Use of acrylates in epoxy systems

Abstract

An epoxy resin composition comprising: a) a resin component comprising at least one epoxy resin and at least one acrylate compound wherein the weight ratio of the at least one acrylate compound to the at least one epoxy resin is from 0.01 to 1, in particular from 0.05 to 0.7, in particular from 0.1 to 0.5; b) a hardener component comprising at least one amine compound having at least one amine group selected from primary amine groups, secondary amine groups and / or blocked amine groups.

Description

TECHNICAL FIELD

[0001] The present invention relates to an epoxy resin composition comprising an epoxy-based resin component and an amine-based hardener component. Another aspect of the invention relates to a process for casting an article from the epoxy resin composition and to the article obtained from said epoxy resin composition. Furthermore, the invention relates to the use of specifically selected compounds for controlling, in particular reducing, the exotherm during curing of the epoxy resin composition. BACKGROUND

[0002] Epoxy resin compositions cured by amine hardeners at ambient temperature are widely used as casting resins, coatings or adhesives. One example of a casting resin application is the manufacture of transparent, hard and tough resin articles having a glass-like appearance and which can be used for functional and / or decorative purposes. Such casting resins allow the incorporation of shaped materials, such as wood blocks or stone blocks, and present them in a glossy and highly aesthetic manner. For this application, the casting resin should be applicable in thick layers, for example at least 5 to 50 mm, and have a high glass transition temperature (Tg), preferably above 40°C, preferably at least 45°C, and a high transparency, i.e. complete transparency without any haze, cloudiness or other types of visible inhomogeneities, after curing. This is not easily achieved, as many amine hardeners tend to induce a hazy or cloudy appearance. Furthermore, the epoxy curing reaction is highly exothermic, so that when applied in thick layers, the freshly mixed resin tends to overheat, which can lead to discoloration and / or air bubbles. In order to obtain an aesthetically good result, hardeners are usually used which, when reacting with the epoxy resin, only produce a moderate heat peak under still fast and reliable curing, without forming any haze within the cured resin or on its surface. Finally, the cured transparent article should have a high robustness against yellowing, so as not to lose its original appearance upon exposure to light.

[0003] Epoxy resin compositions for such use are known on the market. They usually contain large amounts of alkylphenols, such as nonylphenol. Alkylphenols are diluents and give the resin a high transparency and low heat evolution under still fast and reliable curing, but they are toxic compounds for humans and the environment, requiring special safety measures for handling them. Furthermore, alkylphenols and other types of diluents remain unreacted in the cured resin and can be released therefrom by migration, extraction or evaporation, which aggravates their toxicity. In addition, they can also have an undesirable softening effect on the cured resin, which reduces the Tg. Moreover, some known epoxy compositions can only be cast in rather thin layers if an aesthetically pleasing article is to be produced.

[0004] In this regard, US 2022 / 0411571 A1 (Sika Technology AG) describes, for example, a special curing agent for epoxy resins based on an amine functional adduct of at least one amine and at least one polyoxyalkylene polyamine and a diepoxide. This curing agent enables the production of highly clear, transparent epoxy resin compositions that do not contain toxic diluents such as nonylphenol, exhibit low heat generation during curing yet still cure rapidly and reliably, and possess very high robustness against yellowing. Such epoxy resin compositions are particularly suitable as casting resins for manufacturing transparent articles with a glassy appearance. While this solution is advantageous, it requires a special curing agent.

[0005] WO 95 / 18183 A1 discloses an amine-curable two-component epoxy resin composition, wherein the epoxy resin component contains, in addition to the epoxy resin, a (meth)acrylate functionalized polyol and a polyurethane poly(meth)acrylate. This composition is particularly suitable as an adhesive or a tough, non-brittle coating. Transparency properties are not addressed in this disclosure.

[0006] EP 0 374 310 A1 discloses an epoxy coating composition comprising a cured reaction product of an epoxy resin and an acrylate reacted with a polyether polyamine. The coating exhibits no surface blush or blemishes and possesses improved impact strength or toughness, as assessed by Gardner impact testing. However, transparency properties were not evaluated.

[0007] Therefore, new and improved solutions still need to be developed to reduce or overcome the aforementioned defects. Summary of the Invention

[0008] One object of the present invention is to provide a solution that allows for the production of improved epoxy compositions suitable for casting resins. In particular, the epoxy composition should be able to produce uniform castings, especially castings with high transparency, high Tg, good mechanical properties, and / or high resistance to yellowing.

[0009] Surprisingly, it has been found that the object of the present invention can be achieved by the epoxy resin composition according to claim 1.

[0010] As already shown, when a certain proportion of acrylate compounds is added to the resin component, epoxy resin products that are resistant to yellowing, highly uniform, and substantially free of visible discoloration and bubbles can be produced.

[0011] Without being bound by theory, it is believed that the use of acrylates in the resin component reduces the exothermic reaction during the curing process of at least one epoxy resin. This is presumably due to the fairly rapid initial Michael addition reaction between the acrylate and at least one amine compound in the hardener component, resulting in the formation of a first molecular network in the cured epoxy composition. This, in turn, slows down the highly exothermic reaction between the at least one amine compound and the epoxy groups of at least one epoxy resin to some extent. Surprisingly, the rheological properties during the curing reaction and the mechanical properties of the cured epoxy composition are almost unaffected. In particular, shrinkage is reduced when compared to compositions without any acrylates.

[0012] Furthermore, the epoxy compositions of the present invention allow for higher casting volumes with layer thicknesses of 100 mm or more in a single pass.

