(METH)acrylate based reactive diluent compositions for unsaturated polyester resins

Abstract

This invention relates to a (meth)acrylate-based reactive diluent composition that facilitates styrene-free curing of unsaturated polyester resins. The reactive diluent composition comprises a (meth)acrylate monomer and a compatibilizing agent comprising at least one (meth)acrylate group and at least one additional vinyl unsaturated group.

Description

Technical Field

[0001] Unsaturated polyester (UP) resins are unsaturated synthetic resins formed by the reaction of dibasic organic acids and polyhydroxy alcohols. Unsaturated polyester resins are widely used in various applications, such as coatings, adhesives, linings, gel coatings, or composites. In composites including sheet molding compounds (SMCs) and integral molding compounds (BMCs), UP resins are reinforced with solid materials (e.g., glass fibers) to obtain fiber-reinforced plastics (FRPs). UP resins with high filler content are used in clay, polymer concrete, chemical tackifiers, coloring pastes, or artificial marble.

[0002] UP resins can be cured with reactive diluents (i.e., solvents with crosslinking / curing reactivity, such as styrene). Essentially, UP resins are cured with a high styrene content (typically up to 50% by weight). Therefore, most UP resins consist of a solution of unsaturated polyester in styrene. Due to regulatory, health, and safety factors, many companies aim to reduce the styrene content in resins, which can cause organ damage and potentially reproductive toxicity, thereby developing styrene-reduced or even styrene-free systems. Styrene structural analogs are often used as alternatives to styrene, but this is merely a temporary solution to avoid the direct use of styrene. Examples of this workaround are 4-methylstyrene, 4-trimethylbutylstyrene, or 2,4,6-trimethylstyrene.

[0003] Despite its unfavorable physiological properties, styrene continues to be used in UP resins because it is extremely inexpensive, has high diluting power, and readily copolymerizes with the unsaturated portion of the polyester resin.

[0004] Compared to styrene, (meth)acrylic acid and its esters (i.e., (meth)acrylates) are less hazardous and safer to handle, so the use of (meth)acrylates as reactive diluents, either individually or in reactive diluent compositions, is particularly desirable. Methacrylates are considered reactive diluents for vinyl ester resins. Vinyl ester resins are epoxy resins functionalized with the terminal groups of (meth)acrylate chains through reaction with (meth)acrylic acid or hydroxy(meth)acrylate. These terminal groups readily crosslink with the methacrylates, which act as reactive diluents, during the final curing step. However, (meth)acrylates do not simply copolymerize / crosslink with UP resins and therefore cannot be used as reactive diluents in these resins.

[0005] Based on the above, the object of the present invention is to provide novel (meth)acrylate-based and styrene-free reactive diluent compositions for UP resins. Ideally, these (meth)acrylate-based reactive diluent compositions include (meth)acrylates with low vapor pressure, or even reactive diluent compositions that result in no VOC or reduced VOC (VOC = volatile organic compounds). Prior Technology

[0006] CN 111978477 A relates to the field of composite materials, particularly sheet-molded composite raw materials, sheet-molded composite products, their manufacturing methods and applications. The sheet-molded composite comprises unsaturated polyester resin, a low-shrinkage agent, an initiator, a diluent monomer, a mercapto-containing compound, glass microspheres, a flame retardant, and a reinforcing agent.

[0007] It does not describe the reactive diluent composition according to the present invention. Nor does it describe a curable resin composition containing this reactive diluent composition or a pre-accelerated blend containing the curable resin composition, nor does it disclose a method for curing unsaturated polyester resin by providing a curable resin composition containing the reactive diluent composition of this patent application.

[0008] WO 2013 / 124273 relates to thermosetting, radiation-curable resin compositions containing methacrylates suitable for (replacing) gaskets.

[0009] The resin composition includes: (a) 30 to 70% by weight of resins containing methacrylates, (b) 2.5-20% by weight of an unsaturated polyester resin comprising a fumaric acid building block as an unsaturated dicarboxylic acid building block and alkoxylated bisphenol A and / or alkoxylated bisphenol F building blocks as diol building blocks. (c) 1-40% by weight of vinyl unsaturated compounds, non-benzyl methacrylates, capable of copolymerizing with (a), (b) and (d); and (d) 5-60% by weight of benzyl methacrylate - (refer to Request 1 and page 11, line 26 to page 2, line 3).

