2 times the amount of the difunctional reactive diluent monomer, such as at least 2.5 times the amount of the difunctional reactive diluent monomer, such as at least 3 times the amount of the difunctional reactive diluent monomer.

[0079] Preferably, the monofunctional reactive diluent monomer is present, based on the total weight of the vinyl ester resin composition, in an amount which is at least 1 .2 times the amount of the trifunctional reactive diluent monomer, such as at least 1 .5 times the amount of the trifunctional reactive diluent monomer, such as at least 2 times the amount of the trifunctional reactive diluent monomer, such as at least 2.5 times the amount of the trifunctional reactive diluent monomer, such as at least 3 times the amount of the trifunctional reactive diluent monomer.

[0080] In some embodiments, the reactive diluent monomer mixture is present, based on the total weight of the vinyl ester resin composition, in an amount of at least 20 wt%, such as at least 25 wt%, such as at least 30 wt%, such as at least 35 wt%, such as at least 40 wt%, such as at least 45 wt%.

[0081] In some embodiments, the reactive diluent monomer mixture is present, based on the total weight of the vinyl ester resin composition, in an amount of at most 80 wt%, such as at most 75 wt%, such as at most 70 wt%, such as at most 65 wt%, such as at most 60 wt%, such as at most 55 wt%.

[0082] In some embodiments, the reactive diluent monomer mixture is present, based on the total weight of the vinyl ester resin composition, in an amount from 20 to 80 wt%, such as from 25 to 80 wt%, such as from 25 to 75 wt%, such as from 30 to 75 wt%, such as from 30 to 70 wt%, such as from 35 to 70 wt%, such as from 35 to 65 wt%, such as from 35 to 60 wt%, such as from 40 to 60 wt%, such as from 45 to 60 wt%, such as from 45 to 55 wt%.

[0083] In some embodiments, the vinyl ester resin composition comprises a styrene monomer as a reactive diluent monomer. In some preferred embodiments, the styrene monomer is present in an amount, based on the total weight of the vinyl ester resin composition, in an amount of less than 5 wt% of styrene monomer, preferably less than 3 wt% of styrene monomer, more preferably less than 1 wt% of styrene monomer.

[0084] In some preferred embodiments, the vinyl ester resin composition is substantially free of styrene. As used herein, the term “substantially free of styrene” means that the vinyl ester resin compositions are formulated without the inclusion of any styrene monomer. For example, the vinyl ester resin composition comprises less than 0.05 wt% of styrene monomer, preferably less than 0.03 wt% of styrene monomer, more preferably less than 0.01 wt% of styrene monomer. As used herein, the term “thickening agent” refers to a substance which increases the viscosity of the vinyl ester resin composition without substantially changing other properties.

[0085] A thickening agent used in combination with the vinyl ester resin composition according to the first aspect to provide a thickened vinyl ester resin composition according to the second aspect. The thickened vinyl ester resin composition has a higher viscosity than the vinyl ester resin composition according to the first aspect which is not yet thickened (herein also referred to as the unthickened vinyl ester resin composition).

[0086] Suitable thickening agents which are typically employed in the field of resins include organic thickening agents such as a (poly)isocyanate-based thickening agent, or inorganic thickening agents such as those comprising a basic or alkaline metal oxide or a basic or alkaline metal hydroxide.

[0087] In some embodiments, suitable (poly)isocyanates for use in the (poly)isocyanate-based thickening agent are those selected from the group consisting of an aliphatic (poly)isocyanate, a cycloaliphatic (poly)isocyanate, an aromatic (poly)isocyanate, and combinations thereof.

[0088] The (poly)isocyanate compound for use in the (poly)isocyanate-based thickening agent has an isocyanate functionality of greater than 2.0. Preferably, the (poly)isocyanate has an isocyanate functionality of at least 2.2, such as at least 2.4, such as at least 2.6, such as at least 2.8, such as at least 3.0.

[0089] In some embodiments, the (poly)isocyanate is a triisocyanate, tetraisocyanate, isocyanate polymers or oligomers, or polymeric MDIs. Examples of triisocyanates include trimethylolpropane triioscyanate (TMTPTI), 1 ,3,5-triisocyanate trimethylhexahydro-1 ,3-5-triazine (TMTHT), biuret-based triisocyanates derived from diisocyanates, such as hexamethylene diioscyanate trimer (HDI trimer), isophorone diisocyanate trimer (IPDI trimer) and toluene diisocyanate trimer (TDI trimer), and isocyanurate-based triisocyanates derived from trimerization of diisocyanates. (Poly)isocyanates suitable are available commercially under various trade names. Examples of suitable commercially available isocyanates include those sold under trade names Desmodur® (Bayer Material Science), Tolonate® (Perstorp), Takenate® (Takeda), Vestanat® (Evonik), Desmotherm® (Bayer Material Science), Bayhydur® (Bayer Material Science), Mondur® (Bayer Material Science), Suprasec (Huntsman Inc.), Lupranate® (BASF), Trixene® (Baxenden), Hartben® (Benasedo), Ucopol® (Sapici), and Basonat® (BASF).

[0090] Specific commercially available aliphatic (poly)isocyanates include hardeners of the aliphatic (poly)isocyanate type, such as those labelled Desmodur® N 100®, N75®, N3200®, N3300®, N3390®, N3600®, N3790®, N3800®, XP2675®, E XP2747®, XP2599®, E3265® , E3370®, Z4470®, XP2489®, XP2838®, XP2763® sold by the company Covestro® (Lervekusen, Germany), or hardeners of the blocked aliphatic (poly)isocyanate type (i.e., whose reactive functions become reactive as of a preset temperature, e.g., of the order of 150 °C), such as those labeled Trixene® BI7950®, BI7951®, B17960®, B17961®, B17963®, B17982®, B1791®, BI7992®, marketed by Braxenden Chemicals Ltd® (Lancashire, United Kingdom), or labeled Desmodur® BL3175®, BL4265®, BL5375®, PL350®, PL340®, BL3370®, BL3475®, BL3272®, BL2078®, marketed by the company Covestro® (Lervekusen, Germany). Specific commercially available polymeric MDIs include Desmodur® 44V40L, Desmodur® 44V70L, Desmodur® 44420L, Suprasec® 5025, Suprasec® 2085, Voronate® M580 and Voronate® M590.

[0091] Further commercially available (poly)isocyanates include those labelled Lupranate® 5143®, MM103®, 219R, 81®, 218®, M10®, R2500U®, M20S®, M20FB®, M70L®, M200®, 241®, 230®, 245®, TF2115®, 78®, 234®, 273®, 266®, 261®, 255®, 268® 5010®, 223®, 5040®, 5110®, 5090®, 5050®, 8020® sold by BASF, and those labelled Mondur® 448®, 489®, 541 -Light®, 1522®, MA 2601®, MR®, MR Light®, MR-5®, MRS®, MRS-2®, MRS-4®, MRS-5®, PC® sold by Bayer Material Science, Tolonate® X F 450, Tolonate® X F 800, Tolonate® X FLO 100, Tolonate® IDT 70 B, Tolonate® D2, Tolonate® HDT-LV, Tolonate® HDT-LV2, Tolonate® FD 90 B, Tolonate® HDT 90, Tolonate® HDT, Tolonate® HDB-LV, Tolonate® HDB 75 and Tolonate® HDB sold by Perstorp, and Vestantat® T 1890 sold by Evonik.

[0092] In some embodiments, suitable basic or alkaline metal oxides or basic or alkaline metal hydroxides are those containing a group I metal, a group II metal or a transition metal. Typically, basic or alkaline metal oxides are metal oxides with a pH higher than 7. Typically, basic or alkaline metal oxides are formed by the reaction of oxygen with metals, especially alkali and alkaline earth metals. Typically, metal hydroxides are hydroxides of metal, usually strong bases with a pH higher than 7. Typically, metal hydroxides are formed from hydroxide ions and ions of metals.

