Source: http://www.google.com/patents/US4954602?ie=ISO-8859-1
Timestamp: 2014-03-07 22:12:34
Document Index: 431042211

Matched Legal Cases: ['arts3', 'arts1', 'arts2', 'arts3', 'arts2', 'Application No. 57']

Patent US4954602 - Liquid, epoxy resin composition - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inAdvanced Patent SearchPatentsA liquid, epoxy resin composition suitable for use in fixation of a stator coil or a rotor coil is disclosed, which comprises (A) a mixture containing (a.sub.1) a Bisphenol A epoxy resin and (a.sub.2) an alicyclic epoxy resin; and (B) a curing agent including (b.sub.1) an acid anhydride, and (b.sub.2)...http://www.google.com/patents/US4954602?utm_source=gb-gplus-sharePatent US4954602 - Liquid, epoxy resin compositionAdvanced Patent SearchPublication numberUS4954602 APublication typeGrantApplication numberUS 07/369,998Publication dateSep 4, 1990Filing dateJun 23, 1989Priority dateJun 24, 1988Fee statusPaidAlso published asEP0349192A2, EP0349192A3Publication number07369998, 369998, US 4954602 A, US 4954602A, US-A-4954602, US4954602 A, US4954602AInventorsIchiro Akutagawa, Toshihiro Hanamori, Kunimitsu Matsuzaki, Shinobu Okamura, Tsutomu YamaguchiOriginal AssigneeSomar CorporationExport CitationBiBTeX, EndNote, RefManPatent Citations (5), Referenced by (2), Classifications (16), Legal Events (5) External Links: USPTO, USPTO Assignment, EspacenetLiquid, epoxy resin compositionUS 4954602 AAbstract A liquid, epoxy resin composition suitable for use in fixation of a stator coil or a rotor coil is disclosed, which comprises (A) a mixture containing (a.sub.1) a Bisphenol A epoxy resin and (a.sub.2) an alicyclic epoxy resin; and (B) a curing agent including (b.sub.1) an acid anhydride, and (b.sub.2) a phenol compound of the general formula: ##STR1## wherein R.sup.1 and R.sup.2 represent independently from each other a lower alkyl, R.sup.3 represents a lower alkylene and n is an integer of 1-5, the amount of the phenol compound (b.sub.2) being in the range of 2-8% based on the weight of the mixture (A).
What is claimed is: 1. A liquid, epoxy resin composition comprising:(A) a mixture containing(a.sub.1) a Bisphenol A epoxy resin, and (a.sub.2) an alicyclic epoxy resin; and (B) a curing agent including(b.sub.1) an acid anhydride, and (b.sub.2) a phenol compound of the general formula: ##STR8## wherein R.sup.1 and R.sup.2 represent independently from each other a lower alkyl, R.sup.3 represents a lower alkylene and n is an integer of 1-5, the amount of said phenol compound being 2-8% based on the weight of the mixture (A). 2. A composition as claimed in claim 1, wherein the Bisphenol A epoxy resin has an epoxy equivalent of 170-270.
3. A composition as claimed in claim 1, wherein the alicyclc epoxy resin is a compound selected from the group consisting of 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexane-carboxylate, vinylcyclohexylene dioxide, bis(3,4-epoxycyclohexylmethyl) adipate or 6-(3,4-epoxycyclohexyl)-1,5-meta-dioxane-3-spiro-3',4'-epoxycylohexane.
4. A composition as claimed in claim 1, wherein the weight ratio of the Bisphenol A epoxy resin to the alicyclic epoxy resin is 3:7 to 9:1.
5. A composition as claimed in claim 1, wherein the acid anhydride is a compound selected from the group consisting of methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylnadic anhydride and methylbutenyltetrahydrophthalic anhydride.
6. A composition as claimed in claim 1, wherein R.sup.1 and R.sup.2 stand independently from each other methyl, ethyl or propyl, R.sup.3 stands for methylene or ethylene and n is an integer of 2-4.
7. A composition as claimed in claim 1, wherein the phenol compound is 2,4,6-tri(N,N-dimethyl)aminomethylphenol or 2-(N,N-dimethyl)aminomethylphenol.
8. A composition as claimed in claim 1, wherein the acid anhydride is used in an amount of 0.5-1.5 mole per one equivalent of the epoxy group of the mixture (A).
9. A composition as claimed in claim 1, wherein the phenol compound is used in an amount of 2.5-5% based on the weight of the mixture (A).
10. A composition as claimed in claim 1, further comprising a diluent selected from the group consisting of 1,6-hexanediol diglycidyl ether, polyalkylenglycol diglycidyl ether, trimethylolpropane triglycidyl ether, butyl glycidyl ether and phenyl glycidyl ether.
11. A composition as claimed in claim 10, wherein the diluent is used in an amount not more than 20% based on the weight of the mixture (A).
