CA2060777A1 - Mixtures of 1-isopropyl-2-aryl imidazole and 1-isopropyl-2-aryl imidazoline as epoxy resin curatives - Google Patents
Mixtures of 1-isopropyl-2-aryl imidazole and 1-isopropyl-2-aryl imidazoline as epoxy resin curativesInfo
- Publication number
- CA2060777A1 CA2060777A1 CA002060777A CA2060777A CA2060777A1 CA 2060777 A1 CA2060777 A1 CA 2060777A1 CA 002060777 A CA002060777 A CA 002060777A CA 2060777 A CA2060777 A CA 2060777A CA 2060777 A1 CA2060777 A1 CA 2060777A1
- Authority
- CA
- Canada
- Prior art keywords
- isopropyl
- aryl
- imidazoline
- imidazole
- epoxy resin
- 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
- C08G59/40—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
- C08G59/50—Amines
- C08G59/5046—Amines heterocyclic
- C08G59/5053—Amines heterocyclic containing only nitrogen as a heteroatom
- C08G59/5073—Amines heterocyclic containing only nitrogen as a heteroatom having two nitrogen atoms in the ring
Abstract
AS EPOXY RESIN CURATIVES
(D#80,931-F) ABSTRACT
An epoxy resin curative composition that provides cured epoxy resins exhibiting improved properties is disclosed. The curative composition comprises a mixture of 1-isopropyl-2-aryl imidazole and 1-isopropyl-2-aryl imidazoline.
(D#80,931-F) ABSTRACT
An epoxy resin curative composition that provides cured epoxy resins exhibiting improved properties is disclosed. The curative composition comprises a mixture of 1-isopropyl-2-aryl imidazole and 1-isopropyl-2-aryl imidazoline.
Description
D# 80,g81-F 206~777 RRS
MIXTURES OF l-ISOPROPYL-2-ARYL IMIDAZOLE
AND l-ISOPROPYL-2-ARYL IMIDAZOLINE
~S ~:~O~Y RESIN CURATIVES
(D# 80,981-F) Field of t~ Invention This invention relates to epoxy resin curin~ agents.
More particularly, this invention relates to the use of a mixture of l-isopropyl-2-aryl imidazole and 1-isopropyl-2-aryl imid~zoline to cure a variety of epoxy resins.
Backqround of the Invention Epoxy resins include ~ broad class of polymeric materials having a wide range of physical properties. The resins are characterized by epoxide groups, which are cured by reaction with certain catalysts or curing agents to provide cured epoxy resin compositions with various desirable properties. The most common epoxy resins are condensation products o~ epichlorohydrin and bisphenol A.
It is known to use substitut~d imida~oles as curing agents for epoxy resins. Co-assigned U. S. Patent No. 4,931,528, for example, discloses the use of 1-isopropyl-2-methyl i~idazole to cure epoxy resins. Japanese Patent No. 63,308,030, to Koei Chem. Ind~ KK, discloses an epoxy resin hardener containing l-alkyl-2-phenyl imidazole. An a~stract of tha Japanese patent names l-propyl-2-phenyl imidazole in a list ~ suitable imidazole curing agents. The imidazole is said to be prepared by dehydxating N-alkyl--ethylene diamine and a nitrile in the presence of a dahydr3ting catalyst.
':
Other methods are known for the preparation of imidazoles. In one process, imidazoles are prepared from imidazolines by dehydrogenation of imidazolines over a catalyst comprising nickel in combination with a transition metal, preferably copper and/or chromium. See, ~or example, co-assigned U. S~ Patent No. 4,927,942, hereby incorporated by referenoe.
Before the discovary of the pre~ent invsntion, it was thought desirable to obtain an essentially quantitative yield of imidazole from a corresponding imidazolin~, and to use the essentially imidazoline-free imidazole as the curing agent.
Surprisingly, however, Applicants have now discovered that a mixture of l-isopropyl-2-aryl imidazole and 1-isopropyl-2-aryl imidazoline can bs ~mployad a~ an epoxy resin curative to provide epoxy resins having improved properties. Whereas it was proviously thought desirable to dehydrogenate all the imidazoline to imidazole, Applicants have discovered, ~urprisingly, that the presence of a significant amount o~ imidazoline actually improves the properties of the curative. Additionally, the less strenuous dehydrogenation condition~ n~cessary to obtain th~ mixture of imidazoline and imidazole make this new curative economically attractive.
SU~mary Qf th~ Inv~ntion The inven~ion relates to an epoxy resin curative composition, comprising a mixture of 1-isopropyl-2-aryl imidazole and l-isopropyl-~-aryl imidazolin~, in which from about 5 to about 50 wt.~ of the mixture i~ l-isopropyl-~-aryl imidazoline.
: .
MIXTURES OF l-ISOPROPYL-2-ARYL IMIDAZOLE
AND l-ISOPROPYL-2-ARYL IMIDAZOLINE
~S ~:~O~Y RESIN CURATIVES
(D# 80,981-F) Field of t~ Invention This invention relates to epoxy resin curin~ agents.
