WO2007059879A1

WO2007059879A1 - Unsaturated polyester or vinyl ester resin composition

Info

Publication number: WO2007059879A1
Application number: PCT/EP2006/010888
Authority: WO
Inventors: Johan Franz Gradus Antonius Jansen; Ivo Ronald Kraeger
Original assignee: DSM IP Assets BV
Current assignee: DSM IP Assets BV
Priority date: 2005-11-25
Filing date: 2006-11-14
Publication date: 2007-05-31
Anticipated expiration: 2008-05-25

Abstract

This invention relates to unsaturated polyester or vinyl ester resin compositions, that are curable with a peroxide, comprising - while being cured - a polymer containing reactive unsaturations, a base, an oxo-component; and optionally a reactive diluent; wherein a. the polymer has an acid value ≤ 10 mg KOH/g; b. the base is either a hydroxide, alkoxide or carboxylate with a redox potential of the metal at most -1 V, or an ammonium ion or amine, or a mixture of such substances; c. the oxo-component is an α-hydroxyoxo-compound according to formula (1) with R1 and R2, identical or different, representing hydrogen, a C1-C40 alkyl, a C6-C40 aryl, a C7-C40 alkylaryl, a C1-C20 ether OR3, a C1-C20 amine NR4R5, with each of R3, R4, and R5 independently selected from the same groups as R1 and R2, and wherein two of the R groups may be joint together to an α-hydroxyoxo cyclic structure of at least 5 carbon atoms, and/or with any of the groups R1, R2, R3, R4, and R5 representing a polymer residue. The invention also relates to methods of curing such resin compositions with a peroxide component, and to use of such resin compositions in. in chemical anchoring, roofing, relining, boats, containers, tanks, pipes, construction, automotive parts, flooring, or windmill blades. The invention finally relates to cured objects and structural parts, having a thickness of at least 0.5 mm obtained from such resin compositions or by such method of curing.

Description

UNSATURATED POLYESTER OR VINYL ESTER RESIN COMPOSITION

This invention relates to an unsaturated polyester resin or vinyl ester resin composition comprising - while being cured -a polymer containing reactive unsaturations, a base, an oxo-component; and optionally a reactive diluent; which composition can be cured with a peroxide component. Generally such resin compositions are non-aqueous systems. They contain at most 5% by weight of water, mainly resulting from the reactions during resin preparation.

Such resin compositions are so-called pre-accelerated resin compositions , if the oxo-component as well as the base is already present in the resin composition before the addition of the peroxide component. In case the oxo-component and/or the base are added together with or after the peroxide addition, then these resin compositions are called accelerated resin compositions.

The present invention also relates to a novel method for curing, in the presence of an oxo-component, unsaturated polyester resin or vinyl ester resin compositions comprising a polymer containing reactive unsaturations, a base, and optionally a reactive diluent. The invention finally relates to use of resin compositions according to the invention, and to cured objects and structural parts obtained according to the invention. As meant herein, objects and structural parts are considered to have a thickness of at least 0,5 mm and appropriate mechanical properties. The term "objects and structural parts" as meant herein, accordingly, also includes cured resin composition products as are used in the field of chemical anchoring, roofing, relining, boats, containers, tanks, pipes, construction, automotive parts, flooring, windmill blades, etc.

The state of the art unsaturated polyester or vinyl ester resin systems generally are cured by means of initiation systems. In general, such unsaturated polyester or vinyl ester resin systems are cured under the influence of peroxides and are accelerated (often even pre-accelerated) by the presence of metal compounds, especially cobalt salts as accelerators. Cobalt naphthenate and cobalt octanoate are the most widely used accelerators. In addition to accelerators, the polyester resins usually also contain inhibitors for ensuring that the resin systems do not gellify prematurely (i.e. that they have a good storage stability). Furthermore, inhibitors are being used to ensure that the resin systems have an appropriate gel time and/or for adjusting the gel-time value of the resin system to an even more suitable value. Most commonly, in the state of the art, polymerization initiation of unsaturated polyester resins, etc. by redox reactions involving peroxides, is accelerated or pre-accelerated by a cobalt compound, which could be in combination with another accelerator. Often oxo-compounds, especially selected from the group of enolisable ketones, are used as accelerator. Reference, for instance, can be made to US-A-3,584,076 and US-A-3, 630,960, wherein 1 ,3 dioxo-compounds also called from the group of enolisable ketones are used as co-accelerators. Also 1 ,3-dioxo-compounds are known to be applicable. Reference, for instance, can be made to interesting results shown by Kolczynski et al. in the proceedings of the 24^th Annual Technical Conference SPI (The Society of the Plastics Industry, Inc.), 1969, Reinforced Plastics/Composites Division, at Section 16-A pages1-8. It can be seen there that curing in the presence of cobalt and 2,4-pentanedione, at the relatively high temperatures usually employed, is much (i.e. about 10 times) faster than in the presence of cobalt alone. In all such prior art references the acid value of the polymer containing reactive unsaturations in the resin compositions employed is in the range 37-50 mg KOH/g of resin.