[0093] In some embodiments, the basic or alkaline metal oxide is a group II metal oxide. In some embodiments, the group II metal oxide is selected from the group consisting of magnesium oxide, calcium oxide and barium oxide. In some embodiments, the group II metal oxide is magnesium oxide. In some embodiments, the group II metal oxide is calcium oxide. In some embodiments, the group II metal hydroxide is barium oxide.

[0094] In some embodiments, the basic or alkaline metal oxide is a transition metal oxide. In some embodiments, the transition metal oxide is zinc oxide.

[0095] In some embodiments, the basic or alkaline metal oxide is a group II metal hydroxide. In some embodiments, the group II metal hydroxide is selected from the group consisting of magnesium hydroxide, calcium hydroxide and barium hydroxide. In some embodiments, the group II metal hydroxide is magnesium hydroxide. In some embodiments, the group II metal hydroxide is calcium hydroxide. In some embodiments, the group II metal hydroxide is barium hydroxide.

[0096] Specific commercially available group II metal oxides include Luvatol® EK 25 NV, Luvatol® EK 30 NV, Luvatol® EK 100 KM, Luvatol® 25 MK, Luvatol® MK 2500 NV, Luvatol® EK 50 F, AM-90762 / 25, AM- 90762 / 35, AM-90762 / 35 FC and AM-90762 / 35 LV. Specific commercially available group II metal hydroxides include Luvatol® EH 35 and PG-90772.

[0097] In some embodiments, the inorganic thickening agent, such as the group II metal oxide or group II metal hydroxide, is combined with a dicarboxylic acid anhydride. Thus, in some embodiments, the vinyl ester oligomer may be modified with a dicarboxylic acid anhydride. Examples of dicarboxylic acid anhydrides include maleic anhydride, citraconic anhydride, itaconic anhydride, phthalic anhydride, tetrabromophthalic anhydride, chlorendic anhydride, glutaric anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, succinic anhydride and methylsuccinic anhydride. In some embodiments, the dicarboxylic acid anhydride is maleic anhydride.

[0098] In some embodiments, the dicarboxylic acid anhydride is present, based on the total weight of the vinyl ester resin composition in an amount from 3 to 9 wt%. Typically, when the dicarboxylic acid anhydride is present within this range, the dicarboxylic acid anhydride may typically be present in an average amount of 1 unit per oligomeric chain, or in an average amount of less than 1 unit per oligomeric chain.

[0099] Thickened vinyl ester resin composition

[0100] As used herein, the thickened vinyl ester resin composition corresponds to the vinyl ester resin composition according to the first aspect which has a higher viscosity relative to the vinyl ester resin composition according to the first aspect due to addition of the thickening agent. Thus, in the context of the thickened vinyl ester resin composition, the vinyl ester resin composition may also be referred to as the unthickened vinyl ester resin composition. The thickened vinyl ester resin composition also refers to the vinyl ester resin composition which is not yet cured.

[0101] Suitably, the vinyl ester resin composition according to the first aspect can undergo a thickening process in which its viscosity increases. A thickening agent can initiate the thickening process. In some embodiments, the vinyl ester resin composition is supplied together with a thickening agent in a kit - that is to say, the thickening agent is not pre-added to the composition.

[0102] Thus, in the second aspect of the invention, there is provided a kit comprising a vinyl ester resin composition according to the first aspect, and a thickening agent as described herein for use in thickening the vinyl ester resin composition to produce a thickened vinyl ester resin composition.

[0103] Thus, in the third aspect of the invention, there is provided a thickened vinyl ester resin composition for a cured-in-place pipe, the thickened vinyl ester resin composition being curable via free radical polymerisation and being derived from the vinyl ester resin composition according to the first aspect and a thickening agent as described herein, or being derived from the kit according to the second aspect.

[0104] In some embodiments, the thickening agent is present, based on the total weight of the thickened vinyl ester resin composition, in an amount of at least 1 .00 wt%, such as at least 2.00 wt%, such as at least 3.00 wt%, such as at least 4.00 wt%, such as at least 5.00 wt%, such as at least 6.00 wt%, such as at least 7.00 wt%, such as at least 8.00 wt%, such as at least 9.00 wt%, such as at least 10.00 wt%.

[0105] In some embodiments, the thickening agent is present, based on the total weight of the thickened vinyl ester resin composition, in an amount of at most 1 .00 wt%, such as at most 2.00 wt%, such as at most

[0106] 3.00 wt%, such as at most 4.00 wt%, such as at most 5.00 wt%, such as at most 6.00 wt%, such as at most 7.00 wt%, such as at most 8.00 wt%, such as at most 9.00 wt%, such as at most 10.00 wt%. In some embodiments, the thickening agent is present, based on the total weight of the thickened vinyl ester resin composition, in an amount from 2.00 to 8.00 wt%, such as 4.00 to 8.00 wt%, such as 6.00 to 8.00 wt%.

[0107] In some embodiments, the thickened vinyl ester resin composition has a viscosity of between 30,000 to 1 ,000,000 cPs, preferably between 100,000 to 600,000 cPs, when measured according to the method provided in the methods section.

[0108] The viscosity of the thickened vinyl ester resin composition is preferably selected for the purposes of its use in a cured-in-place pipe process. If the viscosity is too low, then there may be resin leakages and dry spots. If the viscosity is too high, then the sleeve-shaped laminate may be stiff and difficult to insert through a manhole into the pipe and difficult to inflate to shape. Therefore, in some embodiments, the thickened vinyl ester resin composition having a viscosity of between 30,000 to 1 ,000,000 cPs, when measured according to the method provided in the methods section, is obtained by mixing a vinyl ester resin composition with a thickening agent for a duration of between 96 to 168 hours.

[0109] Further components

[0110] The vinyl ester resin composition may further comprise catalysts, free radical polymerisation initiators, photoinitiators, inhibitors, stabilisers and fillers, and the like. Further possible components may also include antioxidants, acid scavengers, thickeners, flame retardants, silane coupling agents, resin particles, core-shell particle impact modifiers, soluble polymers and block polymers.

[0111] The vinyl ester resin composition may contain a catalyst. This may be any catalyst that may facilitate the reaction between the epoxy compound and the chain-extending reagent, in particular the epoxy group and the suitable functional group on the chain-extending reagent, such as a hydroxyl group or a carboxylic acid group, and the reaction between the vinyl ester oligomer and the end-capping reagent.

[0112] Examples of suitable catalysts that can be used herein include tertiary amines such as triethylamine, N,N- dimethylbenzylamine, N,N-dimethylaniline, 2,4,6-tris(dimethylaminomethyl)phenol, and diazabicyclooctane; quaternary ammonium salts such as trimethylbenzylammonium chloride and methylthiethylammonium chloride; phosphines such as triphenylphosphine (TPP) and tributylphosphine; imidazoles such as 2-methylimidazole, 1 ,2-dimethylimidazole, and 2-ethyl-4-methylimidazole; and triphenylstibine. In some embodiments, the catalyst is triphenylphosphine (TPP). In some embodiments, the catalyst is N,N-dimethylbenzylamine.

[0113] Further examples of suitable catalysts include metal catalysts, such as a chromium complex, for example a chromium(lll) complex or a chromium(VI) complex, and a zinc complex, for example a zinc(l) complex or a zinc(ll) complex. Examples of suitable catalysts include the NACURE series of catalysts from King Industries, Inc., for example NACURE XC-259, the K-PURE series of catalysts, also from King Industries, Inc., for example K-Pure CXC-1765, and the HYCAT series of catalysts from Dimension Technologies Chemical Systems, Inc., for example HYCAT 2000S, HYCAT 3000S and HYCAT OA. The catalyst may be used, based on the total weight of the vinyl ester resin composition, in an amount of from 0.05 wt% to 0.5 wt%.

