CA1037188A - Epoxy resin compositions - Google Patents
Epoxy resin compositionsInfo
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- CA1037188A CA1037188A CA193,539A CA193539A CA1037188A CA 1037188 A CA1037188 A CA 1037188A CA 193539 A CA193539 A CA 193539A CA 1037188 A CA1037188 A CA 1037188A
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- acrylonitrile
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L63/00—Compositions of epoxy resins; Compositions of derivatives of epoxy resins
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- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Epoxy Resins (AREA)
- Adhesives Or Adhesive Processes (AREA)
- Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
- Compositions Of Macromolecular Compounds (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
The present invention relates to the improvement of epoxy resins which have previously been modified by butadiene-acrylonitrile/methacrylonitrile copolymers, by vulcanizing the modifying copolymer with an organic peroxide or sulfur, particularly dicumyl peroxide, in an amount by weight of the copolymer of from 1.5 to 10%, to produce a modified epoxy resin being useful and having properties as a high temperature structural adhesive as well as in coatings and laminates.
The present invention relates to the improvement of epoxy resins which have previously been modified by butadiene-acrylonitrile/methacrylonitrile copolymers, by vulcanizing the modifying copolymer with an organic peroxide or sulfur, particularly dicumyl peroxide, in an amount by weight of the copolymer of from 1.5 to 10%, to produce a modified epoxy resin being useful and having properties as a high temperature structural adhesive as well as in coatings and laminates.
Description
1(;?371~8 This invention relates to a method of modifying curable epoxy resins by vulcanization and to vulcanized epoxy resins having improved high temperature adhesive properties and, in some instances, improved room temperature adhesive properties.
More particularly, the invention provides curable epoxy resin compositions havi~g more than one vicinal epoxy group per molecule, modified by reaction with from .03 to .2, preferably from .08 to .12, parts by weight per part of epoxy resin of polymer of butadiene and acrylonitrile, methacrylonitrile or mixtures thereof, said polymer having pendant reactive groups selected from COOH, OH and SH, and containing from 70 to 90, preferably from 80 to 85, percent by weight of butadiene and from 10 to 30, preferably from 15 to 20, percent by weight of acrylonitrile or methacrylo-nitrile, said epoxy resin characterized in that the modifying polymer is vulcanized with from 1.5 to lO parts by weight or from 3 to 15 parts by weight, respectively, : of an organic peroxide or sulfur, per 100 parts by weight of the reactive polymer modifier, at a temperature of from 120C to 160C for from l.0 to 3.0 hours.
The invention also provides a method of modifying a curable epoxy resin having more than one vicinal epoxy group per molecule by reaction of said resin with from 0.03 to 0.2 parts by weight, based on the weight of epoxy resin, of a polymer of butadiene and acrylonitrile, methacrylo-nitrile or mixtures thereof, said polymer having pendant reactive groups of COOH, OH or SH and containing 70 to 90 weight percent butadiene and 30 to 10 weight percent acrylonitrile or methacrylonitrile, characterized by .... ~, ~^'' 16,540-F -1-1037~88 vulcanizing the modifying polymer with from 1.5 to 10 parts by weight or from 3 to 15 parts by weight, respec-tively, of an organic peroxide or sulfur, per 100 parts by weight of the reactive polymer modifier, at a temperature of from 120C to 160C for from 1.0 to 3.0 hours after reaction of the polymer with the epoxy resin.
The polymer modified solid epoxy resins of the present invention are conveniently prepared by mixing a liquid epoxy resin with the palymer modifier and a dihy-droxyl-containing compound and heating in the presence of a suitable catalyst to cause reaction between the liquid epoxy resin and the reactive groups of the polymer modifier and with the dihydroxyl-containing compound. Then the resultant product is vulcanized with sulfur or an organic peroxide.
Suitable catalysts include those normally employed in the preparation of epoxy resins from polyepoxides and di-hydroxyl-containing compounds such as, for example, tertiary amines, quaternary ammonium compounds and phosphonium com-pounds. Such catalysts and procedures are well known in the art.