[0013] Other aspects of the invention are the subject of the other independent claims. Particularly preferred embodiments of the invention are summarized throughout the specification and the subject matter of the dependent claims. Detailed Implementation

[0014] A first aspect of the present invention relates to an epoxy resin composition comprising: a) A resin component comprising at least one epoxy resin and at least one acrylate compound, wherein the weight ratio of the at least one acrylate compound to the at least one epoxy resin is 0.01–1, particularly 0.05–0.7, particularly 0.1–0.5; b) A curing agent component comprising at least one amine compound having at least one amine group selected from primary amine groups, secondary amine groups and / or blocked amine groups.

[0015] In this paper, the term "primary amine group" refers to an NH2 group bonded to an organic moiety. The term "secondary amine group" refers to an NH group bonded to two organic moieties, which together may be part of a ring.

[0016] "Closed amine group" specifically refers to an aldolimine or ketone imine group. These are condensation products of a primary amine group with an aldehyde or ketone, respectively. Aldolimines and ketoneimines can be hydrolyzed to form the corresponding amine and aldehyde or ketone, respectively.

[0017] The term "open time" or "fit time" in this document refers to the duration of the processability of a newly mixed composition. The end of the open time is generally associated with an increase in the viscosity of the composition that makes it no longer possible to process it without performance defects.

[0018] Substance names that begin with "poly(poly)", such as polyacrylates, polyols, or polyamines, indicate that each molecule of a substance contains two or more functional groups that appear in its name.

[0019] The term “molecular weight” in this article should be understood as the molar mass of a molecule (g / mol). “Average molecular weight” is the number-average Mn of the oligomer or polymer mixture of molecules, usually determined by gel permeation chromatography (GPC) using polystyrene as a standard.

[0020] The epoxy resin compositions of the present invention preferably comprise two or more separate components, particularly the resin component and the curing agent component as described above, and possibly one or more other components. Therefore, the epoxy resin compositions are particularly two-component compositions having two separate components or multi-component compositions having three or more separate components.

[0021] To avoid spontaneous reactions, these components are stored separately. These components can be assembled together as a package. For the use of epoxy resin compositions, these components can be combined with each other. When these components are mixed together, the curing reaction begins, and the composition is applied within the open time after the components are mixed.

[0022] Acrylate compounds, particularly acrylate compounds with a functionality of 1-5, particularly 1-3, particularly 1-2. In other words, at least one acrylate compound particularly contains 1-5, particularly 1-3, particularly 1-2 acryloyl groups of the formula CH2=CHCOO-.

[0023] In a preferred embodiment, at least one acrylate compound does not contain any methacryloyl group of the formula CH2=C(CH3)COO-.

[0024] In particular, at least one acrylate compound is free of acid groups, especially those selected from carboxyl, phosphoric acid, and sulfonic acid groups, and it is free of primary or secondary amine groups. Such acrylate compounds are storage stable in the presence of epoxy resins.

[0025] In the case where at least one acrylate compound contains a hydroxyl group, the functionality relative to the hydroxyl group is preferably not higher than 1.

[0026] In particular, the at least one acrylate compound does not contain any epoxy groups.

[0027] Particularly preferred is that the at least one acrylate compound is an aliphatic alkyl acrylate, wherein the aliphatic alkyl group of the alkyl acrylate may be branched or unbranched, and optionally contains one or more heteroatoms, particularly oxygen. The aliphatic alkyl group is particularly saturated.

[0028] In particular, the average molecular weight of the at least one acrylate compound is less than 2000 g / mol, preferably less than 1000 g / mol, and more preferably less than 700 g / mol. Especially, the average molecular weight is in the range of 100-800 g / mol, particularly 200-600 g / mol.

[0029] Suitable acrylate compounds with a functionality of 1 are preferably acrylates of primary alcohols with an OH functionality of 1, wherein the primary alcohol is preferably selected from fatty alcohols, especially fatty alcohols having 10-15 carbon atoms. Examples of such fatty alcohols are 1-dodecaneol, 1-tridecaneol, 1-tetradecaneol, or mixtures thereof.

[0030] In particular, the acrylate compound with an acrylate functionality of 2 is preferably an acrylate of a diol with an OH functionality of 2, wherein the diol is preferably an aliphatic diol, especially a saturated aliphatic diol, for example selected from 3-methyl-1,5-pentanediol and / or 1,10-decanediol.

[0031] Suitable acrylate compounds having an acrylate functionality of 3 or greater are preferably polyacrylates of polyols having an OH- functionality of 3 or greater, wherein the polyol is preferably selected from glycerol, trimethylolpropane, di(trimethylolpropane), pentaerythritol, di(pentaerythritol), and alkoxylated forms of these polyols. Alkoxylated polyols are preferably selected from ethoxylated glycerol, propoxylated glycerol, ethoxylated trimethylolpropane, and propoxylated trimethylolpropane. In the case of alkoxylated polyols, a low degree of alkoxylation is preferred to obtain an alkoxylated polyol with an average molecular weight of less than 2000 g / mol, preferably less than 1000 g / mol, and more preferably less than 700 g / mol.

[0032] The at least one acrylate compound is specifically selected from: - Monoacrylates, especially those selected from lauryl acrylate and C-acrylate. 12 -C 14 Alkyl esters and / or tridecyl acrylates; - Diacrylates, particularly selected from 3-methyl-1,5-pentanediol diacrylate and / or 1,10-decanediol diacrylate; - Triacrylates, particularly selected from trimethylolpropane triacrylate (TMPTA), pentaerythritol triacrylate and / or ethoxylated 3-trimethylolpropane triacrylate; - Tetraacrylates, especially pentaerythritol tetraacrylate and / or bis(trimethylolpropane) tetraacrylate; and / or - Pentaacrylates, especially dipentaerythritol pentaacrylate (DPHA).

