EP4634262A1

EP4634262A1 - One-component cationic polymerizable composition

Info

Publication number: EP4634262A1
Application number: EP23818453.5A
Authority: EP
Inventors: Christof STORZ; Pascal CICLET; Christian Beisele
Original assignee: Huntsman Advanced Materials Switzerland GmbH
Current assignee: Huntsman Advanced Materials Switzerland GmbH
Priority date: 2022-12-16
Filing date: 2023-12-06
Publication date: 2025-10-22
Also published as: CN120359254A; WO2024126186A1

Abstract

The present disclosure generally relates to a one-component cationic polymerizable composition including an aromatic epoxy resin, an epoxy reactive diluent, a cationic polymerization initiator, a free radical forming compound and optionally a carboxylic acid and its use in impregnation processes.

Description

ONE-COMPONENT CATIONIC POLYMERIZABLE COMPOSITION

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims priority to EP22214069.1 filed 16 December 2022.

FIELD

[0002] The present disclosure generally relates to a one-component cationic polymerizable composition and its use in various applications including impregnating electric motors, generators and transformers in trickle impregnation, hot dip rolling and vacuum impregnation processes.

BACKGROUND

[0003] Resin impregnation of wire coils of rotors or stators is an important process in the production of electric motors. Conventional methods of impregnation are trickle impregnation and dip impregnation using solvent-less based insulation resins. In trickle impregnation, the insulation resin is dripped onto a heated winding that rotates at a moderate speed until complete impregnation is achieved. The subsequent cure of the resin can be realized at cold or elevated temperatures, depending on the resin employed. In dip impregnation, the rotor or stator is preheated and then fixed on an apparatus and dipped, while rotating, into an impregnating bath filled with the insulation resin. After complete impregnation of the windings, the rotor or stator is removed from the impregnating bath while continuing to rotate until the resin has gelled. In some instances, it may be necessary to perform a post cure in an oven to fully cure the resin. [0004] Unsaturated polyester resins and epoxy resins are often used in one component insulation resin systems for trickle impregnation and dip impregnation processes. However, these current state of the art resin systems either lack sufficient storage stability, are too viscous, are unable to cure when applied to an air exposed surface due to oxygen inhibition or cure too slowly at moderate temperature making them unsuitable in current fast production cycles in highly industrialized processes (for e.g., impregnation of stators especially for electric vehicles).

[0005] Accordingly, a need exists for the development of alternative non-toxic insulation resin systems that are capable of being used in impregnation processes and that exhibit good impregnation capability, good adhesion to primary insulation layers, have a fast reactivity at moderate temperatures and are storage stable for an extended period of time.

SUMMARY

[0006] The present disclosure generally provides a one-component cationic polymerizable composition including: (a) an epoxy component comprising an aromatic epoxy resin and an epoxy reactive diluent; (b) a cationic polymerization initiator; (c) a free radical forming compound; and optionally (d) a carboxylic acid.

[0007] In still another embodiment, there is provided the use of the one-component cationic polymerizable composition as an impregnating or coating composition for an electrical motor, transformer and generator.

[0008] In another embodiment there is provided a process of forming an impregnated substrate including the steps of applying the one component cationic polymerizable composition of the present disclosure onto a substrate by dip impregnation, vacuum impregnation or trickle impregnation to form an impregnated substrate and curing the applied composition.

[0009] In another embodiment there is provided a rotary device comprising a rotor and a stator, where the stator comprises a coil conductor and an insulating layer covering the coil conductor, and the insulating layer comprises a cured product of the one-component cationic polymerizable composition.

DETAILED DESCRIPTION

[0010] The present disclosure is generally directed to a one-component cationic polymerizable composition containing an epoxy component comprising an aromatic epoxy resin and an epoxy reactive diluent, a cationic polymerization initiator, a free radical forming compound and optionally a carboxylic acid. The one-component cationic polymerizable composition of the present disclosure has been surprisingly found to not only cure quickly at temperatures ranging from about 120°C to about 140°C, but also reduces the well-known oxygen sensitivity of radical initiated compositions. In addition, the one-component cationic polymerizable composition may exhibit an increased transition temperature range between a long surface gel-time and a highly exothermic cure when a carboxylic acid is present.

[0011] The following terms shall have the following meanings:

[0012] The term "comprising" and derivatives thereof are not intended to exclude the presence of any additional component, step or procedure, whether or not the same is disclosed herein. In order to avoid any doubt, all compositions claimed herein through use of the term "comprising" may include any additional additive, adjuvant, or compound, unless stated to the contrary. In contrast, the term, "consisting essentially of' if appearing herein, excludes from the scope of any succeeding recitation any other component, step or procedure, except those that are not essential to operability and the term "consisting of, if used, excludes any component, step or procedure not specifically delineated or listed. The term "or", unless stated otherwise, refers to the listed members individually as well as in any combination.

[0013] The articles "a" and "an" are used herein to refer to one or to more than one (i.e., to at least one) of the grammatical objects of the article. By way of example, "an epoxy resin" means one epoxy resin or more than one epoxy resin. The phrases "in one embodiment", "according to one embodiment" and the like generally mean the particular feature, structure, or characteristic following the phrase is included in at least one embodiment of the present disclosure and may be included in more than one embodiment of the present disclosure. Importantly, such phrases do not necessarily refer to the same aspect. If the specification states a component or feature "may", "can", "could", or "might" be included or have a characteristic, that particular component or feature is not required to be included or have the characteristic.

