Low chroma curing system

Abstract

A low chroma curing system. The present disclosure relates to an accelerator solution, a pre-accelerated resin composition comprising the accelerator solution, a curable resin composition comprising the pre-accelerated resin composition, and a method of curing a curable resin.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a promoter solution, a pre-accelerated resin composition comprising said promoter solution, a curable resin composition comprising said pre-accelerated resin composition, and a method of curing a curable resin. The compositions and methods of the present disclosure provide a colorless cured product. BACKGROUND

[0002] It is well known that curable resins, such as unsaturated polyester resins, vinyl ester resins, (meth)acrylate resins, can be cured using organic peroxides, and that the curing can be accelerated using metal-based promoters (e.g. WO 2012 / 126917, WO 2015 / 1211778, WO 2020 / 168201). However, such metal-based promoters present significant problems: they can be unstable (i.e. form a precipitate and / or lose performance upon long-term storage), and tend to cause the resins to severely discolor and / or frost upon curing, both of which qualities in the cured resin are not desirable in many applications. Furthermore, many known and commercially available promoters use cobalt metal and / or alkylamines or alkanolamines stabilizers (e.g. diethanolamine; WO 2012 / 126917), however both of these components face a serious risk of being legislated out (e.g. REACH in Europe) due to their poor environmental and toxicity profile.

[0003] It is therefore an object of the present disclosure to provide a curing system that avoids all these drawbacks. SUMMARY

[0004] It has been found that these technical problems are solved by curing a curable resin using a specific promoter composition and a ketone peroxide or hydrogen peroxide. The present disclosure can therefore be summarized by the following aspects: Aspect 1. A composition comprising: (i) a copper compound, (ii) ascorbic acid and / or a fatty acid ester of ascorbic acid, (iii) a bipyridine, and (iv) a solvent, wherein the solvent comprises at least one phosphorous compound having the formula P(R)3 and / or P(R)3=0, wherein each R is independently hydrogen, an alkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms, preferably an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms, more preferably an alkoxy group having 1 to 3 carbon atoms.

[0005] Aspect 2. The composition of aspect 1, wherein the copper compound (i) comprises a copper (II) compound.

[0006] Aspect 3. The composition of aspect 1 or 2, wherein the copper compound (i) is copper (II) acetate.

[0007] Aspect 4. The composition of any of the preceding aspects, wherein the fatty acid ester of ascorbic acid is

[0008] wherein R is a C12-C18 alkyl group.

[0009] Aspect 5. The composition of any of the preceding aspects, wherein the fatty acid ester of ascorbic acid is ascorbyl palmitate.

[0010] Aspect 6. The composition of any of the preceding aspects, wherein (iii) is 2,2’-bipyridine of formula (I): (I) wherein: each R is independently selected from H, alkyl, aryl, heteroaryl, or -A-R 2 wherein A is O or NR 3 and wherein R 2 and R 3 are each independently H, alkyl, aryl, or heteroaryl; Ra is selected from H, alkyl, aryl, heteroaryl, or -A-R 2 wherein A is O or NR 3 and wherein R 2 and R 3 are each independently H, alkyl, aryl, or heteroaryl; Ra’ is selected from H, alkyl, aryl, heteroaryl, or -A-R 2 wherein A is O or NR 3 and wherein R 2 and R 3 are each independently H, alkyl, aryl, or heteroaryl; or Ra and Ra’ together form a ring, preferably a C6 aryl ring.

[0011] Aspect 7. The composition of any of the preceding aspects, wherein (iii) is 2,2’-bipyridine of formula (II) or 2,2’-bipyridine of formula (III): (II) (III) wherein: each R is independently selected from H, alkyl, aryl, heteroaryl, or -A-R 2 wherein A is O or NR 3 and wherein R 2 and R 3 are each independently H, alkyl, aryl, or heteroaryl; and Raand Ra’ are H, or alternatively Raand Ra’ together form a ring, preferably a C6aromatic ring (forming 1,10-phenanthroline).

[0012] Aspect 8. The composition of any one of the preceding claims, wherein (iii) is unsubstituted 2,2’-bipyridine:

[0013] Aspect 9. The composition of any one of the preceding aspects, wherein at least two R groups of the at least one phosphorus compound are alkyl groups or alkoxy groups, more preferably all R groups are alkyl groups or alkoxy groups, most preferably all R groups are alkoxy groups.

[0014] Aspect 10. The composition of any one of the preceding aspects, wherein the solvent (iv) comprises or consists of triethylphosphate.

[0015] Aspect 11. The composition of any one of the preceding aspects, wherein: (i) is copper (II) acetate; (ii) is ascorbic acid and / or ascorbyl palmitate; (iii) is 2,2-bipyridine; and (iv) comprises or consists of triethylphosphate.

[0016] Aspect 12. The composition of any one of the preceding aspects, wherein the accelerator solution consists of components (i), (ii), (iii), and (iv).

