CA2144230A1 - Heat-curable epoxy resin systems having a good reactivity/stability ratio - Google Patents
Heat-curable epoxy resin systems having a good reactivity/stability ratioInfo
- Publication number
- CA2144230A1 CA2144230A1 CA 2144230 CA2144230A CA2144230A1 CA 2144230 A1 CA2144230 A1 CA 2144230A1 CA 2144230 CA2144230 CA 2144230 CA 2144230 A CA2144230 A CA 2144230A CA 2144230 A1 CA2144230 A1 CA 2144230A1
- Authority
- CA
- Canada
- Prior art keywords
- epoxy resin
- octane
- diazabicyclo
- component
- anhydride
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G59/00—Polycondensates containing more than one epoxy group per molecule; Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups
- C08G59/18—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing
- C08G59/68—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing characterised by the catalysts used
- C08G59/686—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing characterised by the catalysts used containing nitrogen
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G59/00—Polycondensates containing more than one epoxy group per molecule; Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups
- C08G59/18—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing
- C08G59/40—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing characterised by the curing agents used
- C08G59/42—Polycarboxylic acids; Anhydrides, halides or low molecular weight esters thereof
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G59/00—Polycondensates containing more than one epoxy group per molecule; Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups
- C08G59/18—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing
- C08G59/68—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing characterised by the catalysts used
- C08G59/72—Complexes of boron halides
Abstract
Heat-curable epoxy resin systems comprising (a) at least one epoxy resin, (b) at least one polycarboxylic acid anhydride, and (c) 1,4-diazabicyclo(2,2,2)octane or a C1-C4alkyl-substituted derivative of 1,4-diazabicyclo(2,2,2)octane as curing accelerator, and wherein one portion of the curing accelerator (c) is replaced by (d) a complex of a boron halide with an amine, have good reactivity at elevated temperatures and comparatively high stability at temperatures below c. 80°C.
Description
219g230 Heat-curable epoxy resin systems havin~; a ~ood reactivity/stability ratio The present invention relates to novel heat-curable epoxy resin systems comprising (a) at least one epoxy resin, (b) at least one polycarboxylic acid anhydride, and (c) 1,4-diazabicyclo-(2,2,2)-octane or a Cl-C4alkyl-substituted derivative of 1,4-diazabicyclo(2,2,2)octane as curing accelerator, to specific compositions which are novel components of such multicomponent systems, to the use of said systems as casting compositions, and to a preferred process for the fabrication of moulded objects using such systems.
Epoxy resin systems or compositions of the above-mentioned kind are disclosed, inter alia, in Japanese published patent specification JP-A-Sho 01-054022 (1989). The curingaccelerator 1,4-diazabicyclo(2,2,2)octane (abbreviated to DABCO or also known astriethylen~li~mine) effects a rapid cure of the compositions at elevated ~Illp~,~dtule, e.g.
from 120C, so that short demoulding times can be achieved. However, epoxy resincompositions containing 1,4-diazabicyclo(2,2,2)octane as curing accelerator are also highly reactive even at moderately elevated lelllpel~tures and therefore have only a relatively poor shelf stability and, especially in the temperature range from 60 to 80C
which frequently has to be applied during the h~nflling and/or processing of thecompositions prior to the cure, have only unsatisfactory stability and a short pot life.
Another tertiary amine mentioned as accelerator in JP-A-Sho 01-054022 is benzyl dime-thylamine. Benzyl dimethylamine, which is often used as curing accelerator in corresponding commercial products, has the same shortcomings as DABCO, and indeed even to a more pronounced degree.
In contrast, epoxy resin systems comprising an anhydride hardener and a complex of a boron halide and a tertiary amine as curing accelerator are substantially more stable at moderately elevated temperatures. Such compositions are disclosed, inter alia, in US-A-3 793 247, but have the converse drawback that they exhibit a relatively poor reactivity at elevated temperature and hence give rise to demoulding times that are often currently no longer economically acceptable.
It is therefore the object of this invention to provide an accelerator for the thermal cure of epoxy resins with polycarboxylic acid anhydrides, which accelerator has a more balanced ratio of reactivity at elevated temperature to stability (to a premature onset of cure) at moderately elevated ~elllpe~ ult; than conventional curing accelerators.
This object is achieved in the practice of this invention by using as curing accelerator a mixture of 1,4-diazabicyclo-(2,2,2)-octane or a Cl-C4alkyl-substituted derivative of 1,4-diazabicyclo-(2,2,2)-octane and a complex of a boron halide with a tertiary amine.
Surprisingly, the l~ ul~;s of this invention accelerate at low temperature the cure of epoxy resins with hardeners such as polycarboxylic acid anhydrides substantially less than pure 1,4-diazabicyclo(2,2,2)octane or benzyl dimethylamine, while their accelerating action at the temperatures normally used for the cure differs from that of the cited accelerators only to a degree that is entirely negligible for actual practice.
The invention thus relates in one of its aspects to a heat-curable epoxy resin composition comprising (a) at least one epoxy resin, (b) at least one polycarboxylic acid anhydride, and (c) 1,4-diazabicyclo(2,2,2)octane or a C1-C4alkyl-substituted derivative of 1,4-diazabicyclo(2,2,2)octane as curing accelerator, and wherein one part of the curing accelerator (c) is replaced by (d) a complex of a boron halide with an amine.
The heat-curable epoxy resin systems of this invention may contain epoxy resins of any kind. These resins desirably contain more than one 1,2-epoxy group per molecule, said groups preferably being terminal epoxy or 2-methyloxiranyl groups and, more particularly, 2,3-epoxypropyl groups, which are attached direct to an oxygen, a nitrogen or a sulfur atom.
The epoxy resins thus typically embrace polyglycidyl and poly(~-methylglycidyl) esters which are obtainable by reacting a compound containing two or more carboxyl groups with epichlorohydrin or ,B-methylepichlorohydrin in the presence of aL~ali. Illustrative examples of compounds containing two or more carboxyl groups are aliphatic carboxylic acids such as oxalic acid, succinic acid, adipic acid, sebacic acid, dimerised or trimerised linoleic acid; cycloaliphatic carboxylic acids such as hexahydrophthalic acid, 4-methyl-hexahydrophthalic acid, tetrahydrophthalic acid, 4-methyltetrahydrophthalic acid; or aromatic carboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid or trimesic acid, and the like.
.