[0114] Curing of the vinyl ester resin composition is preferably carried out by free radical polymerisation using a free radical polymerisation initiator, more preferably a peroxide initiator, at temperatures above ambient temperature. Preferably, the peroxide initiator is a thermal peroxide initiator. Thus, the vinyl ester resin composition is curable via free radical polymerisation.

[0115] Examples of thermal peroxide initiators, such as for curing in a cured-in-place pipe application, include benzoyl peroxide, dibenzoyl peroxide, dicumyl peroxide, di-tertiary butyl peroxide, di(4-t- bbutylcyclohexyl)peroxydicarbonate (Perkadox 16S), t-butyl peroxy-2-ethylhexanoate (Trigonox 21-C50), and t-butyl-peroxy-3,5,5-trimethylhexanoate (Trigonox 42S) (available from Akzo Nobel).

[0116] Examples of azo compound initiators include 2,2'-azobisisobutyronitrile (AIBN), dimethyl 2,2'- azobisisobutyrate, 2,2'-azobis-(2,4-dimethylvaleronitrile), 2,2'-azobis-(2,4-diethylvaleronitrile), 2,2'- azobisisobutyramide, dimethyl 2,2’-azobis(2-ethylpropionate), 2,2’-azobis(2-methylbutyronitrile), 1 ,11- azobis(cyclohexane-1 -carbonitrile), 2,2’-azobis[N-(2-propenyl)-2-methylpropionamide] and the like, and mixtures thereof.

[0117] The vinyl ester resin composition may further comprise a photoinitiator. The photoinitiator may be any common photoinitiator, and may be used alone or in any combination. In some embodiments, the photoinitiator comprises a free-radical photoinitiator. In some embodiments, the free-radical photoinitiator is selected from a phosphine oxide (such as a benzoyl phosphine oxide), an aryl ketone, a benzophenone, a hydroxylated ketone, a ketal, a metallocene, or a combination thereof

[0118] In some embodiments, the free-radical photoinitiator is selected from 2,4,6-trimethylbenzoyl diphenylphosphine oxide, ethyl(2,4,6-trimethylbenzoyl)-phenyl phosphinate, bis(2,4,6-trimethylbenzoyl)- phenylphosphine oxide, diphenyl(2,4,6-trimethylbenzoyl) phosphine oxide, 2-methyl-1-[4- (methylthio)phenyl]-2-morpholinopropanone-1 ,2-benzyl-2-(dimethylamino)-1-[4-(4-morpholinyl)phenyl]-1- butanone, 2-dimethylamino-2-(4-methyl-benzyl)-1 -(4-morpholin-4-yl-phenyl)-butan-1 -one, 4-benzoyl-4'- methyl diphenyl sulphide, 4,4'-bis(diethylamino) benzophenone, 4,4'-bis(N,N'-dimethylamino) benzophenone [Michler's ketone], benzophenone, 4-methyl benzophenone, 2,4,6-trimethyl benzophenone, dimethoxybenzophenone, acetophenone, chlorinated acetophenone, dialkoxyacetophenones, dialkylhydroxyacetophenones, dialkylhydroxyacetophenone esters, benzoin acetate, benzoin, benzoin alkyl ethers, dimethoxybenzoin, dibenzylketone, 1 -hydroxycyclohexyl phenyl ketone, phenyl (l-hydroxyisopropyl)ketone, 2-hydroxy-1-[4-(2-hydroxyethoxy)phenyl]-2-methyl-1- propanone, 4-isopropylphenyl(1-hydroxyisopropyl)ketone, oligo-[2-hydroxy-2-methyl-1-[4-(1 - methylvinyl)phenyl] propanone], camphorquinone, 4,4'-bis(diethylamino) benzophenone, benzil dimethyl ketal, bis(eta 5-2-4-cyclopentadien-1-yl)bis[2,6-difluoro-3-(1 H-pyrrol-1-yl)phenyl]titanium, benzoylcyclohexanol, acyloxime esters, acylphosphine oxides, acylphosphonates, ketosulfides, dibenzoyldisulfides, diphenyl dithiocarbonate, and any combination thereof. Further free-radical photoinitiators include: benzoylphosphine oxides, such as, for example, 2,4,6- trimethylbenzoyl diphenylphosphine oxide (Lucirin TPO from BASF) and 2,4,6-trimethylbenzoyl phenyl, ethoxy phosphine oxide (Lucirin TPO-L from BASF), bis(2,4,6-trimethylbenzoyl)-phenylphosphineoxide (Irgacure 819 or BAPO from Ciba), 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropanone-1 (Irgacure 907 from Ciba), 2-benzyl-2-(dimethylamino)-1-[4-(4-morpholinyl) phenyl]-1-butanone (Irgacure 369 from Ciba), 2-dimethylamino-2-(4-methyl-benzyl)-1-(4-morpholin-4-yl-phenyl)-butan-1-one (Irgacure 379 from Ciba), 4-benzoyl-4'-methyl diphenyl sulphide (Chivacure BMS from Chitec), 4,4'-bis(diethylamino) benzophenone (Chivacure EMK from Chitec), 4,4'-bis(N,N'-dimethylamino) benzophenone (Michler's ketone), camphorquinone, 4,4'-bis(diethylamino) benzophenone (Chivacure EMK from Chitec), 4,4'- bis(N,N'-dimethylamino) benzophenone (Michler's ketone), bis(2,4,6-trimethylbenzoyl)- phenylphosphineoxide (Irgacure 819 or BAPO from Ciba), and metallocenes such as bis(eta 5-2-4- cyclopentadien-1-yl)bis[2,6-difluoro-3-(1 H-pyrrol-1-yl)phenyl] titanium (Irgacure 784 from Ciba), or a mixture thereof. Further free-radical photoinitiators include 2,2-dimethoxy-2phenylacetophenone (Omnirad BDK from IGM) and Omnirad 2022.

[0119] The vinyl ester resin composition may contain inhibitors and stabilisers, which help to prolong the shelf life of the product in storage and to control the working time of the adhesive in use. Such inhibitors are well known to those skilled in the art and may comprise quinones, hydroquinones, substituted phenols and the like. Examples of specific inhibitors include, but are not limited to, 2,6-di-tert-butyl-a- dimethylamino-p-cresol, butylated hydroxytoluene (BHT), butylated hydroxyanisole, hydroquinone, toluhydroquinone, para-methoxyphenol, mono tert-butyl hydroquinone, tert-butyl catechol, oxalic acid, and phenothiazine.

[0120] In some embodiments, the vinyl ester resin composition comprises at least one peroxide initiator and at least one photoinitiator.

[0121] In addition to inhibitors that may be added directly to the vinyl ester resin composition during its preparation, some of the raw materials employed, especially the vinyl ester oligomer or any one of the reactive diluent monomers, may also contain inhibitors introduced by the manufacturer / supplier. Hence, on account of the variety of materials that may be chosen, some with in situ inhibitors, and the variety of initiators, promoters and inhibitors that may be used to prepare a composition, the selection of the complete inhibitor package is generally the final step in the formulating process. Preferred combinations of initiator and promoter for the curing system are those suitable for curing at and / or below ambient temperatures.

[0122] The inhibitor may be present, based on the total weight of the vinyl ester resin composition, in an amount of less than 1.0 wt%, such as less than 0.5 wt%, such as less than 0.1 wt%, such as less than 0.09 wt%, such as less than 0.08 wt%, such as less than 0.07 wt%, such as less than 0.06 wt%.