[0017] Aspect 13. A pre-accelerated resin composition comprising: (i) a curable resin, (ii) the composition according to any one of aspects 1-12, and (iii) optionally a filler.

[0018] Aspect 14. The pre-accelerated resin composition of aspect 13, wherein the curable resin is an unsaturated polyester resin, a vinyl ester resin, or a (meth)acrylate resin.

[0019] Aspect 15. The pre-accelerated resin composition of aspect 13 or 14, wherein the optional filler is an inorganic filler.

[0020] Aspect 16. A curable resin composition comprising: (i) the pre-accelerated resin composition according to any one of aspects 12 to 15, and (ii) at least one peroxide selected from the group consisting of ketone peroxides, organic peroxides comprising hydrogen peroxide, hydrogen peroxide, and mixtures thereof, preferably ketone peroxides or hydrogen peroxide, most preferably ketone peroxides.

[0021] Aspect 17. The curable resin composition of aspect 16, wherein the at least one ketone peroxide is methyl ethyl ketone peroxide (MEKP), methyl isobutyl ketone peroxide (MIBK), methyl isopropyl ketone peroxide (MIKP), cyclohexanone peroxide (CYHP), acetylacetone peroxide, or a combination thereof.

[0022] Aspect 18. A kit-of-parts comprising: (i) a first component comprising a curable resin, (ii) a second component comprising the composition according to any one of aspects 1 to 12, and (iii) a third component comprising at least one peroxide selected from the group consisting of ketone peroxides, organic peroxides comprising hydrogen peroxide, hydrogen peroxide, and mixtures thereof, preferably ketone peroxides or hydrogen peroxide, most preferably ketone peroxides.

[0023] Aspect 19. A method of curing a curable resin, comprising contacting the curable resin with the composition according to any one of aspects 1 to 12 and at least one peroxide selected from the group consisting of ketone peroxides, organic peroxides comprising hydrogen peroxide, hydrogen peroxide, and mixtures thereof, preferably ketone peroxides or hydrogen peroxide, most preferably ketone peroxides.

[0024] Aspect 20. The method of aspect 19, wherein the curable resin is an unsaturated polyester resin, a vinyl ester resin, or a (meth)acrylate resin.

[0025] Aspect 21. The method of aspect 19 or 20, wherein the ketone peroxide is methyl ethyl ketone peroxide (MEKP), methyl isobutyl ketone peroxide (MIBK), methyl isopropyl ketone peroxide (MIKP), cyclohexanone peroxide (CYHP), acetylacetone peroxide, or a combination thereof. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 Close-up photograph of a cured resin according to the present disclosure.

[0027] Figure 2 A is a close-up photograph of a cured resin of Example 2J (comparative).

[0028] Figure 2 B is a close-up photograph of the cured resin of Example 2G (comparative). DETAILED DESCRIPTION

[0029] In a first aspect, the present disclosure relates to an accelerator composition, preferably an accelerator solution, comprising: (i) a copper compound, (ii) ascorbic acid and / or a fatty acid ester of ascorbic acid, (iii) a bipyridine, and (iv) a solvent, wherein the solvent comprises at least one phosphorous compound having the formula P(R)3and / or P(R)3=0, wherein each R is independently hydrogen, an alkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms.

[0030] It was found that this accelerator composition is surprisingly stable and, when combined with a ketone peroxide or hydrogen peroxide, results in excellent curing of the cured resin with no significant coloration or opacity in the cured resin.

[0031] The component (i) of the accelerator composition of the first aspect of the present disclosure is a copper compound. Suitable copper compounds include, but are not limited to, halides, nitrates, sulfates, sulfonates, phosphates, phosphonates, oxides, and carboxylates. Examples of suitable carboxylates include lactates, 2-ethylhexanoates, acetates, propionates, butyrates, oxalates, laurates, oleates, linoleates, palmitates, stearates, acetyl acetonates, octoates, nonoates, heptanoates, neodecanates, acetyl acetonates, or naphthenates. Preferred copper compounds are copper chloride, copper nitrate, copper sulfate, copper lactate, copper 2-ethylhexanoate, copper octoate, copper nonoate, copper heptanoate, copper neodecanoate, copper acetyl acetonate, copper naphthenate, and copper acetate. Copper (II) compounds are preferred. The most preferred copper compound of the present disclosure is copper (II) acetate, preferably copper (II) acetate monohydrate.

[0032] The copper compound is preferably present in the accelerator in an amount of 0.01 to 2 wt%, preferably 0.05 to 1 wt%, preferably 0.1 to 0.5 wt%, relative to the total weight of the accelerator composition.