More particularly, this invention relates to the use of a mixture of l-isopropyl-2-aryl imidazole and 1-isopropyl-2-aryl imid~zoline to cure a variety of epoxy resins.
Backqround of the Invention Epoxy resins include ~ broad class of polymeric materials having a wide range of physical properties. The resins are characterized by epoxide groups, which are cured by reaction with certain catalysts or curing agents to provide cured epoxy resin compositions with various desirable properties. The most common epoxy resins are condensation products o~ epichlorohydrin and bisphenol A.
It is known to use substitut~d imida~oles as curing agents for epoxy resins. Co-assigned U. S. Patent No. 4,931,528, for example, discloses the use of 1-isopropyl-2-methyl i~idazole to cure epoxy resins. Japanese Patent No. 63,308,030, to Koei Chem. Ind~ KK, discloses an epoxy resin hardener containing l-alkyl-2-phenyl imidazole. An a~stract of tha Japanese patent names l-propyl-2-phenyl imidazole in a list ~ suitable imidazole curing agents. The imidazole is said to be prepared by dehydxating N-alkyl--ethylene diamine and a nitrile in the presence of a dahydr3ting catalyst.
':
Other methods are known for the preparation of imidazoles. In one process, imidazoles are prepared from imidazolines by dehydrogenation of imidazolines over a catalyst comprising nickel in combination with a transition metal, preferably copper and/or chromium. See, ~or example, co-assigned U. S~ Patent No. 4,927,942, hereby incorporated by referenoe.
Before the discovary of the pre~ent invsntion, it was thought desirable to obtain an essentially quantitative yield of imidazole from a corresponding imidazolin~, and to use the essentially imidazoline-free imidazole as the curing agent.
Surprisingly, however, Applicants have now discovered that a mixture of l-isopropyl-2-aryl imidazole and 1-isopropyl-2-aryl imidazoline can bs ~mployad a~ an epoxy resin curative to provide epoxy resins having improved properties. Whereas it was proviously thought desirable to dehydrogenate all the imidazoline to imidazole, Applicants have discovered, ~urprisingly, that the presence of a significant amount o~ imidazoline actually improves the properties of the curative. Additionally, the less strenuous dehydrogenation condition~ n~cessary to obtain th~ mixture of imidazoline and imidazole make this new curative economically attractive.
SU~mary Qf th~ Inv~ntion The inven~ion relates to an epoxy resin curative composition, comprising a mixture of 1-isopropyl-2-aryl imidazole and l-isopropyl-~-aryl imidazolin~, in which from about 5 to about 50 wt.~ of the mixture i~ l-isopropyl-~-aryl imidazoline.
: .
2 ~ 7 ~
Ln another of its aspects, the invention relates to a method for curing an epoxy resin, comprising combining (1) from about 1 to about 5 parts by weight of a mixture of 1-isopropyl-2-aryl imidazole and 1-isopropyl-2-aryl imidazoline, in which ~rom about 5 to about 50 wt.% of the mixtur~ i9 1-isopropyl-2-aryl imidazoline, and (2) about 100 parts by weight o~ an epoxy resin.
The invention also relates to a method for curing an epoxy resin, comprising combining (1) from about 1 to about 5 parts by weight o~ a mixtura of l-isopropyl-2-phenyl imidazole and l-isopropyl-2-phenyl imidazoline, in which from about 10 ~o about 25 wt.% of th~ mixture i5 1-isopropyl-2-phenyl imidazoline, and (2) about 100 parts by w~ight of an epoxy r~sin.
Desçrintion of the Preferred ~mbodiments The imidazole csmponent of the curativa composition of the present invention is a member of a group of imidazole~ having the following general ~ormula:
Rl R--N)~N
in which R is H or an alkyl group containing 1 to 18 carbon atoms, R1 is an aryl group, R2 is H or an alkyl group containing 1 to 4 carbon atom~, and R3 is H or an alkyl group containing 1 to 4 carbon atoms.
' 2~6~77 7 Applicants h~ve discovered that a blend or mixture of l-isopropyl-2-aryl imidazole and 1-isopropyl-2-aryl imidazoline surprisingly provides a cured epoxy resin which demonstrates properties that maks the mixture particularly valuable as a curing agent. Preferably, the mix~ure contains ~rom about 5 to about 50 wt.% 1-isopropyl-2-aryl imidazoline. More pre~erably, the mixture contains from about 5 to about 30 wt.% 1-isopropyl-2-aryl imidazoline. It is especially preferred th~t the mixture contain from about 10 to about 25 wt.% 1-isopropyl-2-aryl imidazoline.
~ he structure of the preferred imidazole component, 1-isopropyl-2-phenyl imidazole, may be represented as follows:
~CH3)2CH \ ~
~I
The ~tructure o~ the preferred imidazoline component, l-isopropyl-2-phenyl imidazoline, may be represented as follows:
( CH;~ )2CH~N J~
..
