EP2729517A1

EP2729517A1 - Multi-component resin system

Info

Publication number: EP2729517A1
Application number: EP12734904.1A
Authority: EP
Inventors: Johan Franz Gradus Antonius Jansen; Daniel Haveman; Dragos Popescu
Original assignee: DSM IP Assets BV
Current assignee: DSM IP Assets BV
Priority date: 2011-07-08
Filing date: 2012-07-05
Publication date: 2014-05-14
Also published as: WO2013007602A1

Abstract

The present invention relates to a multi-component resin system comprising (a) a vinyl ester resin; (b) reactive diluent; (c) a copper compound; and (d) a peroxide, wherein the multi-component resin system further comprises (e) a bidentate ligand X-R-Y in an amount of at least 10 mmol/(kg resin and reactive diluent), whereby X and Y are independently selected from NH₂, NHR₁ NR₁R₂, OH and OR₃ with the proviso that at least one of the groups X and Y is NH₂ or NHR₁ R is a C1-C20 alkyl or a C6-C20 aryl; R₁ and R₂ are independently selected from a C1-C20 alkyl and a polymeric residue; R₃ is a C1-C20 alkyl; the multi-component resin system comprises a compound with the following formula R₄-Z-C(O)-OO-R₅ as peroxide (d), in which Z is not present or is O; R₄ is a C1-C20 alkyl or a C6-C20 aryl; R₅ is a C4-C20 alkyl or a C(O)R₆; whereby R₆ is a C1-C20 alkyl or a C6-C20 aryl; the acid value of the primary resin system is lower than 12 mg KOH/g primary resin system; the amount of copper is at least 0.02 mmol Cu/(kg resin and reactive diluent) and at most 1.5 mmol Cu/(kg resin and reactive diluent); the molar ratio between the bidentate ligand X-R-Y and copper is at least 5; and the molar ratio between the bidentate ligand X-R-Y and the peroxide R₄-Z-C(O)-OO-R₅ is from 0.1 up to and including 10.

Description

MULTI-COMPONENT RESIN SYSTEM

The present invention relates to a multi-component resin system comprising (a) a vinyl ester resin; (b) reactive diluent; (c) a copper compound; and (d) a peroxide.

Curing of resin compositions comprising a vinyl ester resin can be done by a free-radical chain growth crosslinking polymerization between the reactive diluent present in the resin composition and the vinyl ester resin. Peroxides can be used as initiators of free-radical chain growth crosslinking polymerization. To accelerate the decomposition of the peroxide, an accelerator can be used. Cobalt naphthenate and cobalt octanoate are the most widely used accelerators, since these cobalt compounds are very effective accelerators for the peroxide decomposition. However, for environmental reasons, the use of cobalt compounds as accelerator for the peroxide decomposition is less preferred.

WO-A-2008/003500 for example describes the radical curing of a vinyl ester resin composition in the presence of a copper²⁺ salt and an amine compound and/or an ammonium salt. In order to obtain efficient radical curing - as demonstrated by short gel time, short peak time and/or high peak temperature - the copper needs to be present in an amount of at least 50 ppm. A disadvantage of the use of copper in such high amounts is that pre-accelerated resin composition containing such high amounts of copper present a green colour while the cured objects thereof have a green or brownish colour. This can be disadvantageous since in some applications, like for example windmills, flooring and marine applications including boats and the so called gel coats, white colored cured objects are desired. It would therefore be advantageous to being able to use a non-colored or less colored pre- accelerated resin composition, such that the color of the object obtained by curing the pre-accelerated resin composition can be easily tuned by pigmenting the pre- accelerated resin composition.

The object of the present invention is therefore being able to obtain a pre-accelerated resin system that, upon curing, may result in a cured object with no or almost no color and at the same time being able to obtain a resin system that can be efficiently cured, i.e. with a short gel time, short peak time and/or high peak temperature. In the curing of vinyl esters, gel time is a very important characteristic of the curing properties. In addition also the time from reaching the gel time to reaching peak temperature, and the level of the peak temperature (higher peak temperature generally results in better curing) are important.