[0033] Component (ii) of the accelerator composition of the first aspect of the disclosure is ascorbic acid and / or a fatty acid ester of ascorbic acid. "Ascorbic acid" as used herein includes L-ascorbic acid (CAS No. 50-81-7) and D-isoascorbic acid (CAS No. 89-65-6). The fatty acid ester of ascorbic acid can be obtained by reacting the free OH group of ascorbic acid with a fatty acid to form the corresponding ester. Any suitable esterification process can be used to obtain the fatty acid ester of ascorbic acid. The fatty acid is preferably derived from a renewable source, such as natural oils. In a preferred embodiment, the fatty acid is palmitic acid (hexadecanoic acid), a straight-chain saturated C16 fatty acid found in animals, plants and microorganisms. In one embodiment, the fatty acid ester of ascorbic acid is

[0034] wherein R is a C8-C30 alkyl group, preferably a C12-C18 alkyl group. The alkyl group can be saturated or unsaturated, and can be branched or straight-chain. Preferably, the fatty acid ester of ascorbic acid is ascorbyl palmitate (CAS No. 137-66-6).

[0035] Component (ii) is preferably present in the accelerator in an amount of 5 to 50 wt%, preferably 10 to 40 wt%, relative to the total weight of the accelerator composition.

[0036] Component (iii) of the accelerator composition of the first aspect of the disclosure is bipyridine. The surprising stability of the accelerator composition is attributed in part to the bipyridine component, as a comparative example using nicotinamide instead of the bipyridine component was found to be stable for less than 9 hours (after which the performance rapidly declined). Component (iii) is preferably 2,2'-bipyridine of formula (I):

[0037] wherein: each R is independently selected from H, alkyl, aryl, heteroaryl, or -A-R 2 wherein A is O or NR 3 and wherein R 2 and R 3 are each independently H, alkyl, aryl, or heteroaryl; Ra is selected from H, alkyl, aryl, heteroaryl, or -A-R 2 wherein A is O or NR 3 and wherein R 2 and R 3 are each independently H, alkyl, aryl, or heteroaryl; Ra' is selected from H, alkyl, aryl, heteroaryl, or -A-R 2 wherein A is O or NR3 , and wherein R 2 and R 3 are each independently H, alkyl, aryl, or heteroaryl; or Raand Ra’ together form a ring, preferably a C6aromatic ring (forming 1,10-phenanthroline). More preferably, component (iii) is 2,2’-bipyridine of formula (II) or 2,2’-bipyridine of formula (III): (II) (III) wherein: each R is independently selected from H, alkyl, aryl, heteroaryl, or A-R 2 , wherein A is O or NR 3 , and wherein R 2 and R 3 are each independently H, alkyl, aryl, or heteroaryl, and Raand Ra’ are H or together form a ring, preferably a C6aromatic ring (forming 1,10-phenanthroline). Preferably, each R is independently selected from H, C1-C6alkyl, or -A-R 2 , wherein A is O, and wherein R 2 is H or C1-C6alkyl. R a and R a’ are preferably H. Non-limiting examples of suitable bipyridines for use as component (iii) include 2,2’-bipyridine, 5,5'-dimethyl-2,2'-bipyridine, 4,4'-dimethyl-2,2'-bipyridine, 4,4’-dimethoxy-2,2-bipyridine, 4,4’-di-tert-butyl-2,2’-bipyridine, and combinations thereof. Most preferably, component (iii) is 2,2’-bipyridine:

[0038] Component (iii) is preferably present in the promoter in an amount of 0.05 to 5 wt%, preferably 0.1 to 3 wt%, more preferably 0.5 to 2 wt%, relative to the total weight of the promoter composition.

[0039] The accelerator composition of the first aspect of this disclosure comprises (iv) a solvent, wherein the solvent contains or is composed of at least one phosphorus compound having the formula P(R)3 (phosphine) and / or P(R)3=O (phosphine oxide), wherein each R is independently hydrogen, an alkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. Solvents not containing at least one of the phosphorus compounds have been found to cause instability (rapid solidification). Preferably, at least two R groups are selected from alkyl groups or alkoxy groups, more preferably all R groups are selected from alkyl groups or alkoxy groups, and even more preferably all R groups are selected from alkoxy groups. Preferably, each R is independently an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms or an alkoxy group having 1 to 3 carbon atoms. More preferably, each R is independently an alkoxy group having 1 to 6 carbon atoms (i.e., tri(C) alkoxy group). 1-6 The solvent comprises at least one phosphorus compound having the formula P(R)3=O, wherein each R is independently an alkyl group having 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms, more preferably 1 to 3 carbon atoms, such as methoxy (R = MeO-), ethoxy (R = EtO-), propoxy (R = PrO-), or isopropoxy (R = iPrO-). Preferably, the solvent comprises at least one phosphorus compound having the formula P(R)3=O, wherein each R is independently an alkyl group having 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms, more preferably 1 to 3 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms, more preferably 1 to 3 carbon atoms. Most preferably triethyl phosphate (triethoxyphosphine oxide; CAS 78-40-0; R = EtO- [i.e., P(OEt)3=O]).