Other suitable epoxy resins are the polyglycidyl and poly(~-methylglycidyl) ethers obtainable by reacting a ccompound containing two or more alcoholic or phenolic hydroxyl groups with epichlorohydrin or ,~-methylepichlorohydrin in the presence of alkali or in the presence of an acid catalyst and subsequent treatment with alkali. Such polyglycidyl ethers may be derived from aliphatic polyhydroxyl compounds such asethylene glycol, poly(oxyethylene) polyols such as diethylene glycol or triethylene glycol, propylene glycol or poly(o~yplupylene) polyols, propane-1,3-diol, butane-1,4-diol, pentane-1,5-diol, hexane-1,6-diol, hexane-2,4,6-triol, 1,1,1-trimethylolpropane or pentaerythritol. Other suitable alcohols are cycloaliphatic alcohols such as 1,1-bis(hydroxymethyl)cyclohex-3-ene, bis(4-hydroxycyclohexyl)methane, 2,2-bis(4-hy-droxycyclohexyl)propane, and alcohols containing aromatic rings in the molecule,typically N,N-bis(2-hydroxyethyl)aniline or 4,4'-bis(2-hydroxyethylamino)diphenylme-thane. ~cîellt;d alcohols cont~ining aromatic rings are polyglycidyl ethers derivable from compounds containing two or more phenolic hydroxyl groups, as from resorcinol, brenzcatechol, hydroquinone, phloroglucinol or from polynuclear phenols, conveniently from bis(4-hydroxyphenyl)methane and 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(3,5-di-bromo-4-hydroxyphenyl)propane, 1,1,2,2-tetrakis(4-hydroxyphenyl)ethane, 4,4'-dihydlo~ydiphenyl, bis(4-hydroxyphenyl)sulfone, or from novolaks based on aldehydes such as formaldehyde, acetaldehyde, chloral, furfural, and phenol or phenol derivatives which are substituted by one or more chlorine atoms or Cl-C9alkyl groups, e.g.
4-chlorophenol, cresol or 4-tert-butylphenol, preferably from phenol-formaldehyde and cresol-formaldehyde novolaks.
It is also possible to use other poly(N-glycidyl) compounds that are obtainable by dehydrohalogenation of reaction products of epichlorohydrin and amines containing at least two active hydrogen atoms bound to amino nitrogen, e.g. from aniline, N-butyl-amine, bis(4-aminophenyl)methane, bis(4-aminophenyl)sulfone or bis(4-methylamino-phenyl)m~th:~nt~. Another N-glycidyl compound which is a suitable epoxy resin for the novel compositions of this invention is triglycidyl isocyanate.
The epoxy resins may also be mixed resins that contain one or more than one gylcidyl ether group and one or more than one glycidyl ester group in a molecule, for example the gylcidyl ether-glycidyl ester of salicylic acid.
Epoxy resins that contain non-terminal epoxy groups may also be used, for example vinylcyclohexene dioxide, dicyclopentadiene dioxide, 3,4-epoxydihydrocyclopentadienyl glycidyl ether, limonene dioxide, 3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohexylcar-boxylate and the 6,6'-dimethyl derivative thereof, the bis(3,4-epoxycyclohexanecarboxyl-ate) of ethylene glycol or 3-(3,4-epoxycyclohexyl-8,9-epoxy-2,4-dioxyspiro[5,5]undecane, epoxidised butadiene polymers or epoxidised copolymers of butadiene with other ethylenically unsaturated compounds such as styrene or vinyl acetate.
It will be readily understood that the compositions of this invention may also contain LulcS of two or more than two epoxy resins of the kind referred to above. Sometimes it can be of advantage to use such mixture comprising a liquid and a solid epoxy resin, for instance a IlU~IUlC of different oligomers.
Particularly plcrelled epoxy resins are 3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohex-anecarboxylate and polyglycidyl ethers of novolaks from form~ldehyde and phenol itself or a phenol derivative which is substituted in the ring by a chlorine atom or a Cl-C4aL~yl group, and, in particular, polyglycidyl ethers of bis(4-hydroxyphenyl)methane (bisphenol F) and/or 2,2'-bis(4-hydroxyphenyl)propane (bisphenol A), or mixed glycidyl ethers of bisphenol A and bisphenol F.
One or more than one polycarboxylic acid anhydride is used as the hardener component (b) of the novel epoxy resin compositions. These anhydrides are most preferably compounds which are liquid or solid at room lelllpclature and have in particular a melting or sublimation point of up to 150C. Illustrative examples of suitable anhydrides are phthalic anhydride, hexahydrophthalic anhydride, methyl-1,2,3,6-tetrahydrophthalic anhydride, hexachloroendomethylene-1,2,3,6-tetrahydrophthalic anhydride or methyl-endomethylenetetrahydrophthalic anhydride, maleic anhydride, succinic anhydride or alkenylsuccinic anhydride, e.g. nonenylsuccinic or dodecenylsuccinic anhydride, polysebacic anhydride, polyacelaic anhydride, pyrromellitic dianhydride, benzophenone-3,3',4,4'-tetracarboxylic acid anhydride. It is of course also possible to use n~ ulcs of one or more than one anhydride. Usually about 0.4 to 11 equivalents of polycarboxylic acid anhydride are used per epoxy equivalent in the novel compositions. Larger amounts of hardener, however, can also be used, e.g. corresponding to a ratio of l.S to 1.6 equivalents of anhydride per epoxy equivalent.
The anhydrides of aromatic polycarboxylic acids are preferred, in particular phthalic anhydride, or of cycloaliphatic polycarboxylic acids, e.g. hexahydrophthalic anhydride and tetrahydrophthalic anhydride, or derivatives of these compounds substituted by 214~230 Cl-C4alkyl groups.
Compound (c) of the novel epoxy resin systems and compositions is either 1,4-diazabicy-clo(2,2,2)octane itself or a derivative thereof which is substituted by one or more than one Cl-C4alkyl group. Those skilled in the art are f:~mili:~r with such compounds some of which are co~ e~cially available or can be obtained by known methods, inter aliaaccording to WO-A-87/03 592. 592. 1,4-Diazabicyclo(2,2,2)octane itself is preferred.
Component (d) of the novel epoxy resin compositions is preferably a complex of boron trifluoride or boron trichloride with an amine. Suitable amines are primary and secondary amines as well as, preferably, tertiary amines. The term "amine" in this context shall also be understood as comprising N-heterocycles.
E~c~llcd complexes have the formula B(Hal)3X, wherein X is an amine of formula H2NRl or NRlR2R3 and Hal is a fluorine or chlorine atom, and R1, R2, R3 are eachindependently of one another an aLkyl radical of 1 to 18 carbon atoms, a cycloaL~yl radical of 3 to 18 carbon atoms, an araLkyl radical of 6 to 18 carbon atoms, an aromatic radical of 6 to 18 carbon atoms, or R1 and R2, together with the nitrogen atom in the above formula, are a five- or six-membered heterocycle to which a further benzene ring may be fused, and R3 has one of the mt~.~ning.~ given above, or Rl, R2 and R3, together with the nitrogen atom in the above formula, are a five- or six-membered heterocycle to which a further benzene ring may be fused.