2~7~7 The l-isopropyl-2-aryl imidazole component of the instant invention may be preparad by a method comprising dehydrogenation of 1-isopropyl-2-aryl imidazoline over a catalys~
comprising (1) nickel and (2) from about 2 to 30 wt.~ coppex and/or chromium, i.e. copper or chromium alone or in combination with the other, at a temperature of about 160 C to about 250 C
and a pressure of about atmospheric to about 200 psig. By adjusting the process conditions of the dehydrogenation procedure, mixtures of imidazole and imidazoline may be obtained exhibitinq various weight ratios of the two components. For example, by lowering ~he temperature of the dehydrogenation reaction, a mixture will be obtained with a greater proportion of the imidazoline component. Various mixture~ may be produced by manipulating the conditions of the process disclosed in co~
assigned U. S. Patent No. 4,927,942, incorporatad herein by reference. Alternatively, the imidazol~ and imidazoline components may be obtained by separate proce~ses, and then blended together to obtain the mixtures of t~e present invention.
The imidazole may be obtained, for example, by the method disclosed in co-assigned U. S. Patent No. ~,921,969, hereby incorporated by re~srence. The imidazolin~ u~d in th~ present invention may ba obtained by th~ w~ known reaction of an organic acid and a diamin~.
Generally, th~ vicinal polyepoxide-containing compositions that may b~ cured with the curatiYe mixtures of the invention are organic matRrial~ having an av~rage o~ at least l.B
2~61~777 reactive 1,2-epoxy groups per molecule. These polyepoxide materials can be monomeric or polymeric, saturated or unsaturated, aliphatic, cycloaliphatic, aromatic or heterocyc].ic, and may be substituted if desired with other substituents besides the epoxy groups, e.g., hydroxyl groups, ether radicals, aromatic halogen atoms and the like. These vicinal polyepoxide-containing compounds typically are of an epoxy equivalent weight (EEW~ of about 150 to about 250. Pre~erably, the polyepoxide-containing compounds have an ep~xy equivalent weight of about 170 to about 220. More preferably, the base resin, which has an epoxide equivalent weight o~ from 175 to 195, is derived by condensing epichlorohydrin with 2,2-bis(p-hydroxyphenyl propane) to form the bis-epoxide derivative of bisphenol ~. After condensation is complete, tha crude resin is freed of residual epichlorohydrin, washed well to remove salt and soluble by-products, and recovered.
Preferred polyepoxides are those o~ glycidyl ethers prepared by epoxidizing the corresponding allyl ethers or by reacting, by known procedures, a molar excess of epichlorohydrin and an aromatic polyhydroxy compound, i.e., isopropylidene bi~phenol, novolac, resorcinol, etc. Th~ epoxy derivativas of methylene or isopropylidene bisphenols are especially preferrQd.
A widely used class o~ polyepoxides which are useful according to the instant invention includes the resinous epoxy polyethers obtained by reacting an epihalohydrin, such as ~ . ... : :
.. . ~ .
.
, .
7 ~ 7 spichlorohydrin and the like, with either a polyhydric phenol or a polyhydric alcohol. Typically the epoxy resins have an average of at least l.B reactive, 1,2-epoxy groups per molecule. An illustrative, but by no means exhaustive, list of suitable dihydric phenols includes 4,4'-isopropylidene bisphenol, 2,4'-dihydroxydiphenylethylmethans, 3,3'-dihydroxydiphenyldiethylmethane, 3,4'-dihydroxydiphenylmethylpropylmethane, 2,3'~dihydroxydiphenyl~thylphenylmethane, 4,4'-dihydroxydiphenylpropylphenylmPthane, 4,4'-dihydroxydiphenylbutylphenylmethane, 2,2'-dihydroxydiphenylditolylmethane, 4,4'-dihydroxydiphenyltolylmethylmethane and the like~ Other polyhydric phenols which may be co-reacted with an epihalohydrin to provide these epoxy polyether~ are such compounds as resorcinol, hydroquinone, substituted hydroquinones, e.g. methylhydroquinone, and the like.
Among the polyhydric alcohols which can be co-reacted with an epihalohydrin to provide these resinous epoxy polyethers are such compound~ a~ ethylene glycol, propylane glycol~, butylene glycol~, pentane diol~, bis(4-hydroxycycloh~xyl) dimethylmothanQ, 1,4-dim~thylolbenzen~, glycerol, 1,2,6-hexanetriol, trimothylolpropan~, mannitol, ~orbitol, erythritol, pentaerythritol, their dimers, trimer~ and higher polymers, e.g., polyethylene glycol~, polypropylene glycols, triglycerol, dipentaerythritol and the like; polyallyl alcohol;
~ - . .: : .-: :
2 ~
polyhydric thioethers, such as 2,2'- or 3,3'-tetrahydroxydipropylsulfide and the like; mercapto alcohols such as monothio glycerol, dithio glycerol and the like;
polyhydric alcohol partial esters, such as monoætearin, pentaerythritol monoacetate and the like; and halogenated polyhydric alcohols, such a~ the monochlerohydrins of glycerol, sorbitol, pentaerythritol and the like.