[0040] Solvent component (iv) may contain or consist of at least one phosphorus compound as described above. Preferably, the at least one phosphorus compound constitutes at least 50 wt% of solvent component (iv), more preferably at least 75 wt% of solvent component (iv), more preferably at least 90 wt% of solvent component (iv), and most preferably at least 99 wt% of solvent component (iv), for example, 100 wt% of solvent component (iv), relative to the total weight of solvent component (iv). If solvent component (iv) contains one or more cosolvents, it preferably comprises, by weight ratio of phosphorus compound to cosolvent, about 50:50 to >99:1, more preferably about 75:25 to >99:1, and most preferably about 90:10 to >99:1. For example, when a solvent mixture of 90:10 triethyl phosphate and butyl carbitol is used instead of 100% triethyl phosphate, a stable analogue of Example 1B (hereinafter) is obtained.

[0041] The solvent component (iv) typically constitutes the mass balance portion of the accelerator composition and is typically present in the accelerator composition in an amount of about 10 to about 90 wt%, preferably about 50 to about 90 wt%, relative to the total weight of the accelerator composition.

[0042] The accelerator composition may optionally contain water. The water content is preferably no more than 50 wt%, more preferably no more than 40 wt%, more preferably no more than 20 wt%, even more preferably no more than 10 wt%, and most preferably no more than 5 wt%, all based on the total weight of the accelerator composition.

[0043] In a preferred embodiment of the first aspect, the accelerator composition comprises: (i) 0.01 to 2 wt% copper compounds, (ii) 5 to 50 wt% of ascorbic acid and / or fatty acid esters of ascorbic acid, (iii) 0.05 to 5 wt% bipyridine, and (iv) A solvent comprising at least one phosphorus compound having the formula P(R)3 and / or P(R)3=O, wherein each R is independently hydrogen, an alkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms.

[0044] In a further preferred embodiment of the first aspect, the accelerator composition comprises: (i) 0.01 to 2 wt% of copper(II) compounds, (ii) 5 to 50 wt% of ascorbic acid and / or fatty acid esters of ascorbic acid, wherein the fatty acid ester of ascorbic acid is

[0045] Where R is a C12-C18 alkyl group (iii) 0.05 to 5 wt% of 2,2'-bipyridine of formula (II) or 2,2′-bipyridine of formula (III): (II) (III) in: Each R is independently selected from H, alkyl, aryl, heteroaryl, or -AR. 2 Where A is O or NR 3 And R 2 and R 3 Each is independently H, alkyl, aryl, or heteroaryl and Ra and Ra' are H or together form a ring, preferably a C6 aromatic ring (thus forming 1,10-phenanthroline), and (iv) A solvent comprising at least one phosphorus compound having the formula P(R)3 and / or P(R)3=O, wherein each R is independently an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms.

[0046] In a further preferred embodiment of the first aspect, the accelerator composition comprises: (i) 0.01 to 2 wt% copper acetate (II), (ii) 5 to 50 wt% ascorbic acid and / or ascorbic acid palmitate, (iii) 0.05 to 5 wt% of a bipyridine selected from the group consisting of 2,2'-bipyridine, 5,5'-dimethyl-2,2'-bipyridine, 4,4'-dimethyl-2,2'-bipyridine, 4,4'-dimethoxy-2,2-bipyridine, 4,4′-di-tert-butyl-2,2′-bipyridine, and combinations thereof, preferably 2,2'-bipyridine, and (iv) A solvent comprising or consisting of one or more phosphorus compounds having the formula P(R)3=O, wherein each R is independently an alkoxy group having 1 to 3 carbon atoms, preferably 2 carbon atoms (i.e., triethyl phosphate).

[0047] In one embodiment, the accelerator composition of the first aspect may consist of components (i)-(iv) as described above.

[0048] The accelerator composition can be prepared by simply mixing the components, optionally with intermediate heating and / or mixing steps.

[0049] In a second aspect, this disclosure relates to a pre-promoted resin composition comprising: (i) Curing resins, (ii) The accelerator composition of the first aspect of this disclosure, and (iii) Optionally, fillers and / or reinforcing fibers.

[0050] Any (free radical) curable resin can be used in the pre-promoted resin composition. Suitable resins include alkyd resins, unsaturated polyester (UP) resins, vinyl ester resins, (meth)acrylate resins, polyurethanes, epoxy resins, and mixtures thereof. Preferred resins are (meth)acrylate resins, UP resins, and vinyl ester resins. In the context of this application, the terms "unsaturated polyester resin" and "UP resin" refer to a combination of an unsaturated polyester resin and an olefinically unsaturated monomer compound. The term "(meth)acrylate resin" includes a combination of an acrylate or methacrylate resin and an olefinically unsaturated monomer compound. UP resins and acrylate resins as defined above are common practice and commercially available.