[0033] In one specific embodiment, at least one acrylate compound is selected from dipentaerythritol pentaacrylate and / or trimethylolpropane triacrylate.

[0034] At least one epoxy resin, preferably a liquid epoxy resin or a mixture of two or more liquid epoxy resins.

[0035] The term "liquid epoxy resin" specifically refers to polyepoxides with a glass transition temperature below 25°C.

[0036] Optionally, the resin component comprising at least one liquid epoxy resin may further contain a small amount of solid epoxy resin.

[0037] Particularly suitable epoxy resins are aromatic epoxy resins, especially the following glycidylated products: bisphenol A, bisphenol F and / or bisphenol A / F; resorcinol, hydroquinone or catechol; other bisphenols or polyphenols, such as bis(4-hydroxy-3-methylphenyl)methane, 2,2-bis(4-hydroxy-3-methylphenyl)propane (bisphenol C), bis(3,5-dimethyl-4-hydroxyphenyl)methane, 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane, 2,2-bis(3,5-dibromo-4-hydroxyphenyl)propane, 2,2-bis(4- Hydroxy-3-tert-butylphenyl)propane, 2,2-bis(4-hydroxyphenyl)butane (bisphenol B), 3,3-bis(4-hydroxyphenyl)pentane, 3,4-bis(4-hydroxyphenyl)hexane, 4,4-bis(4-hydroxyphenyl)heptane, 2,4-bis(4-hydroxyphenyl)-2-methylbutane, 2,4-bis(3,5-dimethyl-4-hydroxyphenyl)-2-methylbutane, 1,1-bis(4-hydroxyphenyl)cyclohexane (bisphenol Z), 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane (bisphenol TMC) 1,1-Bis(4-hydroxyphenyl)-1-phenylethane, 1,4-bis[2-(4-hydroxyphenyl)-2-propyl]benzene (bisphenol P), 1,3-bis[2-(4-hydroxyphenyl)-2-propyl]benzene (bisphenol M), 4,4'-dihydroxybiphenyl (DOD), 4,4'-dihydroxybenzophenone, bis(2-hydroxynaphthyl-1-yl)methane, bis(4-hydroxynaphthyl-1-yl)methane, 1,5-dihydroxynaphthalene, tris(4-hydroxyphenyl)methane, 1,1,2,2-tetra(4-hydroxyphenyl)ethane, bis(4-hydroxyphenyl) Ethers or bis(4-hydroxyphenyl) sulfones; phenolic varnishes, preferably condensation products of phenol or cresol with formaldehyde, paraformaldehyde, acetaldehyde, crotonaldehyde, isobutyraldehyde, 2-ethylhexanal, benzaldehyde or furfural; aromatic amines such as aniline, toluidine, 4-aminophenol, 4,4'-methylenediphenyldiamine, 4,4'-methylenediphenyldi-(N-methyl)amine, 4,4'-[1,4-phenylene-bis(1-methylethylene)]bisaniline (bisaniline P) or 4,4'-[1,3-phenylene-bis(1-methylethylene)]bisaniline (bisaniline M).

[0038] Suitable liquid epoxy resins are other aliphatic or alicyclic polycyclic oxides, especially glycidyl ethers of di-, tri-, or tetrafunctional C2-C30 alcohols, particularly ethylene glycol, propylene glycol, butanediol, hexanediol, octanediol, polypropylene glycol, dimethylolcyclohexane, neopentyl glycol, dibromoneopentyl glycol, castor oil, trimethylolpropane, trimethylolethane, pentaerythritol, sorbitol, or glycerol, or alkoxylated glycerol or alkoxylated trimethylolpropane; hydrogenated bisphenol A, F, or A / F liquid resin, or hydrogenated bisphenol A, F, or A / F glycidylated products; N-glycidyl derivatives of amides or heterocyclic nitrogen bases, such as triglycidyl cyanurate or triglycidyl isocyanurate, or reaction products of epichlorohydrin and hydantoin; epoxy resins derived from olefin oxidation, such as vinylcyclohexene, dicyclopentadiene, cyclohexadiene, cyclododecadiene, cyclododecadiene, isoprene, 1,5-hexadiene, butadiene, polybutadiene, or divinylbenzene.

[0039] The epoxy resin component is preferably a bisphenol-based aromatic liquid epoxy resin. Specifically, the epoxy resin is selected from bisphenol A-diglita-ether, bisphenol F-diglita-ether, and / or bisphenol A / F-diglita-ether. These resins are low in viscosity and enable rapid curing and high hardness.

[0040] Optionally, the resin component contains a small amount of solid bisphenol A resin and / or phenolic varnish glycidyl ether.

[0041] In a further preferred embodiment, the epoxy resin further comprises a diluent that is chemically different from at least one acrylate compound.

[0042] The preferred diluent is one with a boiling point greater than 200°C.

[0043] Preferably, the resin component contains at least one reactive diluent, particularly diglycidyl ether. This reactive diluent improves processing performance without significantly affecting strength.