Illustrative examples of suitable amines are ethylamine, trimethylamine, tri-n-propylamine, N,N-dimethyloctylamine, triphenylamine, N,N'-dimethylaniline,N-benzyldimethylamine, pyridine, the different picolines, collidine (2,4,6-trimethylpyri-dine), quinoline or isoquinoline, piperidine, N-methylpiperidine, N-methylmorpholine, 1,4-diazabicyclo(2,2,2)octane, hexa(N-methyl)melamine, N-cyclohexyldimethylamine or phenylenedi~mines such as 1,4-phenylen-liAmine. Such boron hlide complexes are known and can be prepared by, or in general accordance with, the methods described in US patents 2 890 195 and 3 793 247.
Particularly preferred complexes are complexes of boron trifluoride and, preferably, of boron trichloride, with aliphatic amines in which the aliphatic moieties may each independently of one another contain 1 to 8 carbon atoms. Complexes of BCl3 withN,N-dimethyloctylamine and of BF3 with monoethylamine are most preferred.
21412~0 The epoxy resin compositions contain the curing accelerator, i.e. components (c) and (d) together, in the total amount commonly employed for using tertiary amines as accelerators for anhydride curing, i.e. generally in an amount of 0.05 to 15 % by weight, preferably of 0.3 to 5 % by weight, based on the total amount of epoxy resin and polycarboxylic acid anhydride. It is most preferred to use a total amount of accelerator of less than 2.5 % by weight, typically of 0.5 to 1.5 % by weight, based on the total amount of epoxy resin and polycarboxylic acid anhydride.
The skilled person can vary at will the ratio of the two accelerator components (c) and (d) to each other in acordance with pot-life and storage stability over a relatively wide range.
If necessary by means of simple measurements, for example of the gel time or theviscosity increase of the accelerated epoxy resin compositions, he can quickly determine the ratio of components (c) and (d) that meets his re~luilclllenls. Particularly good results can be achieved if the weight ratio of the DABCO component (c) to the boron halide complex component (d) is from 8 to 92, preferably from 20 to 80 and from 70 to 25, most preferably from 40 to 60 and from 75 to 25. A very balanced reactivity/stability ratio and at the same time a very good Tg value for the cured m~te,ri~l may be achieved with mi~lulc;s of approximately equal parts by weight of components (c) and (d).
The novel compositions may additionally contain the further components commonly employed in the art of heat-curable epoxy resin compositions, typically including plasticisers such as dibutyl phth~ te, dioctyl phthalate, or tricresyl phosphate, suitable inert solvents, reactive diluents, in particular monofunctional epoxides, for example butyl glycidyl ether, isooctyl glycidyl ether, phenyl glycidyl ether or glycidyl esters of monofunctional carboxylic acids, in particular (branched) aliphatic carboxylic acids. Other customary additives include pigments, dyes, flame retardants, wetting agents, antifoams, antioxidants and light stabilisers. In some cases it may also be useful to add polyalkylene polyols such as polyethylene glycol or polypropylene glycol, preferably in an amount of 1 to 30 % by weight, based on epoxy resin, for example to enhance the mechanical properties such as flexibility, of the cured material.
A further group of additives comprises extenders, reinforcing agents and fillers.
Illustrative examples of such additives are asphalt, bitumen, kaolin (china clay), quartz powder, cristobalite, glass powder, glass spheres, chalk, mica, wollastonite, alumina, magnesium oxide, fibre material, also in powdered form such as glass fibres, carbon - 214~230 fibres, metal fibres, polyvinyl chloride, nylon, polyethylene, polyester, cured epoxy material, or flame-proofing fillers, in particular aluminium trihydrate. The fillers may in some cases be surface-treated, e.g. with silane or organotitanium adhesion promoters. It is of course also possible to use Illi~Ul'eS of fillers. The fillers preferably have a particle size in the range from 10 to 3000 llm, more particularly from S0 to 1000 ~m. The content of such fillers in the novel llu~lules may typically be from 20 to 70 % by weight, preferably from 50 to 65 % by weight. Especially when using fillers it can be useful to add an ~nti~ettling agent to the novel epoxy resin compositions, conveniently a thixotropic agent such as silia, bentonite or hydrogenated castor oil. As the antisettling action of the thixotropic agent at the elevated temperatures that may occur in the cure of thecompositions, in particular shortly before gelation, may sometimes be not quite sufficient owing to an initial decrease in viscosity, it may also be useful to add to the novel compositions polymers that are soluble in the hot composition, for example polyvinyl formals, polyvinyl butyrals, polyoxyethylene, polycaprolactones or polyamides, usually in amounts of 0.5 to 20 % by weight, preferably 1 to 3% by weight, based on the epoxy resin.
The epoxy resin compositions of this invention can be formul:~ted in known manner as multicomponent systems, i.e. in the form of a number of single components each of which comprises only a portion of components (a), (b), (c) and (d). In the case of two component systems the accelerator composition can be blended in equal or in different proportions either with the epoxy resin component or, preferably, the hardener component, but also with both components. It will be readily appreciated that it is equally possible to add one constituent of the novel curing accelerator to one of the two components, or to add one constituent to one of the components, for example the hardener component, while using the other constituent of the accelerator unblended. Another multicomponent system of this invention might consist of 1,4-diazabicyclo(2,2,2)octane or a Cl-C4alkyl-substituted derivative of 1,4-diazabicyclo(2,2,2)octane as a first component and a curable composition comprising an epoxy resin, a polycarboxylic acid anhydride and the relatively latent complex of the boron halide with the amine as a further component. A particularly useful system of this invention is one comprising more than two components, namely an epoxy resin component, a hardener component and a curing accelerator system consisting of the above constituents (c) and (d) as third component.
Compositions comprising 1,4-diazabicyclo(2,2,2)octane or a Cl-C4aL~yl-substituted derivative of 1,4-diazabicyclo(2,2,2)octane, a complex of a boron halide with an amine and optionally a polycarboxylic acid anhydride and/or a solvent, e.g. polyethylene glycol 214~230 or dibutyl phthalate, likewise constitute an object of the invention as novel single components of multicomponent systems of this invention.