[0051] Suitable UP resins to be cured by the process of this invention include so-called orthoresins, isoresins, iso-NPG resins, and dicyclopentadiene (DCPD) resins. Examples of such resins include maleic, fumaric, allyl, vinyl, and epoxy resins, bisphenol A resins, terephthalic acid resins, and hybrid resins.

[0052] Vinyl ester resins include acrylate resins based on, for example, methacrylates, diacrylates, dimethacrylates, and oligomers thereof.

[0053] (Meth)acrylate resins include acrylates, methacrylates, diacrylates and dimethacrylates, and their oligomers.

[0054] Examples of olefinically unsaturated monomeric compounds include styrene and styrene derivatives such as α-methylstyrene, vinyltoluene, indene, divinylbenzene, vinylpyrrolidone, vinylsiloxane, vinylcaprolactam, stilbene, as well as diallyl phthalate, dibenzyl acetone, allylbenzene, methyl methacrylate, methyl acrylate, (meth)acrylic acid, diacrylate, dimethacrylate, acrylamide; vinyl acetate, triallyl cyanurate, triallyl isocyanurate, allyl compounds for optical applications (e.g., (di)ethylene glycol diallyl carbonate), chlorostyrene, tert-butylstyrene, tert-butyl acrylate, butanediol dimethacrylate, and mixtures thereof. Suitable examples of reactive diluents for (meth)acrylates include 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, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, glycerol di(meth)acrylate, trimethylolpropane di(meth)acrylate, neopentyl... Diol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, PPG250 di(meth)acrylate, tricyclodecanediethanol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, glycidyl (meth)acrylate, (bis)maleimide, (bis)citronimidide, (bis)itaconimidide, and mixtures thereof.

[0055] The amount of olefinic unsaturated monomer in the pre-accelerated resin composition is preferably at least 1 wt%, more preferably at least 10 wt%, more preferably at least 25 wt%, and most preferably at least 50 wt%, based on the weight of the resin.

[0056] The pre-accelerated resin composition preferably contains an accelerator composition in the following amounts: at least 0.01 parts by weight (pbw) / 100 pbw curing resin (i), preferably at least 0.1 pbw / 100 pbw curing resin (i), and more preferably no more than 5 pbw / 100 pbw curing resin (i), more preferably no more than 3 pbw / 100 pbw curing resin (i). Preferably, the pre-accelerated resin composition contains an accelerator composition in the following amounts: 0.01-5 pbw / 100 pbw curing resin (i), preferably 0.1-3 pbw / 100 pbw curing resin (i).

[0057] The pre-accelerated resin composition may also contain fillers and / or reinforcing fibers (iii). Examples of reinforcing fibers are glass fibers, carbon fibers, aramid fibers (e.g., Twaron®), and natural fibers (e.g., jute, kenaf, hemp, flax, ramie, etc.). The fibers may be in woven form. Examples of fillers are quartz, sand, aluminum hydroxide, magnesium hydroxide, chalk, calcium hydroxide, clay, titanium dioxide, and lime. The properties of the filler component are not limited to any particular filler type. The pre-accelerated resin composition may contain any suitable amount of filler, for example, up to about 500 parts by weight (pbw) of filler (iii) / 100 pbw of cured resin (i), for example, up to 200 parts by weight (pbw) of filler (iii) / 100 pbw of cured resin (i).

[0058] Other optional additives that may be present in the pre-accelerated resin composition include, but are not limited to, pigments, free radical inhibitors, flame retardants, and promoters.

[0059] In a preferred embodiment, the pre-promoted resin composition comprises: (i) Curing resins, (ii) 0.01-5 parts by weight / 100 parts by weight of the accelerator composition of the first aspect of this disclosure, and (iii) 0-500 parts by weight / 100 parts by weight of (i) fillers and / or reinforcing fibers.

[0060] In another preferred embodiment, the pre-promoted resin composition comprises: (i) a curable resin, wherein the curable resin is an unsaturated polyester resin, a vinyl ester resin, a (meth)acrylate resin, or a combination thereof. (ii) 0.01-5 parts by weight / 100 parts by weight of the accelerator composition of the first aspect of this disclosure, and (iii) 0-200 parts by weight / 100 parts by weight of (i) filler and / or reinforcing fibers.

[0061] The pre-accelerated resin of the second aspect of this disclosure can be prepared in various ways, for example, by mixing the various components of the accelerator composition with a resin and optional fillers, or by mixing a resin comprising optional monomers and optional fillers with a pre-prepared accelerator composition according to this disclosure. The latter method is preferred.

[0062] In a third aspect, this disclosure relates to a curable resin composition comprising: (i) the pre-promoted resin composition of the second aspect, and (ii) at least one peroxide selected from the following: ketone peroxide, organic peroxide containing hydrogen peroxide, hydrogen peroxide, and mixtures thereof, preferably ketone peroxide or hydrogen peroxide, most preferably ketone peroxide.