Alternatively, the liquid epoxy resin can be pre-reacted with the modified polymer compound and then the resul-tant product can be reacted with a dihydroxyl-containing com-pound and this product subsequently vulcanized to produce the resultant vulcanized, polymer modified solid epoxy resins of the present invention.
The quantities of liquid epoxy resin and dihydroxyl--containing compound which are employed to produce a solid epoxy resin are well known in the art.
The preparation of the polymer modified solid epoxy resins can be carried out at temperatures from 110C to 16,540-F -2-. .
103~188 150C, preferably from 130C to 140C, and subsequently vulcanized at temperatures of from 120C to 160C, pre-ferably 140C to 150C. The time to complete each reaction is, of course, dependent upon the temperature, but each reaction can usually be completed within from 1 to 3, preferably from 2 to 2.5, hours.
Suitable organic peroxides which may be employed.
as vulcanization agents include, for example, aliphatic peroxides such as, for example, di-t-butyl peroxide, t-butyl hydroperoxide and aromatic peroxides, such as, for example, dicumyl peroxid.e, t-butyl-cumyl peroxide, methyl cumyl peroxide, mixtures thereof and the like.
The organic peroxide vulcanization agent is ' employed. in quantities of from 1.5 to 10, preferably from3 to 4, parts by weight per 100 parts by weight of the reactive polymer modifier employed.
I
' The sulfur vulcanization agent is employed in quantities of from 3 to 15, preferably from 9 to 11, parts by weight per 100 parts by weight of the polymer modifier ~ 20 employed.
; Suitable liquid epoxy resins which can be employed in the present invention include but are not limited to those represented. by the following formulas.
A. O X X
25CH2_cH_cH2 ~ o ~ A ~ O-CH2-CH-CH2 ~ 0 X X OH
CH2-CH-CE~2-O~A ~ i 16,540-F -3-1037~88 wherein A is a divalent hyd.rocarbon group having from 1 to 6 carbon atoms, O O O
.. .. ..
-S-, -S-S-, -S-, -S-, -C-, or -0-;
o X is hydrogen or a halogen atom such as chlorine or S bromine; and n is an integer having an average value of from about 0 to about 5.5.
B. O O
CH2-\H-CH2 / \
O ~R O
0 ~C ~H
X X R X X m ~ wherein m has an average value of from about 1.01 to about : 5~ preferably from about 1.05 to about 4; each X is . ind.ependently hydrogen, halogen, such as chlorine or bromine, or an alkyl group of from 1 to 4 carbon atoms and each R is independently hyd.rogen or an alkyl group of from l to 4 carbon atoms.
Suitable dihyd.roxy compound.s which can be employed to prepare the polymer modified solid epoxy resins of the present invention include but are not limited to those represented by the general formulas:
HO ~ A ~ OH HO ~ A ~ OH
X X X X
wherein each X is independently hydrogen, chlorine or bromine, and A is a d.ivalent hydrocarbon group having from .~ l to 6 carbon atoms, 16,540-F -4-iO37~8 o o o .. .. ..
-S-, -S-S-, -S-, -S-, -C- or -0-o OH
X ~ OH ~
X X OH
wherein each X is independently hydrogen, chlorine, bromine or an alkyl group having from about 1 to 6 carbon atoms.
Suitable reactive polymer modifiers which may be employed include acrylonitrile-butadiene polymers, methacrylonitrile-butad.iene polymers, or acrylonitrile-methacrylonitrile-butadiene polymers, mixtures thereof and. the like which also contain terminal or pendant reactive -COOH groups, -OH groups or -SH groups. Suitable polymers have average molecular weights of from about 2,000 to about 20,000, a reactive group functionality of from 1.2 to 5, preferably from 1.7 to 2.4, and contain from 10 to 30, pre-ferably from 15 to 20, percent by weight of acrylonitrile, methacrylonitrile or mixtures thereof.
; These polymers are known in t:he art and. can be prepared by any suitable process for polymerizing ethyl-enically unsaturated compounds and such processes usually employ free radical catalysts such as 4,4'-azobis(cyano-valeric acid), azobisisobutyronitrile and. the like. Pend.ant or terminal COOH groups can then be converted to an -OH or -SH group if desired.