This object has surprisingly been achieved in that the multi- component resin system further comprises (e) a bidentate ligand X-R-Y in an amount of at least 10 mmol/(kg resin and reactive diluent), whereby X and Y are independently selected from NH₂, NHR^ NR₁R₂, OH and OR₃ with the proviso that at least one of the groups X and Y is NH₂ or NHR^ R is a C1-C20 alkyl or a C6-C20 aryl; R₁ and R₂ are independently selected from a C1-C20 alkyl and a polymeric residue; R₃ is a

C1-C20 alkyl;

the multi-component resin system comprises a compound with the following formula R₄-Z-C(0)-00-R₅ as peroxide (d), in which Z is not present or is O; R₄ is a

C1-C20 alkyl or a C6-C20 aryl; R₅ is a C4-C20 alkyl or a C(0)R₆; whereby R₆ is a C1-C20 alkyl or a C6-C20 aryl;

the acid value of the primary resin system is lower than 12 mg KOH/g primary resin system;

the amount of copper is at least 0.02 mmol Cu/(kg resin and reactive diluent) and at most 1.5 mmol Cu/(kg resin and reactive diluent);

the molar ratio between the bidentate ligand X-R-Y and copper is at least 5; and the molar ratio between the bidentate ligand X-R-Y and the peroxide R₄-Z-C(0)-00-R₅ is from 0.1 up to and including 10.

It has surprisingly been found that the curing of the multi-component resin system according to the invention can be efficiently accelerated. This is the more surprising since for example US-A-4524177 discloses that copper compounds in an amounts from 0.0005 to 0.2% by weight, preferably from 0.001 to 0.05% by weight, based on the ethylenically unsaturated compound to be polymerized, can be used for basic stabilization of the ethylenically unsaturated compounds to be polymerized. Thus, this document teaches that copper is an inhibitor. Similar, GB834286 teaches that small amounts of a soluble form of copper in the range 0,25 ppm to 10 ppm of copper improves the inhibiting properties of inter alias aromatic amines, quaternary ammonium salts and amine salts. US6329475 furthermore teaches that an amine acts as an inhibitor for catalyst composition containing copper. Thus the prior art teaches that copper, present in small amounts, acts as an inhibitor for the polymerization of ethylenically unsaturated compounds.

The multi-component resin system comprises a vinyl ester resin or a mixture of vinyl ester resins. As used herein, a vinyl ester resin is an oligomer or polymer comprising at least one (meth)acrylate functional end group, also known as (meth)acrylate functional resins. Preferably, the radical (co)polymerizable resin present in the multi-component resin system according to the present invention is a vinyl ester resin or a mixture of vinyl ester resins.

The vinyl ester resin used in the context of the present invention may be any such resin as is known to the person skilled in the art. Examples thereof can be found in a review article of M. Malik et al. in J. M.S. - Rev. Macromol. Chem. Phys., C40 (2&3), p.139-165 (2000). As described by Malik et al., vinyl ester resins having unsaturated sites only in the terminal position are for example introduced by reaction of epoxy oligomers or polymers (e.g. diglycidyl ether of bisphenol-A, epoxies of the phenol-novolac type, or epoxies based on tetrabromobisphenol-A) with (meth)acrylic acid. Instead of (meth)acrylic acid also (meth)acrylamide may be used. Besides the vinyl ester resins as described in Malik et al., also the class of vinyl ester urethane resins (also referred to urethane (meth)acrylate resins) as well as (meth)acrylate functional polyethers are herein considered to be vinyl ester resins. Preferably, the vinyl ester resin has a number-average molecular weight M_n of at least 500 Dalton. As used herein, the number-average molecular weight (M_n) is determined in

tetrahydrofuran using GPC employing polystyrene standards. Preferred vinyl ester resins are oligomers or polymers containing at least one methacrylate functional end group, also known as methacrylate functional resins. Preferred methacrylate functional resins are urethane methacrylate resins and resins obtained by reaction of an epoxy oligomer or polymer with methacrylic acid or methacrylamide, preferably with methacrylic acid. Most preferred vinyl ester resins are resins obtained by reaction of an epoxy oligomer or polymer with methacrylic acid.

The amount of vinyl ester resin in the multi-component resin system according to the invention is preferably at least 10 wt. % and at most 90 wt.%, relative to the total amount of vinyl ester resin and reactive diluent.

The multi-component resin system according to the present invention comprises a reactive diluent. For clarity purpose, a reactive diluent is a diluent for the vinyl ester resins present in the composition according to the invention, and is able to copolymerize with the vinyl ester resins present in the composition according to the invention.