[0014] The term “about” as used herein can allow for a degree of variability in a value or range, for example, it may be within 10%, within 5%, or within 1%, or within 0.5% of a stated value or of a stated limit of a range.

[0015] Values expressed in a range format should be interpreted in a flexible manner to include not only the numerical values explicitly recited as the limits of the range, but to also include all of the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. For example, a range such as from 1 to 6, should be considered to have specifically disclosed sub-ranges, such as, from 1 to 3, from 2 to 4, from 3 to 6, etc., as well as individual numbers within that range, for example, 1, 2, 3, 4, 5, and 6. This applies regardless of the breadth of the range. [0016] The terms “preferred” and “preferably” refer to embodiments that may afford certain benefits, under certain circumstances. However, other embodiments may also be preferred, under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful and is not intended to exclude other embodiments from the scope of the present disclosure.

[0017] The term “one-component" or "one-part" composition refers to a composition which is contained in a single container, preferably a moisture-tight container, and which composition has certain storage stability. In comparison, a "two component" composition refers to a composition where two components (A and B) are physically separated from each other (for instance, in separate cartridges, compartments, totes, drums or other containers), wherein components A and B are physically combined (admixed) at the time the composition is to be used to form a cured resin.

[0018] The term "storage stability" refers to the ability of a composition to be stored at ambient temperature in a suitable container under exclusion of moisture for a certain time interval, such as at least three months or at least four months or at least five months or at least six months, without undergoing significant changes in application or end-use properties (for e.g. with minor (less than about 5% or less than about 4% or less than about 3%) or no crystallisation and/or with minor (less than about 5% or less than about 4% or less than about 3%) or no increase in viscosity).

[0019] The term "ambient temperature" refers to the temperature of the surrounding work environment (e.g., the temperature of the area, building or room where the composition is used), exclusive of any temperature changes that occur as a result of the direct application of heat to the composition to facilitate curing. The ambient temperature may be within a range from about 10°C to about 30°C, more specifically from about 15°C to about 25°C.

[0020] The term “primary insulation” refers to electrical insulation, i.e., insulation that does not conduct electricity. Primary insulation may include, but is not limited to, polysulfone, polyphyenyl sulfone (“PPSU”), polysulfide, polyphenylene sulfide (“PPS”), polyetherketone (“PEK”), polyether-ether-ketone (“PEEK”), polyaryletherketone (“PAEK”), polyamide etherketone, thermoplastic polyimide and aromatic polyamide, [0021] Where substituent groups are specified by their conventional chemical formula, written from left to right, they equally encompass the chemically identical substituents that would result from writing the structure from right to left, for example, -CH2O- is equivalent to -OCH2-.

[0022] The term “optional” or “optionally” means that the subsequently described event or circumstance may or may not occur, and that the description includes instances where said event or circumstance occurs and instances where it does not.

[0023] The term “substantially free” refers to a composition in which a particular compound or moiety is present in an amount that has no material effect on the composition. In some embodiments, “substantially free” may refer to a composition in which the particular compound or moiety is present in the composition in an amount of less than 2% by weight, or less than 1% by weight, or less than 0.5% by weight, or less than 0.1% by weight, or less than 0.05% by weight, or even less than 0.01% by weight based on the total weight of the composition, or that no amount of that particular compound or moiety is present in the respective composition. [0024] According to one embodiment, the present disclosure is directed to a one- component cationic polymerizable composition including: (a) an epoxy component comprising at least about 50 wt.% of an aromatic epoxy resin and less than about 50 wt.% of an epoxy reactive diluent, where the wt.% is based on the total weight of the epoxy component; (b) a cationic polymerization initiator; (c) a free radical forming compound selected from the group consisting of benzopinacol, a peroxide and an azo compound; and optionally (d) a carboxylic acid; wherein the epoxy reactive diluent is selected from the group consisting of glycidyl ethers of monofunctional C4-C30 alcohols, glycidyl ethers of difunctional C2-C15 alcohols, glycidyl ethers of trifunctional or multifunctional alcohols, glycidyl ethers of phenol compounds, glycidyl amines of aniline compounds or mono- or difunctional aliphatic or cycloaliphatic amines, and glycidyl esters of monocarboxylic or dicarboxylic acid. In one embodiment, the one-component cationic polymerizable composition is substantially free of an alkaline filler, such as calcium carbonate, magnesium oxide, zinc oxide, silicon dioxide, titanium oxide and aluminium oxide.

[0025] Aromatic epoxy resins as referred to herein are epoxy resins containing at least one aromatic unit in the backbone or in a side chain, if present. Typically, the aromatic epoxy resins include at least one aromatic epoxide, such as for example a phenyl glycidyl ether, preferably at a terminal position of the resin backbone or side chain if present. Aromatic epoxy resins that can be used include, for example, the reaction product of phenols (phenols and formaldehyde) and epichlorohydrin, peracid epoxies, glycidyl esters, glycidyl ethers, the reaction product of epichlorohydrin and amino phenols, and the reaction product of epichlorohydrin and glyoxal tetraphenol. Phenols as referred to above include polynuclear phenols (i.e., compounds having at least two phenol functional groups). Typical examples of polynuclear phenols are bisphenols.