The novel epoxy resin systems or single components for the preparation of said systems can be obtained by mixing their constituents using conventional means such as stirrers, kne?,-lers, rolls or mills, with or without heating said constituents or components. As it is usually desired to mix the epoxy resin with the hardener below the curing ~enlpel~ture, it can be useful to premix other constituents of the novel system, conveniently the curing accelerator (c) and (d), but also fillers or other additives, initally with the epoxy resin or the hardener, as in this case higher temperaturees can usually be applied.
The cure of the final mibc~ult; is normally effected in the Lempel~ture range from 80 to 200C, preferably from 90 to 160C.
The heat-curable systems of this invention can be used as casting resins for all utilities for which heat-curable epoxy resin systems are employed, typically for making prepregs or l~min~tes, for surface coatings, for casting electrical and electronic components, as adhesives or for fabricating moulded objects. The invention therefore also relates to the use of the described curable systems as casting compositions, preferably as electrical casting compositions.
The moulded objects can be fabricated by conventional methods, for example by hand. A
further possibility is the use of the automatic pressure gelation method that is disclosed, inter alia, in EP-A-0 333 456.
A further object of the invention is accordingly a process for the production of moulded objects using the above described epoxy resin system, which comprises mixing a component of said system comprising the epoxy resin and a component of said system that comprises the hardener as well as the other optional constituents of the system at a temperature below the curing temperature, e.g. in the temperature range from 40 to 80C, preferably from 40 to 60C, and introducing said mixture under normal or elevated pressure, e.g. a pressure of 1.5 to 6 bar, preferably from 1.5 to 3 bar, into a mould in which the temperature is sufficiently high to effect cure of the resin moulding material, and preferably introducing uncured resin moulding m:~teri~l continuously in such an amount as to compensate for any shrinkage of the resin moulding material in the mould occurring in the course of the cure.
`- 21~4230 Example 1: 100 g of diglycidyl ether of bisphenol A (epoxy value 5.2 eq/kg) are homogeneously mixed with 79.8 g of a mixture of methyltetrahydrophthalic anhydride isomers (0.85 mol of anhydride/epoxide equivalent) and with each of the amounts of 1,4-diazabicyclo(2,2,2)octane (DABCO) indicated in Table 1 below and boron trichloride-octyl dimethylamine complex.
The mixtures are tested to determine the following values: the time for the viscosity to reach 1500 mPa-s at a temperature of 80C (viscosity build-up according to DIN 53015/Hoeppler falling-ball viscosimeter; sample c. 10 ml), the Gelnorm gelation time (15 ml sample) according to DIN 16945, Sheet 1, using a Gelnorm(~) gel timer (supplied by GEL INSTl?UMENT AD, CH), as well as the softening temperature Tg according to IEC Standard 15a of the Int. Electrotechnical Commission using a Mettler TA 3000~ (heating up rate 10C/minute; weighed sample c. 30 milligrams). The values measured are also shown in Table 1.
Table 1:
Example No. 1.1 1.2 1.3 1.4 1.5 Amounts of DABCO
in grams 0-7 0.5 0.35 0.2 0.0 Bcl3l(cH3)2N(c8Hls)-complex 0.0 0.2 0.35 0.5 0.7 Viscosity build-up [min~150 205 270 -* -*
Gel time ** at 80 C 3h46' 5h20' 6h33' 9hO8'27hO6' 100C 52'50" lhO6' lh24' lh36'2h48' 140 C 3'43" 5'42" 5'38" 6'34" 8'22"
Tg [C] 133 132 134 131 127 * not measured ** ' = minutes; " = seconds - 21442~0 Example 2: 100 g of a mixed diglycidyl ether of bisphenol A and bisphenol F (epoxy value of the mixture 5.65 eq/kg) are homogeneously mixed with 80 g of a mixture of methyltetrahydrophthalic anhydride isomers (0.85 mol of anhydride/epoxide equivalent), 11 g of polyethylene glycol 400 (molecular weight 400), 0.2 g of 1,4-diazabicyclo(2,2,2)-octane and O.S g of boron trichloride-octyl dimethylamine complex and quartz powder W 12 to a composition that contains 65 % by weight of quartz powder.
The epoxy resin system has the following properties:
gel time at 80 C 7h30' 100 C lhS0' 140 C 7'37"-The following ~lopellies are determined after a cure of 4 hours at 100C and 10 hours at 140C:
Tg(dete~ ined as in Example 1) 90C;
flexural strengthl lSl N/mm2;
modulus of elasticity from flexural testl 11060 N/mm2;
impact strength2 11 kJ/m2.
1 according to ISO 178; specimen measuring 60xlOx4 millimetres 2 according to ISO 179/lD; specimen measuring 60xlOx4 millimetres The gel time at 80C of this composition is accordingly more than twice, and hence the pot-life is also more than twice, that of a similar epoxy resin composition containing benzyl dimethylamine as curing accelerator, while the other data listed above are at least as good as those of a similar composition containing benzyl dimethylamine.
Epoxy resin systems or compositions of the above-mentioned kind are disclosed, inter alia, in Japanese published patent specification JP-A-Sho 01-054022 (1989). The curingaccelerator 1,4-diazabicyclo(2,2,2)octane (abbreviated to DABCO or also known astriethylen~li~mine) effects a rapid cure of the compositions at elevated ~Illp~,~dtule, e.g.
from 120C, so that short demoulding times can be achieved. However, epoxy resincompositions containing 1,4-diazabicyclo(2,2,2)octane as curing accelerator are also highly reactive even at moderately elevated lelllpel~tures and therefore have only a relatively poor shelf stability and, especially in the temperature range from 60 to 80C
which frequently has to be applied during the h~nflling and/or processing of thecompositions prior to the cure, have only unsatisfactory stability and a short pot life.
Another tertiary amine mentioned as accelerator in JP-A-Sho 01-054022 is benzyl dime-thylamine. Benzyl dimethylamine, which is often used as curing accelerator in corresponding commercial products, has the same shortcomings as DABCO, and indeed even to a more pronounced degree.
In contrast, epoxy resin systems comprising an anhydride hardener and a complex of a boron halide and a tertiary amine as curing accelerator are substantially more stable at moderately elevated temperatures. Such compositions are disclosed, inter alia, in US-A-3 793 247, but have the converse drawback that they exhibit a relatively poor reactivity at elevated temperature and hence give rise to demoulding times that are often currently no longer economically acceptable.
It is therefore the object of this invention to provide an accelerator for the thermal cure of epoxy resins with polycarboxylic acid anhydrides, which accelerator has a more balanced ratio of reactivity at elevated temperature to stability (to a premature onset of cure) at moderately elevated ~elllpe~ ult; than conventional curing accelerators.