12. A composition as claimed in claim 1 and exhibiting a gellation time at 150
13. A composition as claimed in claim 1, and being a two-component type composition consisting of said mixture (A) as a first component and said curing agent (B) as a second component.
14. A method of fixing windings of a coil with a composition according to claim 1, comprising the steps of:heating the windings to a temperature of 100 dropping the composition onto the heated windings to impregnate the windings with the composition; and heating the impregnated windings at 100 the composition to cure. Description
DETAILED DESCRIPTION OF THE INVENTION The Bisphenol A epoxy resin to be used in the present invention is a product obtained by reaction of Bisphenol A with epichlorohydrin and preferably has an epoxy equivalent of 170-270. The term "epoxy equivalent" used in the present specification is intended to refer to so-called "weight per epoxy equivalent" which is a weight (g) of the epoxy resin providing 1 g equivalent of the epoxy group. Epikote #828 and #834 (manufactured by Yuka Shell Epoxy Inc.) and Adeca 4100 and 4300 (manufactured by Asahi Denka Inc.) are illustrative of suitable Bisphenol A epoxy resins.
The alicyclic epoxy resin (or cycloaliphatic epoxy resin) to be used in conjunction with the Bisphenol A epoxy resin may be, for example, 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate of the formula: ##STR3## vinylcyclohexylene dioxide of the formula: ##STR4## bis(3,4-epoxycyclohexylmethyl) adipate of the formula: ##STR5## or 6-(3,4-epoxycyclohexyl)-1,5-meta-dioxane-3-spiro-3',4'-epoxycylohexane of the formula: ##STR6##
The weight ratio of the Bisphenol A epoxy resin to the alicyclic epoxy resin is generally 3:7 to 9:1. A proportion of the Bisphenol A epoxy resin below the above specified range tends to cause reduction of mechanical strength, such as resistance to cracking, of the cured body obtained from the epoxy resin composition. On the other hand, when the proportion of the Bisphenol A epoxy resin exceeds the above upper limit, the penetrability of the resulting composition becomes poor and the heat resistance of the cured body thereof becomes also poor. The weight ratio of the Bisphenol A epoxy resin to the alicyclic epoxy resin is preferably 70:30 to 85:15.
A diluent having a low molecular weight and a low viscosity and containing one or more epoxy groups may be incorporated into the epoxy resin composition as a reactive diluent, if desired. Examples of such diluents include 1,6-hexanediol diglycidyl ether, polyalkyleneglycol diglycidyl ether, trimethylolpropane triglycidyl ether, butyl glycidyl ether and phenyl glycidyl ether. The amount of the diluent is generally 20% or less based on the total weight of the Bisphenol A epoxy resin and the alicyclic epoxy resin. The addition of the diluent is effective in lowering the viscosity of the epoxy resin composition.
As a curing agent for the above mixed epoxy resins, the present invention employs a combination of an acid anhydride and a specific phenol compound expressed by the above general formula (I). The acid anhydride may be, for example, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylnadic anhydride and methylbutenyltetrahydrophthalic anhydride.
As the phenol compound, there may be preferably used a compound of the formula (I) in which R.sup.1 and R.sup.2 stand independently from each other methyl, ethyl or propyl, R.sup.3 stands for methylene or ethylene and n is an integer of 2-4. Especially suitably used are 2,4,6-tri(N,N-dimethylaminomethyl)-phenol and 2-(N,N-dimethyl)aminomethylphenol. The phenol compound serves to act not only as a curing accelerator but also as a coloring-preventing agent. When an imidazole compound is used as a curing accelerator, the cured resin becomes black in color. In contrast, the phenol compound does not cause such a coloring of the cured resin.
The acid anhydride is generally used in an amount of 0.5-1.5 mole, preferably 0.8-1.2 mole per one equivalent of the epoxy group of the Bisphenol A and alicyclic epoxy resins (the mixture (A)). It is important that the phenol compound be used in an amount of 2-8% based on the weight of the mixture (A). An amount of the phenol compound below 2.0% by weight is undesirable because a relatively long time is required for causing the composition to gel and to lose fluidity during the initial stage of the curing (gellation time). Too high an amount of the phenol compound, on the other hand, tends to result in the coloring of the cured resin. Very good results (gellation time at 150 obtainable with the use of the phenol compound in an amount of 2.5-5% by weight based on the mixture (A) and this range is preferred.
The epoxy resin composition of the present invention may further contain one or more additives such as a filler, e.g. silica, alumina or hydrated alumina, a flame retarder, a coloring agent, an antifoaming agent and a plasticizer, as desired.
During storage and transportation, the composition according to the present invention is preferably rendered in the form of a two-component pack type composition consisting of the mixture (A) as a first component pack and the curing agent (B) as a second component pack. The above-mentioned diluent and the above additives may be incorporated into the first component pack (A).