Another ~lass of polymeric polyepoxides which can be cured by the product~ of the invention in accordance with the present invention includes the epoxy novolac resins obtained by reacting, preferably in the presence of a basic catalyst, e.g., sodium or potas~ium hydroxide, an epihalohydrin, such as epichlorohydrin, with the re~inous conden~ate of an aldehyde, e.g., formaldehyde, and either a monohydric phenol, e.g., phenol itself, or a polyhydric phenol. Further detail~ concerning the nature and preparation of these epoxy novolac resins can ~e obtained in Lee, H. and Neville, K., H~nd~Qok o~ Epo~y ~esins, McGraw Hill Book Co., New York, 1967.
Those skilled in the art will appreci~te that the polyepoxide compositions which are useful according to the practice o~ the pr~s~nt invention aro not limited to tho~
containing the above de~cri~ed polyepoxides, but that these polyepoxides are provided hQre merely as being representative of the class of poly~poxides as a whole.
A novel curative compesition of the present invention should be present in the epoxy resin in an amount sufficient to , .. : ,.
, - , . ,..-. ' '' ~ ' , provide 1 to 5 parts by weight (pbw) of the 1-isopropyl-2-aryl imidazole/ l-isopropyl-2 aryl imidazoline mixture per 10~ ~r47 7 7 by weight epoxy resin. The curative compositions of ths pres nt invention may be combined with the epoxy resin at ambient temperature. Preferably, after combining the curative composition and the epoxy resin, the epoxy resin is heated to a temperature of about 125 C to about 250 C for about l to about 36 hours. The novel method of this invention is further illustrated in the examples that follow. The method of curing epoxy resins with the curing compositions of the presant invention allows for the production of compositions with properties permitting a vari~ty of applications. Properties that may be obtained by variations of the invention are demonstrated in the examples.
In the ~xamples, the following properties were measured:
Shore D hardne~s - ~AST~ D-2240-81) Measures, at 0 and at 10 seconds, indentation hardness with durometer.
HDT - (ASTM D) Heat distortion temperature is the temperature at which a polymar sample distorts under load upon heating under specified conditions. HDT's al~o may be used to indicate the d~gree o~ cros~-linking or extQnt o~ curQ o~ an epoxy resin.
Izod Impact Strength (ft-lb/in~ - Izod impact testing is carried out with a pendulum-type device. The tast specimen is positioned as a cantilever beam with th~ notched side facing the ' ~
~6077 ~
striker. Five samples are tes~ed for impact with each formulation, the average being recorded as Izod impact strength.
Tensile Strength, psi - The rupturs strength (stres~ applied at break) per unit area of material subjected to a specified dynamic load. "Ultimate tensile strength" i8 the force, at break, whèn a sample is pulled apart.
Tensile Modulus, psi - Stress/strain Flexural Strenyth, psi - A measure of the ability of a material to withstand failuxe due to bending.
Flexural modulus, p~i ~ Stress/strain The invention will be further illustrated by the following examples, which are given by way of illustration and not a~ limitation~ on the scope o~ this invention. The entire text of every patent~ patent application or other reference mentioned above i8 hereby incorporated herein by re~erence.
1~
2~fi~7 Propenie~: Epoxy Rc~in Curcd wilh l-laop~pyl-2-A~ mia~OlO v~.
EDOXV Re~in Cured wilh Mixture of l-lsovror~1-2-ArYI Imida~o~ ro~ -Argl Imidazolino ~ , - -- -~. . _ _ ¦ Formulation_ __ I . 2 3 4 Liquid EPOXY R~8;nl 100 pbw 100 pb~v 100 pbw 100 pbw i . .~ ._ I-isopropyl-2-phenyl in~idazol~2 2.0 pbw 1.8 pbw 1.6 pbw 1-4 pbw I .
¦ I-iDopropyl-2-phenyl in~idazolino 0.2 pbw 0.4 pbw 0.6 pbw Propertie~ or Cur~d 1/8 u~ch Costi~g~
j _~ _ . _ Shoro D Hnrdne~ (~10 6ec.) ~9-XI 95-92 92-89 94-91 .
}IDT, ~C ~ 264 p9i 183.81 238.3 238.3 178.5 . _ _ Izod l~npacl Stronglh, fl-lblin 0.03 0.08 0.10 0.08 , Tensil~ Suenglh, pai . . 2800 1700 2400 Tensile Mollulus, pai 393000 451000 424000 465000 _ - _~.. .. ...
Elongalion llt Bre~l~, X 0.9 0.7 0.4 0.6 Flexual Strcnglh, p8i 5950 4600 _ 440- .. . _ 5000 Flexural Modulua, pai 349000 375000 370000 375000 Porconl Wcighl Gairl, 24 hr. walor boil I.12 0.90 _ . 0.88 0.88 Perconl W~ight G~in, 3 hr ~celoni boil ~.034 -0.03~ . _ ~.034 I EEW ~ 185 2 Punly ~ 99 ~.
3 Cured ~wo houra ~ 100 C and ~our ho~n a? 210 C.
4 Slighl wci~hl lou noted.
Among the properties improved by the use of the imidazole/imidazoline mixture of the present invention, especially noteworthy is the surprising increase in heat distortion temperatur~ (HDT) obtained in formulations 2 and 3, as compared with the heat distortion temperature of the resin cured with the essentially pure imidazole (formulation 1).