This object is achieved in the practice of this invention by using as curing accelerator a mixture of 1,4-diazabicyclo-(2,2,2)-octane or a Cl-C4alkyl-substituted derivative of 1,4-diazabicyclo-(2,2,2)-octane and a complex of a boron halide with a tertiary amine.
Surprisingly, the l~ ul~;s of this invention accelerate at low temperature the cure of epoxy resins with hardeners such as polycarboxylic acid anhydrides substantially less than pure 1,4-diazabicyclo(2,2,2)octane or benzyl dimethylamine, while their accelerating action at the temperatures normally used for the cure differs from that of the cited accelerators only to a degree that is entirely negligible for actual practice.
The invention thus relates in one of its aspects to a heat-curable epoxy resin composition comprising (a) at least one epoxy resin, (b) at least one polycarboxylic acid anhydride, and (c) 1,4-diazabicyclo(2,2,2)octane or a C1-C4alkyl-substituted derivative of 1,4-diazabicyclo(2,2,2)octane as curing accelerator, and wherein one part of the curing accelerator (c) is replaced by (d) a complex of a boron halide with an amine.
The heat-curable epoxy resin systems of this invention may contain epoxy resins of any kind. These resins desirably contain more than one 1,2-epoxy group per molecule, said groups preferably being terminal epoxy or 2-methyloxiranyl groups and, more particularly, 2,3-epoxypropyl groups, which are attached direct to an oxygen, a nitrogen or a sulfur atom.
The epoxy resins thus typically embrace polyglycidyl and poly(~-methylglycidyl) esters which are obtainable by reacting a compound containing two or more carboxyl groups with epichlorohydrin or ,B-methylepichlorohydrin in the presence of aL~ali. Illustrative examples of compounds containing two or more carboxyl groups are aliphatic carboxylic acids such as oxalic acid, succinic acid, adipic acid, sebacic acid, dimerised or trimerised linoleic acid; cycloaliphatic carboxylic acids such as hexahydrophthalic acid, 4-methyl-hexahydrophthalic acid, tetrahydrophthalic acid, 4-methyltetrahydrophthalic acid; or aromatic carboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid or trimesic acid, and the like.
.
Other suitable epoxy resins are the polyglycidyl and poly(~-methylglycidyl) ethers obtainable by reacting a ccompound containing two or more alcoholic or phenolic hydroxyl groups with epichlorohydrin or ,~-methylepichlorohydrin in the presence of alkali or in the presence of an acid catalyst and subsequent treatment with alkali. Such polyglycidyl ethers may be derived from aliphatic polyhydroxyl compounds such asethylene glycol, poly(oxyethylene) polyols such as diethylene glycol or triethylene glycol, propylene glycol or poly(o~yplupylene) polyols, propane-1,3-diol, butane-1,4-diol, pentane-1,5-diol, hexane-1,6-diol, hexane-2,4,6-triol, 1,1,1-trimethylolpropane or pentaerythritol. Other suitable alcohols are cycloaliphatic alcohols such as 1,1-bis(hydroxymethyl)cyclohex-3-ene, bis(4-hydroxycyclohexyl)methane, 2,2-bis(4-hy-droxycyclohexyl)propane, and alcohols containing aromatic rings in the molecule,typically N,N-bis(2-hydroxyethyl)aniline or 4,4'-bis(2-hydroxyethylamino)diphenylme-thane. ~cîellt;d alcohols cont~ining aromatic rings are polyglycidyl ethers derivable from compounds containing two or more phenolic hydroxyl groups, as from resorcinol, brenzcatechol, hydroquinone, phloroglucinol or from polynuclear phenols, conveniently from bis(4-hydroxyphenyl)methane and 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(3,5-di-bromo-4-hydroxyphenyl)propane, 1,1,2,2-tetrakis(4-hydroxyphenyl)ethane, 4,4'-dihydlo~ydiphenyl, bis(4-hydroxyphenyl)sulfone, or from novolaks based on aldehydes such as formaldehyde, acetaldehyde, chloral, furfural, and phenol or phenol derivatives which are substituted by one or more chlorine atoms or Cl-C9alkyl groups, e.g.
4-chlorophenol, cresol or 4-tert-butylphenol, preferably from phenol-formaldehyde and cresol-formaldehyde novolaks.
It is also possible to use other poly(N-glycidyl) compounds that are obtainable by dehydrohalogenation of reaction products of epichlorohydrin and amines containing at least two active hydrogen atoms bound to amino nitrogen, e.g. from aniline, N-butyl-amine, bis(4-aminophenyl)methane, bis(4-aminophenyl)sulfone or bis(4-methylamino-phenyl)m~th:~nt~. Another N-glycidyl compound which is a suitable epoxy resin for the novel compositions of this invention is triglycidyl isocyanate.
The epoxy resins may also be mixed resins that contain one or more than one gylcidyl ether group and one or more than one glycidyl ester group in a molecule, for example the gylcidyl ether-glycidyl ester of salicylic acid.
Epoxy resins that contain non-terminal epoxy groups may also be used, for example vinylcyclohexene dioxide, dicyclopentadiene dioxide, 3,4-epoxydihydrocyclopentadienyl glycidyl ether, limonene dioxide, 3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohexylcar-boxylate and the 6,6'-dimethyl derivative thereof, the bis(3,4-epoxycyclohexanecarboxyl-ate) of ethylene glycol or 3-(3,4-epoxycyclohexyl-8,9-epoxy-2,4-dioxyspiro[5,5]undecane, epoxidised butadiene polymers or epoxidised copolymers of butadiene with other ethylenically unsaturated compounds such as styrene or vinyl acetate.
It will be readily understood that the compositions of this invention may also contain LulcS of two or more than two epoxy resins of the kind referred to above. Sometimes it can be of advantage to use such mixture comprising a liquid and a solid epoxy resin, for instance a IlU~IUlC of different oligomers.
Particularly plcrelled epoxy resins are 3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohex-anecarboxylate and polyglycidyl ethers of novolaks from form~ldehyde and phenol itself or a phenol derivative which is substituted in the ring by a chlorine atom or a Cl-C4aL~yl group, and, in particular, polyglycidyl ethers of bis(4-hydroxyphenyl)methane (bisphenol F) and/or 2,2'-bis(4-hydroxyphenyl)propane (bisphenol A), or mixed glycidyl ethers of bisphenol A and bisphenol F.