[0010] It does not describe the reactive diluent composition according to the present invention. Nor does it describe a curable resin composition containing the reactive diluent composition or a pre-accelerated blend containing the curable resin composition, nor does it disclose a method for curing unsaturated polyester resin by providing a curable resin composition containing the reactive diluent composition of this patent application.

[0011] JP 2003-206306 relates to molding materials containing methyl methacrylate. The molding material comprises a resin (A) including vinyl monomers (a), vinyl monomers (b), and a polymer (c), a filler (B), and a curing agent (C).

[0012] It does not describe the reactive diluent composition according to the present invention. Nor does it describe a curable resin composition containing the reactive diluent composition or a pre-accelerated formulation containing the curable resin composition, nor does it disclose a method for curing unsaturated polyester resin by providing a curable resin composition containing the reactive diluent composition of this patent application. Summary of the Invention

[0013] In a first aspect, the present invention provides a reactive diluent composition comprising (meth)acrylate monomers and a compatibilizer, or composed of (meth)acrylate monomers and a compatibilizer; wherein the compatibilizer comprises at least one (meth)acrylate group and at least one additional vinyl unsaturated group.

[0014] Secondly, the present invention relates to a curable resin composition comprising at least one unsaturated polyester resin (UPR) and the above-described reactive diluent composition.

[0015] Thirdly, the present invention relates to a pre-accelerated formulation comprising the above-mentioned curable resin composition and at least one accelerator.

[0016] Fourthly, the present invention provides a styrene-free method for curing unsaturated polyester resin, the method comprising: (a) Provide a curable resin composition, or, alternatively, the aforementioned pre-accelerated formulations. (b) Optionally, at least one organic or inorganic additive may be added, and (c) The curing process is initiated by adding an initiator. Implementation

[0017] The inventors of this case have developed a (meth)acrylate-based reactive diluent composition that facilitates styrene-free curing of UP resins.

[0018] More specifically, the inventors of this case have discovered that by adding a compatibilizer, i.e., a multifunctional molecule, preferably a difunctional molecule containing at least one (meth)acrylate group and at least one additional vinyl unsaturated group, UP resin can be copolymerized with (meth)acrylate. The at least one additional vinyl unsaturated group can be, for example, vinyl, allyl, or alkenyl.

[0019] Accordingly, the present invention provides a reactive diluent composition comprising (meth)acrylate monomers and a compatibilizer, or composed of (meth)acrylate monomers and a compatibilizer, wherein the compatibilizer comprises at least one (meth)acrylate group and at least one additional vinyl unsaturated group. The (meth)acrylate monomer and the compatibilizer are different chemical compounds.

[0020] In this invention, the term "(meth)acrylate" refers to methacrylate or acrylate.

[0021] In the compatibilizer, at least one (meth)acrylate group and at least one additional vinyl unsaturated group may be linked by a linking group (containing a straight-chain, cyclic, or branched alkyl or (alkyl)aryl group having a chain length of C1 to C20), which optionally contains one or more heteroatoms, such as O, N, or S.

[0022] The compatibilizer may be selected from the group consisting of: vinyl ether (meth) acrylates, allyl ether (meth) acrylates, and alkenyl (meth) acrylates. Vinyl ether (meth) acrylates include, for example, monovinyl ether mono(meth) acrylate, monovinyl ether di(meth) acrylate, monovinyl ether tri(meth) acrylate, monovinyl ether tetra(meth) acrylate; divinyl ether mono(meth) acrylate, divinyl ether di(meth) acrylate, divinyl ether tri(meth) acrylate; and trivinyl ether mono(meth) acrylate, trivinyl ether di(meth) acrylate. Allyl ether (meth)acrylates include, for example, monoallyl ether mono(meth)acrylate, monoallyl ether di(meth)acrylate, monoallyl ether tri(meth)acrylate, monoallyl ether tetra(meth)acrylate; diallyl ether mono(meth)acrylate, diallyl ether di(meth)acrylate, diallyl ether tri(meth)acrylate; and triallyl ether mono(meth)acrylate, triallyl ether di(meth)acrylate. Alkenyl (meth)acrylates include mono, di, tri, and tetra(meth)acrylates containing one or more vinyl unsaturated alkenyl (C=C) groups, which are different from (meth)acrylates.