[0044] In particular, the diluent is an epoxy-functional reactive diluent, especially selected from butanediol diglycidyl ether, neopentyl glycol diglycidyl ether, hexanediol diglycidyl ether, cyclohexanediethanol diglycidyl ether, trimethylolpropane di or triglycidyl ether, phenyl glycidyl ether, tolyl glycidyl ether, guaiacol glycidyl ether, 4-methoxyphenyl glycidyl ether, p-n-butylphenyl glycidyl ether, p-tert-butylphenyl glycidyl ether, 4-nonylphenyl glycidyl ether, 4-dodecylphenyl glycidyl ether, cashew phenol glycidyl ether, benzyl glycidyl ether, allyl glycidyl ether, butyl glycidyl ether, hexyl glycidyl ether, 2-ethylhexyl glycidyl ether and natural alcohols such as C8-C10 alcohols, C12-C14 alcohols and C13-C15 alcohols.

[0045] Preferred are butanediol diglycidyl ether, neopentyl glycol diglycidyl ether, hexanediol diglycidyl ether, p-tert-butylphenyl glycidyl ether, C12-C14- or C13-C15 alkyl glycidyl ether or mixtures thereof.

[0046] Other diluents may be selected from xylene, 2-methoxyethanol, dimethoxyethanol, 2-ethoxyethanol, 2-propoxyethanol, 2-isopropoxyethanol, 2-butoxyethanol, 2-phenoxyethanol, 2-benzyloxyethanol, benzyl alcohol, ethylene glycol, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, ethylene glycol diphenyl ether, diethylene glycol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-butyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol di-n-butyl ether, propylene glycol butyl ether, propylene glycol phenyl ether, dipropylene glycol, dipropylene glycol monomethyl ether Dipropylene glycol dimethyl ether, dipropylene glycol di-n-butyl ether, diphenylmethane, diisopropylnaphthalene, petroleum fractions such as Solvesso® grade (from Exxon), cashew phenol (from cashew nut shell oil containing 3-(8,11-pentadecadienyl)-phenol as the main component), styrene-modified phenol, bisphenol, aromatic hydrocarbon resins, especially those containing phenolic groups, alkoxylated phenol, especially ethoxylated or propoxylated phenol, especially 2-phenoxyethanol, adipate esters, sebate esters, phthalates, benzoates, organophosphates or sulfonates or sulfonamides.

[0047] The at least one amine compound is particularly an aliphatic, alicyclic, or aryliphatic polyamine, especially having (i) at least two primary amine groups or (ii) at least one primary amine group and at least one secondary amine group. In particular, the polyamine contains 2, 3, or 4 amine groups.

[0048] "Aliphatic polyamines" refer to polyamines that have an aliphatic structure containing at least one aryl group.

[0049] The average molecular weight of the at least one polyamine is particularly less than 2000 g / mol, especially less than 1000 g / mol, for example in the range of 170 to 500 g / mol.

[0050] For example, the at least one amine compound is selected from 2,2-dimethyl-1,3-propanediamine, 1,3-pentanediamine (DAMP), 1,5-pentanediamine, 1,5-diamino-2-methylpentane (MPMD), 2-butyl-2-ethyl-1,5-pentanediamine (C11-neo-diamine), 1,6-hexanediamine, 2,5-dimethyl-1,6-hexanediamine, 2,2(4),4-trimethyl-1,6-hexanediamine (TMD), 1,7-heptanediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,10-decanediamine, 1,11-undecanediamine, 1,12-dodecanediamine, 1,2- 1,3- or 1,4-diaminocyclohexane, 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, bis(4-aminocyclohexyl)methane, bis(4-amino-3-methylcyclohexyl)methane, bis(4-amino-3-ethylcyclohexyl)methane, bis(4-amino-3,5-dimethylcyclohexyl)methane, bis(4-amino-3-ethyl-5-methylcyclohexyl)methane, 1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane (isophorone diamine or IPDA), 2(4)-methyl-1,3-diaminocyclohexane, 2,5(2,6)-bis(aminomethyl)bicyclo[2.2.1]heptane (NBDA), 3(4),8(9)-bis(aminomethyl)tricyclo[5.2.1.0] 2,6] Decane, 1,4-diamino-2,2,6-trimethylcyclohexane (TMCDA), 1,8-menthanediamine, 3,9-bis(3-aminopropyl)-2,4,8,10-tetraoxaspiro[5.5]undecane, 1,3-bis(aminomethyl)benzene (MXDA), 1,4-bis(aminomethyl)benzene, bis(2-aminoethyl) ether, 3,6-dioxaoctane-1,8-diamine, 4,7-dioxadecane-1,10-diamine, 4,7-dioxadecane-2,9-diamine, 4,9-dioxadodecane-1,12-diamine, 5,8-dioxadodecane-3,10-diamine, 4,7,10-trioxatridecane-1,13-diamine, or higher oligomers of these diamines, bis(3-aminopropyl)polytetrahydrofuran or other polytetrahydrofuran diamines, polyoxyalkylene diamines or triamines, particularly Jeffamine® D-230, Jeffamine® D-400, Jeffamine® D-2000, Jeffamine® EDR-104, Jeffamine® EDR-148, Jeffamine® EDR-176, Jeffamine® T-403, Jeffamine® T-3000 or Jeffamine® T-5000 (All from Huntsman), bis(6-aminohexyl)amine (BHMT), diethylenetriamine (DETA), triethylenetetramine (TETA), tetraethylenepentamine (TEPA), pentaethylenehexamine (PEHA) or their higher homologues, dipropyltriamine (DPTA), N-(2-aminoethyl)-1,3-propanediamine (N3-amine), N,N'-bis(3-aminopropyl)ethylenediamine (N4-amine) N,N′-bis(3-aminopropyl)-1,4-diaminobutane, N5-(3-aminopropyl)-2-methyl-1,5-pentanediamine, N3-(3-aminopentyl)-1,3-pentanediamine, N5-(3-amino-1-ethylpropyl)-2-methyl-1,5-pentanediamine, N,N′-bis(3-amino-1-ethylpropyl)-2-methyl-1,5-pentanediamine, or adducts of these polyamines with monoepoxides or diepoxides.