[0026] The aromatic epoxy resin may be in liquid, solid or semi-solid form or a blend thereof. Suitable aromatic epoxy resins may comprise blends of two or more aromatic epoxy resins selected from di -functional, tri -functional, and/or tetrafunctional epoxy resins.

[0027] Examples of difunctional epoxy resins include those based on: bisphenol F, bisphenol A (optionally brominated), bisphenol S, phenol, phenol and cresol epoxy novolacs, aromatic glycidyl amines, naphthalene, or any combination thereof. Trifunctional epoxy resins include triglycidyl para-aminophenol, and triglycidyl metaaminophenol). Tetra-functional epoxy resins include N,N,N',N'-tetraglycidyl-m- xylenediamine and N,N,N',N'-tetraglycidylmethylenedianiline (e.g., MY0720 and MY0721 from Huntsman Advanced Materials Americas LLC). Other suitable multifunctional epoxy resins include the phenol novolac epoxy resins and cresol novolac epoxy resins available under the trade names Araldite® EPN and ECN (from Huntsman Advanced Materials Americas LLC).

[0028] The aromatic epoxy resin preferably has an epoxy equivalent weight of about 100 g/equivalent to about 1000 g/equivalent, or about 200 g/equivalent to about 600 g/equivalent, or about 300 g/equivalent to about 400 g/equivalent (determinable in accordance with DIN 16945).

[0029] In one embodiment, the epoxy component contains the aromatic epoxy resin in an amount of at least about 60 wt.%, or at least about 70 wt.%, or at least about 80 wt.%, at least about 90 wt.%, based on the total weight of the epoxy component. In still another embodiment, the epoxy component contains the aromatic epoxy resin in an amount of at least about 50 wt.% to about 99 wt.%, or at least about 60 wt.% to about 95 wt.%, or at least about 70 wt.% to about 90 wt.%, based on the total weight of the epoxy component.

[0030] The epoxy component also includes an epoxy reactive diluent. In the context of this disclosure, “epoxy reactive diluents” are meant to be low-viscosity glycidyl ethers of mono-, di- or multifunctional, aliphatic or aromatic alcohols or alkylphenols, glycidyl amines, or glycidyl carboxylates, and are used to increase flexibility and workability by diluting high viscous epoxy resins. The use of epoxy reactive diluents improves properties such as processing viscosity, pot life and wettability of pigments or fillers/additives. Flammability and mechanical properties can also be optimized by using epoxy reactive diluents.

[0031] The epoxy reactive diluent are more particularly: (i) glycidyl ethers of monofunctional saturated or unsaturated, branched or unbranched, cyclic or open-chain C4- C30 alcohols, for e.g., butanol glycidyl ether, hexanol glycidyl ether, 2-ethylhexanol ether, allyl glycidyl ether, tetrahydrofurfuryl and furfuryl glycidyl ethers, and trimethoxysilyl glycidyl ether; (ii) glycidyl ethers of difunctional saturated or unsaturated, branched or unbranched, cyclic or open-chain C2-C15 alcohols, for e.g., ethylene glycol, butanediol, hexanediol, and octanediol glycidyl ethers, cyclohexanedimethanol diglycidyl ether, and neopentyl glycol diglycidyl ether; (iii) glycidyl ethers of trifunctional or polyfunctional, saturated or unsaturated, branched or unbranched, cyclic or open-chain alcohols such as epoxidized castor oil, epoxidized trimethylolpropane, epoxidized pentaerythritol or polyglycidyl ethers of aliphatic polyols such as sorbitol, glycerol, and trimethylolpropane; (iv) glycidyl ethers of phenol compounds, such as phenyl glycidyl ether, cresol glycidyl ether, p-tert-butylphenyl glycidyl ether, nonylphenol glycidyl ether, and 3-n-pentadecenyl glycidyl ether (from cashew nut shell oil) (v) glycidyl amines of aniline compounds or mono- or difunctional aliphatic or cycloaliphatic amines such as N,N-diglycidylaniline and N,N-diglycidylcyclohexylamine; and (vi) glycidyl esters monocarboxylic or dicarboxylic acids such as glycidyl neodecanoate, glycidyl methacrylate, glycidyl benzoate, diglycidyl phthalate, tetrahydrophthalate, and hexahydrophthalate, and diglycidyl esters of dimeric fatty acids.

[0032] In one embodiment, the epoxy component contains the epoxy reactive diluent in an amount of less than about 40 wt.%, or at less than about 30 wt.%, or at less than about 20 wt.%, or less than about 15 wt.%, or less than about 10 wt.% based on the total weight of the epoxy component. In another embodiment, the epoxy component contains the epoxy reactive diluent in an amount of about 1 wt.% to less than about 50 wt.%, or about 5 wt.% to less than about 45 wt.%, or about 10 wt.% to less than about 30 wt.%, based on the total weight of the epoxy component.

[0033] In another embodiment, the epoxy component may further include an additional epoxy resin such as vinyl cyclohexene dioxide, limonene dioxide, limonene monoxide, vinyl cyclohexene monoxide, 3,4-epoxycyclohexlmethyl acrylate, 3,4-epoxy-6-methyl cyclohexylmethyl 9, 10-epoxy stearate, and l,2-bis(2,3-epoxy-2-methylpropoxy)ethane.