Ln another of its aspects, the invention relates to a method for curing an epoxy resin, comprising combining (1) from about 1 to about 5 parts by weight of a mixture of 1-isopropyl-2-aryl imidazole and 1-isopropyl-2-aryl imidazoline, in which ~rom about 5 to about 50 wt.% of the mixtur~ i9 1-isopropyl-2-aryl imidazoline, and (2) about 100 parts by weight o~ an epoxy resin.
The invention also relates to a method for curing an epoxy resin, comprising combining (1) from about 1 to about 5 parts by weight o~ a mixtura of l-isopropyl-2-phenyl imidazole and l-isopropyl-2-phenyl imidazoline, in which from about 10 ~o about 25 wt.% of th~ mixture i5 1-isopropyl-2-phenyl imidazoline, and (2) about 100 parts by w~ight of an epoxy r~sin.
Desçrintion of the Preferred ~mbodiments The imidazole csmponent of the curativa composition of the present invention is a member of a group of imidazole~ having the following general ~ormula:
Rl R--N)~N
in which R is H or an alkyl group containing 1 to 18 carbon atoms, R1 is an aryl group, R2 is H or an alkyl group containing 1 to 4 carbon atom~, and R3 is H or an alkyl group containing 1 to 4 carbon atoms.
' 2~6~77 7 Applicants h~ve discovered that a blend or mixture of l-isopropyl-2-aryl imidazole and 1-isopropyl-2-aryl imidazoline surprisingly provides a cured epoxy resin which demonstrates properties that maks the mixture particularly valuable as a curing agent. Preferably, the mix~ure contains ~rom about 5 to about 50 wt.% 1-isopropyl-2-aryl imidazoline. More pre~erably, the mixture contains from about 5 to about 30 wt.% 1-isopropyl-2-aryl imidazoline. It is especially preferred th~t the mixture contain from about 10 to about 25 wt.% 1-isopropyl-2-aryl imidazoline.
~ he structure of the preferred imidazole component, 1-isopropyl-2-phenyl imidazole, may be represented as follows:
~CH3)2CH \ ~
~I
The ~tructure o~ the preferred imidazoline component, l-isopropyl-2-phenyl imidazoline, may be represented as follows:
( CH;~ )2CH~N J~
..
2~7~7 The l-isopropyl-2-aryl imidazole component of the instant invention may be preparad by a method comprising dehydrogenation of 1-isopropyl-2-aryl imidazoline over a catalys~
comprising (1) nickel and (2) from about 2 to 30 wt.~ coppex and/or chromium, i.e. copper or chromium alone or in combination with the other, at a temperature of about 160 C to about 250 C
and a pressure of about atmospheric to about 200 psig. By adjusting the process conditions of the dehydrogenation procedure, mixtures of imidazole and imidazoline may be obtained exhibitinq various weight ratios of the two components. For example, by lowering ~he temperature of the dehydrogenation reaction, a mixture will be obtained with a greater proportion of the imidazoline component. Various mixture~ may be produced by manipulating the conditions of the process disclosed in co~
assigned U. S. Patent No. 4,927,942, incorporatad herein by reference. Alternatively, the imidazol~ and imidazoline components may be obtained by separate proce~ses, and then blended together to obtain the mixtures of t~e present invention.
The imidazole may be obtained, for example, by the method disclosed in co-assigned U. S. Patent No. ~,921,969, hereby incorporated by re~srence. The imidazolin~ u~d in th~ present invention may ba obtained by th~ w~ known reaction of an organic acid and a diamin~.
Generally, th~ vicinal polyepoxide-containing compositions that may b~ cured with the curatiYe mixtures of the invention are organic matRrial~ having an av~rage o~ at least l.B
2~61~777 reactive 1,2-epoxy groups per molecule. These polyepoxide materials can be monomeric or polymeric, saturated or unsaturated, aliphatic, cycloaliphatic, aromatic or heterocyc].ic, and may be substituted if desired with other substituents besides the epoxy groups, e.g., hydroxyl groups, ether radicals, aromatic halogen atoms and the like. These vicinal polyepoxide-containing compounds typically are of an epoxy equivalent weight (EEW~ of about 150 to about 250. Pre~erably, the polyepoxide-containing compounds have an ep~xy equivalent weight of about 170 to about 220. More preferably, the base resin, which has an epoxide equivalent weight o~ from 175 to 195, is derived by condensing epichlorohydrin with 2,2-bis(p-hydroxyphenyl propane) to form the bis-epoxide derivative of bisphenol ~. After condensation is complete, tha crude resin is freed of residual epichlorohydrin, washed well to remove salt and soluble by-products, and recovered.
Preferred polyepoxides are those o~ glycidyl ethers prepared by epoxidizing the corresponding allyl ethers or by reacting, by known procedures, a molar excess of epichlorohydrin and an aromatic polyhydroxy compound, i.e., isopropylidene bi~phenol, novolac, resorcinol, etc. Th~ epoxy derivativas of methylene or isopropylidene bisphenols are especially preferrQd.
A widely used class o~ polyepoxides which are useful according to the instant invention includes the resinous epoxy polyethers obtained by reacting an epihalohydrin, such as ~ . ... : :
.. . ~ .