[0023] Advantageously, the compatibilizer is selected from the group consisting of: 4-(vinyloxy)butyl methacrylate, 2-(allyloxy)ethyl methacrylate, isoprenol methacrylate, 2,2-bis((allyloxy)methyl)butyl methacrylate, 2-((allyloxy)methyl)-2-ethylpropyl-1,3-dimethylbis(2-methacrylate), and eugenol methacrylate; particularly preferred are 4-(vinyloxy)butyl methacrylate, 2-(allyloxy)ethyl methacrylate, and isoprenol methacrylate, because they exhibit good resin compatibility and curing properties.

[0024] The (meth)acrylate monomer may be selected from alkyl (meth)acrylates, (alkyl)aryl (meth)acrylates, hydroxyalkyl (meth)acrylates, (poly)ether methacrylates, di, tri, tetra-methacrylates, and mixtures thereof that have straight-chain or straight-chain C1-20 alkyl groups.

[0025] Examples of suitable (meth)acrylate monomers include methacrylate, isobornyl (meth)acrylate, norbornyl (meth)acrylate, tributyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, cyclohexyl (meth)acrylate, isohexyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 2-propylheptyl (meth)acrylate, isodecyl (meth)acrylate, isotridecyl (meth)acrylate, benzyl (meth)acrylate, isobornyl (meth)acrylate, 3,3,5-trimethylcyclohexylmethacrylate, borneolyl (meth)acrylate, and borneolyl (meth)acrylate. Flake base (meth)acrylate, dihydrodicyclopentadienyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, docosyl (meth)acrylate, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, hydroxyethyl phosphate (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, ethyl triethylene glycol (meth)acrylate, butyl diethylene glycol (meth)acrylate, glycidyl (meth)acrylate, glyceryl methyl acetal (meth)acrylate, isopropylidene glyceryl (meth)acrylate, isosorbide mono-(meth)acrylate, isosorbide di-(meth)acrylate, 3(4),8(9)-diisobutylenyloxymethyl-tricyclo[5.2.1.0 (2.6)]decane (3,8-dihydroxymethyl-tricyclo[5.2.1.0 (2.6)]decane (3,8-dihydroxymethyl-tricyclo[5.2.1.0 (2.6)]decane) 2.6] Decanane dimethacrylate), allyl (meth)acrylate, ethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, polyethylene glycol 200 di(meth)acrylate, 1,3-butanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 2,3-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate and its isomers, glycerol di(meth)acrylate, tri... Hydroxymethyl propane di(meth)acrylate, neopentyl glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, PPG250 di(meth)acrylate, tricyclodecane dihydroxymethyl di(meth)acrylate, 1,10-decanediol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, propylene oxide (meth)acrylate, and mixtures thereof.

[0026] Advantageously, the (meth)acrylate monoester is selected from meth methacrylate, glyceryl methyl acetal methacrylate, benzyl methacrylate, cyclohexyl methacrylate, isobornyl methacrylate, 1,4-butanediol dimethacrylate, polyethylene glycol 200 dimethacrylate, ethylene glycol dimethacrylate, butyl diethylene glycol methacrylate, and ethyl triethylene glycol methacrylate.

[0027] It is worth noting that methacrylate monomers, as reactive diluents with low vapor pressure, are beneficial for formulating low- or even VOC-free resin compositions. The use of styrene in composite resins leads to the release of styrene vapors into the working environment. This exposes workers and the environment to hazardous vapors. Compared to styrene, methyl methacrylate is a less hazardous compound, but it is still classified as a VOC due to its high vapor pressure. Therefore, using methacrylate monomers with higher molecular weights and thus lower vapor pressures (such as benzyl methacrylate, glyceryl methyl acetal methacrylate, or 1,4-butanediol dimethacrylate) is beneficial for reducing VOC content.

[0028] In a particularly preferred embodiment of the present invention, the (meth)acrylate monosystem is benzyl methacrylate and the compatibilizer is 4-(vinyloxy)butyl methacrylate, 2-(allyloxy)ethyl methacrylate or isopentenyl methacrylate.

[0029] This invention also relates to a reactive diluent composition comprising: (a) 50% to 99% by weight of the (meth)acrylate monomer or a mixture of different (meth)acrylate monomers; (b) 1% to 50% by weight of a compatibilizer, wherein the compatibilizer comprises at least one (meth)acrylate group and at least one additional vinyl unsaturated group; and (c) 0% to 0.5% by weight of polymerization inhibitors.

[0030] The contents of each component (a), (b), and (c) are based on the total amount of the reactive diluent composition. In a particular specific example, the proportions of (a), (b), and (c) are summed to 100% by weight.