Examples of suitable reactive diluents are, for instance, alkenyl aromatic monomer, such as for example styrene and divinylbenzene, (meth)acrylates, vinyl ethers and vinyl amides but all other reactive monomers for use in the field of thermosetting resins as are known to the person skilled in the art can be used. Non- limited examples of reactive diluents are styrene, alpha-methyl styrene, chlorostyrene, vinyl toluene, divinyl benzene, methyl methacrylate, n-butyl methacrylate,

cyclohexylmethacrylate, tert.butyl styrene, tert.butylacrylate, butanediol dimethacrylate, 2-hydroxypropyl methacrylate, 2-hydroxyethyl methacrylate, acetoacetoxyethyl methacrylate and mixtures thereof. Suitable examples of (meth)acrylates reactive diluents are PEG200 di(meth)acrylate, 1 ,4-butanediol di(meth)acrylate, 1 ,3-butanediol di(meth)acrylate, 2,3-butanedioldi(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, tetraethylene glycol di(meth)acrylate and

trimethylolpropanetri(meth)acrylate. Preferably, a (meth)acrylate is used as reactive diluent. Especially preferred reactive diluents are the methacrylate functional reactive diluents like methyl methacrylate, butanediol dimethacrylate and mixtures thereof. As used herein, a methacrylate functional reactive diluent (also referred to as methacrylate reactive diluent) is a monomer or an oligomer comprising at least one methacrylate group. Generally, the methacrylate reactive diluent has a number-average molecular weight M_n lower than 500 Dalton. As used herein, the number-average molecular weight (M_n) is determined in tetrahydrofuran using GPC employing polystyrene standards. Suitable examples of other methacrylate reactive diluents are PEG200 dimethacrylate, 1 ,4-butanediol dimethacrylate, 1 ,3-butanediol dimethacrylate,

2,3-butanedioldimethacrylate, 1 ,6-hexanediol dimethacrylate and its isomers, diethyleneglycol dimethacrylate, triethyleneglycol dimethacrylate, glycerol

dimethacrylate, trimethylolpropane dimethacrylate, neopentyl glycol dimethacrylate, dipropyleneglycol dimethacrylate, tripropyleneglycol dimethacrylate, PPG250 dimethacrylate, tricyclodecane dimethylol dimethacrylate, 1 ,10-decanediol

dimethacrylate, tetraethylene glycol dimethacrylate and

trimethylolpropanetrimethacrylate.

In a preferred embodiment of the invention, the multi-component resin system comprises a methacrylate reactive diluent. In a more preferred embodiment of the invention, the reactive diluent in the multi-component resin system is a

methacrylate reactive diluent or a mixture of methacrylate reactive diluents. The amount of reactive diluent relative to the total amount of vinyl ester resin and reactive diluent is preferably at least 10 wt.%, more preferably at least 20 wt.%, even more preferably at least 25 wt.% and even more preferably at least 30 wt.%. The amount of reactive diluent relative to the total amount of vinyl ester resin and reactive diluent is preferably at most 90 wt.%, more preferably at most 80 wt.%, even more preferably at most 75 wt.% and even more preferably at most 70 wt.%.

As used herein, the acid value of the primary resin system is determined titrimetrically according to ISO 21 14-2000.

As used herein, the term "primary resin system" is understood to mean the total weight of the multi-component resin system, but excluding peroxide and also any non-soluble compounds, such as fillers, as may be used when applying the resin system for its intended uses. The primary resin system therefore consists of the the vinyl ester resin(s), reactive diluent(s) as well as other solvents as may be present, and any additives soluble in the resin diluted in reactive diluent (such as accelerators, promoters, inhibitors, low-profile agents, colorants (dyes), thixotropic agents, release agents). Thus, as used herein, the primary resin system consists of the vinyl ester resins present in the multi-component resin system, any solvent present in the multi- component resin system and any additive present in the multi-component resin system that is soluble in the resin diluted in reactive diluent. The amount of additives soluble in the resin diluted in reactive diluent usually may be as from 1 to 25 wt.% of the primary resin system. The primary resin system, however, explicitly does not include compounds not being soluble (at room temperature) in the resin diluted in reactive diluent, such as fillers (e.g. glass or carbon fibers), talc, clay, solid pigments (such as, for instance, titanium dioxide (titanium white)), flame retardants, e.g. aluminum oxide hydrates, etc.