[0051] Also suitable are N-benzyl-1,2-ethylenediamine, N-benzyl-1,2-propanediamine, N-benzyl-2-methyl-1,5-pentanediamine, N-benzyl-1,3-bis(aminomethyl)benzene, N-(2-ethylhexyl)-1,3-bis(aminomethyl)benzene, 2-aminoethylpiperazine, 3-dimethylaminopropylamine (DMAPA), 3-(3-(dimethylamino)propylamino)propylamine (DMAPAPA), N-benzyldiethylenetriamine, N-benzyltriethylenetetramine, N''-benzyl-N,N'-bis(3-aminopropyl)ethylenediamine, or adducts of these polyamines with monoepoxides or diepoxides.

[0052] In another preferred embodiment, the at least one amine compound comprises or is composed of a diamine and / or a triamine, particularly a polyoxyalkylene diamine and / or a polyoxyalkylene triamine.

[0053] In particular, the at least one amine compound is selected from polyoxypropylene diamines, such as Jeffamine® D-230 or Jeffamine® D-400 (both from Huntsman) with an average molecular weight of 170 to 500 g / mol; or polyoxypropylene triamines, such as Jeffamine® T-403 (from Huntsman) with an average molecular weight of 300 to 500 g / mol.

[0054] In a preferred embodiment, the at least one epoxy resin comprises or is composed of bisphenol A-diglycidyl ether, and the at least one acrylate compound comprises or is composed of triacrylate or pentaacrylate. Preferably, in this case, the at least one amine compound may comprise or be composed of triamine, particularly polyoxypropylene triamine.

[0055] In another preferred embodiment, the at least one epoxy resin comprises or is composed of bisphenol A-diglycidyl ether, the at least one acrylate comprises or is composed of monofunctional acrylates, and the at least one amine compound comprises or is composed of triamines, particularly polyoxyalkylene triamines. In particular, this composition exhibits high resistance to yellowing.

[0056] The weight ratio of at least one epoxy resin to at least one acrylate compound and optional diluent (especially reactive diluent) is preferably >50% by weight, especially >60% by weight, particularly >65% by weight, for example 70-95% by weight.

[0057] Specifically, relative to the total weight of the resin components, the resin components comprise: (i) at least one epoxy resin in amounts of 50–99% by weight, particularly 60–95% by weight, especially 70–92% by weight, for example 75–85% by weight; (ii) 1–50% by weight, especially 5–40% by weight, particularly 8–30% by weight, for example 15–25% by weight of at least one acrylate compound; (iii) 0 – 40% by weight, especially 1 – 30% by weight, particularly 5 – 28% by weight, for example 15 – 25% by weight of diluent.

[0058] The hardener component preferably contains at least one amine compound at 50-100% by weight, especially 70-100% by weight, particularly 90-100% by weight, and for example 100% by weight, relative to the total weight of the hardener component.

[0059] In particular, the weight ratio between the hardener component and the resin component is 1:10 to 10:1, especially 2:10 to 10:10, especially 3:10 to 6:10, for example 3.5:10 to 5:10.

[0060] In a preferred embodiment, the molar ratio of the sum of the acryloyl group (CH2=CHCOO-) of at least one acrylate compound, the epoxy group of at least one epoxy resin, and any other group (especially optional epoxy functional reactive diluent) that is reactive to the amine group of at least one amine compound to the number of amine groups of at least one amine compound is 0.5 to 1.5, particularly 0.7 to 1.2.

[0061] Particularly preferably, the epoxy resin composition is formulated such that it is transparent to light in the visible spectrum in the cured state. Preferably, this composition contains at least one stabilizer that resists light or UV radiation.

[0062] Specifically, the filler content in the epoxy resin composition is 0-2% by weight, particularly 0-1% by weight, and especially 0% by weight, relative to the total weight of the epoxy resin composition. In a preferred embodiment, the epoxy resin composition is filler-free.

[0063] Preferably, the resin component has a color index of less than 40 on the platinum-cobalt scale, particularly less than 25, especially less than 20, and especially less than 15 (measured according to DIN EN ISO 6271:2016-05). This is a common method for comparing the intensity of yellow samples. The smaller the value, the less yellow the resin component. This helps to reduce yellowing of the cured sample.

[0064] The epoxy resin composition may contain other components.

[0065] Other possible components are accelerators, preferably salicylic acid, p-toluenesulfonic acid, methyl p-toluenesulfonate, calcium nitrate, 2,4,6-tris(dimethylaminomethyl)phenol or combinations thereof.

[0066] Another preferred component is an additive, such as a surfactant, a stabilizer against oxidation, heat, light or UV radiation, and / or a biocide.

[0067] Other optional ingredients include additional reactive diluents, such as epoxidized soybean oil, epoxidized linseed oil, acetylated polyols, butyrolactone, carbonates, aldehydes, isocyanates or silicones with reactive groups, solvents, additional amines, substances with thiol groups, polymers, pyrolytic silica, fibers such as glass fibers, polyamide fibers or polyethylene fibers, hollow spheres made of glass, rheology modifiers, adhesion promoters such as organoalkoxysilanes or flame retardants.