.
, .
7 ~ 7 spichlorohydrin and the like, with either a polyhydric phenol or a polyhydric alcohol. Typically the epoxy resins have an average of at least l.B reactive, 1,2-epoxy groups per molecule. An illustrative, but by no means exhaustive, list of suitable dihydric phenols includes 4,4'-isopropylidene bisphenol, 2,4'-dihydroxydiphenylethylmethans, 3,3'-dihydroxydiphenyldiethylmethane, 3,4'-dihydroxydiphenylmethylpropylmethane, 2,3'~dihydroxydiphenyl~thylphenylmethane, 4,4'-dihydroxydiphenylpropylphenylmPthane, 4,4'-dihydroxydiphenylbutylphenylmethane, 2,2'-dihydroxydiphenylditolylmethane, 4,4'-dihydroxydiphenyltolylmethylmethane and the like~ Other polyhydric phenols which may be co-reacted with an epihalohydrin to provide these epoxy polyether~ are such compounds as resorcinol, hydroquinone, substituted hydroquinones, e.g. methylhydroquinone, and the like.
Among the polyhydric alcohols which can be co-reacted with an epihalohydrin to provide these resinous epoxy polyethers are such compound~ a~ ethylene glycol, propylane glycol~, butylene glycol~, pentane diol~, bis(4-hydroxycycloh~xyl) dimethylmothanQ, 1,4-dim~thylolbenzen~, glycerol, 1,2,6-hexanetriol, trimothylolpropan~, mannitol, ~orbitol, erythritol, pentaerythritol, their dimers, trimer~ and higher polymers, e.g., polyethylene glycol~, polypropylene glycols, triglycerol, dipentaerythritol and the like; polyallyl alcohol;
~ - . .: : .-: :
2 ~
polyhydric thioethers, such as 2,2'- or 3,3'-tetrahydroxydipropylsulfide and the like; mercapto alcohols such as monothio glycerol, dithio glycerol and the like;
polyhydric alcohol partial esters, such as monoætearin, pentaerythritol monoacetate and the like; and halogenated polyhydric alcohols, such a~ the monochlerohydrins of glycerol, sorbitol, pentaerythritol and the like.
Another ~lass of polymeric polyepoxides which can be cured by the product~ of the invention in accordance with the present invention includes the epoxy novolac resins obtained by reacting, preferably in the presence of a basic catalyst, e.g., sodium or potas~ium hydroxide, an epihalohydrin, such as epichlorohydrin, with the re~inous conden~ate of an aldehyde, e.g., formaldehyde, and either a monohydric phenol, e.g., phenol itself, or a polyhydric phenol. Further detail~ concerning the nature and preparation of these epoxy novolac resins can ~e obtained in Lee, H. and Neville, K., H~nd~Qok o~ Epo~y ~esins, McGraw Hill Book Co., New York, 1967.
Those skilled in the art will appreci~te that the polyepoxide compositions which are useful according to the practice o~ the pr~s~nt invention aro not limited to tho~
containing the above de~cri~ed polyepoxides, but that these polyepoxides are provided hQre merely as being representative of the class of poly~poxides as a whole.
A novel curative compesition of the present invention should be present in the epoxy resin in an amount sufficient to , .. : ,.
, - , . ,..-. ' '' ~ ' , provide 1 to 5 parts by weight (pbw) of the 1-isopropyl-2-aryl imidazole/ l-isopropyl-2 aryl imidazoline mixture per 10~ ~r47 7 7 by weight epoxy resin. The curative compositions of ths pres nt invention may be combined with the epoxy resin at ambient temperature. Preferably, after combining the curative composition and the epoxy resin, the epoxy resin is heated to a temperature of about 125 C to about 250 C for about l to about 36 hours. The novel method of this invention is further illustrated in the examples that follow. The method of curing epoxy resins with the curing compositions of the presant invention allows for the production of compositions with properties permitting a vari~ty of applications. Properties that may be obtained by variations of the invention are demonstrated in the examples.
In the ~xamples, the following properties were measured:
Shore D hardne~s - ~AST~ D-2240-81) Measures, at 0 and at 10 seconds, indentation hardness with durometer.
HDT - (ASTM D) Heat distortion temperature is the temperature at which a polymar sample distorts under load upon heating under specified conditions. HDT's al~o may be used to indicate the d~gree o~ cros~-linking or extQnt o~ curQ o~ an epoxy resin.
Izod Impact Strength (ft-lb/in~ - Izod impact testing is carried out with a pendulum-type device. The tast specimen is positioned as a cantilever beam with th~ notched side facing the ' ~
~6077 ~
striker. Five samples are tes~ed for impact with each formulation, the average being recorded as Izod impact strength.
Tensile Strength, psi - The rupturs strength (stres~ applied at break) per unit area of material subjected to a specified dynamic load. "Ultimate tensile strength" i8 the force, at break, whèn a sample is pulled apart.
Tensile Modulus, psi - Stress/strain Flexural Strenyth, psi - A measure of the ability of a material to withstand failuxe due to bending.