[0034] The one component cationic polymerizable composition also includes a cationic polymerization initiator. The cationic polymerization initiator may be (i) an aromatic sulfonium salt-based thermal cationic polymerization initiator; (ii) a phosphonium saltbased thermal cationic polymerization initiator; (iii) a quaternary ammonium salt-based thermal cationic polymerization initiator; (iv) an aluminum complex-based thermal cationic polymerization initiator; (v) an aromatic iodonium salt-based thermal cationic polymerization initiator; (vi) an aromatic diazonium salt-based thermal cationic polymerization initiator; or (vii) a pyridinium-based thermal cationic polymerization initiator.

[0035] Examples of (i) the aromatic sulfonium salt-based thermal cationic polymerization initiator include: hexafluoroantimonate salts such as (2-ethoxy-l-methyl-2- oxoethyl)methyl-2-naphthalenyisulfonium hexafluoroantimonate, 4-

(methoxy carbonyloxy )phenylbenzylmethylsulfonium hexafluoroantimonate, 4- acetoxyphenyldimethylsulfonium hexafluoroantimonate, 4- hydroxyphenylbenzylmethylsulfonium hexafluoroantimonate, 4-hydroxyphenyl(o-methyl benzyl)methylsulfonium hexafluoroantimonate, 4-hydroxyphenyl(a- naphthylmethyl)methylsulfonium hexafluoroantimonate, diphenyl-4-

(pheny Ithi o)pheny 1 sulfonium hexafluoroantimonate, triphenyl sulfonium hexafluoroantimonate, bis[4-(di(4-(2-hydroxyethoxy))phenylsulfonio)phenyl]sulfide bishexafluoroantimonate, and bis[4-(diphenylsulfonio)phenyl]sulfide bishexafluoroantimonate; hexafluorophosphate salts such as (2-ethoxy-l-methyl-2- oxoethyl)methyl-2-naphthalenylsulfonium hexafluorophosphate, 4- acetoxyphenylbenzylmethylsulfonium hexafluorophosphate, 4-hydroxyphenyl(o- methylbenzyl)methylsulfonium hexafluorophosphate, 4-hydroxyphenyl(a- naphthylmethyl)methylsulfonium hexafluorophosphate, diphenyl-4-

(phenylthio)phenylsulfonium hexafluorophosphate, triphenyl sulfonium hexafluorophosphate, bis[4-(di(4-(2-hydroxyethoxy))phenylsulfonio)phenyl]sulfide bi shexafluorophosphate, and bis [4-(diphenyl sulfonio)phenyl] sulfide bishexafluorophosphate; hexafluoroarsenate salts such as 4-hydroxyphenyl(o- methylbenzyl)methylsulfonium hexafluoroarsenate, and 4- hydroxyphenylbenzylmethylsulfonium hexafluoroarsenate; tetrafluoroborate salts such as (2-ethoxy- 1 -methyl-2-oxoethyl)methyl-2-naphthalenylsulfonium tetrafluoroborate, 4- hydroxyphenyl(o-methylbenzyl)methylsulfonium tetrafluoroborate, 4- hydroxyphenylbenzylmethylsulfonium tetrafluoroborate, diphenyl-4-

(phenylthio)phenylsulfonium tetrafluoroborate, triphenyl sulfonium tetrafluoroborate, bis[4-(di(4-(2-hydroxyethoxy))phenylsulfonio)phenyl]sulfide bistetrafluoroborate, and bis[4-(diphenylsulfonio)phenyl]sulfide bistetrafluoroborate; trifluoromethanesulfonate salts such as 4-hydroxyphenyl(o-methylbenzyl)methylsulfonium trifluoromethanesulfonate, and 4-hydroxyphenylbenzylmethylsulfonium trifluoromethanesulfonate; trifluoromethanesulfonate salts such as diphenyl-4- (phenylthio)phenylsulfonium trifluoromethanesulfonate; bis(trifluoromethanesulfone)imide salts such as 4-hydroxyphenyl(a- naphthylmethyl)methylsulfonium bis(trifluoromethanesulfone)imide, and 4- hydroxyphenylbenzylmethylsulfonium bis(trifluoromethanesulfone)imide; tetrakis(pentafluorophenyl)borate salts such as (2-ethoxy- l-methyl-2-oxoethyl)methyl-2- naphthalenylsulfonium tetrakis(pentafluorophenyl)borate, 4-

(methoxycarbonyloxy)phenylbenzylmethylsulfonium tetrakis(pentafluorophenyl)borate, 4-hydroxyphenyl(o-methylbenzyl)methylsulfonium tetrakis(pentafluorophenyl)borate, 4- hydroxyphenyl(a-naphthylmethyl)methylsulfonium tetrakis(pentafluorophenyl)borate, 4- hydroxyphenylbenzylmethylsulfonium tetrakis(pentafluorophenyl)borate, diphenyl-4- (phenylthio)phenylsulfonium tetrakis(pentafluorophenyl)borate, triphenyl sulfonium tetrakis(pentafluorophenyl)borate, bis[4-(di(4-(2- hydroxyethoxy))phenylsulfonio)phenyl]sulfide tetrakis(pentafluorophenyl)borate, and bis[4-(diphenylsulfonio)phenyl]sulfide tetrakis(pentafluorophenyl)borate.