[0031] The (meth)acrylate monomer and the compatibilizer have the meanings defined above.

[0032] The ratio of the amount of (meth)acrylate monomer to the amount of compatibilizer is between 1:1 and 70:1, or between 3:1 and 40:1, or between 10:1 and 25:1, and preferably 20:1.

[0033] To prevent unwanted polymerization reactions, polymerization inhibitors (stabilizers) can be used in the reactive diluent compositions according to the present invention. In the context of this invention, the terms "(polymerization reaction) inhibitor" and "stabilizer" are used synonymously. Advantageously, the polymerization inhibitor is selected from the group consisting of: hydroquinone, hydroquinone ethers (e.g., hydroquinone monomethyl ether or di- and tri-butylcatechol), phenthiazoline... The polymerization inhibitor is selected from the group consisting of phenothiazine, N,N'-(diphenyl)-p-phenylenediamine, 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxy, p-phenylenediamine, methyl blue, or stereoinhibiting phenols. Preferably, the polymerization inhibitor is selected from hydroquinone monomethyl ether, phenothiazine, etc. 2,4-Dimethyl-6-tert-butylphenol, 2,6-di-tert-butyl-4-methylphenol, octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate (e.g., IRGANOX 1076), and 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxy, and mixtures thereof.

[0034] Furthermore, the present invention relates to a curable resin composition comprising at least one unsaturated polyester resin and the above-mentioned reactive diluent composition.

[0035] In a preferred embodiment, the curable resin composition comprises: (a) 30% to 65% by weight of unsaturated polyester resin; (b) 35% to 70% by weight of the reactive diluent composition; and (c) 0% to 20% by weight of one or more other organic or inorganic additives.

[0036] The contents of each component (a), (b), and (c) are based on the total amount of the curable resin composition. In a particular example, the proportions of (a), (b), and (c) are summed to 100% by weight.

[0037] The suitable UP resin cured by the method of this invention is so-called ortho-resin, iso-resin, iso-NPG resin, and dicyclopentadiene (DCPD) resin. The UP resins defined above are generally known and commercially available.

[0038] For example, ortho-resins are based on phthalic anhydride, maleic anhydride, or fumaric acid and glycols (e.g., ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propanediol, 1,3-propanediol, dipropylene glycol, tripropylene glycol, neopentyl glycol) or hydrogenated bisphenol A. Typically, 1,2-propanediol derivatives are used in conjunction with reactive diluents. Iso-resins are usually prepared from isophthalic acid, maleic anhydride, or fumaric acid and glycols. Compared to ortho-resins, iso-resins generally contain a higher content of reactive diluents. Bisphenol A-fumaric acid esters are based on ethoxylated bisphenol A and fumaric acid. Chlorendic acid is a resin obtained in the preparation of UP-resins from chlorinated / bromine-containing anhydrides or phenols.

[0039] The curable resin composition may additionally contain organic or inorganic additives, such as fillers, fibers, pigments, dispersants, inhibitors, auxiliaries, and accelerators. Examples of fibers used in the manufacture of fiber-reinforced plastics include glass fibers, carbon fibers, aramid fibers, polyamide fibers, boron fibers, ceramic fibers, metal fibers, and natural fibers (such as jute, kenaf, industrial hemp, flax, ramie, etc.) or any combination thereof. The fiber content depends on the fiber type, the manufacturing process, and the end application. For example, in SMC formulations, the glass fiber content is preferably up to 35% by weight, combined with a high filler content of up to 40% by weight. The resin content in SMC applications is preferably between 10% and 20% by weight. BMC formulations contain a higher filler content (preferably 60% by weight) and a lower fiber content (preferably 15% by weight). In hand coating, a fiber content of up to 60% by weight is preferred. In spray coating applications, a medium glass fiber content of 30-35% by weight is preferred, in which case chopped glass fibers are mainly used. In fiber winding and pultrusion, 30-80% by weight of glass wool is used.

[0040] The curable resin composition may contain at least one filler. This filler may be selected from the group consisting of calcium carbonate, barium sulfate, quartz, talc, calcium sulfate, calcium silicate, and / or kaolin. For flame retardancy, ATH (aluminum trihydride) or antimony oxide may be added as a filler. Alternatively, or in addition, the fiber-reinforced resin may also contain at least one other additive selected from the group consisting of inhibitors, hindrances, thixotropic agents (e.g., fused silica), and / or UV absorbers, or mixtures thereof.