[0123] Where the vinyl ester resin composition contains inhibitors and stabilisers, the vinyl ester resin composition may further contain diluents for said inhibitors and stabilisers. The vinyl ester resin composition may further comprise one or more fillers. Examples of fillers include both organic and inorganic particulate fillers. The filler may possess a surface functionality or not, the surface functionality comprising a polymerisation group that is capable of (co)polymerisation with one or more of the components for preparing the vinyl ester oligomer. The filler may comprise organic or inorganic particles of micron size or less, such as nanoparticles. Examples include core-shell particles, inorganic particles, pigments or plasticisers. In some embodiments, the particulate filler comprises an inorganic filler, such as SiO2, AIO2, TiO2, ZnO2, SnO2, Am-SnO2, ZrO2, Sb-SnO2, AI2O3 or carbon black. In some embodiments, the particulate filler comprises an organic filler, such as polyurethane particles, polystyrene particles, poly(methyl methacrylate) particles or polycarbonate particles. Further examples of fillers include, but are not limited to, glass fibres, glass microspheres, silicas, talc, boron fibres, carbon fibres, clays, waxes, graphite, graphene, carbon nanotubes, and aluminium trihydrate.

[0124] In some embodiments, the vinyl ester resin composition comprises the one or more fillers in an amount of at least 0.1 wt%, or at least 1 wt%, or at least 5 wt%, or at least 10 wt%, or at least 15 wt%, or at least 20 wt%, or at least 30 wt%, or at least 40 wt%, or at least 50 wt%, based on the total weight of the vinyl ester resin composition.

[0125] In some embodiments, the vinyl ester resin composition comprises the one or more fillers in an amount of up to 90 wt%, or up to 80 wt%, or up to 70 wt%, or up to 60 wt%, or up to 50 wt%, or up to 40 wt%, or up to 30 wt%, or up to 20 wt%, based on the total weight of the vinyl ester resin composition.

[0126] In some embodiments, the vinyl ester resin composition comprises the one or more fillers in an amount of up to 50 wt%, based on the total weight of the vinyl ester resin composition. In some embodiments, the vinyl ester resin composition comprises the one or more fillers in an amount from 0.1 to 50 wt% or from 1 to 50 wt%, based on the total weight of the vinyl ester resin composition.

[0127] Method of preparing the vinyl ester resin composition

[0128] The fourth aspect of the invention relates to methods of preparing the vinyl ester resin composition of the vinyl ester resin composition of the first aspect.

[0129] Thus, in a fourth aspect of the invention, there is provided a method of preparing a vinyl ester resin composition according to the first aspect, the method comprising the following steps of:

[0130] (i) reacting an epoxy compound and a chain-extending reagent to obtain a first lower molecular weight vinyl ester oligomer;

[0131] (ii) mixing the reaction mixture comprising the first lower molecular weight vinyl ester oligomer obtained in step (i) with an a,p-unsaturated monocarboxylic acid, a (meth)acrylate ester or a (meth)acrylate anhydride to obtain a second vinyl ester oligomer with reactive unsaturated groups, wherein the second vinyl ester oligomer has a higher molecular weight that the first vinyl ester oligomer; (iii) blending the reaction mixture comprising the second vinyl ester oligomer with reactive unsaturated groups with a reactive monomer diluent mixture to obtain the vinyl ester resin composition; wherein the reactive diluent monomer mixture comprises a monofunctional reactive diluent monomer, a difunctional reactive diluent monomer and a trifunctional reactive diluent monomer.

[0132] The fifth aspect of the invention relates to methods of preparing the thickened vinyl ester resin composition of the vinyl ester resin composition of the first aspect.

[0133] Thus, in a fifth aspect of the invention, there is provided a method of preparing a vinyl ester resin composition according to the first aspect, the method comprising the following steps of:

[0134] (iv) reacting an epoxy compound and a chain-extending reagent to obtain a first lower molecular weight vinyl ester oligomer;

[0135] (v) mixing the reaction mixture comprising the first lower molecular weight vinyl ester oligomer obtained in step (i) with an a,p-unsaturated monocarboxylic acid, a (meth)acrylate ester or a (meth)acrylate anhydride to obtain a second vinyl ester oligomer with reactive unsaturated groups, wherein the second vinyl ester oligomer has a higher molecular weight that the first vinyl ester oligomer;

[0136] (vi) blending the reaction mixture comprising the second vinyl ester oligomer with reactive unsaturated groups with a reactive monomer diluent mixture to obtain the vinyl ester resin composition; wherein the reactive diluent monomer mixture comprises a monofunctional reactive diluent monomer, a difunctional reactive diluent monomer and a trifunctional reactive diluent monomer.

[0137] The invention also relates to cured products of the vinyl ester resin composition according to the first aspect and cured products of the thickened vinyl ester resin composition according to the third aspect.

[0138] The vinyl ester resin composition or the thickened vinyl ester resin composition of the invention may be cured by any one of the initiators as described herein. In some embodiments, the vinyl ester resin composition or the thickened vinyl ester resin composition may be cured by a thermal peroxide initiator and / or a photoinitiator. Elevated temperatures may be required for curing for a cured-in-place-pipe process, and may be achieved by passing steam through the pipe.

[0139] The vinyl ester resin composition or the thickened vinyl ester resin composition of the invention may require curing by radiation when the composition comprises a photoinitiator. In some embodiments, the vinyl ester resin composition or the thickened vinyl ester resin composition may be cured by actinic rays having sufficient energy to initiate polymerisation or a cross-linking reaction. The actinic rays may include, but are not limited to, a-rays, y-rays, ultraviolet (UV) radiation, visible light and electron beams.

[0140] Preferably, UV radiation is the source of energy for the curing of the vinyl ester resin composition or the thickened vinyl ester resin composition. Thus, the vinyl ester resin composition or the thickened vinyl ester resin composition is a UV-curable composition. In some embodiments, the vinyl ester resin composition is cured by a mercury lamp, such as a low-pressure mercury lamp, a medium-pressure mercury lamp or a high-pressure mercury lamp. For example, the vinyl ester resin composition or the thickened vinyl ester resin composition may be cured by a mercury lamp emitting UV-A light at a wavelength of 315 to 400 nm, UV-B light at a wavelength of 280 to 315 nm, or UV-C light at a wavelength of 100 to 280 nm. Preferably, the wavelength of UV light is 365 to 455 nm, such as 385 to 425 nm, such as 390 to 405 nm, such as about 395 nm.

[0141] Cured-in-i

[0142] In a sixth aspect of the present invention, there is provided a use of the thickened vinyl ester resin composition according to the third aspect, or a kit according to the second aspect, or the vinyl ester resin composition according to the first aspect, for a cured-in-place pipe process.

[0143] The cured-in-place pipe process comprises the use of the vinyl ester resin composition for a sleeveshaped article for use in (re)lining. The sleeve-shaped article may be impregnated with the vinyl ester resin composition according to the first aspect or the thickened vinyl ester resin composition according to the third aspect, wherein at least one of the surfaces of the article is provided with a barrier layer that is impermeable to the vinyl ester resin composition or the thickened vinyl ester resin composition.

[0144] In some embodiments, the sleeve-shaped article is a cured-in-place pipe. In some embodiments, the cured-in-place pipe is selected from the group consisting of a sewer pipe, a potable water pipe, a high- pressure pipe and an industrial pipe. In some embodiments, the sleeve-shaped article holds or carries potable water.

[0145] Thus, in a seventh aspect of the invention, there is provided a cured product comprising the thickened vinyl ester resin composition according to the third aspect.

[0146] Thus, in an eighth aspect of the invention, there is provided a cured-in-place pipe comprising the thickened vinyl ester resin composition according to the third aspect.

[0147] Vinyl ester resin compositions of the invention, when cured according to any one of the embodiments as described herein, may be defined as cured products. In this connection, the cured-in-place pipe involves the curing of the thickened vinyl ester resin composition to produce a cured product comprising the thickened vinyl ester resin composition. In a cured-in-place pipe process, the curing typically takes place via the insertion of a UV light source inside the sleeve-shaped article to expose the thickened vinyl ester resin composition to UV light and / or via the addition of steam inside the sleeve-shaped article to expose the thickened vinyl ester resin composition to an elevated temperature. Thus, the invention also relates to a cured-in-place pipe comprising the cured product of the thickened vinyl ester resin composition.