[0063] The at least one peroxide (ii) is preferably one or more ketone peroxides, more preferably selected from one or more ketone peroxides including: methyl ethyl ketone peroxide (MEKP), methyl isopropyl ketone peroxide (MIKP), methyl isobutyl ketone peroxide (MIBK), cyclohexanone peroxide (CYHP), acetylacetone peroxide, and combinations thereof. MEKP and MIKP are particularly preferred, and MIKP is most preferred.

[0064] The total amount of (ketone) peroxide in the curable resin composition is preferably 0.03-5 parts by weight (pbw), calculated as the number of parts by weight of pure peroxide / 100 pbw of the curable resin composition of the pre-accelerated resin composition (i); more preferably 0.5-4 parts by weight (pbw), calculated as the number of parts by weight of pure peroxide / 100 pbw of the curable resin composition of the pre-accelerated resin composition (i).

[0065] In the fourth aspect, this disclosure relates to a multi-part kit that includes: (i) A first component containing a curable resin. (ii) a second component comprising the accelerator composition of the first aspect, and (iii) A third component comprising at least one peroxide selected from the following: ketone peroxide, organic peroxide containing hydrogen peroxide, hydrogen peroxide, and mixtures thereof, preferably ketone peroxide or hydrogen peroxide, most preferably ketone peroxide.

[0066] The curable resin, the accelerator composition, and the (ketone) peroxide are as described above. The first component (i) may optionally further comprise fillers and / or reinforcing fibers. Non-limiting examples of suitable reinforcing fibers include glass fibers, carbon fibers, aramid fibers (e.g., Twaron®), and natural fibers (e.g., jute, kenaf, hemp, flax, ramie, etc.). The fibers may be in woven form. Examples of fillers include quartz, sand, aluminum hydroxide, magnesium hydroxide, chalk, calcium hydroxide, clay, titanium dioxide, and lime. The properties of the filler component are not limited to any particular filler type. The first component (i) may contain any suitable amount of filler, for example, up to about 200 parts by weight (pbw) of filler per 100 pbw of curable resin. Other optional additives that may be present in the first component (i) include, but are not limited to, pigments, free radical inhibitors, flame retardants, and initiators. If the first component contains fillers or additives, the third component preferably contains a ketone peroxide.

[0067] In use, the first component, the second component, and the third component are mixed together, and the resulting mixture is cured to form a cured resin.

[0068] In a fifth aspect, this disclosure relates to a method for curing a curable resin, comprising contacting the curable resin with an accelerator composition of the first aspect and at least one peroxide selected from: ketone peroxides, organic peroxides containing hydrogen peroxide, hydrogen peroxide, and mixtures thereof, preferably ketone peroxides or hydrogen peroxide, most preferably ketone peroxides. In a preferred embodiment, the accelerator composition is added to the curable resin to form a mixture, and then the at least one ketone peroxide is added to the mixture. In an alternative embodiment, the at least one ketone peroxide is added to the curable resin to form a mixture, and then the accelerator composition is added to the mixture.

[0069] Once again, the curable resin, the accelerator composition, and the (ketone) peroxide are as described above.

[0070] When the curable resin, the (ketone) peroxide, the accelerator composition, and any optional other components have been combined, these compounds are mixed and dispersed. The curing process can be carried out at any temperature from -15°C to 250°C. Preferably, it is carried out at ambient temperatures commonly used in applications such as hand lay-up molding, spray molding, filament winding, resin transfer molding, coating (e.g., gel coat and standard coating), button production, centrifugal casting, corrugated sheets or plates, heavy-duty lining systems, kitchen sinks produced via casting compounds, etc. However, it can also be used in SMC, BMC, pultrusion technologies, etc., for which temperatures up to 180°C, more preferably up to 150°C, and most preferably up to 100°C are used. The cured composition may undergo a post-curing treatment to further optimize hardness. This post-curing treatment is typically carried out at temperatures ranging from 40 to 180°C for 30 minutes to 15 hours.

[0071] The cured resin is used in a variety of applications, including marine applications, chemical anchoring, roofing, construction, lining, pipes and tanks, flooring, wind turbine blades, laminates, polymer concrete, tabletops, washbasins, and sanitary products.

[0072] It should be noted that the various elements of this disclosure, including but not limited to the preferred ranges of the various parameters, can be combined unless they are mutually exclusive. Example

[0073] This disclosure will be illustrated by the following examples, but is not limited thereto or restricted thereto.

[0074] Reactivity was determined by exothermic measurements according to the modified standard NEN-EN ISO 584. Experiments in the examples were conducted using a constant starting temperature of 20°C. Temperature-time curves were recorded on a Eurotherm Chessell 6100A recorder. Gel time (GT) = the time, in minutes, elapsed between the start of the experiment and the monitoring temperature reaching 5.6°C above the starting temperature. Time to peak (TTP) = the time elapsed between the start of the experiment and the moment the peak temperature was reached. Peak exothermic (PE) = the highest temperature reached. In the following examples, gel time (GT), time to peak (TTP), and peak exothermic (PE) were measured using a Eurotherm Chessell 6100A recorder. The opacity and color of the cured resin were determined visually.