[0041] The curable resin composition may additionally contain iron oxide, titanium dioxide, zinc sulfide, zinc oxide and / or organic or inorganic color pigments as pigments.

[0042] Ammonium, alkali metal or alkaline earth metal carboxylates and 1,3-diones (e.g., acetoacetone or diethylacetoacetamide) are suitable as accelerators.

[0043] In addition to the above, the present invention provides a pre-accelerated formulation comprising the above-described reactive curable resin composition and at least one accelerator. Suitable accelerators are cobalt(II) salts or complexes, such as cobalt halides, nitrates, sulfates, sulfonates, phosphates, phosphonates, oxides, or carboxylates. Suitable carboxylates include lactates, 2-ethylhexanoates, acetates, propions, butyrates, oxalates, laurates, oleates, linoleates, palmitates, stearates, acetylacetonates, octanoates, nonanoates, heptanoates, neodecanoates, or naphthates. The cobalt(II) salt or complex is preferably an alkylcarboxylate cobalt, such as cobalt(II) ethylhexanoate, cobalt(II) octanoate, or cobalt acetylacetonate or a cyclopentadienyl complex of cobalt. Particularly preferred are (2-ethylhexanoate)cobalt, (neodecanoate)cobalt, or (naphthalate)cobalt. Furthermore, polymer-bonded cobalt accelerators are suitable.

[0044] Alternatively, accelerators based on copper(I) or copper(II) salts or complexes are suitable. Suitable copper salts or complexes are, for example, copper halides (e.g., chlorides), nitrates, sulfates, or alkyl carboxylates. Suitable carboxylates are, for example, lactates, 2-ethylhexanoates, acetates, propions, butyrates, oxalates, laurates, oleates, linoleates, palmitates, stearates, acetylacetate, octanoates, nonanoates, heptanoates, neodecanoates, or naphthates. The copper(I) or copper(II) salt or complex is preferably an alkyl carboxylate. Copper(II) pyruvate and copper(II)-(2-ethylhexanoic acid) are particularly preferred.

[0045] Alternatively, an accelerator based on an iron salt or complex may be suitable. Preferably, the iron(II) coordination compound is selected from the group consisting of iron(II) species that coordinate with mono- and poly-donor N and / or O-donor ligands. Alternatively, the iron salt or complex present in the accelerator system (b) may also be selected from the group consisting of iron halides, carboxylates, 1,3-dioxane complexes, and cyclopentadienyl iron complexes.

[0046] Curing typically begins by adding an accelerator and an initiator to the curable resin composition according to the invention, or by adding an initiator to a pre-accelerated blend.

[0047] Accordingly, the present invention relates to a styrene-free method for curing unsaturated polyester resin, the method comprising: (a) Providing the above-described curable resin composition, or, alternatively, the above-described pre-accelerated formulation, (b) Optionally, at least one of the above-mentioned organic or inorganic additives may be added, and (c) The curing process is initiated by adding an initiator.

[0048] Peroxides suitable for curing this UP resin include inorganic and organic peroxides, such as commonly used ketone peroxides, peroxide esters, diaryl peroxides, dialkyl peroxides, and peroxydicarbonates, but peroxycarbonates, peroxyketones, hydroperoxides, diacyl peroxides, and hydrogen peroxide are also acceptable. Preferred peroxides are organic hydroperoxides, ketone peroxides, peroxy esters, and peroxycarbonates. More preferably, hydroperoxides and ketone peroxides are preferred. Preferred hydroperoxides include cumyl hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, tributyl hydroperoxide, isopropylcumyl hydroperoxide, tripentyl hydroperoxide, 2,5-dimethylhexyl-2,5-dihydroperoxide, turpentine hydroperoxide, and para-dimethylhexyl-2,5-dihydroperoxide. Alkyl hydrogen peroxide, terpene hydrogen peroxide, and pinene hydrogen peroxide. Preferred ketone peroxides include methyl ethyl ketone peroxide, methyl isopropyl ketone peroxide, methyl isobutyl ketone peroxide, cyclohexanone peroxide, and acetylacetone peroxide. Mixtures of two or more peroxides can also be used; for example, combinations of hydrogen peroxide or ketone peroxides with peroxy esters.