[0036] Examples of (ii) the phosphonium salt-based thermal cationic polymerization initiator include ethyltriphenylphosphonium hexafluoroantimonate, and tetrabutylphosphonium hexafluoroantimonate.

[0037] Examples of (iii) the quaternary ammonium salt-based thermal cationic polymerization initiator include N,N-dimethyl-N-benzylanilinium hexafluoroantimonate, N,N-diethyl-N-benzylanilinium tetrafluoroborate, N,N-dimethyl-N-benzylpyridinium hexafluoroantimonate, N,N-diethyl-N-benzylpyridinium trifluoromethanesulfonic acid, N,N-dimethyl-N-(4-methoxybenzyl)pyridinium hexafluoroantimonate, N,N-diethyl-N-(4- methoxybenzyl)pyridinium hexafluoroantimonate, N,N-diethyl-N-(4- methoxybenzyl)toluidinium hexafluoroantimonate, and N,N-dimethyl-N-(4- methoxybenzyl)toluidinium hexafluoroantimonate.

[0038] Examples of (iv) the aluminum complex-based thermal cationic polymerization initiator include aluminum carboxylates; aluminum alkoxide, aluminium chloride, aluminum (alkoxide) acetoacetic acid chelate, acetoacetonato aluminum, and ethyl acetoacetato aluminum.

[0039] Examples of (v) the aromatic iodonium salt-based thermal cationic polymerization initiator include phenyliodonium hexafluorophosphate, diphenyliodonium hexafluoroantimonate, diphenyliodonium tetrafluoroborate, diphenyliodonium tetrakis(pentafluorophenyl)borate, diphenyliodonium hexafluorophosphate, diphenyliodonium trifluoromethanesulfonate, bis(dodecylphenyl)iodonium hexafluorophosphate, bis(dodecylphenyl)iodonium hexafluoroantimonate, bis(dodecylphenyl)iodonium tetrafluoroborate, bis(dodecylphenyl)iodonium tetrakis(pentafluorophenyl)borate, 4-methylphenyl-4-(l-methylethyl)phenyliodonium hexafluorophosphate, 4-methylphenyl-4-(l-methylethyl)phenyliodonium hexafluoroantimonate, 4-methylphenyl-4-(l-methylethyl)phenyliodonium tetrafluoroborate, 4-isopropyl-4'-methyldiphenyliodonium tetrakis(pentafluorophenyl)borate and 4-methylphenyl-4-(l -methylethyl)phenyliodonium tetrakis(pentafluorophenyl)borate. [0040] Examples of (vi) the aromatic diazonium salt-based thermal cationic polymerization initiator include phenyl di azonium hexafluorophosphate, phenyl di azonium hexafluoroantimonate, phenyl di azonium tetrafluoroborate and phenyl di azonium tetrakis(pentafluorophenyl)borate.

[0041] Examples of (vii) the pyridinium -based thermal cationic polymerization initiator include l-benzyl-2-cyanopyridinium hexafluorophosphate, l-benzyl-2-cyanopyridinium hexafluoroantimonate, 1 -benzyl -2-cyanopyridinium tetrafluoroborate, l-benzyl-2- cyanopyridinium tetrakis(pentafluorophenyl)borate, 1 -(naphthylmethyl)-2- cyanopyridinium hexafluorophosphate, 1 -(naphthylmethyl)-2-cyanopyridinium hexafluoroantimonate, l-(naphthylmethyl)-2-cyanopyridinium tetrafluoroborate, and 1- (naphthylmethyl)-2-cyanopyridinium tetrakis(pentafluorophenyl)borate.

[0042] These cationic polymerization initiators may be used alone, or as a mixture of two or more kinds thereof. In one preferable embodiment, the polymerization initiator is an aromatic iodonium salt-based thermal cationic polymerization initiator. In another embodiment, the aromatic iodonium salt-based thermal cationic polymerization initiator is diphenyliodonium hexafluorophosphate, di(4-methylphenyl)iodonium hexafluorophosphate, diaryliodonium hexafluoroantimonate, (4-methylphenyl)[4-(2- methylpropyl) phenyl] iodonium hexafluoroantimonate, (4-methylphenyl)[4-(2- methylpropyl)phenyl]iodonium hexafluorophosphate, (4-methylphenyl)[4-(2- methylpropyl) phenyl] iodonium tetrafluoroborate, 4-octyloxyphenyl phenyliodonium hexafluoroantimonate, 4-(2-hydroxytetradecyloxyphenyl)phenyliodonium hexafluoroantimonate, or 4-isopropyl-4'-methyldiphenyliodonium borate.

[0043] In one embodiment, the one-component cationic polymerizable composition contains the cationic polymerization initiator in an amount of less than about 5 wt.%, or less than about 4 wt.%, or less than about 3 wt.%, or less than about 2 wt.% or less than about 1 wt.%, based on the total weight of the one-component cationic polymerizable composition. In another embodiment, the one-component cationic polymerizable composition contains the cationic polymerization initiator in an amount of from about 0.01 wt.% to about 3 wt.%, or from about 0.1 wt.% to about 1 wt.%, based on the total weight of the one-component cationic polymerizable composition.