In use, the components (A) and (B) are mixed and the mixture is applied dropwise to a coil to be fixed such as a stator or rotor coil of a motor or a generator, while rotating the coil to prevent the applied composition from running down. It is desirable to previously heat the coil to a curing temperature before the application of the composition. The curing may be performed at a temperature of 100-180
The following examples will further illustrate the present invention, in which "part" is by weight.
EXAMPLE 1 An epoxy resin mixture (A) and a curing agent (B) having the following formulations were prepared:
______________________________________Epoxy resin mixture (A):Bisphenol A epoxy resin*1                    80    parts3,4-Epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate*2                    15    parts1,6-Hexanediol diglycidyl ether*3                    5     partsCuring agent (B):Methylbutenyltetrahydrophthalicanhydride*4              60    partsMethyltetrahydrophthalic anhydride                    43    parts2,4,6-Tri(N,N-dimethylaminomethyl)-phenol*5                 3     parts______________________________________ *1: ADECA EP4300, manufactured by Asahi Denka K. K., epoxy equivalent: 180-200 *2: SEROXIDE 2021, manufactured by Dicel Kagaku Kogyo K. K. *3: ADECA ED503, manufactured by Asahi Denka K. K. *4: EPICURE YH306, manufactured by Yuka Shell Epoxy Inc. *5: compound of the following formula: ##STR7##
The thus obtained epoxy resin mixture (A) and the curing agent (B) were blended with a blending ratio (A)/(B) of 100/115 (wt/wt) to obtain an epoxy resin composition.
A copper wire (diameter: 2 mm) was wound around a core to obtain a rotor coil having five-layered windings. The coil was heated to 160 onto which was applied dropwise the above epoxy resin composition while slowing rotating the coil. The coil impregnated with the epoxy resin composition was maintained at 160 composition. The windings were found to be tightly and integrally fixed with each other. No change in color or in bonding was observed even when the coil was allowed to stand at 180 cooling, the coil was cut along a plane crossing the winding direction. It was found that the resin had penetrated into entire interstices of the coil.
EXAMPLE 2 An epoxy resin mixture (A) and a curing agent (B) having the following formulations were prepared:
______________________________________Epoxy resin mixture (A):Bisphenol A epoxy resin*6                  60 parts3,4-Epoxycyclohexylmethyl (3,4-                  40 partsepoxy)cyclohexane carboxylate*2Curing agent (B):Methyltetrahydrophtalic anhydride *7                  97 parts2,4,6-Tri(N,N-dimethylaminomethyl)-                   4 partsphenol*5______________________________________ *2: the same as used in Example 1 *5: the same as used in Example 1 *6: Epicote 828, Epoxy equivalent: 184-194, manufactured by Yuka Shell Epoxy Inc. *7: Epicron B570 manufactured by Dainihon Ink Kagaku Kogyo K. K.
The thus obtained epoxy resin mixture (A) and the curing agent (B) were blended with a blending ratio (A)/(B) of 1:1 (wt/wt) to obtain an epoxy resin composition having an initial viscosity at 25 This composition was tested for gellation time, curability and coloring and was found to show a gellation time of 80 seconds, good curability and no coloring. The test methods are as follows:
Gellation time The composition (0.4 cc) is dropped onto a plate heated previously heated to 150 gel and to lose its fluicity is measured.
Curability The composition is applied to a coil in the same manner as that in Example 1, heated at 160 glass transition point of the resin is measured. When the measured glass transition point has reached its maximum value, the curability is regarded as being good. If not yet reached, then the curability is regarded as being poor.
Coloring The composition is processed to obtain a cured test piece having a size of 100 for 24 hours. If the aged test piece shows a light transmittance of more than 10%, the test piece is regarded as being free of coloring. If exceeds 10%, the test piece is regarded to be colored.
EXAMPLE 3 Example 2 was repeated in the same manner as described except that the Bisphenol A and alicyclic epoxy resins were used in amounts of 80 parts and 20 parts, respectively. The resulting composition showed an initial viscosity at 25 good curability, and was free of coloring.
EXAMPLE 4 Example 2 was repeated in the same manner as described except that the phenol compound was used in an amount of 2.5 parts. The resulting composition showed an initial viscosity at 25 gellation time of 110 seconds and good curability, and was free of coloring.
EXAMPLE 5 Example 2 was repeated in the same manner as described except that the phenol compound was used in an amount of 5 parts. The resulting composition showed an initial viscosity at 25 gellation time of 70 seconds and good curability, and was free of coloring.
COMPARATIVE EXAMPLE 1 Example 2 was repeated in the same manner as described except that 3 parts of 2-ethyl-4-methylimidazole were used in lieu of 4 parts of the phenol compound. The resulting composition showed an initial viscosity at 25 curability, but was colored.