[0148] Further embodiments

[0149] In further embodiments, a vinyl ester resin composition for a cured-in-place pipe, the vinyl ester resin composition being thickenable using isocyanates and / or metal oxides and / or metal hydroxides, being curable by free radical polymerisation, and comprising:

[0150] (a) a vinyl ester oligomer having a number average molecular weight of between 500 and 3000, as measured by gel permeation chromatography according to the method provided in the methods section; and

[0151] (b) a reactive diluent monomer mixture; wherein the reactive diluent monomer mixture comprises a monofunctional reactive diluent monomer, a difunctional reactive diluent monomer and a trifunctional reactive diluent monomer, and wherein the monofunctional reactive diluent monomer is present, based on the total weight of the vinyl ester resin composition, in an amount which is greater than the amount of the difunctional reactive diluent monomer or the amount of the trifunctional reactive diluent monomer.

[0152] In further embodiments, a vinyl ester resin composition for a cured-in-place pipe, the vinyl ester resin composition being thickenable using isocyanates and / or metal oxides and / or metal hydroxides, being curable by free radical polymerisation, and comprising:

[0153] (a) a vinyl ester oligomer having a number average molecular weight of between 500 and 3000, as measured by gel permeation chromatography according to the method provided in the methods section; and

[0154] (b) a reactive diluent monomer mixture; wherein the reactive diluent monomer mixture comprises a (meth)acrylate monomer, a di(meth)acrylate monomer and a tri(meth)acrylate monomer, wherein the (meth)acrylate monomer is present, based on the total weight of the reactive diluent monomer mixture, in an amount from 40 to 80 wt%, wherein the di(meth)acrylate monomer is present, based on the total weight of the reactive diluent monomer mixture, in an amount from 10 to 30 wt%, and wherein the tri(meth)acrylate monomer is present, based on the total weight of the reactive diluent monomer mixture, in an amount from 10 to 30 wt%.

[0155] In further embodiments, a vinyl ester resin composition for a cured-in-place pipe, the vinyl ester resin composition being thickenable using isocyanates and / or metal oxides and / or metal hydroxides, being curable by free radical polymerisation, and comprising: (a) a vinyl ester oligomer having a number average molecular weight of between 500 and 3000, as measured by gel permeation chromatography according to the method provided in the methods section, and being derived from:

[0156] (i) an epoxy compound comprising at least two epoxy groups;

[0157] (ii) an aromatic chain-extending reagent; and

[0158] (iii) a compound selected from an a,p-unsaturated monocarboxylic acid, a (meth)acrylate ester or a (meth)acrylate anhydride; and

[0159] (b) a reactive diluent monomer mixture; wherein the reactive diluent monomer mixture comprises a (meth)acrylate monomer, a di(meth)acrylate monomer and a tri(meth)acrylate monomer, wherein the (meth)acrylate monomer is present, based on the total weight of the reactive diluent monomer mixture, in an amount from 40 to 80 wt%, wherein the di(meth)acrylate monomer is present, based on the total weight of the reactive diluent monomer mixture, in an amount from 10 to 30 wt%, and wherein the tri(meth)acrylate monomer is present, based on the total weight of the reactive diluent monomer mixture, in an amount from 10 to 30 wt%.

[0160] Further aspects

[0161] In further aspects, a use of a reactive diluent monomer mixture in a vinyl ester resin composition for an accelerated thickening process, wherein the reactive diluent monomer mixture comprises a monofunctional reactive diluent monomer, a difunctional reactive diluent monomer and a trifunctional reactive diluent monomer.

[0162] In further aspects, a thickened vinyl ester resin composition obtained by subjecting a thickenable vinyl ester resin composition to 2.40 wt% of thickening agent for 120 hours, characterised in that the thickened vinyl ester resin composition has a viscosity which is at least a 150% increase, such as at least a 160% increase, such as at least a 170% increase, such as at least a 180% increase, such as at least a 190% increase, such as at least a 200% increase, relative to the viscosity of the thickenable vinyl ester resin composition, wherein the thickening agent is a (poly)isocyanate-based thickening agent comprising a (poly)isocyanate compound having an isocyanate functionality of greater than 2.0 and wherein the thickenable vinyl ester resin composition comprises a reactive diluent monomer mixture comprising a reactive diluent monomer, optionally selected from a monofunctional reactive diluent monomer, a difunctional reactive diluent monomer and a trifunctional reactive diluent monomer, or a combination thereof.

[0163] In further aspects, a thickened vinyl ester resin composition obtained by subjecting a thickenable vinyl ester resin composition to 8.00 wt% of thickening agent for 48 hours, characterised in that the thickened vinyl ester resin composition has a viscosity which is at least a 1 ,500% increase, such as at least a 1 ,600% increase, such as at least a 1 ,700% increase, such as at least a 1 ,800% increase, such as at least a 1 ,900% increase, such as at least a 2,000% increase, relative to the viscosity of the thickenable vinyl ester resin composition, wherein the thickening agent is a (poly)isocyanate-based thickening agent comprising a (poly)isocyanate compound having an isocyanate functionality of greater than 2.0 and wherein the thickenable vinyl ester resin composition comprises a reactive diluent monomer mixture comprising a reactive diluent monomer, optionally selected from a monofunctional reactive diluent monomer, a difunctional reactive diluent monomer and a trifunctional reactive diluent monomer, or a combination thereof.

[0164] The vinyl ester resin composition may be characterised by its normalised viscosity gradient (NVG) for a specified thickening agent.

[0165] The normalised viscosity gradient (NVG) is a measure of the viscosity (cPs) increase for a particular amount (wt%) of a specified thickening agent over a particular duration of time (hr) for a thickened vinyl ester resin composition as a percentage relative to the viscosity of the (thickened) vinyl ester resin composition at a state of 5 hours after addition of the specified thickening agent.

[0166] The normalised viscosity gradient (NVG) is calculated using Equation 1 : wherein p2 is the viscosity (cPs) at a second later time, pi is the viscosity (cPs) at 5 hours after addition of the specified thickening agent, t2 is the second later time (hr), and TA is the amount of the specified thickening agent (wt%), wherein the viscosity (pi and P2) is each measured according to the methods provided in the method section.

[0167] In further aspects, a vinyl ester resin composition, characterised in that the vinyl ester resin composition has a normalised viscosity gradient (NVG) of at least 40 cPs h1wt%1, such as at least 140cPs h1wt%1, such as at least 800cPs h1wt%1, such as at least 1400cPs h1wt%1, wherein the thickening agent is a (poly)isocyanate-based thickening agent comprising a (poly)isocyanate compound having an isocyanate functionality of greater than 2.0, optionally wherein the (poly)isocyanate compound is an aliphatic (poly)isocyanate compound, and wherein the viscosity is measured according to the methods provided in the method section.

[0168] In further aspects, a vinyl ester resin composition, characterised in that the vinyl ester resin composition has a normalised viscosity gradient (NVG) of at least 50 cPs h1wt%1, such as at least 200cPs h1wt%1, such as at least 1000 cPs h1wt%1, such as at least 2000 cPs h1wt%1, wherein the thickening agent comprises a group II metal oxide, such as magnesium oxide, and wherein the viscosity is measured according to the methods provided in the method section.

[0169] *****

[0170] The features disclosed in the foregoing description, or in the following claims, or in the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for obtaining the disclosed results, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

[0171] While the invention has been described in conjunction with the exemplary embodiments described above, many equivalent modifications and variations will be apparent to those skilled in the art when given this disclosure. Accordingly, the exemplary embodiments of the invention set forth above are considered to be illustrative and not limiting. Various changes to the described embodiments may be made without departing from the spirit and scope of the invention.