One or more than one polycarboxylic acid anhydride is used as the hardener component (b) of the novel epoxy resin compositions. These anhydrides are most preferably compounds which are liquid or solid at room lelllpclature and have in particular a melting or sublimation point of up to 150C. Illustrative examples of suitable anhydrides are phthalic anhydride, hexahydrophthalic anhydride, methyl-1,2,3,6-tetrahydrophthalic anhydride, hexachloroendomethylene-1,2,3,6-tetrahydrophthalic anhydride or methyl-endomethylenetetrahydrophthalic anhydride, maleic anhydride, succinic anhydride or alkenylsuccinic anhydride, e.g. nonenylsuccinic or dodecenylsuccinic anhydride, polysebacic anhydride, polyacelaic anhydride, pyrromellitic dianhydride, benzophenone-3,3',4,4'-tetracarboxylic acid anhydride. It is of course also possible to use n~ ulcs of one or more than one anhydride. Usually about 0.4 to 11 equivalents of polycarboxylic acid anhydride are used per epoxy equivalent in the novel compositions. Larger amounts of hardener, however, can also be used, e.g. corresponding to a ratio of l.S to 1.6 equivalents of anhydride per epoxy equivalent.
The anhydrides of aromatic polycarboxylic acids are preferred, in particular phthalic anhydride, or of cycloaliphatic polycarboxylic acids, e.g. hexahydrophthalic anhydride and tetrahydrophthalic anhydride, or derivatives of these compounds substituted by 214~230 Cl-C4alkyl groups.
Compound (c) of the novel epoxy resin systems and compositions is either 1,4-diazabicy-clo(2,2,2)octane itself or a derivative thereof which is substituted by one or more than one Cl-C4alkyl group. Those skilled in the art are f:~mili:~r with such compounds some of which are co~ e~cially available or can be obtained by known methods, inter aliaaccording to WO-A-87/03 592. 592. 1,4-Diazabicyclo(2,2,2)octane itself is preferred.
Component (d) of the novel epoxy resin compositions is preferably a complex of boron trifluoride or boron trichloride with an amine. Suitable amines are primary and secondary amines as well as, preferably, tertiary amines. The term "amine" in this context shall also be understood as comprising N-heterocycles.
E~c~llcd complexes have the formula B(Hal)3X, wherein X is an amine of formula H2NRl or NRlR2R3 and Hal is a fluorine or chlorine atom, and R1, R2, R3 are eachindependently of one another an aLkyl radical of 1 to 18 carbon atoms, a cycloaL~yl radical of 3 to 18 carbon atoms, an araLkyl radical of 6 to 18 carbon atoms, an aromatic radical of 6 to 18 carbon atoms, or R1 and R2, together with the nitrogen atom in the above formula, are a five- or six-membered heterocycle to which a further benzene ring may be fused, and R3 has one of the mt~.~ning.~ given above, or Rl, R2 and R3, together with the nitrogen atom in the above formula, are a five- or six-membered heterocycle to which a further benzene ring may be fused.
Illustrative examples of suitable amines are ethylamine, trimethylamine, tri-n-propylamine, N,N-dimethyloctylamine, triphenylamine, N,N'-dimethylaniline,N-benzyldimethylamine, pyridine, the different picolines, collidine (2,4,6-trimethylpyri-dine), quinoline or isoquinoline, piperidine, N-methylpiperidine, N-methylmorpholine, 1,4-diazabicyclo(2,2,2)octane, hexa(N-methyl)melamine, N-cyclohexyldimethylamine or phenylenedi~mines such as 1,4-phenylen-liAmine. Such boron hlide complexes are known and can be prepared by, or in general accordance with, the methods described in US patents 2 890 195 and 3 793 247.
Particularly preferred complexes are complexes of boron trifluoride and, preferably, of boron trichloride, with aliphatic amines in which the aliphatic moieties may each independently of one another contain 1 to 8 carbon atoms. Complexes of BCl3 withN,N-dimethyloctylamine and of BF3 with monoethylamine are most preferred.
21412~0 The epoxy resin compositions contain the curing accelerator, i.e. components (c) and (d) together, in the total amount commonly employed for using tertiary amines as accelerators for anhydride curing, i.e. generally in an amount of 0.05 to 15 % by weight, preferably of 0.3 to 5 % by weight, based on the total amount of epoxy resin and polycarboxylic acid anhydride. It is most preferred to use a total amount of accelerator of less than 2.5 % by weight, typically of 0.5 to 1.5 % by weight, based on the total amount of epoxy resin and polycarboxylic acid anhydride.
The skilled person can vary at will the ratio of the two accelerator components (c) and (d) to each other in acordance with pot-life and storage stability over a relatively wide range.
If necessary by means of simple measurements, for example of the gel time or theviscosity increase of the accelerated epoxy resin compositions, he can quickly determine the ratio of components (c) and (d) that meets his re~luilclllenls. Particularly good results can be achieved if the weight ratio of the DABCO component (c) to the boron halide complex component (d) is from 8 to 92, preferably from 20 to 80 and from 70 to 25, most preferably from 40 to 60 and from 75 to 25. A very balanced reactivity/stability ratio and at the same time a very good Tg value for the cured m~te,ri~l may be achieved with mi~lulc;s of approximately equal parts by weight of components (c) and (d).
The novel compositions may additionally contain the further components commonly employed in the art of heat-curable epoxy resin compositions, typically including plasticisers such as dibutyl phth~ te, dioctyl phthalate, or tricresyl phosphate, suitable inert solvents, reactive diluents, in particular monofunctional epoxides, for example butyl glycidyl ether, isooctyl glycidyl ether, phenyl glycidyl ether or glycidyl esters of monofunctional carboxylic acids, in particular (branched) aliphatic carboxylic acids. Other customary additives include pigments, dyes, flame retardants, wetting agents, antifoams, antioxidants and light stabilisers. In some cases it may also be useful to add polyalkylene polyols such as polyethylene glycol or polypropylene glycol, preferably in an amount of 1 to 30 % by weight, based on epoxy resin, for example to enhance the mechanical properties such as flexibility, of the cured material.
A further group of additives comprises extenders, reinforcing agents and fillers.
Illustrative examples of such additives are asphalt, bitumen, kaolin (china clay), quartz powder, cristobalite, glass powder, glass spheres, chalk, mica, wollastonite, alumina, magnesium oxide, fibre material, also in powdered form such as glass fibres, carbon - 214~230 fibres, metal fibres, polyvinyl chloride, nylon, polyethylene, polyester, cured epoxy material, or flame-proofing fillers, in particular aluminium trihydrate. The fillers may in some cases be surface-treated, e.g. with silane or organotitanium adhesion promoters. It is of course also possible to use Illi~Ul'eS of fillers. The fillers preferably have a particle size in the range from 10 to 3000 llm, more particularly from S0 to 1000 ~m. The content of such fillers in the novel llu~lules may typically be from 20 to 70 % by weight, preferably from 50 to 65 % by weight. Especially when using fillers it can be useful to add an ~nti~ettling agent to the novel epoxy resin compositions, conveniently a thixotropic agent such as silia, bentonite or hydrogenated castor oil. As the antisettling action of the thixotropic agent at the elevated temperatures that may occur in the cure of thecompositions, in particular shortly before gelation, may sometimes be not quite sufficient owing to an initial decrease in viscosity, it may also be useful to add to the novel compositions polymers that are soluble in the hot composition, for example polyvinyl formals, polyvinyl butyrals, polyoxyethylene, polycaprolactones or polyamides, usually in amounts of 0.5 to 20 % by weight, preferably 1 to 3% by weight, based on the epoxy resin.