A major disadvantage of these formulations is the suspect toxicity (carcinogeneity) of the cobalt soaps used. Consequently there is a long felt need for environmentally more benign formulations and curing systems, which are not based on cobalt. Moreover, there remains need for resin compositions that are readily curable with peroxides at low temperature, for instance at ambient temperature. The inventors now have found that the aforementioned disadvantages of the resin compositions of the state of the art can be overcome. Namely, they have surprisingly found that an unsaturated polyester resin or vinyl ester resin composition comprising - while being cured - a polymer containing reactive unsaturations, a base, an oxo-component; and optionally optionally a reactive diluent; exhibits the desired curing properties if it has the following characteristics:

(a) the polymer containing reactive unsaturations has an acid value < 10 mg KOH/g; and (b) the base is either an organic or inorganic hydroxide, alkoxide or carboxylate of which the cation has a redox potential of the metal of at most -1 V, or is an ammonium ion or an amine, or is a mixture of any of such substances; and

(c) the oxo-component is an α-hydroxyoxo-compound according to formula 1 :

formula 1

with R₁ and R₂, being identical or different from each other, and representing a group selected from the groups consisting of hydrogen (H), a C₁-C₄₀ alkyl group, a C₆-C₄₀ aryl group, a C₇-C₄₀ alkylaryl group, a Ci-C₂₀ ether group OR₃, a C₁-C₂₀ amine group

NR₄R₅, with each of the groups R₃, R₄, and R₅ independently selected from the same type of groups as R₁ and R₂, and wherein two of the R groups may be joint together to form an α-hydroxyoxo cyclic structure of at least 5 carbon atoms, and/or with any of the groups R₁, R₂, R₃, R₄, and R₅ representing a polymer residue. As meant herein, each of the groups R₁, R₂, R₃, R₄, and R₅ also may carry one or more substituents, which, for instance may be selected from the group of halogen atoms, alkoxy groups, amino groups, etc. Moreover, the groups R₁, R₂, R₃, R₄, and R₅ may contain one or more heteroatoms.

It is to be noted, that resin compositions containing reactive unsaturations (e.g. unsaturated polyester or vinyl ester resin systems), which do not contain cobalt compound, and which comprise one or more α-hydroxy ketones, are well known in the area of photoinitiated polymerisation. Reference can, for instance, be made to the large overview of hydroxy ketones as photoinitiators, which is presented in the Sita Technology Series on: Chemistry & Technology of UV&EB Formulation for Coatings, Inks & Paints, volume III; Photoinitiators for Free Radical, Cationic and Anionic polymerisation, 2^nd ed., by J. V. Crivello and K. Dietlikker, Wiley, New York, 1998, p141.

Generally, when α-hydroxyoxo-compounds are employed in these photo polymerizable compositions, α,α-dialkyl-α-hydroxy-arylketones are used, which do not contain an α-hydrogen as the compounds according to the invention.

Without exposure to light α,α-dialkyl-α-hydroxy-arylketones are incapable of curing with a peroxide. This illustrates that knowledge obtained in the area of photoinitiated polymerisation cannot be translated directly into peroxide curing systems. Benzoin is the only α-hydroxyketone, which is employed in photo polymerisations and can be used according to the present invention. However, in photo polymerisations using benzoin no additional base is added, as is the case in the formulations according to the invention. Moreover no indication on the importance of acid value can be found. Furthermore use of photoinitiated polymerisation is limited to thin -coating type - applications instead of construction type applications.

Other unsaturated polyester or vinyl ester compositions, which comprise α-hydroxy-ketones are known from GB1393923 and NL7209994. In both cases polymerization is performed via decomposition of a peroxide, which process is analogous to the present invention. However, the acid values of the resins used in these references are ranging from 14-21 , which is clearly higher than the acid values < 10 mg KOH/g as are required according to the present invention. Furthermore, an acidic phosphorous compound is added which increases the acid value of the resin even further. This is opposite to the current invention in which a base is required.

Unsatured polyester or vinyl ester compositions, which comprise α- hydroxyketones are also known from DE1150805, which describes the use of α- hydroxyketones as catalyst for the decomposition of peroxides of unsaturated polyesters which, according to the examples shown, have an acid value of 45 mg KOH/g. Although efficient curing is observed at 82 ⁰C curing is slow at room temperature.

According to a preferred embodiment of the invention the polymer containing reactive unsaturations has an acid value < 5 mg KOH/g. More preferably said polymer has an acid value < 3 mg KOH/g, and most preferably it has an acid value < 1 mg KOH/g.

The base in the resin compositions according to the invention is either an organic or inorganic oxide, hydroxide, alkoxide or carboxylate of which the cation has a redox potential of the metal of at most -1 V, or is an ammonium ion; or a nitrogen-containing organic compound.

Suitable carboxylates are, for instance, acetates, benzoates, butyrates, propionates, adipates, mono-/di-/tri-chloroacetates, mono-/di-/tri- fluoroacetates, naphthenates, neodecanoates, valerates, oleates, stearates, tartrates, ascorbates, succinates, maleates, fumarates, phthalates, citrates, acrylates, methacrylates, itaconates, gluconates, glutarates, etc. Suitable alkoxides are, for instance, methoxides, ethoxides, propoxides, butoxides, t-butoxides, phenolates, etc. As meant herein, the term "redox potential of the metal" refers to the values, in V (Volt), for the transition Mⁿ⁺ to M (wee versa), for any specific metal M. These values can be found in CRC Handbook of Chemistry and Physics, 84^th Edition (2003-2004) in Section 8, Electrochemical Series, table 1 , pages 8-23 to 8-27, CRC Press LLC, Boca Raton / London / New York / Washington, D. C. For convenience, some redox potentials for metals are given below for a number of elements, the redox potentials (in V) shown between brackets: Li (-3,0), Na (-2,7), K (-2,9), Rb (-2,9), Cs (-2,9), Be (-1 ,7), Mg (-2,4), Ca (-3,0), Sr (-2,9), Ba (-2,9), Sc (-2,1), Y (-2,4), Al (-1 ,7). All these metals are examples of suitable metals with cations having a redox potential of the metal of at most -1 V.