[0049] A particularly preferred peroxide is methyl ethyl ketone peroxide. Those skilled in the art will understand that these peroxides can be combined with conventional additives (such as fillers, pigments, and repressors). Examples of repressors are hydrophilic esters and hydrocarbon solvents. The amount of peroxide used to cure the resin is preferably at least 0.1 / 100 resin (phr), more preferably at least 0.5 phr, and most preferably at least 1 phr. The amount of peroxide preferably does not exceed 8 phr, more preferably not more than 5 phr, and most preferably not more than 2 phr.

[0050] Advantageously, the initiator is an organic peroxide, preferably selected from the group consisting of methyl ethyl ketone peroxide (MEKP), benzyl peroxide (BPO), cumene hydroperoxide (CuHP), or any combination thereof.

[0051] The curing method for fiber-reinforced plastics can be self-curing The curing process can be carried out at any temperature from -15°C to a maximum of 250°C, depending on the initiator system, the accelerator system, the compound corresponding to the curing rate, and the resin composition to be cured. Preferably, it is carried out at ambient temperatures generally used in applications (e.g., hand lamination, spraying, fiber winding, resin transfer molding), coating (e.g., gel coating and standard coating), button making, centrifugal casting, corrugated sheets or plates, lining systems, kitchen sinks via casting lamination, etc. However, it can also be used in sheet molding composites (SMC), integral molding composites (BMC), pultrusion composite techniques, etc., where the temperature used is up to 180°C, more preferably up to 150°C, and most importantly up to 100°C.

[0052] Generally, fiber-reinforced resins (fiber-reinforced plastics - FRP) offer advantages such as high relative strength, good surface conditions, high corrosion resistance, and high resistance to chemical corrosion. Due to these advantages, they are primarily used as building materials, industrial materials, tanks, containers, ships, automobiles, trains, and other components.

[0053] Example

[0054] [1] [Synthetic Procedure for Monomers] [] []

[0055] [1.1] [General Synthesis Procedure for Monomers] [] []

[0056] All reactions and product handling were carried out in standard laboratory glassware under ambient conditions. Methyl methacrylate, methacrylic anhydride (MAAH), methacrylic chloride, 2-allyloxyethanol, 4-hydroxybutylvinyl ether, isopentenol, eugenol, 2-((allyloxy)methyl)-2-ethylprop-1,3-diol, and 2,2-bis((allyloxy)methyl)but-1-ol were obtained from commercial / industrial suppliers and used as received without further purification.

[0057] Eugenol methacrylate was synthesized according to the following literature procedure (e.g., described in Stanzione, JF, III, Sadler, JM, La Scala, JJ and Wool, RP (2012), Lignin Model Compounds as Bio‐Based Reactive Diluents for Liquid Molding Resins. ChemSusChem, 5: 1291-1297).

[0058] Isoprene methacrylate was synthesized according to the following literature procedure (e.g., described in Jacob M. Berlin, Katie Campbell, Tobias Ritter, Timothy W. Funk, Anatoly Chlenov, and Robert H. Grubbs, Ruthenium-Catalyzed Ring-Closing Metathesis to Form Tetrasubstituted Olefins Org. Lett. 2007 9 (7), 1339-1342).

[0059] 4-(vinyloxy)butyl methacrylate was synthesized according to the following literature procedure (e.g., described in Farzad Seidi, Victor Druet, Nguyen Huynh, Treethip Phakkeereea and Daniel Crespy Hemiaminal ether linkages provide a selective release of payloads from polymer conjugates Chem. Commun., 2018, 54, 13730-13733).

[0060] 2-(allyloxy)ethyl methacrylate was synthesized according to the following literature procedure (e.g., described in Xiao-Guang Sun, Craig L. Reeder, and John B. Kerr Synthesis and Characterization of Network Type Single Ion Conductors Macromolecules 2004, 37, 6, 2219-2227).

[0061] 2,2-bis((allyloxy)methyl)butyl methacrylate and 2-((allyloxy)methyl)-2-ethylpropyl-1,3-dimethyl methacrylate were synthesized according to the following literature procedure (e.g., described in US 4640940 A).

[0062] [2] [] [General analytical techniques for monomers]

[0063] Unless otherwise noted, NMR spectra were recorded at 300 K on a Bruker Avance 300 or 400 spectrometer with residual solvent resonance as the internal standard (¹H NMR: THF-d8: 1.72 ppm, C₆D₆: 7.16 ppm, toluene-d8 (tol-d8): 2.08 ppm; CDCl₃: 7.26 ppm. ¹³C{¹H} NMR: THF-d8: 25.31 ppm, C₆D₆: 128.06 ppm, CDCl₃: 77.16 ppm). Chemical shift δ is expressed in ppm as an external standard (¹H, ¹³C{¹H}) for tetramethylsilane. The 1H and 13C NMR signals were identified in part based on 2D NMR spectra (1H, 1H-COSY; 1H, 13C-HSQC; 1H, 13C-HMQC).