Flexural modulus, p~i ~ Stress/strain The invention will be further illustrated by the following examples, which are given by way of illustration and not a~ limitation~ on the scope o~ this invention. The entire text of every patent~ patent application or other reference mentioned above i8 hereby incorporated herein by re~erence.
1~
2~fi~7 Propenie~: Epoxy Rc~in Curcd wilh l-laop~pyl-2-A~ mia~OlO v~.
EDOXV Re~in Cured wilh Mixture of l-lsovror~1-2-ArYI Imida~o~ ro~ -Argl Imidazolino ~ , - -- -~. . _ _ ¦ Formulation_ __ I . 2 3 4 Liquid EPOXY R~8;nl 100 pbw 100 pb~v 100 pbw 100 pbw i . .~ ._ I-isopropyl-2-phenyl in~idazol~2 2.0 pbw 1.8 pbw 1.6 pbw 1-4 pbw I .
¦ I-iDopropyl-2-phenyl in~idazolino 0.2 pbw 0.4 pbw 0.6 pbw Propertie~ or Cur~d 1/8 u~ch Costi~g~
j _~ _ . _ Shoro D Hnrdne~ (~10 6ec.) ~9-XI 95-92 92-89 94-91 .
}IDT, ~C ~ 264 p9i 183.81 238.3 238.3 178.5 . _ _ Izod l~npacl Stronglh, fl-lblin 0.03 0.08 0.10 0.08 , Tensil~ Suenglh, pai . . 2800 1700 2400 Tensile Mollulus, pai 393000 451000 424000 465000 _ - _~.. .. ...
Elongalion llt Bre~l~, X 0.9 0.7 0.4 0.6 Flexual Strcnglh, p8i 5950 4600 _ 440- .. . _ 5000 Flexural Modulua, pai 349000 375000 370000 375000 Porconl Wcighl Gairl, 24 hr. walor boil I.12 0.90 _ . 0.88 0.88 Perconl W~ight G~in, 3 hr ~celoni boil ~.034 -0.03~ . _ ~.034 I EEW ~ 185 2 Punly ~ 99 ~.
3 Cured ~wo houra ~ 100 C and ~our ho~n a? 210 C.
4 Slighl wci~hl lou noted.
Among the properties improved by the use of the imidazole/imidazoline mixture of the present invention, especially noteworthy is the surprising increase in heat distortion temperatur~ (HDT) obtained in formulations 2 and 3, as compared with the heat distortion temperature of the resin cured with the essentially pure imidazole (formulation 1).
Claims (17)
1. An epoxy resin curative composition, comprising a mixture of 1-isopropyl-2-aryl imidazole and 1-isopropyl-2-aryl imidazoline, in which from about 5 to about 50 wt.% of the mixture is 1-isopropyl-2-aryl imidazoline.
2. The composition of Claim 1, in which from about 5 to about 30 wt.% of the mixture is 1-isopropyl-2-aryl imidazoline.
3. The composition of Claim 1, in which from about 10 to about 25 wt.% of the mixture is 1-isopropyl-2-aryl imidazoline.
4. The composition of Claim 1, in which the 1-isopropyl-2-aryl imidazole is 1-isopropyl-2-phenyl imidazole and in which the 1-isopropyl-2-aryl imidazoline is 1-isopropyl-2-phenyl imidazoline.
5. The composition of Claim 4, in which from about 5 to about 30 wt.% of the mixture is 1-isopropyl-2-phenyl imidazoline.
6. The composition of Claim 4, in which from about 10 to about 25 wt.% of the mixture is 1-isopropyl-2-phenyl imidazoline.
7. A method for curing an epoxy resin, comprising combining (1) from about 1 to about 5 parts by weight of a mixture of 1-isopropyl-2-aryl imidazole and 1-isopropyl-2-aryl imidazoline, in which from about 5 to about 50 wt.% of the mixture is 1-isopropyl-2-aryl imidazoline, and (2) about 100 parts by weight of an epoxy resin.
8. The method of Claim 7, in which from about 5 to about 30 wt.% of the mixture is 1-isopropyl-2-aryl imidazoline.
9. The method of Claim 7, in which from about 10 to about 25 wt.% of the mixture is 1-isopropyl-2-aryl imidazoline.
10. The method of Claim 7, in which the 1-isopropyl-2-aryl imidazole is 1-isopropyl-2-phenyl imidazole and in which the 1-isopropyl-2-aryl imidazoline is 1-isopropyl-2-phenyl imidazoline.
11. The method of Claim 10, in which from about 5 to about 30 wt.% of the mixture is 1-isopropyl-2-phenyl imidazoline.
12. The method of Claim 10, in which from about 10 to about 25 wt.% of the mixture is 1-isopropyl-2-phenyl imidazoline.
13. The method of Claim 7, in which the epoxy resin is a diglycidyl ether of bisphenol A, having an epoxy equivalent weight of from about 170 to about 220.
14. The method of Claim 7, further comprising the second step of heating the epoxy resin to a temperature of about 125 °C to about 250 °C for about 1 to about 36 hours.