Preferred bases that are to be used in the resin compositions according to the invention will be described herein below in more detail. Of course, also mixtures of such bases may be applied according to the invention. Preferably, in the resin compositions according to the invention, the cation in at least one of the bases has a redox potential of the metal of at most -1.5 V.

According to another preferred embodiment at least one of said bases is based on an alkaline or earth alkaline metal, or is an ammonium salt.

Suitable examples of such metal ion cations already have been shown above, together with their redox potential values of the metal.

Most preferably, at least one of said bases is based on lithium, sodium or potassium.

Suitable examples of ammonium ions in the ammonium salts can be represented by the general formula R¹R²R³R⁴N⁺, wherein R¹, R², R³, and R⁴ each individually may represent hydrogen (H), or a C₁-C_2O alkyl, aryl, alkylaryl or arylalkyl group, that each optionally may contain one or more hetero-atoms (e.g. oxygen, phosphor, nitrogen or sulphur atoms) and/or substituents. The groups may be linear, or branched; they also may contain one or more unsaturations or substituents. Merely by way of example such ammonium ions might be, for instance, mono-, di-, tri-, or tetra- methylammonium; mono-, di-, tri-, or tetra-ethylammonium; mono-, di-, tri-, or tetrabutylammonium; trimethylbenzylammonium; dimethylbenzylammonium; mono-, di- , tri-, or tetraoctylammonium; hydroxylammonium; hydrazonium; etc.

R¹ in the above formula can also be selected from the group of -OR² and -NR²R³ groups, R² and R³ having the same meaning as described above. As the bases are used in an organic media it is preferred in another embodiment of the invention that at least one of the said bases is an organosoluble salt.

Organic bases are by their nature organosoluble compounds. Accordingly, it is preferred that at least one of the said bases is an organic base. The group of nitrogen-containing compounds, including not only the aforementioned ammonium salts, but also the subclass of amines, forms an important class of organic bases.

Suitable examples of nitrogen-containing compounds to be used as bases in the resin compositions according to the invention are ammonium oxides, hydroxides and alkoxides. Examples of the ammonium ions already have been listed above. Other suitable examples of nitrogen-containing compounds (in principle non- ionic, but possibly becoming positively charged in situ; the nitrogen compound then can be present in the form of a salt) can be represented by the general formula R¹R²R³N, wherein R¹, R², and R³ each individually may have the meaning as described above. This general formula R¹R²R³N also represents nitrogen compounds, wherein the nitrogen atom shown in the formula is part of a cyclic system formed by two of the groups R¹, R², and R³, or is present in the form of an imine group or as a phosphazene (in which latter cases the general formula in fact can be represented as R¹R²N). Of course, R¹, R², and R³ themselves also individually may contain additional nitrogen atoms. Merely by way of example such nitrogen-containing compounds might be chosen, for instance, from 1 ,8-diazabicyclo-[5,4,0]-undec-7-ene (DBU); 1 ,4-diazabicyclo-[2,2,2]-octane (DABCO); 1 ,5-diazabicyclo-[4,3,0]-non-5-ene (DBN); morpholine; piperidine; dimethylaniline; N,N-di-isopropanol-toluidine (DiPT); hydroxylamine; alkylhydrazides; alkylhydrazines; imines (e.g. benzylidenephenylamine; N-[(E)-ethylidene]-2-methylpropanamine; 5-methyl-1 -pyrroline;

2,4,4-trimethyl-2-oxazoline; 4-phenylimino-2-pentanone); phosphazenes (e.g. compounds known as P₄-t-Bu and P₄-t-Oct); etc.

Thus, advantageously, at least one of the said bases is a nitrogen-containing compound, in particular an amine. In a very preferred embodiment of the invention, at least one of the bases in the resin composition according to the invention is a tertiary amine, most preferably an aliphatic tertiary amine.

Especially suitable organic tertiary amines from the above mentioned list are: DABCO, DBU, DBN and the phosphazene bases.

The amount of base can vary between wide ranges and the man skilled in the art can easily access via simple gel time measurements how much base is required. Preferably, the base is present in an amount of from 0.001 to 2,000 mmol/kg of the polymer containing reactive unsaturations, preferably in an amount of from 0.01 to 200 mmol/kg, and most preferably in an amount of from 0.1 to 100 mmol/kg of polymer containing reactive unsaturations. It is to be noted that it already has been described in literature (see for instance US-A-5,235,010 and WO90/12824) that acceleration of the curing of UP resins in the presence of oxygen-containing compounds and metal ions can take place in simultaneous presence of a nitrogen compound (ammonia, ammonium salts, heterocyclic nitrogenous bases, and amines, as well as their addition compounds with anhydrides or epoxides). However, the present invention is not disclosed nor suggested by anyone of such prior art references, or combinations thereof.

The oxo-component used in the resin compositions according to the invention is, as mentioned above, an α-hydroxyoxo-compound according to formula 1 :

formula 1

with R₁ and R₂, being identical or different from each other, and representing a group selected from the groups consisting of hydrogen (H), a Ci-C₄₀ alkyl group, a C₆-C₄₀ aryl group, a C₇-C₄₀ alkylaryl group, a C₁-C₂₀ ether group OR₃, a C₁-C₂₀ amine group NR₄R₅, with each of the groups R₃, R₄, and R₅ independently selected from the same type of groups as R₁ and R₂, and wherein two of the R groups may be joint together to form an α-hydroxyoxo cyclic structure of at least 5 carbon atoms, and/or with any of the groups R₁, R₂, R₃, R₄, and R₅ representing a polymer residue.