[0044] The one-component cationic polymerizable composition further includes a free radical forming compound. The free radical forming compound is generally a peroxide or benzopinacol although other free radical forming compounds, such as azo compounds, may also be employed. In some embodiments, the free radical forming compound is a compound having a one hour half-life in the temperature range of about 100°C to about 130°C.

[0045] Any peroxide which is liquid or soluble in the one-component cationic polymerizable composition is suitable. Specific examples of such peroxides are methyl ethyl ketone peroxide, benzoyl peroxide, di-tert-butyl peroxide, tert-butyl hydroperoxide, isopropyl peroxydicarbonate, dichlorobenzoyl peroxide, lauroyl peroxide, acetyl peroxide, tert-butyl peracetate, tert-butyl perbenzoate, dicumyl peroxide, diethyl peroxide, di-tert- arnyl peroxide, and cyclohexyl hydroperoxide. Specific examples of azo compounds include 2,2'-azobis[N-(2-propenyl)-2-methyl propionamide], 1- [(cyano- 1 -methyl ethyl)azo] formamide, 2,2'-azobis(N-butyl-2-methyl propionamide), 2,2 '-azobi s(N- cyclohexyl-2-methyl propionamide), 2,2'-azobis (2-methyl-N-[2-(l-hydroxybutyl)] propionamide), 2,2'-azobis(2-methyl-N-[2-(l-hydroxybutyl)]propionamide), and 2,2'- azobis(2-methyl-N-[l,l-bis(hydroxymethyl)-2-hydroxyethyl]propionamide).

[0046] In one embodiment, the one-component cationic polymerizable composition includes the free radical forming compound in an amount of less than about 5 wt.%, or less than about 4 wt.%, or less than about 3 wt.%, or less than about 2 wt.% or less than about 1 wt.%, based on the total weight of the one-component cationic polymerizable composition. In another embodiment, the one-component cationic polymerizable composition includes the free radical forming compound in an amount of from about 0.01 wt.% to about 5 wt.%, or from about 0.1 wt.% to about 3 wt.%, based on the total weight of the one-component cationic polymerizable composition.

[0047] In one embodiment, the one-component cationic polymerizable composition also includes a carboxylic acid. The carboxylic acid includes those having 1 to 20 carbon atoms. In particular, the carboxylic acid may be formic acid, acetic acid, propanoic acid, butanoic acid, iso-butanoic acid, n- valeric acid, pivalic acid, caproic acid, heptanoic acid, octanoic acid, decanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, acrylic acid, methacrylic acid, oleic acid, elaidic acid, linoleic acid, linolenic acid, cyclohexane carboxylic acid, benzoic acid, phenylacetic acid, o-, m-, p-toluoylic acid, o-, p-chlorobenzoic acid, o-, p-nitrobenzoic acid, salicylic acid, p-hydroxybenzoic acid, anthranilic acid, p-aminobenzoic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, maleic acid, fumaric acid, phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, trimesic acid, pyromellitic acid, hemimellitic acid and mixtures of two or more thereof.

[0048] In one embodiment, the one-component cationic polymerizable composition includes the carboxylic acid in an amount of less than about 5 wt.%, or less than about 4 wt.%, or less than about 3 wt.%, or less than about 2 wt.%, or less than about 1 wt.%, based on the total weight of the one-component cationic polymerizable composition. In another embodiment, the one-component cationic polymerizable composition includes the carboxylic acid in an amount of from about 0.01 wt.% by wt. to about 5 wt.%, or from about 0.1 wt.% to about 3 wt.%, based on the total weight of the one-component cationic polymerizable composition.

[0049] In further embodiments, the one-component cationic polymerizable composition may include one or more additives including, but not limited to, plasticizers, extenders, pigments and dyes, such as carbon black, oxide colorants and titanium oxide, as well as flame retardants, antifoams, thixotropic agents, flow control agents, adhesion promoters (for e.g., epoxy-silanes) and anti-oxidants (for e.g., sterically hindered phenols). Other additives may include fillers for example: metal powder, wood flour, glass powder, glass beads, semi-metal and metal oxides such as SiO2 (silica sand, silica flour, silanized silica flour, synthetic silica flour, silanized synthetic silica flour), semi-metal and metal carbides (SiC and boron carbide), semi-metal and metal nitrides (AIN and BN), metal carbonates (dolomite, chalk, CaCCh), metal sulfides (barite, gypsum), rock flour such as from hydromagnesite and huntite and natural or synthetic minerals mainly from the silicate row such as zeolites (in particular molecular sieves), talc, mica, kaloin, wollastonite and others. [0050] The additives may also contain fungicides, anti-foaming agents, anti-statics, lubricants, anti-precipitation agents, hydrophobic agents and demoulding agents.

[0051] The optional additives may also be selected from the group of toughening agents, for e.g., CTBN-type tougheners, core-shell tougheners, block-copolymers (such as silicone-butyrolacton-type), and urethanes, for e.g., phenol-terminated polyurethane adducts such as Flexibilizer DY 965 from Huntsman Advanced Materials LLC.

[0052] The one-component cationic polymerizable compositions according to this disclosure can be prepared by mixing the individual components at ambient temperature or at slightly elevated temperatures and, if necessary, by means of suitable mills, for e.g., ball mills or pin mills, kneaders or mixers.