COMPARATIVE EXAMPLE 2 Example 2 was repeated in the same manner as described except that the phenol compound was used in an amount of 1 part. The resulting composition showed an initial viscosity at 25 time of 180 seconds and, and was free of coloring. However, the curability was poor.
BACKGROUND OF THE INVENTION This invention relates generally to an epoxy resin composition and, more particularly, to a liquid, epoxy resin composition having a good penetrability and suitable for fixing stator or rotor coils.
In fabrication of motors and generators to be used in automobiles, epoxy resin compositions have been hitherto used for fixing stator coils or armature coils. One known epoxy resin composition of this type is composed of 3,4-epoxycyclohexyl-methyl-(3,4-epoxy)cycloheanecarboxylate, methylnadic anhydride and resorcinol (Japanese Unexamined Patent Application No. 57-174314). In use, this composition is mixed with a small amount of triethanolamine and the mixture is applied to a coil to be fixed. The curing is performed at 120 180 because it requires a long curing time. Another problem of the known epoxy resin composition is related to the coloring of the composition when it is heated for curing.
SUMMARY OF THE INVENTION It is, therefore, an object of the present invention to provide a novel epoxy resin composition which is devoid of the drawbacks of the conventional epoxy resin composition.
It is a special object of the present invention to provide an epoxy resin composition which has good penetrability into interstices of coil windings, which can fix the coil tightly and which can give a cured body excellent in both heat-resistance and mechanical strength.
It is a further object of the present invention to provide an epoxy resin composition of the above-mentioned type which can be cured with a relatively short period of time and which does not color when heated to a curing temperature.
It is yet a further object of the present invention to provide an epoxy resin composition which has a long pot life or shelf life.
In accomplishing the foregoing objects, the present invention provides a liquid, epoxy resin composition comprising:
(A) a mixture containing
(a.sub.1) a Bisphenol A epoxy resin, and
(a.sub.2) an alicyclic epoxy resin; and
(B) a curing agent including
(b.sub.1) an acid anhydride, and
(b.sub.2) a phenol compound of the general formula: ##STR2## wherein R.sup.1 and R.sup.2 represent independently from each other a lower alkyl, R.sup.3 represents a lower alkylene and n is an integer of 1-5, the amount of the phenol compound being 2-8% based on the weight of the mixture (A).
Patent CitationsCited PatentFiling datePublication dateApplicantTitleUS4026862 *Feb 11, 1974May 31, 1977Westinghouse Electric CorporationCarboxylic acid storage stabilizers for latent catalyst cured epoxy resinsUS4069202 *Oct 17, 1975Jan 17, 1978Shell Oil CompanyCurable polyepoxide casting compositionsUS4271079 *Sep 5, 1979Jun 2, 1981Dainippon Ink & Chemicals, Inc.5-(2,5-Dioxotetrahydrofuryl)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydrideUS4420604 *Jan 23, 1981Dec 13, 1983The Oakland CorporationAdmixture of 2,4,6-tris(dimethyl aminomethyl)phenyl as a curing agent for an epoxy thread locking compositionUS4617330 *Mar 28, 1985Oct 14, 1986Kabushiki Kaisha ToshibaEpoxy resin composition for cast molding* Cited by examinerReferenced byCiting PatentFiling datePublication dateApplicantTitleUS6558812 *Sep 20, 2001May 6, 2003Shin-Etsu Chemical Co., Ltd.Liquid epoxy resin composition and semiconductor deviceUS20090245709 *Apr 12, 2007Oct 1, 2009Ntn CorporationPore-sealing agent, member for coating spray deposit, and beaning* Cited by examinerClassifications U.S. Classification528/93, 528/103International ClassificationC08G59/22, C08G59/62, C08G59/68, C08G59/00, C08L63/00, C08G59/42, C08G59/20, H01B3/40Cooperative ClassificationC08G59/686, C08G59/226, C08G59/4215European ClassificationC08G59/22B, C08G59/42D, C08G59/68DLegal EventsDateCodeEventDescriptionApr 11, 2002FPAYFee paymentYear of fee payment: 12Feb 23, 1998FPAYFee paymentYear of fee payment: 8Feb 25, 1994FPAYFee paymentYear of fee payment: 4Mar 17, 1992CCCertificate of correctionAug 23, 1989ASAssignmentOwner name: SOMAR CORPORATION, JAPANFree format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNORS:AKUTAGAWA, ICHIRO;YAMAGUCHI, TSUTOMU;HANAMORI, TOSHIHIRO;AND OTHERS;REEL/FRAME:005124/0321Effective date: 19890727RotateOriginal ImageGoogle Home - Sitemap - USPTO Bulk Downloads - Privacy Policy - Terms of Service - About Google Patents - Send FeedbackData provided by IFI CLAIMS Patent Services©2012 Google