The multi-component resin system comprises a copper compound (b), preferably a copper²⁺ compound. The copper^ compound is preferably a copper salt or complex. Even more preferably, the copper compound is a copper²⁺ salt. In view of the solubility of the copper compound in the resin composition, the copper compound is preferably an organo soluble copper compound like for instance copper carboxylates, copper acetoacetates and/or copper chlorides. It will be clear that, instead of a single copper compound also a mixture of copper compounds can be used. The multi- component resin system preferably comprises a copper carboxylate, more preferably a C C₃o carboxylate and even more preferably a C Ci₆ carboxylate. The amount of copper compound in the multi-component resin system is such that the amount of copper in the multi-component resin system is at least 0.02 mmol Cu/(kg resin and reactive diluent) and at most 1 .5 mmol Cu/(kg resin and reactive diluent). In a preferred embodiment, the amount of copper^ in the multi- component resin system is at least 0.02 mmol Cu²7(kg resin and reactive diluent) and at most 1 .5 mmol Cu²7(kg resin and reactive diluent). As used herein, per kg resin and reactive diluent is meant to be per kg vinyl ester resins and reactive diluents.

The multi-component resin system according to the invention comprises (e) a bidentate ligand X-R-Y, whereby X and Y are independently selected from NH₂, NHR^ NR₁R₂, OH and OR₃ with the proviso that at least one of the groups X and Y is NH₂ or NHR^ R is a C1 -C20 alkyl or a C6-C20 aryl; R₁ and R₂ are

independently selected from a C1 -C20 alkyl and a polymeric residue; R₃ is a

C1 -C20 alkyl. Preferably, Ri and R₂ are independently selected from a C1 -C20 alkyl. Preferably, X is NH₂ and Y is NH₂, NHR₁ or OH. More preferably, X is NH₂ and Y is NH₂. Preferably, R is a C1 -C20 alkyl, more preferably a C2-C8 alkyl. It will be clear that, instead of a single bidentate ligand X-R-Y a mixture of bidentate ligands X-R-Y can be used.

The amount of bidentate ligand X-R-Y in the multi-component resin system is at least 10 mmol/(kg resin and reactive diluent), preferably at least

20 mmol/(kg resin and reactive diluent), more preferably at least 40 mmol/(kg resin and reactive diluent). The amount of bidentate ligand X-R-Y in the multi-component resin system is preferably at most 1000 mmol/(kg resin and reactive diluent), more preferably at most 500 mmol/(kg resin and reactive diluent), even more preferably at most 250 mmol/(kg resin and reactive diluent) and even more preferably at most

200 mmol/(kg resin and reactive diluent). The amount of bidentate ligand X-R-Y in the multi-component resin system is preferably ranging from 20 mmol/(kg resin and reactive diluent) up to and including 500 mmol/(kg resin and reactive diluent) and even more preferably ranging from 100 mmol/(kg resin and reactive diluent) up to and including 200 mmol/(kg resin and reactive diluent).

Preferably, the molar ratio between the bidentate ligand X-R-Y and the copper in the multi-component resin system is at least 10, more preferably at least 50 and even more preferably at least 100.

The multi-component resin system according to the invention comprises a compound with the following formula R₄-Z-C(0)-00-R₅ as peroxide, in which Z is not present or is O; R₄ is a C1 -C20 alkyl or a C6-C20 aryl; R₅ is a C4-C20 alkyl or a C(0)R₆; whereby R₆ is a C1-C20 alkyl or a C6-C20 aryl. Preferably, the multi-component resin system according to the invention comprises a compound with the following formula R₄-Z-C(0)-00-R₅ as peroxide, in which Z is not present, R₄ is C6 aryl and R₅ is tertiar butyl. It will be clear that, instead of a single peroxide compound with formula R₄-Z-C(0)-00-R₅ also a mixture of peroxide compounds with formula R₄-Z-C(0)-00-R₅ can be used.

The molar ratio between the bidentate ligand X-R-Y and the peroxide R -Z-C(0)-00-R₅ in the multi-component resin system is preferably from 0.2 up to and including 8, preferably from 0.5 up to and including 5.

The multi-component resin system according to the invention is preferably essentially free of cobalt. Essentially free of cobalt means that the cobalt concentration is lower than 0,1 mmol Co per kg vinyl ester resin and reactive diluent, preferably lower than 0,01 mmol Co per kg vinyl ester resin and reactive diluent. Most preferably the multi-component resin system is free of cobalt.

The multi-component resin system according to the invention is preferably essentially free of vanadium. Essentially free of vanadium means that the vanadium concentration is lower than 0,1 mmol V per kg vinyl ester resin and reactive diluent, preferably lower than 0,01 mmol V per kg vinyl ester resin and reactive diluent. Most preferably the multi-component resin system is free of vanadium.