[0053] The curing of the presently disclosed one-component cationic polymerizable compositions may be made by known manner. It can take place, in general, by heating the composition to temperatures within a range from about 50°C to about 250°C, preferably from about 110°C to about 150°C. Thus, according to another embodiment, there is provided a cured or cross-linked product obtained by curing the one component epoxyresin based compositions.

[0054] According to still another embodiment, there is provided a storage stable packaged product comprising: a) a container having at least an outlet; and b) the one-component cationic polymerizable composition of the present disclosure. [0055] According to one embodiment, the packaged product comprises a container having a closure means, such as a lid, cover, cap, or plug to seal the container. In another embodiment, the sealed container also has a nozzle or pour spout. The sealed container may have the shape of a cylinder, oval, round, rectangle, canister, tub, square or jug and contains the one-component cationic polymerizable composition of the present disclosure. [0056] In yet another embodiment, the container may be made from any material, such as steel, glass, aluminum, cardboard, tin-plate, plastics including, but not limited to, high density polyethylene (HDPE), polypropylene (PP), polyvinyl chloride (PVC), polyethylene terephthalate (PET), oriented polypropylene (OPP), polyethylene (PE) or polyamide and including mixtures, laminates or other combinations of these.

[0057] The one-component cationic polymerizable compositions disclosed herein may be useful in castings, pottings, encapsulation, coatings, composites, or laminates, more specifically, in electrical or electronic castings, electrical or electronic pottings, electrical or electronic encapsulation, electrical laminates, structural composites, or protective coatings. The compositions of the present disclosure may also be used in other various end-use applications including, for example, as an adhesive, in structural laminates, electrical laminates, coatings, castings, structures for the aerospace industry, circuit boards for the electronics industry, as well as for the formation of skis, ski poles, fishing rods, and other outdoor sports equipment. The compositions disclosed herein may also be used in electrical varnishes, encapsulants, semiconductors, filament wound pipe, storage tanks, liners for pumps, and corrosion resistant coatings, among others.

[0058] In yet another embodiment, there is also provided an article produced by curing the one-component cationic polymerizable compositions of the present disclosure by application of heat. The article may include for example a casting, a potting, an encapsulation, a coating, a composite, or a laminate. The article may also include for example, a printed wire board, an electrical or electronic casting, an electrical or electronic potting, an electrical or electronic encapsulation, an electrical laminate, a structural composite, or a protective coating. The curing reaction of the one-component cationic polymerizable compositions may be conducted at a temperature, generally, within a range from about 40°C to about 250°C or from about 100°C to about 220°C or from about 110°C and about 140°C. The time of curing may be for a predetermined period of time which can range from minutes up to hours, generally the reaction time is more than about 5 minutes and less than about 24 hours, preferably between about 5 minutes and about 6 hours, and more preferably between about 5 minutes and about 2 hours. In other embodiments, curing may occur at a first temperature followed by a second temperature or post-treatment, such post-treatments ordinarily being at temperatures above 100°C or above 140°C.

[0059] In one embodiment, the one-component cationic polymerizable composition has, when cured at at least one temperature between 110°C and 120° C, a gel time no greater than about 800 seconds, preferably no greater than about 750 seconds and still more preferably no greater than about 720 seconds. Gel time for purposes of this disclosure is measured by methods using a Geltimer device in which a stamper made of aluminium or stainless steel performs an up-down cycle in a test tube filled with the composition to be tested. When the point of gelation is reached, the test tube is pulled up by the stamper stopping the timer and the gel time is read off the timer.

[0060] In another embodiment, the one-component cationic polymerizable composition has, when cured at at least one temperature between 120°C and 145°C, a surface gel time no greater than about 75 minutes, or no greater than about 60 minutes, or no greater than about 45 minutes or no greater than about 30 minutes as measured by a method in which a sample of the composition to be tested is applied onto a preheated hot-plate at a temperature between 120°C and 145°C and a time is measured from the start of the experiment to when the air exposed surface of the droplet becomes non-tacky.

[0061] In one particular embodiment, there is provided the use of the one-component cationic polymerizable composition as an impregnating and coating composition for electrical motors, transformers and generators (for e.g., the wound conductors of a stator, rotor, generator or transformer).

[0062] According to another embodiment, the one-component cationic polymerizable composition of the present disclosure may be applied to a substrate by trickle impregnation, dip impregnation or vacuum impregnation. In some embodiments, the substrate may be one or more components of an electrical motor or generator, such as the coils or windings on conductor of a stator or rotor or transformer or the like. In still other embodiments, the substrate may comprise a primary insulation layer and the one-component cationic polymerizable composition can be applied onto the primary insulation layer by trickle impregnation, dip impregnation or vacuum impregnation.

[0063] Thus, in still another embodiment there is provided a process of forming an impregnated substrate comprising the steps of: applying the one component epoxy resinbased composition of the present disclosure by dip impregnation, vacuum impregnation or trickle impregnation onto a substrate to form an impregnated substrate and curing the applied composition. In some embodiments, the substrate comprises a primary insulation layer, and the one component epoxy-resin based composition is applied onto the primary insulation layer. In still another embodiment, there is provided a substrate, such as a wound conductor of a stator, rotor, transformer or generator, impregnated with the one component epoxy resin-based composition.

[0064] The present disclosure will now be further described with reference to the following non-limiting examples.