The epoxy resin compositions of this invention can be formul:~ted in known manner as multicomponent systems, i.e. in the form of a number of single components each of which comprises only a portion of components (a), (b), (c) and (d). In the case of two component systems the accelerator composition can be blended in equal or in different proportions either with the epoxy resin component or, preferably, the hardener component, but also with both components. It will be readily appreciated that it is equally possible to add one constituent of the novel curing accelerator to one of the two components, or to add one constituent to one of the components, for example the hardener component, while using the other constituent of the accelerator unblended. Another multicomponent system of this invention might consist of 1,4-diazabicyclo(2,2,2)octane or a Cl-C4alkyl-substituted derivative of 1,4-diazabicyclo(2,2,2)octane as a first component and a curable composition comprising an epoxy resin, a polycarboxylic acid anhydride and the relatively latent complex of the boron halide with the amine as a further component. A particularly useful system of this invention is one comprising more than two components, namely an epoxy resin component, a hardener component and a curing accelerator system consisting of the above constituents (c) and (d) as third component.
Compositions comprising 1,4-diazabicyclo(2,2,2)octane or a Cl-C4aL~yl-substituted derivative of 1,4-diazabicyclo(2,2,2)octane, a complex of a boron halide with an amine and optionally a polycarboxylic acid anhydride and/or a solvent, e.g. polyethylene glycol 214~230 or dibutyl phthalate, likewise constitute an object of the invention as novel single components of multicomponent systems of this invention.
The novel epoxy resin systems or single components for the preparation of said systems can be obtained by mixing their constituents using conventional means such as stirrers, kne?,-lers, rolls or mills, with or without heating said constituents or components. As it is usually desired to mix the epoxy resin with the hardener below the curing ~enlpel~ture, it can be useful to premix other constituents of the novel system, conveniently the curing accelerator (c) and (d), but also fillers or other additives, initally with the epoxy resin or the hardener, as in this case higher temperaturees can usually be applied.
The cure of the final mibc~ult; is normally effected in the Lempel~ture range from 80 to 200C, preferably from 90 to 160C.
The heat-curable systems of this invention can be used as casting resins for all utilities for which heat-curable epoxy resin systems are employed, typically for making prepregs or l~min~tes, for surface coatings, for casting electrical and electronic components, as adhesives or for fabricating moulded objects. The invention therefore also relates to the use of the described curable systems as casting compositions, preferably as electrical casting compositions.
The moulded objects can be fabricated by conventional methods, for example by hand. A
further possibility is the use of the automatic pressure gelation method that is disclosed, inter alia, in EP-A-0 333 456.
A further object of the invention is accordingly a process for the production of moulded objects using the above described epoxy resin system, which comprises mixing a component of said system comprising the epoxy resin and a component of said system that comprises the hardener as well as the other optional constituents of the system at a temperature below the curing temperature, e.g. in the temperature range from 40 to 80C, preferably from 40 to 60C, and introducing said mixture under normal or elevated pressure, e.g. a pressure of 1.5 to 6 bar, preferably from 1.5 to 3 bar, into a mould in which the temperature is sufficiently high to effect cure of the resin moulding material, and preferably introducing uncured resin moulding m:~teri~l continuously in such an amount as to compensate for any shrinkage of the resin moulding material in the mould occurring in the course of the cure.
`- 21~4230 Example 1: 100 g of diglycidyl ether of bisphenol A (epoxy value 5.2 eq/kg) are homogeneously mixed with 79.8 g of a mixture of methyltetrahydrophthalic anhydride isomers (0.85 mol of anhydride/epoxide equivalent) and with each of the amounts of 1,4-diazabicyclo(2,2,2)octane (DABCO) indicated in Table 1 below and boron trichloride-octyl dimethylamine complex.
The mixtures are tested to determine the following values: the time for the viscosity to reach 1500 mPa-s at a temperature of 80C (viscosity build-up according to DIN 53015/Hoeppler falling-ball viscosimeter; sample c. 10 ml), the Gelnorm gelation time (15 ml sample) according to DIN 16945, Sheet 1, using a Gelnorm(~) gel timer (supplied by GEL INSTl?UMENT AD, CH), as well as the softening temperature Tg according to IEC Standard 15a of the Int. Electrotechnical Commission using a Mettler TA 3000~ (heating up rate 10C/minute; weighed sample c. 30 milligrams). The values measured are also shown in Table 1.
Table 1:
Example No. 1.1 1.2 1.3 1.4 1.5 Amounts of DABCO
in grams 0-7 0.5 0.35 0.2 0.0 Bcl3l(cH3)2N(c8Hls)-complex 0.0 0.2 0.35 0.5 0.7 Viscosity build-up [min~150 205 270 -* -*
Gel time ** at 80 C 3h46' 5h20' 6h33' 9hO8'27hO6' 100C 52'50" lhO6' lh24' lh36'2h48' 140 C 3'43" 5'42" 5'38" 6'34" 8'22"
Tg [C] 133 132 134 131 127 * not measured ** ' = minutes; " = seconds - 21442~0 Example 2: 100 g of a mixed diglycidyl ether of bisphenol A and bisphenol F (epoxy value of the mixture 5.65 eq/kg) are homogeneously mixed with 80 g of a mixture of methyltetrahydrophthalic anhydride isomers (0.85 mol of anhydride/epoxide equivalent), 11 g of polyethylene glycol 400 (molecular weight 400), 0.2 g of 1,4-diazabicyclo(2,2,2)-octane and O.S g of boron trichloride-octyl dimethylamine complex and quartz powder W 12 to a composition that contains 65 % by weight of quartz powder.
The epoxy resin system has the following properties:
gel time at 80 C 7h30' 100 C lhS0' 140 C 7'37"-The following ~lopellies are determined after a cure of 4 hours at 100C and 10 hours at 140C:
Tg(dete~ ined as in Example 1) 90C;
flexural strengthl lSl N/mm2;
modulus of elasticity from flexural testl 11060 N/mm2;
impact strength2 11 kJ/m2.