The multi-component resin system preferably further comprises a radical inhibitor. These radical inhibitors are preferably chosen from the group of phenolic compounds, benzoquinones, hydroquinones, catechols, stable radicals and/or phenothiazines. Suitable examples of radical inhibitors that can be used in the compositions according to the invention are, for instance, 2-methoxyphenol,

4-methoxyphenol, 2,6-di-t-butyl-4-methylphenol, 2,6-di-t-butylphenol,

2,4,6-trimethyl-phenol, 2,4,6-tris-dimethylaminomethyl phenol,

4,4'-thio-bis(3-methyl-6-t-butylphenol), 4,4'-isopropylidene diphenol,

2,4-di-t-butylphenol, 6,6'-di-t-butyl-2,2'-methylene di-p-cresol, hydroquinone,

2-methylhydroquinone, 2-t-butylhydroquinone, 2,5-di-t-butylhydroquinone,

2,6-di-t-butylhydroquinone, 2,6-dimethylhydroquinone , 2,3,5-trimethylhydroquinone, catechol, 4-t-butylcatechol, 4,6-di-t-butylcatechol, benzoquinone,

2,3,5,6-tetrachloro-1 ,4-benzoquinone, methylbenzoquinone, 2,6-dimethylbenzoquinone, napthoquinone, 1 -oxyl-2,2,6,6-tetramethylpiperidine,

1-oxyl-2,2,6,6-tetramethylpiperidine-4-ol (a compound also referred to as TEMPOL), 1-oxyl-2,2,6,6-tetramethylpiperidine-4-one (a compound also referred to as TEMPON), 1-oxyl-2,2,6,6-tetramethyl-4-carboxyl-piperidine (a compound also referred to as 4-carboxy-TEMPO), 1-oxyl-2,2,5,5-tetramethylpyrrolidine,

1-oxyl-2,2,5,5-tetramethyl-3-carboxylpyrrolidine (also called 3-carboxy-PROXYL), galvinoxyl, aluminium-N-nitrosophenyl hydroxylamine, diethylhydroxylamine, phenothiazine and/or derivatives or combinations of any of these compounds.

Advantageously, the amount of radical inhibitor in the multi-component resin system (relative to the total amount of compounds (a) and (b)) is in the range of from 0.0001 to 10 % by weight. More preferably, the amount of inhibitor in the multi-component resin system is in the range of from 0.001 to 1 % by weight.

The multi-component resin system according to the invention may further comprise (in)organic filler. The amount of (in)organic filler relative to the total amount of compounds (a) and (b) is preferably from 10 to 90 wt.%. Preferably, the multi-component resin system comprises fibre as filler. Suitable fillers are aluminium trihydrate, calcium carbonate, mica, glass, microcrystalline silica, quartz, barite and/or talc. These fillers may be present in the form of sands, flours or molded objects, especially in the form of fibers or spheres. Examples of fibres are glass fibres and carbon fibres.

The use of the multi-component resin system according to the invention requires mixing of the compounds (a), (b), (c) and (e) together with a hardener, in particular compound (d) to obtain a cured resin network. As used herein, multi-component systems means a system with at least two spatially separated components whereby the peroxide is present in one component that does not comprise radical copolymerizable compounds including compound (a) and reactive diluent (b) in order to prevent premature radical copolymerization of the compounds (a) and reactive diluents (b) prior to the use of the multi-component system to obtain the cured network. At the moment that the radically copolymerization of compound (a) and reactive diluent (b) is desired, at least a peroxide as described above is added to this composition. Preferably, said adding is done by mixing the peroxide into the composition comprising compounds (a) and reactive diluents (b). The multi-component system according to the invention comprises at least two components.

In a preferred embodiment, the multi-component resin system comprises at least two components A and B, whereby component A comprises resin (a), reactive diluent (b), copper compound (c) and bidentate ligand (e) and component B comprises peroxide (d), whereby compounds (a), (b), (c), (d) and (e) are as defined above. In a preferred embodiment, the multi-component resin system is a two component system consisting of a first component A and a second component B, whereby component A comprises vinyl ester resin (a), reactive diluent (b), copper compound (c) and bidentate ligand (e) and component B comprises peroxide (d), whereby compounds (a), (b), (c), (d) and (e) are as defined above. The use of the two component resin system according to the invention requires mixing of the components A and B to obtain a cured resin network.