[0068] The opaque epoxy resin composition according to the invention may contain additional components, particularly fillers, such as calcium carbonate, barite, talc, quartz powder, quartz sand, silicon carbide, iron mica, dolomite, wollastonite, kaolin, mica, molecular sieve, alumina, aluminum hydroxide, magnesium hydroxide, silicon dioxide, cement, gypsum, fly ash, carbon black, graphite, metal powder, PVC powder or hollow spheres, and / or pigments such as titanium dioxide or iron oxide, and / or fibers or nanomaterials such as carbon fibers, metal fibers, ceramic fibers or carbon nanotubes.

[0069] In this document, the term "filler" specifically refers to solid particulate substances that are insoluble in the composition.

[0070] The transparent epoxy resin composition according to the invention may further contain dyes to obtain a transparent colored appearance similar to colored glass, such as light blue, light green, or light red.

[0071] In particular, as described above, the resin component and the hardener component of the epoxy resin composition are each stored in separate containers. Other components of the epoxy resin composition may be part of the resin component and / or the hardener component, while components reactive to amines are part of the resin component, and components reactive to epoxides are part of the hardener component.

[0072] Suitable containers, especially drums, buckets, bags, barrels, cylinders, cans, boxes or tubes, for storing resin components or hardener components.

[0073] In particular, each component is stable during storage. This means that it can be stored for months to a year or longer before use without undergoing any degree of change in properties related to its use.

[0074] For the use of epoxy resin compositions, the resin components, hardener components, and (if present) other components are mixed together shortly before or during application.

[0075] Therefore, another aspect of the present invention relates to a method for mixing components of an epoxy resin composition as described herein.

[0076] The mixing ratio of the components is preferably selected as described above.

[0077] These components can be mixed with each other by any suitable method. This can be done continuously or in batches. If mixing is done before application, it should be ensured that no excessive time elapses between mixing and application to ensure application within the applicable period. Mixing is preferably carried out at ambient temperature or slightly elevated temperature, particularly at 10-50°C, preferably 15-30°C, and especially 15-25°C.

[0078] As described above, the curing of the epoxy resin composition begins with a chemical reaction during the mixing of the components. Curing is typically carried out at temperatures of 10-150°C, preferably at ambient temperature. If desired, post-curing can be carried out at elevated temperatures, preferably 50-150°C. The curing time depends on factors including temperature, the reactivity and stoichiometry of the reactive components, and the presence of accelerators and / or diluents.

[0079] In particular, the epoxy resin composition of the present invention is configured to have a high Tg after curing. Preferably, the Tg measured by thermomechanical analysis (TMA) according to ISO 11359-2:2021-11 is above 35°C, more preferably above 40°C, and particularly at least 45°C. This material is durable and stable under environmental conditions.

[0080] Another aspect of the present invention relates to a method for casting articles, the method comprising the following steps: (i) Mixing the components of the epoxy resin composition as described above, (ii) The mixed composition is poured into a mold with a layer thickness of at least 1 mm, particularly in the range of 5 to 200 mm, preferably in the range of 10 to 150 mm, more preferably in the range of 30 to 120 mm, particularly in the range of 50 to 100 mm, during its useful life.

[0081] (iii) Optionally, another portion of the components of the epoxy resin composition as described in step (i) is mixed, and then, within its pot life, another layer of the mixed composition is poured onto the already applied, at least partially cured layer. (iv) Optionally repeat step (iii) until the article reaches its desired thickness. (v) Solidify the cast product.

[0082] In step (i), mixing is preferably performed as described above with respect to the mixing method.

[0083] In step (ii), the mixed composition is poured into the mold in a single operation until the defined layer thickness is achieved. In particular, in step (ii), the mixed composition is poured into the mold with a layer thickness of at least 50 mm, especially at least 100 mm, especially at least 120 mm. This method with a relatively high layer thickness is possible due to the epoxy composition of the present invention.

[0084] In one particular implementation, optional steps (iii) and (iv) are omitted. In this case, the entire article can be produced in a single operation. Overall, this improves the uniformity and quality of the articles to be produced.

[0085] Another aspect of the invention relates to an article, preferably selected from painting, collage, paperweight, decorative ball, tray, decorative plate, tabletop and side table, comprising a cured epoxy resin composition as described herein or comprising a cured epoxy resin composition obtainable by the methods described above.

[0086] Another aspect of the invention relates to the use of at least one acrylate compound for controlling, in particular for reducing, exothermic reactions during the curing process of an epoxy resin composition comprising: a) a resin component comprising at least one epoxy resin and b) a curing agent component comprising at least one amine compound having at least one amine group selected from primary amine groups, secondary amine groups and / or blocked amine groups.

[0087] Another aspect of the invention relates to the use of at least one acrylate compound for reducing yellowing of epoxy resin compositions comprising: a) a resin component comprising at least one epoxy resin and b) a curing component comprising at least one amine compound having at least one amine group selected from primary amine groups, secondary amine groups and / or blocked amine groups.

[0088] Through these uses, at least one acrylate compound is added to and / or present in the resin component of the epoxy resin composition, particularly before and / or during curing.

[0089] Therefore, at least one acrylate compound and epoxy resin composition are defined as described above with respect to the epoxy resin composition according to the invention.

[0090] Other advantageous embodiments and combinations of features of the present invention will become apparent from the following exemplary embodiments and all patent claims.