[0172] For the avoidance of any doubt, any theoretical explanations provided herein are provided for the purposes of improving the understanding of a reader. The inventors do not wish to be bound by any of these theoretical explanations.

[0173] Any section headings used herein are for organizational purposes only and are not to be construed as limiting the subject matter described.

[0174] Throughout this specification, including the claims which follow, unless the context requires otherwise, the word “comprise” and “include”, and variations such as “comprises”, “comprising”, and “including” will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

[0175] It must be noted that, as used in the specification and the appended claims, the singular forms “a,” “an”, and “the” include plural referents unless the context clearly dictates otherwise. Ranges may be expressed herein as from “about” one particular value, and / or to “about” another particular value. When such a range is expressed, another embodiment includes from the one particular value and / or to the other particular value. Similarly, when values are expressed as approximations, by the use of the antecedent “about,” it will be understood that the particular value forms another embodiment. The term “about” in relation to a numerical value is optional and means for example + / - 10%.

[0176] Examples

[0177] Materials

[0178] EPIKOTE® 828 is a diglycidyl ether of bisphenol A (DGEBA) prepared from the reaction between bisphenol A and epichlorohydrin obtained from Westlake Epoxy.

[0179] Bisphenol A (BPA) was obtained from Tokyo Chemical Company.

[0180] Triphenyl phosphine (TPP) was obtained from Sigma Aldrich Company Ltd.

[0181] Desmodur XP2675 is an aliphatic isocyanate thickening agent obtained from Covestro.

[0182] Desmodur 44V40L is an aromatic isocyanate thickening agent obtained from Covestro.

[0183] Luvatol EK 30 NV is a magnesium oxide thickening agent obtained from Lehmann & Voss.

[0184] Luvatol MK 2500 NV is a magnesium oxide thickening agent obtained from Lehmann & Voss. The monofunctional reactive diluent monomer MM-1 was a (meth)acrylate monomer obtained from GEO Speciality Chemicals.

[0185] The difunctional reactive diluent monomer DM-1 was a di(meth)acrylate monomer obtained from Sartomer.

[0186] The trifunctional reactive diluent monomer TM-1 was a tri (meth) acrylate monomer obtained from Sartomer.

[0187] Methods

[0188] The viscosity was measured using a Brookfield® RVDV1 viscometer and was measured using the specific protocol:

[0189] An appropriate amount of vinyl ester resin composition was mixed in a UV-resistant container, such as a plastic container, together with an appropriate amount of thickening agent. The amount of material in the container was sufficient to provide an accurate measurement of the viscosity, for example a container with a size that is large enough to hold 400 g of the combination of vinyl ester resin composition and thickening agent. The container holding the mixture was kept in the dark, such as inside a temperature- controlled incubator, at a temperature of 22 to 24 °C which was held throughout the entire viscosity testing. The mixture was mixed for 5 minutes at 1000 rpm (revolutions per minute) to disperse the thickening agent. The viscosity was measured using spindle 3 at 30 rpm at different time intervals after mixing, such as at 0 hours after mixing, or 1 , 2, 3, 4, 5, 6, 16, 20, 22, 24, 40, 48, 72, 96, 168, 336 or 360 hours after mixing, until the viscosity of the vinyl ester resin composition exceeded the viscosity range for the given spindle at the given speed. A smaller spindle (i.e. , spindle 4) was then used at 30 rpm to measure the viscosity of the vinyl ester resin composition, such as at 24, 48, 72, 96,168, 336 or 360 hours after mixing, until the viscosity of the vinyl ester resin composition exceeded the viscosity range for the given spindle at the given speed. This process was then repeated for spindles 5-7 at 30 rpm. When the viscosity of the vinyl ester resin composition exceeded the viscosity range for spindle 7 at 30 rpm, the speed was decreased in decrements to 10, 5, 2.5, 1.0 and 0.5 rpm accordingly (the step changes occurring when the viscosity of the vinyl ester resin composition exceeded the viscosity range for spindle 7 at the given speed). The point at which the viscosity of the vinyl ester resin composition has exceeded the viscosity range for a given spindle at a given speed, such that the spindle is changed from a larger to a smaller spindle or at which the speed is reduced when using spindle 7, is provided by Chapter II of the Brookfield Dial Viscometer Operating Instructions, Manual No. M / 85-150-P700, pages 5-8.

[0190] The thickening rate of the vinyl ester resin composition after addition of thickening agent was then determined by a plot of viscosity of the composition against time.

[0191] Number average molecular weight The number average molecular weight Mn was measured using gel permeation chromatography in accordance with the following measurement conditions: GPC setup: Viscotex GPC Max, Column Oven, Viscotek VE3580RI detector; GPC software: OmniSec 4.5; Column: Phenomenex Phenogel 5pm Linear / Mixed Guard column 30 x 4.6mm, Phenogel 5pm Linear (2) column 300 x 4.6mm & Phenogel 5pm 50A column 300 x 4.6mm; Mobile phase: THF; Sample; Solvent: THF with 0.2% Toluene as flow marker; Flow rate: 0.35ml / min; Column Temperature: 40°C; Injection volume: 20pL; Detector Temperature: 35°C; Sample Prep: ~0.025g dissolved in 5.0ml Solvent, filtered through a 0.45pm PTFE syringe filter; Calibration Standards: Agilent Polystyrene High EasyVials; Elution time: 30 minutes.

[0192] Table 1 - Vinyl ester resin compositions

[0193] The following vinyl ester resin compositions shown in Table 1 correspond to the unthickened vinyl ester resin compositions according to the first aspect. That is, the vinyl ester resin compositions show in Table 1 do not yet comprise a thickening agent which increases the viscosity of the vinyl ester resin compositions to obtain their respective thickened vinyl ester resin compositions.

[0194] The vinyl ester resin compositions described in Table 1 below were generally prepared according to the following general protocol, unless obtained by a different means specified:

[0195] In the first stage, under nitrogen atmosphere, the epoxy compound, the chain-extending reagent and a suitable amount of catalyst (TPP) were weighed into a round bottomed flask with an overhead mechanical stirrer, a gas feed, a temperature probe and in inlet. The reaction mixture was then heated to a temperature of between 120 °C to 130 °C under an inert atmosphere and monitored via melt viscosity and epoxy equivalent weight (EEW) value.

[0196] In the second stage, under a gas mixture of 50:50 air itrogen, the temperature was set to 100 °C to 125 °C and the end-capping reagent was weighed together with a suitable amount of catalyst (TPP) and a first set of inhibitors were added into the reaction mixture by drip feeding over the course of 1 .5 to 4 hours into the reaction mixture. The reaction mixture was monitored via melt viscosity and epoxy equivalent weight (EEW) value.

[0197] In the third stage, a second set of inhibitors was added to the reaction mixture. The temperature was set to 80 °C and then the reactive diluent monomer mixture and a third set of inhibitors were added to the reaction mixture under vigorous stirring together with a photoinitiator. The reaction mixture was then cooled to a temperature of between 20 °C to 25 °C (room temperature). Once cooled, the reaction mixture was decanted from the reaction vessel to obtain a vinyl ester resin composition.

[0198] Inventive Compositions 1 and 2 and Reference Compositions 1 and 2 are described below:

[0199] Inventive Composition 1 corresponds to a styrene-free vinyl ester resin composition according to the first aspect. Inventive Composition 1 was prepared as follows: 1305 g of an epoxy resin obtained from the reaction between EPIKOTE® 828 and bisphenol A was heated to a temperature of 80 °C with continuous stirring under nitrogen atmosphere and 283g of bisphenol A was added. The reaction mixture was heated to 110 °C and 0.7g of triphenyl phosphine was added. After the exotherm was allowed to subside, the reaction was maintained for 1 hour before allowing to cool down to 115 °C with continuous stirring under lean oxygen atmosphere. A mixture of 385 g of methacrylic acid, 2.0 g of triphenyl phosphine, 0.20 g of hydroquinone and 0.20 g of paramethoxyphenol was fed into the reaction mixture over a period of 4 hours at a temperature of between 115 to 120 °C. The reaction was maintained at this temperature until the acid value reached below 12 mg KOH / g. The reaction mixture was then allowed to cool down to 40 °C and the reactive diluent monomer mixture comprising the (meth)acrylate monomer, the di(meth)acrylate monomer and the tri(meth)acrylate monomer was added into the reaction mixture. When the temperature of the reaction mixture reached below 40 °C, 7.2 g of Omnirad 819 was added.