The present invention further relates to a process for radically curing a resin composition comprising (a) a vinyl ester resin and (b) reactive diluent in the presence of a copper compound (c) and a peroxide (d), whereby the radical curing is effected in the presence of a compound with the following formula R₄-Z-C(0)-00-R₅ as peroxide (d), in which Z is not present or is O; R₄ is a C1-C20 alkyl or a C6-C20 aryl; R₅ is a C4-C20 alkyl or a C(0)R₆; whereby R₆ is a C1-C20 alkyl or a C6-C20 aryl;

the radical curing is effected in the further presence of a bidentate ligand X-R-Y (e) in an amount of at least 10 mmol/(kg resin and reactive diluent), whereby X and Y are independently selected from NH₂, NHRi , NRiR₂, OH and OR₃ with the proviso that at least one of the groups X and Y is NH₂ or NHR^ R is a C1-C20 alkyl or a C6-C20 aryl; Ri and R₂ are independently selected from a C1-C20 alkyl and a polymeric residue; R₃ is a C1-C20 alkyl;

the molar ratio between the bidentate ligand X-R-Y and the copper is at least 5; and the molar ratio between the bidentate ligand X-R-Y and the peroxide R₄-Z-C(0)-00-R₅ is from 0.1 up to and including 10.

The process according to the invention is preferably effected at a temperature in the range of from -20 to +150 °C, more preferably in the range of from -20 to +100 °C and even more preferably in the range of from -20 to + 40 °C.

The process according to the invention is preferably effected in the substantial absence of cobalt. Substantial absence of cobalt means that the cobalt concentration is lower than 0,1 mmol Co per kg vinyl ester resin and reactive diluent, preferably lower than 0,01 mmol Co per kg vinyl ester resin and reactive diluent. Most preferably the process according to the invention is effected in the absence of cobalt.

The process according to the invention is preferably effected also in the substantial absence of vanadium. Substantial absence of vanadium means that the vanadium concentration is lower than 0,1 mmol V per kg vinyl ester resin and reactive diluent, preferably lower than 0,01 mmol V per kg vinyl ester resin and reactive diluent. Most preferably the process according to the invention is effected in the absence of vanadium.

The present invention further relates to cured structural objects obtained by mixing the compounds of the multi-component system as described above or by mixing components (A) and (B) of the two-component resin system as described above or obtained with the process for radical curing as described above.

The present invention further relates to the use of the cured objects in anyone of the areas of automotive parts, boats, chemical anchoring, roofing, construction, containers, relining, pipes, tanks, flooring or windmill blades

Measurements

Gel time equipment

In the Examples and Comparative Experiments presented hereinafter, it is mentioned that curing was monitored by means of a gel time equipment. This is intended to mean that both the gel time (T_gei or T₂₅->35°c) and peak time (Tp_eak or T25- _Peak) were determined by exotherm measurements according to the method of DIN 16945 when curing the resin with the initiating systems as indicated in the Examples and Comparative Examples. The equipment used therefore was a Soform gel timer, with a Peakpro software package and National Instruments hardware; the waterbath and thermostat used were respectively Haake W26, and Haake DL30.

Synthesis of resin A

A reactor was charged with 1516.75g bisphenol A diglycidyl ether,

293.74 g bisphenol A and 3 g triphenyl phosphine. The reactor was heated to

1 10°C-1 15°C at which temperature an exothermic reaction starts. After the exothermic reaction, the mixture is stirred for an additional 30 min before it was allowed to cool to 1 10°C. At 1 10°C, 0.57g 2-methyl hydroquinone and 459.74 g methacrylic acid were added in 4 portions with 15 min intervals. Next the reactor was stirred for an additional hour during which the reaction was heated to 120°C after which it was kept at 120°C for 2 additional hours. Next the reaction mixture was cooled to 90 °C at which temperature 244.4 g butyl methacrylate was added. After cooling to room temperature, 2509g butanedioldimethacylate was added. The resulting resin A had an acid value of 4.9 mg KOH/g resin A and an epoxy equivalent weight around 10000. Examples 1A-D and Comparative Experiment A

To 10Og g of resin A was added x g Cu naftenate (8 wt. % Cu metal solution in spirits) and 1g Dytek A (1 ,5-diamino-2-methylpentane). After stirring for 5 min, 1g t-butyl per benzoate (Trigonox C) was added and the curing was monitored with the gel time equipment. The results are depicted in table 1.

Table 1

with amounts of Cu as low as 0.06 mmol Cu/kg resin A.