[0091] Brief description of the attached figures

[0092] The accompanying drawings, used to explain the embodiments, show: Figure 1 It shows the temperature change of two different epoxy resin compositions over time during the curing process; Figure 2 It is Figure 1 A photograph of a transparent article produced from an epoxy resin composition. When compared with a reference sample ( Figure 2 Compared to the right side, the left-side article produced using the epoxy resin composition according to the present invention ( Figure 2 The left side of the color has a lower yellow discoloration; Figures 3-5 This refers to the temperature change over time during the curing process of another epoxy resin composition containing different types of acrylates. Figure 6 This refers to the temperature change over time during the curing process of other epoxy resin compositions; Figure 7 It is in a larger batch size Figure 6 The temperature changes over time during the curing process of two other epoxy resin compositions.

[0093] Exemplary Implementation

[0094] Substances and materials

[0095] For exemplary embodiments, the substances and materials shown in Table 1 are used. “EEW” represents epoxy equivalent weight. “AHEW” represents amine hydrogen equivalent weight. Unless otherwise specified, the substances used are from Sigma-Aldrich.

[0096] Table 1

[0097] Example 1

[0098] At room temperature, the resin and hardener components shown in Table 2 (total: 1.2 kg) were placed into separate containers. The two components were then mixed together to begin the curing process and poured into a conical mold with an internal depth of approximately 12 cm. During curing, the temperature change over time was measured using a thermocouple located at the center of the cured epoxy resin composition.

[0099] Table 2 (ratios in wt%) = Reference Sample 1)= Weight ratio of resin component to hardener component 2) = Processing additives Figure 1 The temperature changes of two samples, R1 and A, over time are shown. The differences in temperature changes are clearly visible. Due to the presence of acrylate (SR399; 10% by weight of the total resin component), the peak temperature of sample A (≈55℃) is much lower than the peak temperature of the reference sample R1 (≈90℃).

[0100] like Figure 2 As shown, when compared with reference sample R1 ( Figure 2 Compared to the right side, this results in sample A ( Figure 2 (Left side) Less yellow discoloration.

[0101] Example 2

[0102] Experiments similar to those in Example 1 were conducted using other acrylates, namely monoacrylates, diacrylates, and polyacrylates. The specific types of acrylates used and the proportions of epoxy resin and reactive diluent replaced by acrylates are shown in [the table / document / etc.]. Figure 3 , 4 And 5 (weight % relative to the total weight of the resin components).

[0103] Figure 3 , 4 Figures 5 and 6 show the temperature changes of these samples over time. R2 is a reference sample that is substantially the same as sample R1. Note that due to different experimental conditions, the absolute temperatures of Examples 1 and 2 cannot be compared.

[0104] like Figures 3 to 5 As shown, the peak temperature can be significantly reduced for all tested acrylates compared to the reference sample R2.

[0105] Example 3

[0106] The resin and hardener components shown in Table 3 were supplied in separate containers at room temperature (total batch size: 1.2 kg). The two components were then mixed together to begin the curing process and poured into a conical mold with an internal depth of approximately 12 cm. During curing, the temperature change over time was measured using a thermocouple located at the center of the cured epoxy resin composition.

[0107] Table 3 (ratios in wt%) = Reference Sample 1)= Weight ratio of resin component to hardener component Figure 6 The temperature changes of two reference samples R3 and R4 and sample B over time are shown. The differences in temperature changes are clearly visible. Due to the presence of acrylate (SR489), the peak temperature of sample B is much lower than that of reference sample R3, and also lower than that of reference sample R4.

[0108] It is worth noting that reference sample R4 has a lower proportion of amine compounds in its hardener composition. This results in delayed curing compared to reference sample R3.

[0109] To evaluate the processing properties of the epoxy compositions in Table 3 and the mechanical properties of articles produced using these compositions, viscosity, hardness, and glass transition temperature (Tg) were measured. Table 4 provides an overview of the results.

[0110] Table 4 = Reference Sample

[0111] 1) Immediate viscosity of components after mixing: measured using an RM 200 rheometer (Lamy Rheology) at 2000 s. -1 The shear rate was measured at 25°C.

[0112] 2) After 7 days at 23°C

[0113] 3) Measurement by thermomechanical analysis (TMA) according to ISO 11359-2:2021-11

[0114] As is evident from the data presented in Table 4, although the lowest peak temperature can be obtained by using acrylate (sample B), acrylate does not affect processing and mechanical properties.

[0115] Example 4

[0116] Although Experiment 3 ( Figure 6 The peak temperature difference between reference sample R4 and sample B (with 20% SR489 by weight) may seem small, but this effect is significant when higher applied volumes or higher layer thicknesses are involved.

[0117] Figure 7 The temperature variations over time for two samples, R4 and B, are shown, where an 8 kg batch (instead of 1.2 kg in Example 3) was produced and poured into a mold. This resulted in a 100 mm layer thickness of the epoxy resin composition.

[0118] like Figure 7 Figure 7 As shown, the use of acrylate is clearly beneficial because the peak temperature can be reduced by more than 25°C, resulting in a more uniform cured product.

[0119] Those skilled in the art will understand that the invention may be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments currently disclosed are to be considered illustrative rather than restrictive in all respects.

Claims

1. An epoxy resin composition comprising: a) A resin component comprising at least one epoxy resin and at least one acrylate compound, wherein the weight ratio of the at least one acrylate compound to the at least one epoxy resin is 0.01–1, particularly 0.05–0.7, particularly 0.1–0.5; b) A curing agent component comprising at least one amine compound having at least one amine group selected from primary amine groups, secondary amine groups and / or blocked amine groups.