Another method. is to employ ethylenically un-saturated monomers containing -COOH, -OH or -SH groups in the initial polymerization. Suitable such monomers include, 16,540-F _5_ lQ37~88 for example, acrylic acid., methacrylic acid, allyl alcohol, allyl mercaptan, mixtures thereof and the like.
The modified epoxy resins of the present invention can be employed in adhesives, coatings, laminates and the like.
The mod.ified epoxy resins of the present invention can be cured with the usual curing agents or curing catalysts for epoxy resins including primary, secondary, and. tertiary aliphatic amines, aziridines, polycarboxylic acid.s and. anhydrides thereof, Lewis acids, polythiols, dicyandiamid.es, aromatic amines, mixtures thereof and the like. The curing agents or curing catalysts may be employed in quantities known in the art and the curing agents are usually employed in quantities of from 80% to 200% of the theoretical stoichiometric quantity.
The modified epoxy resins of the present invention can be employed.with the usual modifiers and additives including fire retardant agents, pigments, dyes, flow control agents, curing accelerators, fillers, mold release agents, mixtures thereof and the like.
Example 1 A. Preparation of Modified Solid Epoxy Resin Vulcanized. With DicumYl Perox de To a reaction vessel equipped with stirrer and temperature control means, was added 15 grams of a butadiene-acrylonitrile polymer containing 1.85 carboxyl groups per ; molecule, 18~8% by weight of acrylonitrile and an average molecular weight of 3,500, 150 grams of the diglycidyl ether of bisphenol A having an epoxid.e equivalent weight of about 190 and 43 grams of bisphenol A. The mixture was heated to 100C and .3 gram of tetrabutyl phosphonium acetate-acetic 16,540-F -6-~037~8B
acid complex catalyst as a 70% solution in methanol was added. The mixture was heated at 140C for 30 minutes.
This 30 minute interval was to permit the carboxyl groups to react with the epoxy. After 30 minu~es .5 gram of dicumyl peroxide was added. The reaction temperature has usually started to exotherm prior to addition of the peroxide and the exotherm continues to a temperature of approximately 180C.
The temperature was then maintained at approximately 160C
for 2.5 hours to complete the reaction between the epoxy resin and the bisphenol A. The resultant modified solid resin was light yellow in color and had an epoxide content of 7. 8~o (EEW 555) and a ~urran's softening point of 70C.
B. Preparation of Modified Solid Epoxy Resin Vulcanized With Sulfur To a reaction vessel equipped with stirrer and temperature control means was added 15 grams of a poly-butadiene-acrylonitrile polymer containing 1.85 carboxyl groups per molecule, 18. 8% by weight of acrylonitrile and an average molecular weight of 3J500, 150 grams of diglycidyl ether of bisphenol A having an epoxide equivalent weight of about 190 and 43 grams of bisphenol A. The mixture was heated to 100C and .3 gram of tetrabutyl phosphonium acetate-acetic acid complex catalyst as a 70/O solution in methanol was added. The mixture was heated at 140C for 30 minutes. This 30 minute interval was to permit the carboxyl groups to react with the epoxy. After 30 minutes 1.5 grams of sulfur was added. The reaction temperature has usually started to exotherm prior to addition of the sulfur and the exotherm continues to a temperature of approximately 180C. The temperature was then maintained at approximately 160C for 2.5 hours to complete the reaction between the 16,540-F -7-103~1W
epoxy resin and the bisphenol A. The resultant modified solid resin was light yellow in color and had. an epoxide content of 7~/O (EEW 544) and a Durran~s softening point of 70C.
C. Preparation of Mod.ified.Solid Epoxy Resin Without Vulcanization (For Comparative Purposes) The reactants and. procedure of Part A above was repeated except that the dicumyl peroxide was omitted. The resultant solid epoxy resin was white opaque in color and had an epoxide content of 8.~/o (an average epoxide equivalent weight, EEW, of about 525) and a Durran's softening point of about 69C.