[0200] Inventive Composition 2 corresponds to a further styrene-free vinyl ester resin composition according to the first aspect. Inventive Composition 2 was prepared as follows: 1770 g of an epoxy resin obtained from the reaction between EPIKOTE® 828 and bisphenol A was heated to a temperature of 80 °C with continuous stirring under nitrogen atmosphere and 480 g of bisphenol A was added. The reaction mixture was heated to 110 °C and 1 .6 g of triphenyl phosphine was added. After the exotherm was allowed to subside, the reaction was maintained for 1 hour before allowing to cool down to 115 °C with continuous stirring under lean oxygen atmosphere. A mixture of 448 g of methacrylic acid, 3.0 g of triphenyl phosphine, 0.24 g of hydroquinone and 0.24 g of paramethoxyphenol was fed into the reaction mixture over a period of 4 hours at a temperature of between 115 to 120 °C. The reaction was maintained at this temperature until the acid value reached below 12 mg KOH / g and then a specified amount of maleic anhydride was added into the reaction mixture. The reaction mixture was then allowed to cool down to 40 °C and the reactive diluent monomer mixture comprising the (meth)acrylate monomer, the di(meth)acrylate monomer and the tri(meth)acrylate monomer was added into the reaction mixture. When the temperature of the reaction mixture reached below 40 °C, 10.0 g of Omnirad 819 was added.

[0201] Reference Composition 1 corresponds to a reproduction of a styrene-free vinyl ester resin composition comprising a mixture of two trifunctional reactive diluent monomers as described in the prior art.

[0202] Reference Composition 1 was prepared as follows: 68.6 wt% of diglycidyl ether of bisphenol A, 31 .2 wt% of methacrylic acid with diallyldimethylammonium chloride and butylated hydroxytoluene at 1300 ppm and 1000 ppm, respectively, and the reaction mixture was heated to 120 °C until an acid number of 11 mg KOH / g and a viscosity of 40 P at a temperature of 60 °C were achieved, and then ethoxylated trimethylolpropane triacrylate (EOTMPTA) was added until a solids content of 60 wt% was achieved to obtain VE Oligomer B. The mixture was also added with trimethylolpropane triacrylate (TMPTA).

[0203] Reference Composition 2 corresponds to a commercially available styrene-free vinyl ester resin composition comprising a single difunctional reactive diluent monomer. Reference Composition 2 was prepared as follows: 865 g of epoxy resin was heated up to 115 °C with continuous stirring under lean oxygen atmosphere. A mixture of 394 g of methacrylic acid, 3.0 g of triphenyl phosphine, 0.15 g hydroquinone and 0.15 g paramethoxyphenol was fed into the reaction mixture over a period of 4 hours at a temperature of between 115 to 120 °C. The reaction was maintained at this temperature until the acid value reached below 12 mg KOH / g to obtain VE Oligomer C. The reaction mixture was then allowed to cool down to 40 °C and dipropylene glycol diacrylate (DPGDA) was added into the reaction mixture.

[0204] When the temperature of the reaction mixture reached below 40 °C, 3.2 g of Omnirad 819 was added. Table 2 - Inventive Examples 1 to 2 and Reference Example 1

[0205] In Table 2 below, Inventive Examples 1 to 2 and Reference Example 1 each correspond to a vinyl ester resin composition of Table 1 , further subjected to addition of an isocyanate thickening agent to obtain their respective thickened vinyl ester resin compositions according to the third aspect.

[0206] Specifically, Inventive Example 1 corresponds to Inventive Composition 1 , further subjected to addition of 8.0 wt% of Desmodur XP2675. Reference Example 1 corresponds to Reference Composition 1 , further subjected to addition of 8.0 wt% of Desmodur XP2675. Inventive Example 2 corresponds to Inventive Composition 1 , further subjected to addition of 7.0 wt% of Desmodur 44V40L.

[0207] As shown in Table 2 above, it can be seen that Inventive Example 1 exhibits a greater increase in viscosity over time than Reference Example 1. In particular, Inventive Example 1 differs from Reference Example 1 by the use of the combination of the vinyl ester oligomer (VE Oligomer A) having a number average molecular weight Mn of 2000, and a reactive diluent monomer mixture comprising a (meth)acrylate monomer, a di(meth)acrylate monomer and a tri(meth)acrylate monomer, and the result of this change is an improved thickening profile after, for example, 48 hours (29,730 cPs vs 13,010 cPs) and after 120 hours (> 400,000 cPs vs 18,060 cPs). Furthermore, the comparable increase in viscosity exhibited by Inventive Example 2 shows that vinyl ester resin compositions according to the first aspect may achieve similarly high viscosities over 120 hours for different isocyanate thickening agents.

[0208] Moreover, the Examples of Table 2 closely correspond to the amount of thickening agent which would be used in a typical CiPP process. Accordingly, the final viscosity achieved by Inventive Examples 1 and 2 at 120 hours corresponds to the end viscosity of the thickened vinyl ester resin composition for a CiPP process. The desirable viscosity increased is attributed to the combination of a vinyl ester oligomer having a number average molecular weight Mn of between 500 and 3000, as measured by gel permeation chromatography according to the method provided in the methods section, and a monofunctional reactive diluent monomer, a difunctional reactive diluent monomer and a trifunctional reactive diluent monomer.

[0209] Table 3 - Inventive Examples 3 to 5 and Reference Example 2

[0210] In Table 3 below, Inventive Examples 3 to 5 and Reference Example 2 each correspond to a vinyl ester resin composition of Table 1 , further subjected to addition of a magnesium oxide thickening agent to obtain their respective thickened vinyl ester resin compositions according to the third aspect.

[0211] Specifically, Inventive Example 3 corresponds to Inventive Composition 1 , further subjected to addition of 3 wt% of Luvatol EK 30 NV. Reference Example 2 corresponds to Reference Composition 2, further subjected to addition of 3 wt% of Luvatol EK 30 NV. Inventive Example 4 corresponds to Inventive Composition 1 , further subjected to addition of 0.5 wt% water and 3 wt% Luvatol MK25000NV. Inventive Example 4 corresponds to Inventive Composition 1 , further subjected to addition of 0.5 wt% water and 4 wt% Luvatol MK25000NV.

[0212]

[0213] As shown in Table 3 above, it can be seen that Inventive Example 3 exhibits a greater increase in viscosity over time than Reference Example 2. In particular, Inventive Example 3 differs from Reference Example 2 only by the use of a reactive diluent monomer mixture comprising a (meth)acrylate monomer, a di(meth)acrylate monomer and a tri(meth)acrylate monomer, and the result of this change is an improved thickening profile after, for example, 24 hours (> 1 ,000,000 cPs vs 182,000 cPs).

[0214] It is also shown that increasing the amount of magnesium oxide thickening agent may improve the thickening profile. For instance, after 96 hours, a composition with 3 wt% Luvatol MK25000NV (Inventive Example 6) achieves 272,800 cPs while a composition with 4 wt% Luvatol MK25000NV (Inventive Example 7) achieves 272,500 cPs.

[0215] Table 4 - Inventive Examples 6 to 8

[0216] In Table 4 below, Inventive Examples 6 to 8 each correspond to a vinyl ester resin composition of Table 1 , further subjected to addition of a magnesium oxide thickening agent to obtain their respective thickened vinyl ester resin compositions according to the third aspect.