2. The epoxy resin composition according to claim 1, wherein the at least one acrylate compound is an aliphatic alkyl acrylate, wherein the aliphatic alkyl group of the alkyl acrylate may be branched or unbranched and optionally contains one or more heteroatoms, particularly oxygen, and wherein the acrylate compound contains 1-5, particularly 1-3, particularly 1-2 acryloyl groups.

3. The epoxy resin composition according to any one of the preceding claims, wherein the at least one acrylate compound is selected from: - Monoacrylate, selected from lauryl acrylate, C-acrylate 12 -C 14 Alkyl esters and / or tridecyl acrylates; - Diacrylate, selected from 3-methyl-1,5-pentanediol diacrylate and / or 1,10-decanediol diacrylate; - Triacrylate, selected from trimethylolpropane triacrylate, pentaerythritol triacrylate and / or ethoxylated 3-trimethylolpropane triacrylate; - Tetraacrylate, selected from pentaerythritol tetraacrylate and / or bis(trimethylolpropane) tetraacrylate; and / or - Pentaacrylate, selected from dipentaerythritol pentaacrylate.

4. The epoxy resin composition according to any one of the preceding claims, wherein the epoxy resin is selected from bisphenol A-diglita ether, bisphenol F-diglita ether and / or bisphenol A / F-diglita ether.

5. The epoxy resin composition according to any one of the preceding claims, wherein the epoxy resin further comprises an epoxy-functional reactive diluent, particularly selected from butanediol diglycidyl ether, neopentyl glycol diglycidyl ether, hexanediol diglycidyl ether, cyclohexanediethanol diglycidyl ether, trimethylolpropane di or triglycidyl ether, phenyl glycidyl ether, toluene glycidyl ether, guaiacol glycidyl ether, 4-methoxyphenyl glycidyl ether, p-n-butylphenyl glycidyl ether, p-tert-butylphenyl glycidyl ether, 4-nonylphenyl glycidyl ether, 4-dodecylphenyl glycidyl ether, cashew phenol glycidyl ether, benzyl glycidyl ether, allyl glycidyl ether, butyl glycidyl ether, hexyl glycidyl ether, 2-ethylhexyl glycidyl ether, and glycidyl ethers of natural alcohols such as C8-C10 alcohols, C12-C14 alcohols, and C13-C15 alcohols.

6. The epoxy resin composition according to any one of the preceding claims, wherein the at least one amine compound is an aliphatic, alicyclic, or aryliphatic polyamine having (i) at least two primary amine groups or (ii) at least one primary amine group and at least one secondary amine group, particularly the at least one amine compound being a polyoxypropylene triamine, for example having an average molecular weight of 300-500 g / mol.

7. The epoxy resin composition according to any one of the preceding claims, wherein the weight ratio of at least one epoxy resin to at least one acrylate compound and optional diluent is > 50% by weight, especially > 60% by weight, especially > 65% by weight, for example 70-95% by weight.

8. The epoxy resin composition according to any one of the preceding claims, wherein the resin component, relative to the total weight of the resin components, comprises: (i) at least one epoxy resin comprising 50–99% by weight, particularly 60–95% by weight, particularly 70–92% by weight, for example 75–85% by weight; (ii) 1-50% by weight, especially 5-40% by weight, especially 8-30% by weight, for example 15-25% by weight of at least one acrylate compound; (iii) 0 – 40% by weight, especially 1 – 30% by weight, especially 5 – 28% by weight, for example 15 – 25% by weight of diluent.

9. The epoxy resin composition according to any one of the preceding claims, wherein the weight ratio of the curing agent component to the resin component is 1:10 to 10:1, especially 2:10 to 10:10, especially 3:10 to 6:10, for example 3.5:10 to 5:

10.

10. The epoxy resin according to any one of the preceding claims, wherein the sum of the acryloyl group (CH2=CHCOO-) of at least one acrylate compound and the epoxy group of at least one epoxy resin and any other group reactive to the amine group of the at least one amine compound, especially optional epoxy-functional reactive diluent, is in a molar ratio of 0.5 to 1.5, particularly 0.7 to 1.2, to the number of amine groups of the at least one amine compound.

11. The epoxy resin composition according to any one of the preceding claims, wherein the epoxy resin composition is formulated such that it is transparent to light in the visible spectrum in the cured state.

12. A method for casting products, comprising the following steps: (i) Mixing the components of the epoxy resin composition as described in any of the preceding claims. (ii) During the pot life of the mixed composition, it is poured into a mold with a layer thickness of at least 1 mm, especially 5-200 mm, preferably 10-150 mm, more preferably 30-120 mm, and particularly 50-100 mm. (iii) Optionally, another portion of the components of the epoxy resin composition as described in step (i) is mixed, and then, during its pot life, another layer of the mixed composition is poured onto the already applied, at least partially cured layer. (iv) Optionally, repeat step (iii) until the article has reached its desired thickness. (v) Solidify the cast product.

13. The method of claim 12, wherein in step (ii), the mixed composition is poured into a mold with a layer thickness of at least 50 mm, particularly at least 100 mm.

14. An article, preferably selected from paintings, collages, paperweights, decorative balls, trays, decorative plates, tabletops and side tables, comprising an epoxy resin composition in a cured state according to any one of claims 1-12 or comprising an epoxy resin composition cured by a method obtainable according to any one of claims 12-13.

15. Use of at least one acrylate compound for controlling, and particularly for reducing, exothermic processes during the curing of an epoxy resin composition comprising: a) a resin component comprising at least one epoxy resin and b) a curing agent component comprising at least one amine compound having at least one amine group selected from primary amine groups, secondary amine groups and / or blocked amine groups.

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