D. PreParation of Adhesives From A, B and C PrePared Above The following adhesive formulation was melt mixed.
and applied to aluminum, Type 2024 T-3 strips. Two such strips were overlapped. 1/2 inch and cured at 175C for about 1.5 hours. The resultant test strips were tested accord.ing to ASTM D-1002-64 at 77F and 250F. The results are given in Table I.
Ad.hesive Formulation 20 grams of solid epoxy resin prepared in A, B or C.
lO grams of aluminum powder 0.4 grams of colloidal silica 0.6 grams of d.icyand.iamide TABLE I
EPOXY Resin EmPloYed Tensile Shear Strenath, PSi 77 F. 250F.
A (vulcanized with dicumvl peroxide) 6450 3300 B (vulcanized with sulfur) 5750 1500 C (unvulcanized) 5680 1100 16,540-F I -8-. . .
~037~88 Example 2 A. Preparation of Vulcanized Carboxyl Containing Polymer Modified Epoxy Resin To a reaction vessel equipped.with stirrer and temperature control means was add.ed. 15 grams of an acrylo-nitrile-butadiene copolymer having an average molecular weight of 3,400, an acrylonitrile content of l~/o and carboxyl functionality of 2.4, and 103.5 gm of the di-glycidyl ether of bisphenol A having an epoxid.e equivalent weight of about 190. The mixture was heated to 100C and.
.2 gm of tetrabutyl phosphonium acetate~acetic acid complex catalyst as a 70% solution in methanol was added. The mixture was held at 100C for 30 minutes. This 30 minutes interval was to permit the carboxyl groups to react with the epoxy.
After 30 minutes the temperature was raised to 145C and 18 grams of bisphenol S was added. After 5 minutes to allow mixing of the bisphenol S, .5 gm dicumyl-peroxide was added The reaction was continued. for one hour at 145C. The . average EEW of the resultant solid epoxy resin was about 380.
B. Preparation of Unvulcanized Carboxyl Containing PolYmer Modified EPOXY Resin (ComParative) The procedure was the same as in A. above except for the final step in that no d.icumyl peroxide was ad.ded.
The average EEW of the resultant solid epoxy resin was about 375.
C. PreParation and Testinq of Adhesives from A and B
Adhesives were prepared from the resins prepared in A and B above employing the following formulation.
20 grams of epoxy resin 10 grams of aluminum powder .4 grams of colloidal silica .6 grams of dicyandiamide 16,540-F _g_ 10371~8 The adhesives were applied to aluminum strips and cured at 175C for 2 hours, and. the lap shear strengths at 77F and 250F were determined according to ASTM D-1002-64.
The results are given below.
Lap Shear Strenqth, psi Epoxy Resin Employed~ 77F. 250F.
A. Vulcanized 5650 3750 B. Unvulanized 4600 2100 Example 3 A. Prepaxation of Vulcanized Mercaptan (SH) Containinq PolYmer-Modified EpoxY Resin To a reaction vessel equipped with stirrer and temperature control means was added 15 grams of an acrylo-nitrile-butadiene copolymer having an average molecular weight of 3,000, an acrylonitrile content of 24% and mercaptan (SH) functionality of 1.6, and 150 grams of the diglycidyl ether of bisphenol A having an epoxide equivalent weight of about 190. The mixture was heated. to 100C and .16 gm of tetrabutyl-phosphonium acetate-acetic acid complex catalyst as a 70/O solution in methanol was added. The mixture was held at 100C for 30 minutes.
This 30 minutes interval was to permit the mercaptan groups to react with the epoxy. After 30 minutes the tempera-ture was raised to 145C. and..5 gram of dicumyl-peroxide was ad.ded.. The reaction was continued. for one hour at 145C.
The resultant vulcanized polymer modified epoxy resin was a light amber colored. liquid having an average EEW of about 205.
B. Preparation of Unvulcanized Mercaptan Containing Polymer Modified EPoxY Resin (Comparative) The procedure was the same as in A above except that the reaction was completed. after 30 minutes at 100C and no d.icumyl peroxide was employed.
16,540-F -10-103718~
The average EEW of the light amber liquid resin was about 205.