These compounds can be in an keto/enol tautomeric equilibrium. This indicates that they can be in equilibrium with enolic structures like below formula 2, with R₁ and R₂ having the same meaning as in formula 1 :

formula 2

Accordingly, within the scope of the present invention, also compounds of formula 2 can be applied equivalents to the α-hydroxyoxo-compounds of formula 1. Even when compounds of formula 2 are added, under the conditions in the resin composition and/or under the curing conditions, they will be in some kind of equilibrium with compounds having the α-hydroxyoxo structure of formula 1. α-Hydroxyoxo-compounds may react both intermolecularly and intramolecularly, with formation of acetal or ketal functionalities. As do the compounds of formula 2, also these acetal or ketal structures are in equilibrium with the α-hydroxyoxo form. Although such compounds can be added in their acetal or ketal form to the resin they will equilibrate into compounds of formula 1 under the conditions, which are present in the resin composition and/or the curing. Examples of suitable compounds according to formula 1 are, for instance, acetol, hydroxyacetone, dihydroxyacetone, benzoin, aryl substituted benzoins, furoin, 2-hydroxypropanal, gluconic acid.

Examples of suitable compounds which lead to compounds according to formula 1 in the resin composition and/or under the curing conditions of such resin composition are, for instance, without being limited thereto:

(a) compounds which can be (partly) present in their enol form such as, for instance, 2,3-dihydroxy-2-butenoic acid, crotonic acid, rhodizonic acid, and ascorbic acid;

(b) compounds which can be (partly) present in their intermolecular ketal form (dimeric), such as, for instance, acetoin (3-hydroxy-2-butanone), adipoine (or 2- hydroxy-cyclohexanone), and 5-hydroxy-4-octanone;

(c) compounds which can be (partly) present in their intramolecular ketal form such as, for instance, xylulose, hex-3-ulose, psicose, sorbose, fructose, tagatose, and arabino- hex-2-ulosonate;

(d) compounds which can be (partly) present in their intramolecular acetal form such as, for instance, ribose, xylose, lyxose, and arabinose.

Obviously, suitable derivatives and mixtures thereof can be used as well.

Again it should be explicitly noted that under the conditions existing in the resin compositions according to the invention during the curing process all these compounds are at least partially present in their α-hydroxyoxo form.

Preferably, in the resin compositions according to the invention the group R₁ of the α-hydroxyoxo-compound of formula 1 is hydrogen (H), or a C₁-Ci₀ group, or an OR₃ group in which R₃ is a C₁-C₂₀ alkyl, aryl, or alkylaryl group.

Also preferably, in the resin compositions according to the invention the group R₂ of the α-hydroxyoxo-compound is a C₁-C₁₀ alkyl group. R₁ and R₂ may - together with the carbon atoms carrying the oxo and the hydroxy group - form an aliphatic cycle. Moreover any of R₁ and R₂ may be substituted. In a specific embodiment R₁ represents hydrogen (H).

The amount of α-hydroxyoxo-compound in the resin compositions according to the invention can vary between wide ranges. Preferably the amount of the one or more α-hydroxyoxo-compounds is between 0.001 and 25 % by weight, calculated on the total weight of the resin composition, excluding fillers and the like.

More preferably, said amount of α-hydroxy-oxo-compounds is between 0.01 and 10 % by weight, and most preferably between 0.1 and 5 % by weight.

It can be relatively difficult to directly dissolve the α- hydroxyoxo-compounds in the polymer containing reactive unsaturations (and as such into the resin composition according to the invention). It therefore can be very suitable that the α-hydroxyoxo-compound applied is first dissolved in a suitable solvent prior to its addition to the resin composition. In such case the resin composition will also contain a suitable solvent for the α-hydroxyoxo-compound. Suitable examples of solvents that can be used for dissolving the α-hydroxyoxo-compound into the resin composition are, for instance, water, alcohols, triethylphosphate, amides (e.g. acetamide, vinylpyrrolidone, N-vinylcaprolactam, dimethylformamide), and ethers (e.g. tetrahydrofuran). Most preferably such solvents are chosen that are appropriately miscible with the polymer containing reactive unsaturations.

The polymer containing reactive unsaturations as is comprised in the unsaturated polyester resin or vinyl ester resin compositions according to the present invention, may suitably be selected from the unsaturated polyester resins or vinyl ester resins as are known to the skilled man. Examples of suitable unsaturated polyester or vinyl ester resins to be used as polymer containing reactive unsaturations in the resins of the present invention are, subdivided in the categories as classified by Malik et al., M.S. - Rev. Macromol. Chem. Phys., C40(2&3), p.139-165 (2000).

(1) Ortho-resins: these are based on phthalic anhydride, maleic anhydride, or fumaric acid and glycols, such as 1 ,2-propylene glycol, ethylene glycol, diethylene glycol, triethylene glycol, 1 ,3-propylene glycol, dipropylene glycol, tripropylene glycol, neopentyl glycol or hydrogenated bisphenol-A. Commonly the ones derived from 1 ,2-propylene glycol are used in combination with a reactive diluent such as styrene.

(2) Iso-resins: these are prepared from isophthalic acid, maleic anhydride or fumaric acid, and glycols. These resins may contain higher proportions of reactive diluent than the ortho resins. (3) Bisphenol-A-fumarates: these are based on ethoxylated bisphenol-A and fumaric acid.

(4) Chlorendics: are resins prepared from chlorine/bromine containing anhydrides or phenols in the preparation of the UP resins.

(5) Vinyl ester resins: these are resins, which are mostly used because of their because of their hydrolytic resistance and excellent mechanical properties, as well as for their low styrene emission, are having unsaturated sites only in the terminal position, introduced by reaction of epoxy resins (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 these classes of resins also so-called dicyclopentadiene (DCPD) resins can be distinguished.