[0075] Example 1 The following accelerator compositions (200g per batch) were prepared by combining the ingredients in the table below in the stated amounts and then mixing (stirring) the resulting compositions at 50°C for 60 minutes:

[0076]

[0077]

[0078]

[0079]

[0080]

[0081] These accelerator compositions have been found to be surprisingly stable, showing no significant precipitation or performance loss even after 4 weeks of storage. The surprising stability of these accelerator compositions is attributed to the bipyridine component in combination with the solvent type, as a comparative example using nicotinamide instead of the bipyridine component was found to be stable for less than 9 hours (after which performance rapidly declined), and the same was true for another comparative example using tris(2-ethylhexyl) phosphate instead of triethyl phosphate (rapid and significant precipitation formation). Therefore, these stable accelerator compositions provide a viable alternative to those using cobalt metal accelerators and / or amine stabilizers (which are threatened with legislative bans due to their poor toxicity profile).

[0082] Example 2 Accelerator composition Ex. 1B was tested with various types of peroxides to attempt to address the known problems of yellowing and blooming. Surprisingly, these problems were resolved when ketone peroxides were used; the use of other organic peroxides resulted in discoloration (X), blooming (O), or both. Further unexpectedly, these problems were also resolved when hydrogen peroxide (H₂O₂) was used. Interestingly, these problems were not resolved (the resin did not cure) when pure organic hydroperoxides (e.g., cumene hydroperoxide (Ex. 2J) and tert-butyl hydroperoxide) were used. Based on these findings, and not wanting to be bound or limited by theory, it is speculated that the effectiveness of ketone peroxides in this curing system may be partly related to the fact that ketone peroxides typically contain a certain amount of hydrogen peroxide (due to the dynamic equilibrium that often exists in ketone peroxides under standard laboratory conditions). Examples 2A-2M were each carried out by mixing the stated reagents in stated amounts (parts by weight) in test tubes (accelerator and resin added first, then peroxide), and then allowing the MMA resin to cure.

[0083]

[0084] C = colorless X = Yellow or Brown CX = Nearly colorless (with very slight yellowing) T = Transparent O = Opaque ("Frosty") N / A = Poor cure * MMA = Methyl methacrylate 1 Methyl isopropyl ketone peroxide (MIKP) 2 Methyl ethyl ketone peroxide (MEKP) 3 tert-butyl peroxybenzoate 4 Benzoyl peroxide 5 Benzoyl peroxide 6 dilauryl peroxide 7 2,5-Dimethyl-2,5-di(2-ethylhexanoylperoxy)hexane 8 tert-butyl peroxy-2-ethylhexanoate 9 tert-butyl peroxy-3,5,5-trimethylhexanoate 10 Cucurbit hydroperoxide 11Peroxy-2-ethylhexyl tert-butyl carbonate 12 1,1-Di(tert-butylperoxy)cyclohexane The specific accelerator compositions disclosed herein, in combination with ketone peroxides or hydrogen peroxide, solve two problems associated with curing curable resins: coloration and blooming. To aid in understanding the significant improvements provided by the curing system disclosed herein, Figure 1 and Figure 2 The image provided is a close-up photo of the cured resin. Figure 1 This is a close-up photograph of the cured resin (in a test tube) obtained when the accelerator composition of this disclosure is combined with ketone peroxide (colorless and transparent, “glassy” – the inserted wire is clearly visible, and there is no resin staining or blooming). Figure 2 A is a close-up photograph of Example 2J (in a test tube), in which the cured resin exhibits slight discoloration and severe blooming (the cured resin is opaque—the inserted metal wire is not visible). Figure 2 B is a close-up photograph of Example 2G (in a test tube), in which the cured resin is brown and frosty (the cured resin is opaque—the inserted metal wire cannot be seen).

[0085] Example 3 Accelerator compositions 1A-D were combined with ketone peroxides to determine whether the significant improvements observed in Example 2 could be reproduced in other unsaturated resins and other accelerators of Example 1. In all cases, the cured resins were colorless and transparent—no discoloration or "blooming" (opaqueness) issues were observed. All exhibited excellent gel time (GT), time to peak (TTP), and peak exothermic (PE).

[0086]

[0087] 1 Advalite 35065-0 2 Beyone 700-T-01 3 Butanox P-50 § The experiment could not be conducted due to the reaction being too fast.

[0088] 1 Palatal P4-01 2 Butanox M-50 3 Butanox P-50

[0089] Example 4 A further advantage of the curing system disclosed herein is that fillers can be successfully incorporated into the cured resin. For example, aluminum hydroxide (ATH) and quartz can be successfully incorporated into the cured resin to obtain an intentionally opaque cured resin, wherein the opacity and color of the cured resin are entirely derived from the fillers.