[0217] Specifically, Inventive Examples 6 to 8 each correspond to Inventive Composition 2, further subjected to addition of 3 wt% of Luvatol EK 30 NV and 0.25 wt% of water. Each of Inventive Examples 6 to 8 also include maleic anhydride as a dicarboxylic anhydride which is incorporated into the vinyl ester oligomer. Inventive Example 6 further includes 96.6 g of maleic anhydride. Inventive Example 7 further includes 60 g of maleic anhydride. Inventive Example 8 further includes 30 g of maleic anhydride. Thus, Inventive Examples 6 to 8 differ by the amount of maleic anhydride.

[0218] Table 5 - Inventive Examples 9 to 12

[0219] In Table 5 below, Inventive Examples 9 to 12 each correspond to a vinyl ester resin composition of Table 1 , further subjected to addition of a magnesium oxide thickening agent to obtain their respective thickened vinyl ester resin compositions according to the third aspect.

[0220] Specifically, Inventive Examples 9 to 12 each correspond to Inventive Composition 2 above, further subjected to addition of 3 wt% of Luvatol EK 30 NV and 0.25 wt% of water. However, Inventive Examples 9 to 12 differ to Inventive Examples 6 to 8 by the precise amounts of Epoxy Type 828, BPA, methacrylic acid and the number average molecular weight of the vinyl ester oligomer. Each of Inventive Examples 9 to 12 also include maleic anhydride as a dicarboxylic anhydride which is incorporated into the vinyl ester oligomer. Inventive Example 9 further includes 40 g of maleic anhydride. Inventive Example 10 further includes 80 g of maleic anhydride. Inventive Example 11 further includes 120 g of maleic anhydride. Inventive Example 12 further includes 160 g of maleic anhydride. Thus, each pair of consecutive Inventive Examples in Inventive Examples 9 to 12 (such as between Inventive Example 9 and Inventive Example 10) differs by a difference of 40 g of maleic anhydride. As shown in Table 4 above, increasing the amount of maleic anhydride improves the thickening profile.

[0221] For instance, after 24 hours, a composition with 60 g of maleic anhydride (Inventive Example 7) achieves 292,000 cPs while a composition with 30 g of maleic anhydride (Inventive Example 8) achieves 4,160 cPs. However, as shown in Table 5 above, decreasing the amount of maleic anhydride improves the thickening profile. For instance, after 24 hours, a composition with 40 g of maleic anhydride (Inventive Example 9) achieves 6,600 cPs while a composition with 160 g of maleic anhydride (Inventive Example 12) achieves 2,370 cPs.

[0222] Thus, there is an optimum proportion of the thickening agent and the functional groups of the vinyl ester oligomer (close to 1 :1) which provides optimum thickening and a higher viscosity plateau. For instance, if the amount of thickening agent is too low, then there is insufficient branching of the chains of the oligomers. If the amount of thickening agent is too high, then there are fewer connections between the chains of the oligomers, resulting in a smaller network and thereby lowering the viscosity plateau.

Claims

Claims:1 . A vinyl ester resin composition for a cured-in-place pipe, the vinyl ester resin composition being thickenable using isocyanates and / or metal oxides and / or metal hydroxides, being curable by free radical polymerisation, and comprising:(a) a vinyl ester oligomer having a number average molecular weight of between 500 and 3000, as measured by gel permeation chromatography according to the method provided in the methods section; and(b) a reactive diluent monomer mixture; wherein the reactive diluent monomer mixture comprises a monofunctional reactive diluent monomer, a difunctional reactive diluent monomer and a trifunctional reactive diluent monomer.

2. The vinyl ester resin composition according to claim 1 , wherein the monofunctional reactive diluent monomer is present, based on the total weight of the vinyl ester resin composition, in an amount which is greater than the amount of the difunctional reactive diluent monomer or the amount of the trifunctional reactive diluent monomer.

3. The vinyl ester resin composition according to claim 1 or 2, wherein the monofunctional reactive diluent monomer is present, based on the total weight of the vinyl ester resin composition, in an amount which is greater than the sum of the amounts of all other reactive diluent monomers.

4. The vinyl ester resin composition according to any one of claims 1 to 3, wherein the monofunctional reactive diluent monomer is present, based on the total weight of the reactive diluent monomer mixture, in an amount from 40 to 80 wt%.

5. The vinyl ester resin composition according to any one of claims 1 to 4, wherein the difunctional reactive diluent monomer is present, based on the total weight of the reactive diluent monomer mixture, in an amount from 10 to 30 wt%.

6. The vinyl ester resin composition according to any one of claims 1 to 5, wherein the trifunctional reactive diluent monomer is present, based on the total weight of the reactive diluent monomer mixture, in an amount from 10 to 30 wt%.

7. The vinyl ester resin composition according to any one of claims 1 to 6, wherein the monofunctional reactive diluent monomer is a (meth)acrylate reactive diluent monomer.

8. The vinyl ester resin composition according to any one of claims 1 to 7, wherein the difunctional reactive diluent monomer is a di(meth)acrylate reactive diluent monomer.

9. The vinyl ester resin composition according to any one of claims 1 to 8, wherein the trifunctional reactive diluent monomer is a tri(meth)acrylate reactive diluent monomer.

10. The vinyl ester resin composition according to any one of claims 1 to 9, wherein the reactive diluent monomer mixture is present, based on the total weight of the vinyl ester resin composition, in an amount from 30 to 70 wt%, such as 35 to 65 wt%, such as 40 to 60 wt%, such as 45 to 55 wt%.11 . The vinyl ester resin composition according to any one of claims 1 to 10, wherein the vinyl ester resin composition is modified with an acid anhydride, preferably maleic anhydride.

12. The vinyl ester resin composition according to any one of claims 1 to 11 , wherein the vinyl ester oligomer has a number average molecular weight of between 600 and 3000, as measured by gel permeation chromatography according to the method provided in the methods section.

13. The vinyl ester resin composition according to any one of claims 1 to 12, wherein the vinyl ester resin composition is substantially free of styrene.

14. A kit comprising a vinyl ester resin composition according to any one of claims 1 to 13, and a thickening agent for use in thickening the vinyl ester resin composition to produce a thickened vinyl ester resin composition.

15. A thickened vinyl ester resin composition for a cured-in-place pipe, the thickened vinyl ester resin composition being curable via free radical polymerisation and being derived from:(i) the vinyl ester resin composition according to any one of claims 1 to 13, and(ii) a thickening agent.

16. The kit according to claim 14 or the thickened vinyl ester resin composition according to claim 15, wherein the thickening agent is a (poly)isocyanate-based thickening agent comprising a (poly)isocyanate compound having an isocyanate functionality of greater than 2.0, optionally wherein the (poly)isocyanate compound is an aliphatic (poly)isocyanate compound, or wherein the thickening agent comprises a group II metal oxide or a group II metal hydroxide.

17. The kit according to claim 14 or 16 or the thickened vinyl ester resin composition according to claim 14 or 15, wherein the thickening agent is present, based on the total weight of the thickened vinyl ester resin composition, in an amount from 2.00 to 8.00 wt%, such 4.00 to 8.00 wt%, such as 6.00 to 8.00 wt%.

18. The thickened vinyl ester resin composition according to any one of claims 15 to 17, wherein the thickened vinyl ester resin composition has a viscosity of between 30,000 to 1 ,000,000 cPs, preferably between 100,000 to 600,000 cPs, when measured according to the method provided in the methods section.

19. Use of the thickened vinyl ester resin composition according to any one of claims 15 to 18 or the kit according to claim 14 for a cured-in-place pipe process.

20. A cured product of the thickened vinyl ester resin composition according to any one of claims 15 to 18.

21. A cured-in-place pipe comprising the cured product according to claim 20.

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