All of these resins, as can suitably used in the context of the present invention, may be modified according to methods known to the skilled man, e.g. for achieving lower acid number, hydroxyl number or anhydride number, or for becoming more flexible due to insertion of flexible units in the backbone, etc. The class of DCPD- resins is obtained either by modification of any of the above resin types by Diels-Alder reaction with cyclopentadiene, or they are obtained alternatively by first reacting maleic acid with dicyclopentadiene, followed by the resin manufacture as shown above. Of course, also other reactive groups curable by reaction with peroxides may be present in the resins, for instance reactive groups derived from itaconic acid, citraconic acid and allylic groups, etc. Accordingly, the polymers containing reactive unsaturations used in the present invention may contain solvents. The solvents may be inert to the polymer containing reactive unsaturations or may be reactive therewith during the curing step. Reactive solvents are particularly preferred. Examples of suitable reactive solvents are styrene, α-methylstyrene, (meth) acrylates, N-vinylpyrrolidone and N-vinylcaprolactam. Preferably the polymer containing reactive unsaturations contains at least 5 wt.% of a reactive solvent.

The unsaturated polyester resins and vinyl ester resins as are being used in the context of the present invention may be any type of such resins, but preferably are chosen from the group of DCPD-resins, iso-phthalic resins, ortho- phthalic resins and vinyl ester resins. More detailed examples of resins belonging to such groups of resins have been shown in the foregoing part of the specification.

According to a preferred embodiment of the invention the molecular weight of the polymer containing reactive unsaturations in the resin compositions of the invention is in the range of from 500 to 200,000 g/mole, more preferably in the range of from 750 to 75,000 g/mole, and most preferably in the range of from 1 ,000 to 10,000 g/mole. The latter, narrowest range, is particularly preferred because in said range most appropriate viscosity is achieved for handling the composition. For reducing or adjustment of the viscosity it also can be useful to employ diluents. Most preferably, reactive diluents are employed. According to another preferred embodiment of the invention the resin composition therefore also contains one or more reactive diluents. A list of possible reactive diluents is shown above. The resin handling properties, particularly for being used in techniques like vacuum injection, etc. are generally improved by such use of reactive diluents. However, the amount of such reactive diluent in the resin compositions according to the invention is not critical. Preferably, the reactive diluent is a methacrylate and/or styrene.

It is further noted that inhibitors can be applied to control the gel time of the resin compositions according to the invention. Accordingly, in another favourable embodiment of the invention the resin composition also contains one or more inhibitors.

Preferably the inhibitors are selected from the groups of: (i) phenolic inhibitors; (ii) N-oxyl based inhibitors; (iii) phenothiazine inhibitors; or (iv) any combination of phenolic and/or -oxyl based and/or phenothiazine inhibitors. More preferably, the resin composition contains one or more inhibitors selected from the groups of phenolic and/or N-oxyl based inhibitors.

The amount of inhibitor, preferably of phenolic and/or N-oxyl based inhibitor, as used in the context of the present invention, may, however, vary within rather wide ranges, and may be chosen as a first indication of the gel time as is desired to be achieved.

Preferably, the inhibitor is used in an amount of from about 0.001 to 35 mmol per kg of the resin composition excluding fillers and the like, more preferably in an amount of more than 0.01 , and most preferably in an amount of more than 0.1 mmol per kg of the resin composition excluding fillers and the like. The skilled man quite easily can assess, in dependence of the type of inhibitor selected, which amount thereof leads to good results according to the invention.

Suitable examples of inhibitors that can be used in the resin 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-i ,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), aluminium-N-nitrosophenyl hydroxylamine, diethylhydroxylamine, phenothiazine and/or derivatives or combinations of any of these compounds. The resins as are being used in the resin compositions according to the invention all can be cured by means of peroxide curing. According to the present invention, in addition to the peroxide specific hydroxy-oxo-compounds and bases are applied as accelerator, but also other (co-)accelerators can be applied. The peroxides used for the initiation can be any peroxide known to the skilled man for being used in curing of unsaturated polyester resins and vinyl ester resins. Such peroxides include organic and inorganic peroxides, whether solid or liquid; also hydrogen peroxide may be applied. Examples of suitable peroxides are, for instance, peroxy carbonates (of the formula -OC(O)O-), peroxyesters (of the formula -C(O)OO-), diacylperoxides (of the formula -C(O)OOC(O)-), dialkylperoxides (of the formula -OO-), etc. They can also be oligomeric or polymeric in nature. An extensive series of examples of suitable peroxides can be found, for instance, in US 2002/0091214-A1 , paragraph [0018]. The skilled man can easily obtain information about the peroxides and the precautions to be taken in handling the peroxides in the instructions as given by the peroxide producers. Preferably, the peroxide is chosen from the group of organic peroxides. Examples of suitable organic peroxides are: tertiary alkyl hydroperoxides (such as, for instance, t-butyl hydroperoxide), and other hydroperoxides (such as, for instance, cumene hydroperoxide), the special class of hydroperoxides formed by the group of ketone peroxides (such as, for instance, methyl ethyl ketone peroxide and acetylacetone peroxide), peroxyesters or peracids (such as, for instance, t-butyl peresters, benzoyl peroxide, peracetates and perbenzoates, lauryl peroxide, including (di)peroxyesters), perethers (such as, for instance, peroxy diethyl ether). Often the organic peroxides used as curing agent are tertiary peresters or tertiary hydroperoxides, i.e. peroxy compounds having tertiary carbon atoms directly united to an -OO-acyl or -OOH group. Clearly also mixtures of these peroxides with other peroxides may be used in the context of the present invention. The peroxides may also be mixed peroxides, i.e. peroxides containing any two of different peroxygen-bearing moieties in one molecule). In case a solid peroxide is being used for the curing, the peroxide is preferably benzoyl peroxide (BPO).