Examples

[0065] Example 1. One component cationic polymerizable compositions according to the present disclosure.

As shown below in Table 1, various amounts of each component were added to a vessel and mixed to form the compositions. The gel time and surface gel times for the composition were then measured as described above and the results are shown below.

Table 1

a) if not noted otherwise all components are mixed at ambient conditions until a homogenous solution is reached b) pre-dissolved in Araldite® GY 250 at 50°C c) highly exothermic cure d) test stopped after 180 min

[0066] It was found that the addition of 10 parts by weight of an aliphatic epoxy reactive diluent (butanediol diglycidyl ether) significantly accelerated the gel time as well as the surface gel -time (see Ex.l v. Comp. Ex.l). Furthermore, it was observed that the combination of the epoxy reactive diluent with a carboxylic acid compound (maleic acid) led to an increase of the transition temperature range between long surface gel-times and a highly exothermic cure (see Ex. 2). The same behaviour can also be seen when tert-butyl peroxybenzoate is used in place of benzopinacol (see Ex.3 and Ex.4 v. Comp. Ex.2). [0067] Although making and using various embodiments of the present invention have been described in detail above, it should be appreciated that the present invention provides many applicable inventive concepts that can be embodied in a wide variety of specific contexts. The specific embodiments discussed herein are merely illustrative of specific ways to make and use the invention, and do not delimit the scope of the invention.

Claims

CLAIMS What is claimed is:

1. A one-component cationic polymerizable composition comprising: (a) an epoxy component comprising at least 50 wt.% of an aromatic epoxy resin and less than about 50 wt.% of an epoxy reactive diluent, where the wt.% is based on the total weight of the epoxy component; (b) a cationic polymerization initiator; and (c) a free radical forming compound selected from the group consisting of benzopinacol, a peroxide and an azo compound, wherein the epoxy reactive diluent is selected from the group consisting of glycidyl ethers of monofunctional C4C30 alcohols, glycidyl ethers of difunctional C2-C15 alcohols, glycidyl ethers of trifunctional or polyfunctional alcohols, glycidyl ethers of phenol compounds, glycidyl amines of aniline compounds or mono- or difunctional aliphatic or cycloaliphatic amines, and glycidyl esters of monocarboxylic or dicarboxylic acids.

2. The one-component cationic polymerizable composition of claim 1, wherein the aromatic epoxy resin is a bisphenol A epoxy resin or a bisphenol F epoxy resin.

3. The one-component cationic polymerizable composition of claim 1, wherein the aromatic epoxy resin is a phenol novolac epoxy resin or a cresol novolac epoxy resin.

4. The one-component cationic polymerizable composition of any of claims 1 to 3, wherein the cationic polymerization initiator is an aromatic iodonium salt-based cationic polymerization initiator, preferably wherein the aromatic iodonium salt-based cationic polymerization initiator is a diphenyliodonium tetrakis(pentafhiorophenyl)borate.

5. The one-component cationic polymerizable composition of any one of claims 1 to 4, wherein the free radical forming compound is benzopinacol.

6. The one-component cationic polymerizable composition of any one of claims 1 to 4, wherein the free radical forming compound is a peroxide.

7. The one-component cationic polymerizable composition of any of claims 1 to 6, wherein the composition further comprises a carboxylic acid, preferably in an amount of about 0.01 wt.% to about 5 wt.%, where the wt.% is based on the total weight of the one-component cationic polymerizable composition.

8. The one component cationic polymerizable composition of any of claims 1 to 7, further comprising one or more additives.

9. The one-component cationic polymerizable composition of any of claims 1 to 8, wherein

(a) the aromatic epoxy resin is present in an amount of at least about 60 wt.% to about 95 wt.% and the epoxy reactive diluent is present in an amount of about 5 wt.% to less than about 40 wt.%, based on the total weight of the epoxy component;

(b) the cationic polymerization initiator is present in an amount of about 0.01 wt.% to about 5 wt%, based on the total weight of the one-component cationic polymerizable composition; and

(c) the free radical forming compound is present in an amount of about 0.01 wt.% to about 5 wt.%, based on the total weight of the one-component cationic polymerizable composition.

10. A packaged product comprising a) a container having at least an outlet; and b) the one- component cationic polymerizable composition of any of claims 1 to 9.

11. The packaged product of claim 10, wherein the one-component cationic polymerizable composition of any of claims 1 to 9 has a storage stability of at least 6 months at 25°C.

12. Use of the one-component cationic polymerizable composition of any of claims 1 to 9 to impregnate protectively coat or adhere an electrical or electronic casting, an electrical or electronic potting, an electrical or electronic encapsulation, an electrical laminate or a structural composite.

13. Use of the one-component cationic polymerizable composition of any of claims 1 to 9 as an impregnating or coating composition for electrical motors, transformers and generators.

14. A process of forming an impregnated substrate comprising the steps of applying the one-component cationic polymerizable composition of any of claims 1 to 9 onto a substrate by dip impregnation, vacuum impregnation or trickle impregnation to form an impregnated substrate and curing the applied composition.

15. The process of claim 14, wherein the substrate comprises a primary insulation layer and the one-component cationic polymerizable composition is applied onto the primary insulation layer, preferably wherein the substrate is a wound conductor of a rotor or stator.