Examples 2A-F and Comparative Experiments B and C

To 100g g resin A was added 0.01 g Cu naftenate (8 wt.% Cu metal solution in spirits) and y g Dytek A. After stirring for 5 min, 1g t-butyl per benzoate (Trigonox C) was added and the curing was monitored with the gel time equipment. The results are depicted in table 2.

Table 2

Dytek A m mo l/kg Gel time Peak time Peak temp resin A (min) (min) (°C)

Comb B 0.01 0.86 >24

Comp C 0.1 8.6 >24

2A 0.5 43 201 21 1 101

2B 1 86 1 18 125 1 16

2D 2 172 77 82 127 Comparative Experiments D and E

All the experiments in table 2 were repeated with Cobalt, (Nuodex Co 10, Rockwood) and with a Vanadyl compound (VN-2 Akzo) in the same metal concentration. In none of these comparative experiments curing was observed.

These examples especially combined with the comparative experiments clearly show that the use of Co or V in combination with a bidentate ligand and peroxide as claimed does not result in efficient curing, while the claimed combination of Cu, bidentate ligand and peroxide in the amounts as claimed results in efficient curing.

Example 3A-C and Comparative Experiment F-N

To 100g resin A was added 0.01 g Cu naftenate (8 wt.% Cu metal solution in spirits) and 0.5g of various possible ligands. After stirring for 5 min, 1g t-butyl per benzoate (Trigonox C) was added and the curing was monitored with the gel time equipment. The results are depicted in table 3.

Table 3

Gel time Peak time Peak temp (min) (min) (°C)

Comp F Aniline >24

Comp G N-methyl aniline >24

Comp H N,N-dimethylaniline >24

Comp I Triethylamine >24

Comp J Diethylamine >24

3A Ethanol amine 104 1 10 132

3B Ethylene diamine 276 299 69

3C Dytek A 201 21 1 101

Comp K Tetramethylethylene diamine >24

Comp L Ethylene glycol >24

Comp M Propylene glycol >24

Comp N Diethylene glycol >24 These examples combined with the comparative experiments clearly demonstrate that the ligand should be at least a bidentate ligand in which at least one of the functional groups is a primary or secondary amine. Examples 4A-f and Comparative Experiments O-P

To 100g g resin A was added, 0.01 g Cu naftenate (8 wt.% Cu metal solution in spirits) and 0.5g Dytek A. After stirring for 5 min, 1g peroxide (obtained from Akzo Nobel; see Table 4) was added and the curing was monitored with the gel time equipment. The results are depicted in table 4

Table 4

From Examples 4A-4C and Comparative Experiments O and P, it becomes clear that the use of percarbonyl compounds like peresters, peranhydrides and monopercabonates in combination with the Cu and bidentate ligand as claimed results in efficient curing, while the use of hydroperoxides in combination with the Cu and bidentate ligand as claimed does not result in efficient curing.

Examples 5A-D and Comparative Experiments Q-R

To 100g g resin A, various amount of methacrylic acid was added. Next, 0.01 g Cu naftenate (8 wt.% Cu metal solution in spirits) and 0.5g Dytek A were added. Hereafter, the acid value was determined. After stirring for 5 min, 1g t-butyl per benzoate (Trigonox C) was added and the curing was monitored with the gel time equipment. The results are depicted in table 5. Table 5

From examples 5a-5d and comparative experiments Q and R, it is clear that in terms of curing efficiency the acid value of the resin needs to be less than 12 mg KOH/g primary resin system.

Claims

Multi-component resin system comprising

(a) a vinyl ester resin;

(b) reactive diluent;

(c) a copper compound; and

(d) a peroxide,

characterized in that the multi-component resin system further comprises

(e) a bidentate ligand X-R-Y in an amount of at least 10 mmol/(kg resin and reactive diluent), whereby X and Y are independently selected from NH₂, NHRL NR₁ R₂, OH and OR₃ with the proviso that at least one of the groups X and Y is NH₂ or NHR^ R is a C1-C20 alkyl or a C6-C20 aryl; R₁ and R₂ are independently selected from a C1-C20 alkyl and a polymeric residue; R₃ is a C1-C20 alkyl;

the multi-component resin system comprises a compound with the following formula R₄-Z-C(0)-00-R₅ as peroxide (d), in which Z is not present or is O; R₄ is a C1-C20 alkyl or a C6-C20 aryl; R₅ is a C4-C20 alkyl or a C(0)R₆; whereby R₆ is a C1-C20 alkyl or a C6-C20 aryl;

the molar ratio between the bidentate ligand X-R-Y and copper is at least 5; and the molar ratio between the bidentate ligand X-R-Y and the peroxide

R₄-Z-C(0)-00-R₅ is from 0.1 up to and including 10.