1 according to ISO 178; specimen measuring 60xlOx4 millimetres 2 according to ISO 179/lD; specimen measuring 60xlOx4 millimetres The gel time at 80C of this composition is accordingly more than twice, and hence the pot-life is also more than twice, that of a similar epoxy resin composition containing benzyl dimethylamine as curing accelerator, while the other data listed above are at least as good as those of a similar composition containing benzyl dimethylamine.
Claims (10)
1. A heat-curable epoxy resin system comprising (a) at least one epoxy resin, (b) at least one polycarboxylic acid anhydride, and (c) 1,4-diazabicyclo(2,2,2)octane or a C1-C4alkyl-substituted derivative of 1,4-diazabicyclo(2,2,2)octane as curing accelerator, and wherein one portion of the curing accelerator (c) is replaced by (d) a complex of a boron halide with an amine.
2. An epoxy resin system according to claim 1, comprising 1,4-diazabicyclo(2,2,2)octane as component (c).
3. An epoxy resin system according to claim 1, wherein the complex has the formula B(Hal)3X, wherein X is an amine of formula H2NR1 or NR1R2R3 and Hal is a fluorine or chlorine atom, and R1, R2, R3 are each independently of one another an alkyl radical of 1 to 18 carbon atoms, a cycloalkyl radical of 3 to 18 carbon atoms, an aralkyl radical of 6 to 18 carbon atoms, an aromatic radical of 6 to 18 carbon atoms, or R1 and R2, together with the nitrogen atom in the above formula, are a five- or six-membered heterocycle to which a further benzene ring may be fused, and R3 has one of the meanings given above, or R1, R2 and R3, together with the nitrogen atom in the above formula, are a five- or six-membered heterocycle to which a further benzene ring may be fused.
4. An epoxy resin system according to claim 1, wherein the weight ratio of component (c) to component (d) is from 8 to 92 and from 75 to 25.
5. An epoxy resin system according to claim 1, wherein the epoxy resin is a glycidyl ether of bis(4-hydroxyphenyl)methane (bisphenol F) and/or of 2,2'-bis(4-hydroxyphenyl)pro-pane (bisphenol A), or is a mixed glycidyl ether of bisphenol A and bisphenol F.
6. An epoxy resin system according to claim 1, which contains an anhydride of anaromatic or cycloaliphatic polycarboxylic acid.
7. An epoxy resin system according to claim 1 in the form of a number of single components each comprising only a portion of the constituents (a), (b), (c) and (d).
8. A composition comprising 1,4-diazabicyclo(2,2,2)octane or a C1-C4alkyl-substituted derivative of 1,4-diazabicyclo(2,2,2)octane, a complex of a boron halide with an amine and optionally a polycarboxylic acid anhydride and/or a solvent.
9. Use of an epoxy resin system as claimed in claim 1 as casting composition, preferably as electrical casting composition.
10. A process for fabricating moulded objects using an epoxy resin composition as claimed in claim 1, which comprises mixing a component of said system comprising the epoxy resin and a component of said system that comprises the hardener as well as the other optional constituents of the system at a temperature below the curing temperature, and introducing said mixture under normal or elevated pressure, into a mould in which the temperature is sufficiently high to effect cure of the resin moulding material, and preferably introducing uncured resin moulding material continuously in such an amount as to compensate for any shrinkage of the resin moulding material in the mould occurring in the course of the cure.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CH720/94-3 | 1994-03-10 | ||
| CH72094 | 1994-03-10 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2144230A1 true CA2144230A1 (en) | 1995-09-11 |
Family
ID=4193621
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2144230 Abandoned CA2144230A1 (en) | 1994-03-10 | 1995-03-08 | Heat-curable epoxy resin systems having a good reactivity/stability ratio |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP0671427B1 (en) |
| JP (1) | JP3477591B2 (en) |
| CA (1) | CA2144230A1 (en) |
| DE (1) | DE59502297D1 (en) |
| ES (1) | ES2118521T3 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102341427A (en) * | 2009-03-06 | 2012-02-01 | 西门子公司 | Cast resin system for isolators |
| US8779032B2 (en) | 2009-03-30 | 2014-07-15 | 3M Innovative Properties Company | Epoxy resin based core filler material developing low exothermic heat |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2023101268A (en) * | 2022-01-07 | 2023-07-20 | ナガセケムテックス株式会社 | Thermosetting resin composition |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1520206A1 (en) * | 1963-07-26 | 1969-10-09 | Licentia Gmbh | Impregnation, immersion or adhesive resin based on an epoxy resin mixed with BF3 amine complex as hardener, which cures quickly under the action of heat and has an improved pot life |
| GB1317048A (en) * | 1970-08-11 | 1973-05-16 | Ciba Geigy Uk Ltd | Curable epoxide resin compositions |
| US4663072A (en) * | 1984-12-24 | 1987-05-05 | Ford Motor Company | Acid anhydride mixtures in paste form useful for curing epoxy resins and a dual catalyst system therefor |
| US4698408A (en) * | 1986-07-21 | 1987-10-06 | Ashland Oil, Inc. | Sag resistant two-component urethane adhesives with improved thermal stability |
| JPS6454022A (en) * | 1987-08-25 | 1989-03-01 | Toshiba Corp | Epoxy resin casting composition |
-
1995
- 1995-03-01 EP EP95810128A patent/EP0671427B1/en not_active Expired - Lifetime
- 1995-03-01 ES ES95810128T patent/ES2118521T3/en not_active Expired - Lifetime
- 1995-03-01 DE DE59502297T patent/DE59502297D1/en not_active Expired - Lifetime
- 1995-03-08 CA CA 2144230 patent/CA2144230A1/en not_active Abandoned
- 1995-03-10 JP JP07982595A patent/JP3477591B2/en not_active Expired - Lifetime
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102341427A (en) * | 2009-03-06 | 2012-02-01 | 西门子公司 | Cast resin system for isolators |
| CN102341427B (en) * | 2009-03-06 | 2014-06-11 | 西门子公司 | Cast resin system for isolators |
| US8779032B2 (en) | 2009-03-30 | 2014-07-15 | 3M Innovative Properties Company | Epoxy resin based core filler material developing low exothermic heat |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3477591B2 (en) | 2003-12-10 |
| EP0671427A1 (en) | 1995-09-13 |
| DE59502297D1 (en) | 1998-07-02 |
| EP0671427B1 (en) | 1998-05-27 |
| ES2118521T3 (en) | 1998-09-16 |
| JPH07278269A (en) | 1995-10-24 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Dead |