[0064] [3] [Polymerization Reaction and Composite Resins]

[0065] [3.1] [Components used] [surface] [1] [Components used] [] Components Standard unsaturated polyester resin (UPR 1) (Based on isophthalic acid and standard diol, solid) resin VISIOMER® GLYFOMA Reactive diluent VISIOMER® BNMA Reactive diluent VISIOMER® BDGMA Reactive diluent VISIOMER® PEG200DMA Reactive diluent MMA (Roehm) Reactive diluent Styrene (Merck) Reactive diluent VISIOMER® 1,4-BDDMA Reactive diluent VISIOMER® EGDMA Reactive diluent 4-(Vinyloxy)butyl methacrylate compatibilizer Isopentenyl methacrylate compatibilizer 2-(allyloxy)ethyl methacrylate compatibilizer Eugenol methacrylate compatibilizer TMP diallyl ether methacrylate = 2,2-Bis((allyloxy)methyl)butyl methacrylate compatibilizer TMP monoallyl ether dimethacrylate = 2-((allyloxy)methyl)-2-ethylprop-1,3-dimethyldimethacrylate compatibilizer Butanox M-50 (MEKP, Nouryon) Initiator Butanox P-50 (MIPKP, Nouryon) Initiator Co(II)-2-ethylhexanoate, 65% solution (11% Co metal content, Sigma-Aldrich) Cobalt-based accelerators Nouryact CF12 (1.5-1.7% Cu metal content), Nouryon Copper-based accelerators wt% = weight% phr = number of parts per 100 parts of resin As the resin described herein, the fully formulated resin includes the reactive diluent. MPa = hectopascals HEMA = Hydroxyethyl methacrylate BDGMA = Butyl diethylene methacrylate MMA = Methyl methacrylate BNMA = benzyl methacrylate GLYFOMA = glycerol formal methacrylate 1,4-BDDMA = 1,4-Butanediol dimethacrylate EGDMA = ethylene glycol dimethacrylate MEKP = Methyl ethyl ketone peroxide MIPKP = Methyl isopropyl ketone peroxide TMP = 1,1,1-trimethylolpropane

[0066] [3.2] [method]

[0067] [3.2.1] [Measurement of overall polymerization reaction and polymerization time]

[0068] A total polymerization reaction feedstock solution and various reactive diluents were prepared for the UPR resin. The solid UPR resin was melted at 100°C for 3 hours. The reactive diluent was added to the heated resin and homogenized on a roller bed for 12-24 hours. The prepared feedstock solution was mixed with different compatibilizers according to Tables 1-3. An accelerator was added, and the mixture was homogenized by stirring for 2 minutes, followed by the addition of the initiator solution. The mixture was stirred again for 1.5 minutes and then transferred to standard test tubes (18x180 mm) for curing. The cured resin was then cured in a drying oven at 80°C for 8 hours.

[0069] [3.2.2] [Mechanical Testing]

[0070] Tensile testing was conducted according to EN ISO 527-1. Approximately 110-115 g of resin formulation was used for casting the film (calculated as a 4 mm wet film thickness). The film was cured at RT for 24 hours. All samples were pre-cured in an oven at 80°C for 8 hours prior to tensile testing.

[0071] The comparative examples show that without the addition of a compatibilizer, a cloudy polymer resin is formed. This cloudiness indicates phase separation and therefore incompatibility between the reactive diluent and the UPR resin. Examples 1-6 show that the addition of a compatibilizer results in a clear polymer with no signs of phase separation. Examples 7-12 show that mixtures of reactive diluents can also be used. Examples 11-12 show that the performance of the compatibilizer also depends on the correct selection of the reactive diluent. As demonstrated by using two different peroxides and two different accelerators, the performance of the compatibilizer is independent of the curing system used. [, , ]

[0072] The addition of the compatibilizer compound in this test showed that, apart from the compatibilizer TMP-monallyl ether dimethacrylate, a clear polymer complex was formed. [] [, , ] [] []

[0073] The mechanical tests showed that styrene-free UPR formulations using benzyl methacrylate as a reactive diluent and compatibilizer exhibited mechanical properties similar to standard styrene-based UPR resins.