Multi-component resin system according to claim 1 , characterized in that the multi-component resin system comprises a copper²⁺ salt as copper compound, preferably a copper carboxylate and/or a copper halide.

Multi-component resin system according to claim 1 or 2, characterized in that the amount of bidentate ligand X-R-Y is at most 250 mmol/(kg resin and reactive diluent).

Multi-component resin system according to anyone of the preceding claims, characterized in that the molar ratio between the bidentate ligand X-R-Y and the peroxide R₄-Z-C(0)-00-R₅ is from 0.2 up to and including 8, preferably from 0.5 up to and including 5. Multi-component resin system according to anyone of the preceding claims, characterized in that the amount of bidentate ligand X-R-Y in the multi- component resin system is at least 40 mmol/(kg resin and reactive diluent). Multi-component resin system according to anyone of the preceding claims, characterized in that the molar ratio between the bidentate ligand X-R-Y and the copper is at least 10, more preferably at least 50 and even more preferably at least 100.

Multi-component resin system according to anyone of the preceding claims, characterized in that X is NH₂ and Y is NH₂, NHR₁ or OH.

Multi-component resin system according to anyone of claims 1-7,

characterized in that X is NH₂ and Y is NH₂.

Multi-component resin system according to anyone of the preceding claims, characterized in that R is a C1-C20 alkyl, more preferably a C2-C8 alkyl.

Multi-component resin system according to anyone of the preceding claims, characterized in that Z is not present, R₄ is C6 aryl and R₅ is tertiar butyl.

Multi-component resin system according to anyone of the preceding claims, characterized in that the cobalt concentration in the multi-component resin system is lower than 0,01 mmol Co per kg vinyl ester resin and reactive diluent and the vanadium concentration in the multi-component resin system is lower than 0,01 mmol V per kg vinyl ester resin and reactive diluent.

Multi-component resin system according to anyone of the preceding claims, characterized in that the multi-component resin system comprises a methacrylate reactive diluent.

Multi-component resin system according to anyone of the preceding claims, characterized in that the reactive diluent in the multi-component resin system is a methacrylate reactive diluent or a mixture of methacrylate reactive diluents. Multi-component resin system according to anyone of the preceding claims, characterized in that the multi-component resin system is a two-component resin system consisting of a first component A and a second component B, whereby component A comprises (a) a vinyl ester resin; (b) reactive diluent; (c) a copper compound, and bidentate ligand (e) and component B comprises peroxide (d), whereby compounds (a), (b), (c), (d) and (e) are as defined in anyone of claims 1-13. Process for radically curing a resin composition comprising (a) a vinyl ester resin and (b) reactive diluent in the presence of a copper compound (c) and a peroxide (d), characterized in that

the radical curing is effected in the presence of a compound with the following formula R₄-Z-C(0)-00-R₅ as peroxide (d), in which Z is not present or is O; R₄ is a C1-C20 alkyl or a C6-C20 aryl; R₅ is a C4-C20 alkyl or a C(0)R₆; whereby R₆ is a C1-C20 alkyl or a C6-C20 aryl;

the radical curing is effected in the further presence of a bidentate ligand X-R-Y (e) in an amount of at least 10 mmol/(kg resin and reactive diluent), whereby X and Y are independently selected from NH₂, NHR^ NR₁R₂, OH and OR₃ with the proviso that at least one of the groups X and Y is NH₂ or NHR^ R is a C1-C20 alkyl or a C6-C20 aryl; Ri and R₂ are independently selected from a C1-C20 alkyl and a polymeric residue; R₃ is a C1-C20 alkyl;

the molar ratio between the bidentate ligand X-R-Y and the copper is at least 5; and

the molar ratio between the bidentate ligand X-R-Y and the peroxide

R₄-Z-C(0)-00-R₅ is from 0.1 up to and including 10.

Process according to claim 15, characterized in that the process is effected in the presence of less than 0,01 mmol Co per kg vinyl ester resin and reactive diluent and less than 0,01 mmol V per kg vinyl ester resin and reactive diluent. Cured object obtained by mixing the compounds of the multi-component system according to anyone of claims 1-14 or obtained by the process according to claim 15 or 16.

Use of the cured object of claim 17 in automotive, boats, chemical anchoring, roofing, construction, containers, relining, pipes, tanks, flooring or windmill blades.