It is thus preferred, that the resin composition is curable with a liquid or dissolved peroxide component, more preferably with a liquid or dissolved hydroperoxide component.

The liquid peroxide or hydroperoxide as used, of course, also may be a mixture of peroxides and/or hydroperoxides. Handling of liquid hydroperoxides, especially when the resin compositions are cured for their final use is generally easiest: they have better mixing properties and dissolve more quickly in the polymer containing reactive unsaturations in the resin composition to be cured.

In particular it is preferred that the peroxide is selected from the group of ketone peroxides, a special class of hydroperoxides. The peroxide being most preferred in terms of handling properties and economics is methyl ethyl ketone peroxide (MEK peroxide).

The inventors have found that the curing according to the present invention, in another embodiment thereof, can be co- accelerated via the addition of a transition metal. In such other embodiment of the invention the composition, accordingly, further comprises a transition metal salt or complex. Preferably the transition metals are from the group of transition metals in which the transition metal salt or complex possesses a redox potential between -1 and +2 V. For a description of redox potentials see the reference cited above.

Preferably, in this embodiment of the present invention, the transition metal is selected from the group of transition metals with the atomic numbers 21-30 or 39-48. More preferably the transition metal or complex is selected from transition metals with the atomic number 21-30. Most preferably they are selected from V, Mn, Fe and Cu.

The amount of transition metal to be added can vary widely and depends for instance on the activity and on the color of the transition metal salts or complexes. A man skilled in the art can easily determine the best amounts of transition metal. However, it is preferred that the amount of transition metal or complex is between 0.0001 and 10% relative to the amount of polymer containing reactive unsaturations. In view of the suspect toxicity of cobalt it is evident, that it is preferred that the resin compositions according to the invention should be essentially free of cobalt. The term "essentially free of cobalt" as meant herein indicates that the content of cobalt (atomic number 27) is lower than about 0.015 mmol/kg, preferably even lower than about 0.005 mmol/kg, of the polymer containing reactive unsaturations, and most preferably the resin composition is completely free of cobalt.

The invention also relates to a method for curing, in the presence of an oxo-component, of unsaturated polyester resin or vinyl ester resin compositions comprising a polymer containing reactive unsaturations, a base, and optionally a reactive diluent; wherein (a) the resin composition has an acid value < 10 mg KOH/g; and

(b) the base is either an organic or inorganic hydroxide, alkoxide or carboxylate of which the cation has a redox potential of the metal of at most -1 V, or is an ammonium ion or an amine, or is a mixture of any of such substances; and

(c) the oxo-component is an α-hydroxyoxo-compound according to formula 1 :

with R₁ and R₂, being identical or different from each other, and representing a group selected from the groups consisting of hydrogen (H), a C₁-C₄₀ alkyl group, a C₆-C₄₀ aryl group, a C₇-C₄₀ alkylaryl group, a C₁-C₂₀ ether group OR₃, a C₁-C₂₀ amine group

NR₄R₅, with each of the groups R₃, R₄, and R₅ independently selected from the same type of groups as R₁ and R₂, and wherein two of the R groups may be joint together to form an α-hydroxyoxo cyclic structure of at least 5 carbon atoms, and/or with any of the groups R₁, R₂, R₃, R₄, and R₅ representing a polymer residue, and wherein

(d) the curing is performed with a peroxide component. Most preferably, in such method for curing, the α-hydroxyoxo-compound is present in the resin composition before the peroxide is added for curing.

Moreover, the invention also relates to use of a resin composition according to the invention in chemical anchoring, roofing, relining, boats, containers, tanks, pipes, construction, automotive parts, flooring, or windmill blades.

And finally, the invention relates to cured objects and structural parts, having a thickness of at least 0.5 mm, obtained from a resin composition according to the invention by curing with a peroxide, or obtained by the method for curing as described herein or in the uses of the compositions as described herein.

The invention is now further illustrated in the following experimental part by means of the examples and comparative experiments without being restricted to the specific examples shown.

Monitoring of curing

In the Examples and Comparative Examples presented hereinafter curing was monitored by means of standard gel time equipment. Monitoring of curing, as done herein, means that both the gel time (T_geι or T₂5.>_35°c) and peak time (T_peak or T₂5->_Peak) were determined by exotherm measurements according to the method of DIN 16945 when curing the resin with the peroxides as indicated in the individual Examples and Comparative Examples. The equipment used for this monitoring was a Soform gel timer, with a Peakpro software package and National Instruments hardware; the waterbath and thermostat apparatuses used were respectively Haake W26, and Haake DL30.

Resins and peroxides used

The resins as have been used in the Examples and Comparative Examples, except for the SR231 resin of Example 5 (which is commercially available from Cray Valley, France) are all resins commercially available from DSM Composite Resins, Schaffhausen, Switzerland.

Of these resins the Palatal type resins are ortho-type unsaturated polyester resins (in styrene); the Daron type resins are methacrylate resins (in styrene), and SR231 is a pure (meth)acrylate type resin without additional solvent.