15. A method for curing an epoxy resin, comprising combining (1) from about 1 to about 5 parts by weight of a mixture of 1-isopropyl-2-phenyl imidazole and 1-isopropyl-2-phenyl imidazoline, in which from about 10 to about 25 wt.% of the mixtures is 1-isopropyl-2-phenyl imidazoline, and (2) about 100 parts by weight of an epoxy resin.
16. The method of Claim 15, in which the epoxy resin is a diglycidyl ether of bisphenol A, haviny an epoxy equivalent weight of from about 170 to about 220.
17. The method of Claim 15, further comprising the second step of heating the epoxy resin to a temperature of about 125 °C to about 250 °C for about 1 to about 36 hours.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US07/662,142 US5189118A (en) | 1991-02-28 | 1991-02-28 | Mixtures of 1-isopropyl-2-aryl imidazole and 1-isopropyl-2-aryl imidazoline as epoxy resin curatives |
| US07/662,142 | 1991-02-28 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2060777A1 true CA2060777A1 (en) | 1992-08-29 |
Family
ID=24656533
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002060777A Abandoned CA2060777A1 (en) | 1991-02-28 | 1992-02-06 | Mixtures of 1-isopropyl-2-aryl imidazole and 1-isopropyl-2-aryl imidazoline as epoxy resin curatives |
Country Status (4)
| Country | Link |
|---|---|
| US (1) | US5189118A (en) |
| EP (1) | EP0501074A1 (en) |
| JP (1) | JPH0578455A (en) |
| CA (1) | CA2060777A1 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6479585B2 (en) * | 2000-05-26 | 2002-11-12 | H. B. Fuller Licensing & Financing Inc. | Power coating of carboxyl-functional acrylic resin and polyepoxy resin |
| WO2009133168A1 (en) | 2008-04-30 | 2009-11-05 | Sika Technology Ag | Activator for epoxy resin compositions |
| EP2113525A1 (en) | 2008-04-30 | 2009-11-04 | Sika Technology AG | Activator for epoxy resin composites |
Family Cites Families (17)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2847417A (en) * | 1956-07-13 | 1958-08-12 | Houdry Process Corp | Preparation of imidazole compounds |
| US3037028A (en) * | 1959-07-06 | 1962-05-29 | Air Prod & Chem | Synthesis of imidazoles |
| US3225200A (en) * | 1961-08-11 | 1965-12-21 | Commissariat Energie Atomique | Determination of the number of neutrons emitted simultaneously by a source |
| US3715365A (en) * | 1971-02-08 | 1973-02-06 | Jefferson Chem Co Inc | Imidazole synthesis |
| US4060655A (en) * | 1974-02-02 | 1977-11-29 | Hoechst Aktiengesellschaft | Resin coated metal substrates |
| DE2405111C3 (en) * | 1974-02-02 | 1982-08-12 | Hoechst Ag, 6000 Frankfurt | Process for the production of metal substrates coated with cured epoxy resin compositions |
| DE2731335A1 (en) * | 1977-07-12 | 1979-01-25 | Veba Chemie Ag | METHOD FOR BONDING MATERIALS |
| GB2068362B (en) * | 1980-01-25 | 1983-11-16 | Kodak Ltd | Preparation of imidazoles |
| DE3009631A1 (en) * | 1980-03-13 | 1981-09-24 | Basf Ag, 6700 Ludwigshafen | METHOD FOR PRODUCING IMIDAZOLES |
| CH646956A5 (en) * | 1981-12-15 | 1984-12-28 | Ciba Geigy Ag | Imidazolides. |
| JPS62100518A (en) * | 1985-10-26 | 1987-05-11 | Somar Corp | Epoxy resin composition for use in prepreg |
| JPH0625144B2 (en) * | 1986-02-24 | 1994-04-06 | 四国化成工業株式会社 | Novel imidazole compound and method for synthesizing the compound |
| US4732962A (en) * | 1987-02-18 | 1988-03-22 | General Motors Corporation | High temperature epoxy tooling composition of bisphenol-A epoxy, trifunctional epoxy, anhydride curing agent and an imidazole catalyst |
| JPS63308030A (en) * | 1987-06-09 | 1988-12-15 | Koei Chem Co Ltd | Curing agent for epoxy resin |
| US4927942A (en) * | 1988-12-15 | 1990-05-22 | Texaco Chemical Co. | Method for the preparation of imidazoles |
| US4921969A (en) * | 1988-12-15 | 1990-05-01 | Texaco Chemical Co. | Method for the preparation of imidazoles |
| US4931528A (en) * | 1989-05-08 | 1990-06-05 | Texaco Chemical Company | 1-isopropyl-2-methyl imidazole as an epoxy resin curative |
-
1991
- 1991-02-28 US US07/662,142 patent/US5189118A/en not_active Expired - Fee Related
- 1991-12-19 EP EP91311816A patent/EP0501074A1/en not_active Withdrawn
-
1992
- 1992-02-06 CA CA002060777A patent/CA2060777A1/en not_active Abandoned
- 1992-02-21 JP JP4070107A patent/JPH0578455A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| EP0501074A1 (en) | 1992-09-02 |
| JPH0578455A (en) | 1993-03-30 |
| US5189118A (en) | 1993-02-23 |
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