Claims

1. A reactive diluent composition comprising a (meth)acrylate monomer and a compatibilizer; wherein the (meth)acrylate monomer is selected from methyl methacrylate, glycerol methyl acetal methacrylate, isopropyl glycerol methacrylate, benzyl methacrylate, cyclohexyl methacrylate, isobornyl methacrylate, polyethylene glycol 200 dimethacrylate, butyl diethylene glycol methacrylate, and ethyl triethylene glycol methacrylate; wherein the compatibilizer is selected from the group consisting of vinyl ether (meth)acrylate, allyl ether (meth)acrylate, and alkenyl (meth)acrylate; wherein the (meth)acrylate monomer and the compatibilizer are different chemical compounds; and wherein the ratio of the amount of (meth)acrylate monomer to the amount of compatibilizer is between 3:1 and 40:

1.

2. The reactive diluent composition of claim 1, wherein the vinyl ether (meth) acrylate is selected from monovinyl ether mono(meth) acrylate, monovinyl ether di(meth) acrylate, monovinyl ether tri(meth) acrylate, monovinyl ether tetra(meth) acrylate, divinyl ether mono(meth) acrylate, divinyl ether di(meth) acrylate, divinyl ether tri(meth) acrylate, trivinyl ether mono(meth) acrylate, and trivinyl ether di(meth) acrylate.

3. The reactive diluent composition of claim 1, wherein the allyl ether (meth) acrylate is selected from monoallyl ether mono(meth) acrylate, monoallyl ether di(meth) acrylate, monoallyl ether tri(meth) acrylate, monoallyl ether tetra(meth) acrylate, diallyl ether mono(meth) acrylate, diallyl ether di(meth) acrylate, diallyl ether tri(meth) acrylate, triallyl ether mono(meth) acrylate, and triallyl ether di(meth) acrylate.

4. The reactive diluent composition of claim 1, wherein the alkenyl (meth)acrylate is selected from mono, di, tri, and tetra (meth)acrylates containing one or more vinyl unsaturated alkenyl (C=C) groups, which are different from (meth)acrylates.

5. The reactive diluent composition of claim 1, wherein the compatibilizer is selected from the group consisting of 4-(vinyloxy)butyl methacrylate, 2-(allyloxy)ethyl methacrylate, isoprenol methacrylate, 2,2-bis((allyloxy)methyl)butyl methacrylate, 2-((allyloxy)methyl)-2-ethylpropyl-1,3-dimethylbis(2-methacrylate), and eugenol methacrylate.

6. The reactive diluent composition of claim 1, wherein the compatibilizer is 4-(vinyloxy)butyl methacrylate, 2-(allyloxy)ethyl methacrylate, and isopentenyl methacrylate.

7. The reactive diluent composition of claim 1, wherein the (meth)acrylate monosystem is benzyl methacrylate and the compatibilizer is 4-(ethoxy)butyl methacrylate, 2-(allyloxy)ethyl methacrylate or isopentenyl methacrylate.

8. The reactive diluent composition of claim 1, wherein the ratio of the amount of (meth)acrylate monomer to the amount of compatibilizer is between 10:1 and 25:

1.

9. The reactive diluent composition of claim 1 further includes a polymerization inhibitor.

10. The reactive diluent composition of claim 9, wherein the polymerization inhibitor is selected from the group consisting of hydroquinone, hydroquinone ether, phenothiazine, N,N'-(diphenyl)-p-phenylenediamine, 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxy, p-phenylenediamine, methyl blue or stereoinhibiting phenol.

11. The reactive diluent composition of claim 1, comprising: (a) 50% to 99% by weight of the (meth)acrylate monomer; (b) 1% to 50% by weight of the compatibilizer; and (c) 0% to 0.5% by weight of the inhibitor.

12. A curable resin composition comprising at least one unsaturated polyester resin and a reactive diluent composition as claimed in any one of claims 1 to 11.

13. The curable resin composition of claim 12, further comprising at least one organic or inorganic additive.

14. A pre-accelerated formulation comprising a curable resin composition as claimed in claim 12 or 13, and at least one accelerator.

15. A method for curing an unsaturated polyester resin, the method comprising: (a) providing a curable resin composition as claimed in any one of claims 12 or 13, or, alternatively, a pre-accelerated formulation as claimed in claim 14; (b) optionally adding at least one organic or inorganic additive; and (c) initiating the curing process by adding an initiator.