The peroxides as have been used in the Examples and Comparative Examples, are all resins commercially available from Akzo Nobel, The Netherlands. Example 1 and Comparative Examples A-B Example 1

To 98 g Daron XP-41-A-2 (acid value 2.4 mg KOH/g) was added 2 g lithium neodecanoate in white spirits (Li) (2 wt.% Li metal) and 2.1 g benzoin. After stirring for 5 min 2 g Butanox M50 was added. The curing at ambient temperature was monitored with the gel time equipment and the results were as follows: Tgei 8.4 min; T_peak 17.5 min; peak temp 127 ⁰C.

Comparative Example A

To 98 g Palatal 6 (acid value 33 mg KOH/g) was added 2 g lithium neodecanoate in white spirits (Li) (2% Li metal) and 2.1 g benzoin. After stirring for 5 min 2 g Butanox M50 was added. The curing at ambient temperature was monitored with the gel time equipment, but after 1 ,200 min no curing was observed, and then the experiment was stopped.

Comparative Example B

To 98 g Palatal 69 (acid value 20 mg KOH/g) was added 2 g lithium neodecanoate in white spirits (Li) (2% Li metal) and 2.1 g benzoin. After stirring for 5 min 2 g Butanox M50 was added. The curing at ambient temperature was monitored with the gel time equipment, but after 1200 min no curing was observed, and then the experiment was stopped.

These experiments demonstrate that efficient curing only takes place using a resin having an acid value < 10 mg KOH/g.

Examples 2.1-2.4 and Comparative Examples C-J

Examples 2.1-2.4

To x g Daron XP-41-A-2 (amount as indicated in the table) was added 2 g lithium neodecanoate in white spirits (Li) (2% Li metal) and y g of an α- hydroxyoxo-compound (amount and type as indicated in the table). After stirring for 5 min 2 g Butanox M50 was added. The curing at ambient temperature was monitored with the gel time equipment and the results are shown in table 1. Table 1

Comparative Examples C-F

To x g Daron XP-41-A-2 (amount as indicated in the table) was added y g α-hydroxyoxo-compound(amount and type as indicated in the table). After stirring for 5 min 2 g Butanox M50 was added. The curing at ambient temperature was monitored with the gel time equipment and the results are shown in table 2.

Table 2

These Examples 2.1-2.4 and the corresponding Comparative Examples C-F (without Li) clearly demonstrate that curing according to the invention can be performed with various α-hydroxyoxo-compounds. Moreover they demonstrate that bases (e.g. Li) are required for efficient curing.

Comparative Examples G-J

To x g Daron XP-41-A-2 (amount as indicated in the table) was added 2 g lithium neodecanoate in white spirits (Li) (2% Li metal) and y g oxo- compound (amount and type as indicated in the table). After stirring for 5 min 2 g Butanox M50 was added. The curing at ambient temperature was monitored with the gel time equipment and the results are shown in table 3. Table 3

The Examples 2.1-2.4 combined with the Comparative Examples C-J demonstrate that both an α-hydroxyoxo-compound and a base are required for an efficient curing of the resins.

Examples 3.1-3.2 and Comparative Examples K-L Examples 3.1 and 3.2

To 96 g Daron XP-41-A-2 was added 2 g lithium neodecanoate in white spirits (Li) (2% Li metal) and y g α-hydroxyoxo-compound analogue (amount and type as indicated in the table). After stirring for 5 min 2 g Butanox M50 was added. The curing at ambient temperature was monitored with the gel time equipment and the results are shown in table 4.

Table 4

Comparative Examples K-L

To 96 g Daron XP-41-A-2 (acid value 2.4 mg KOH/g) was added y g α-hydroxyoxo-compound analogue (amount and type as indicated in the table). After stirring for 5 min 2 g butanox M50 was added. The curing at ambient temperature was monitored with the gel time equipment and the results are shown in table 5. Table 5

These experiments demonstrate that ketals of an α-hydroxyoxo-compound (like fructose) and enolates (like ascorbic acid) also work according to the invention.

Examples 4.1-4.4 and Comparative Example M

To 490 g Daron XP-45 (acid value 5 mg KOH/g) was added 10 g acetoin. After stirring for 5 min this mixture was divided into 4Og portions to which x g base (as indicated in the table below) was added. After stirring for another 5 min 1.2 g Butanox M50 was added. The curing at ambient temperature was monitored with the gel time equipment and the results are shown in table 6.

Table 6

These Examples demonstrate that both organic as well as inorganic bases can be used according to the invention.

Examples 5.1-5.6

To 462.5 g SR231 (Cray Valley; acid value 0.4 mg KOH/g) was added 25 g adipoin and 12.5g potassium octanoate (15% in PEG). After stirring for 5 min this mixture was divided into 4Og portions to which 1.2 g of various peroxides (as indicated in the table) were added. The curing was monitored with the gel time equipment and the results are shown in table 7. Table 7

These experiments clearly demonstrate that various types of peroxides can be used according to the invention.

Claims

1. Unsaturated polyester or vinyl ester resin composition comprising - while being cured -a polymer containing reactive unsaturations, a base, an oxo -component; and optionally a reactive diluent; and being curable with a peroxide component, wherein a. the polymer containing reactive unsaturations has an acid value < 10 mg

KOH/g; and b. the base is either an organic or inorganic hydroxide, alkoxide or carboxylate of which the cation has a redox potential of the metal of at most -1 V, or is an ammonium ion or an amine, or is a mixture of any of such substances; and c. the oxo-component is an α-hydroxyoxo-compound according to formula 1 :

with R₁ and R₂, being identical or different from each other, and representing a group selected from the groups consisting of hydrogen (H), a C₁-C₄₀ alkyl group, a C₆-C₄₀ aryl group, a C₇-C₄₀ alkylaryl group, a Ci- C₂₀ ether group OR₃, a C₁-C₂₀ amine group NR₄R₅, with each of the groups R₃, R₄, and R₅ independently selected from the same type of groups as R₁ and R₂, and wherein two of the R groups may be joint together to form an α-hydroxyoxo cyclic structure of at least 5 carbon atoms, and/or with any of the groups R₁, R₂, R₃, R₄, and R₅ representing a polymer residue.