[0090]

[0091] 1 Palatal P4-01 Therefore, the curing system disclosed herein allows for the production of filled and cured resins in which the resin does not affect the visual properties provided by the filler.

[0092] Example 5 It has also been observed that the time to peak (TTP) can be modulated by changing the ratio of ascorbic acid (“AA”) to ascorbic acid fatty acid esters (e.g., palmitic ascorbate, “AAP”) in the accelerator composition. Examples 5A-5G use the following accelerator compositions at 2 pbw, wherein the compositions contain different weight ratios of AAP:AA.

[0093]

[0094]

[0095] The ability to controllably regulate TTP is another significant advantage of the accelerator compositions and curing systems disclosed herein.

[0096] Example 6 The curing system reacts well with a range of bipyridines in both the presence and absence of aluminum hydroxide (ATH) filler. The accelerator composition is formulated as follows:

[0097]

[0098] * The amounts in the table correspond to the amount (pbw) of the promoter composition containing the specified bipyridine, not the amount of the specified bipyridine Example 7 Styrene-free resins based on dimethyl itaconate Further experiments confirmed that the curing system disclosed in this paper is highly effective even with very small amounts of accelerators and oxidants.

[0099]

[0100] a​ In this specification, unless expressly otherwise indicated, the word "or" is used as an operator that returns a truth value when one or both of the stated conditions are met, as opposed to the "exclusive OR" operator, which requires only one condition to be met. The word "includes" is used to mean "including" rather than "consisting of". All existing teachings acknowledged above are incorporated herein by reference. Any acknowledgment herein of any previously published document should not be construed as an acknowledgment or representation that its teachings were common knowledge in Europe or elsewhere as of the date of this document.

Claims

1. A composition comprising: (i) Copper compounds, (ii) Ascorbic acid and / or fatty acid esters of ascorbic acid (iii) Bipyridine, and (iv) A solvent comprising at least one phosphorus compound having the formula P(R)3 and / or P(R)3=O, wherein each R is independently hydrogen, an alkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms.

2. The composition of claim 1, wherein the copper compound (i) comprises a copper (II) compound.

3. The composition of claim 1 or 2, wherein the copper compound (i) is copper acetate (II).

4. The composition of any of the preceding claims, wherein the fatty acid ester of said ascorbic acid is Where R is a C8-C30 alkyl group.

5. The composition of any of the preceding claims, wherein the fatty acid ester of said ascorbic acid is ascorbate palmitate, preferably palmitic ascorbate.

6. The composition of any of the preceding claims, wherein (iii) is 2,2′-bipyridine of formula (II) or 2,2′-bipyridine of formula (III): (II) (III) in: Each R is independently selected from H, alkyl, aryl, heteroaryl, or AR. 2 Where A is O or NR 3 And R 2 and R 3 Each is independently H, alkyl, aryl, or heteroaryl; and Ra and Ra' are H or together form a ring, preferably a C6 aromatic ring (which forms 1,10-phenanthroline).

7. The composition of any of the preceding claims, wherein the solvent (iv) comprises or is composed of one or more phosphorus compounds having the formula P(R)3=O, wherein each R is independently an alkoxy group having 1 to 3 carbon atoms.

8. The composition of any one of the preceding claims, wherein: Component (i) is copper acetate (II); Component (ii) is ascorbic acid and / or palmitic acid ascorbate; Component (iii) is 2,2'-bipyridine; and Component (iv) contains or is composed of triethyl phosphate.

9. The composition of any of the preceding claims, wherein the composition comprises components (i), (ii), (iii) and (iv).

10. A pre-accelerated resin composition comprising: (i) Curing resins, (ii) the composition according to any one of claims 1-9, and (iii) Optionally, fillers and / or reinforcing fibers.

11. The pre-accelerated resin composition of claim 10, wherein the curable resin is an unsaturated polyester resin, a vinyl ester resin, a (meth)acrylate resin, or a combination thereof.

12. A curable resin composition comprising: (i) the pre-accelerated resin composition according to claim 10 or 11, and (ii) at least one peroxide selected from the following: ketone peroxides, organic peroxides containing hydrogen peroxide, hydrogen peroxide, and mixtures thereof, preferably ketone peroxides.

13. A multi-part kit that includes: (i) A first component containing a curable resin. (ii) comprising a second component of the composition according to any one of claims 1-9, and (iii) A third component comprising at least one peroxide selected from the following: ketone peroxide, organic peroxide containing hydrogen peroxide, hydrogen peroxide, and mixtures thereof, preferably ketone peroxide.

14. A method for curing a curable resin, comprising contacting the curable resin with a composition according to any one of claims 1-9 and at least one peroxide selected from the group consisting of ketone peroxides, organic peroxides containing hydrogen peroxide, hydrogen peroxide, and mixtures thereof, preferably ketone peroxides.

15. A cured resin that can be obtained by the method of claim 14.

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