2. Resin composition according to claim 1 , wherein the polymer containing reactive unsaturations has an acid value < 5 mg KOH/g.

3. Resin composition according to claim 1 or 2, wherein the polymer containing reactive unsaturations has an acid value < 1 mg KOH/g.

4. Resin composition according to any of the claims 1 to 3, wherein the cation in at least one of the bases has a redox potential of the metal of at most -1.5 V.

5. Resin composition according to any of the claims 1 to 4, wherein at least one of said bases is based on an alkaline or earth alkaline metal, or is an ammonium salt.

6. Resin composition according to claim 5, wherein at least one of said bases is based on lithium, sodium or potassium.

7. Resin composition according to any of the claims 1 to 6, wherein at least one of the said bases is an organosoluble salt.

8. Resin composition according to any of claims 1-7, wherein the base is a tertiary amine, preferably an aliphatic tertiary amine.

9. Resin composition according to any of the claims 1 to 8, wherein the base is present in an amount of from 0.001 to 2,000 mmol/kg of the polymer containing reactive unsaturations, preferably in an amount of from 0.01 to 200 mmol/kg, and most preferably in an amount of from 0.1 to 100 mmol/kg of polymer containing reactive unsaturations.

10. Resin composition according to any of claims 1 to 9, wherein R₁ of the α- hydroxyoxo-compound is hydrogen (H), or a C₁-C₁₀ group, or an OR₃ group in which R₃ is a C₁-C₂₀ alkyl, aryl, or alkylaryl group.

11. Resin composition according to any of claims 1 to 10, wherein R₂ of the α-hydroxyoxo-compound is a Ci-C₁₀ alkyl group.

12. Resin composition according to any of claims 1 to 11 , wherein the amount of the one or more α-hydroxyoxo compounds is between 0.001 and 25 % by weight, calculated on the total weight of the resin composition, excluding fillers and the like.

13. Resin composition according to claim 12, wherein said amount of α-hydroxy- oxo-compounds is between 0.01 and 10 % by weight, preferably between 0.1 and 5 % by weight.

14. Resin composition according to any of claims 1 to 13, wherein the molecular weight of the polymer containing reactive unsaturations is in the range of from 500 to 200,000 g/mole, preferably in the range of from 750 to 75,000 g/mole, and most preferably in the range of from 1 ,000 to 10,000 g/mole.

15. Resin composition according to any of claims 1 to 14, wherein the resin composition also contains one or more reactive diluents.

16. Resin composition according to claim 15, wherein the reactive diluent is a methacrylate and/or styrene.

17. Resin compositions according to any of claims 1 to 16, wherein the resin composition also contains one or more inhibitors.

18. Resin composition according to claim 17, wherein the resin composition contains one or more inhibitors selected from the groups of phenolic and/or N-oxyl based inhibitors.

19. Resin composition according to any of the claims 17 or 18, wherein the inhibitor is used in an amount of from about 0.001 to 35 mmol per kg of the resin composition excluding fillers and the like, more preferably in an amount of more than 0.01 , and most preferably in an amount of more than 0.1 mmol per kg of the resin composition excluding fillers and the like.

20. Resin composition according to any of claims 1 to 19, wherein the resin composition is curable with a liquid or dissolved peroxide component, preferably curable with a liquid or dissolved hydroperoxide component.

21. Resin composition according to any of claims 1 to 20, wherein the resin composition is essentially free of cobalt.

22. Method for curing, in the presence of a oxo component, of unsaturated polyester resin or vinyl ester resin compositions comprising a polymer containing reactive unsaturations, a base, and optionally a reactive diluent; wherein a. the polymer containing reactive unsaturations has an acid value < 10 mg KOH/g; and b. the base is either an organic or inorganic hydroxide, alkoxide or carboxylate of which the cation has a redox potential of the metal of at most -1 V, or is an ammonium ion or an amine, or is a mixture of any of such substances; and c. the oxo-component is an α-hydroxyoxo-compound according to formula 1 :

with R₁ and R₂, being identical or different from each other, and representing a group selected from the groups consisting of hydrogen (H), a C₁-C₄₀ alkyl group, a C₆-C₄₀ aryl group, a C₇-C₄₀ alkylaryl group, a C₁- C₂₀ ether group OR₃, a C₁-C₂₀ amine group NR₄R₅, with each of the groups R₃, R₄, and R₅ independently selected from the same type of groups as R₁ and R₂, and wherein two of the R groups may be joint together to form an α-hydroxyoxo cyclic structure of at least 5 carbon atoms, and/or with any of the groups R₁, R₂, R₃, R₄, and R₅ representing a polymer residue, and wherein d. the curing is performed with a peroxide component.

23. Method for curing, according to claim 22, wherein the α-hydroxyoxo-compound is present in the resin composition before the peroxide is added for curing.

24. Use of a resin composition according to any of the claims 1 to 21 in chemical anchoring, roofing, relining, boats, containers, tanks, pipes, construction, automotive parts, flooring, or windmill blades.

25. Cured objects and structural parts, having a thickness of at least 0.5 mm, obtained from a resin composition according to any of claims 1-21 by curing with a peroxide, or obtained by the method for curing according to claim 22 or

23, or in the use of the composition according to claim 24.