C. PreParation and Testing of Adhesives from A and B
Adhesives were prepared from the resins prepared in A and B above employing the following formulation.
20 grams of epoxy resin 13 grams of aluminum powder 1.0 gram of colloidal silica 1.0 gram of dicyandiamide The adhesives were applied to aluminum strips and, cured at 175C for 2 hours, and the lap shear strengths at 77F and 250F were determined according to ASTM D-1002-64.
The results are given below.
Lap Shear Strenqth. PSi Epoxy Resin EmPloYed 77F. 250F.
A. Vulcanized 3766 1530 B. Unvulcanized 4133 1300 ExamPle 4 To a reaction vessel equipped with stirring and temperature control means was added 150 grams of a diglycidyl ether of bisphenol A having an average EEW of 187 and 30 grams of a carboxyl containing acrylonitrile butadiene polymer having an average molecular weight of about 3500, containing about 18.6% by weight of acrylonitrile and, containing about
More particularly, the invention provides curable epoxy resin compositions havi~g more than one vicinal epoxy group per molecule, modified by reaction with from .03 to .2, preferably from .08 to .12, parts by weight per part of epoxy resin of polymer of butadiene and acrylonitrile, methacrylonitrile or mixtures thereof, said polymer having pendant reactive groups selected from COOH, OH and SH, and containing from 70 to 90, preferably from 80 to 85, percent by weight of butadiene and from 10 to 30, preferably from 15 to 20, percent by weight of acrylonitrile or methacrylo-nitrile, said epoxy resin characterized in that the modifying polymer is vulcanized with from 1.5 to lO parts by weight or from 3 to 15 parts by weight, respectively, : of an organic peroxide or sulfur, per 100 parts by weight of the reactive polymer modifier, at a temperature of from 120C to 160C for from l.0 to 3.0 hours.
The invention also provides a method of modifying a curable epoxy resin having more than one vicinal epoxy group per molecule by reaction of said resin with from 0.03 to 0.2 parts by weight, based on the weight of epoxy resin, of a polymer of butadiene and acrylonitrile, methacrylo-nitrile or mixtures thereof, said polymer having pendant reactive groups of COOH, OH or SH and containing 70 to 90 weight percent butadiene and 30 to 10 weight percent acrylonitrile or methacrylonitrile, characterized by .... ~, ~^'' 16,540-F -1-1037~88 vulcanizing the modifying polymer with from 1.5 to 10 parts by weight or from 3 to 15 parts by weight, respec-tively, of an organic peroxide or sulfur, per 100 parts by weight of the reactive polymer modifier, at a temperature of from 120C to 160C for from 1.0 to 3.0 hours after reaction of the polymer with the epoxy resin.
The polymer modified solid epoxy resins of the present invention are conveniently prepared by mixing a liquid epoxy resin with the palymer modifier and a dihy-droxyl-containing compound and heating in the presence of a suitable catalyst to cause reaction between the liquid epoxy resin and the reactive groups of the polymer modifier and with the dihydroxyl-containing compound. Then the resultant product is vulcanized with sulfur or an organic peroxide.
Suitable catalysts include those normally employed in the preparation of epoxy resins from polyepoxides and di-hydroxyl-containing compounds such as, for example, tertiary amines, quaternary ammonium compounds and phosphonium com-pounds. Such catalysts and procedures are well known in the art.
Alternatively, the liquid epoxy resin can be pre-reacted with the modified polymer compound and then the resul-tant product can be reacted with a dihydroxyl-containing com-pound and this product subsequently vulcanized to produce the resultant vulcanized, polymer modified solid epoxy resins of the present invention.
The quantities of liquid epoxy resin and dihydroxyl--containing compound which are employed to produce a solid epoxy resin are well known in the art.
The preparation of the polymer modified solid epoxy resins can be carried out at temperatures from 110C to 16,540-F -2-. .
103~188 150C, preferably from 130C to 140C, and subsequently vulcanized at temperatures of from 120C to 160C, pre-ferably 140C to 150C. The time to complete each reaction is, of course, dependent upon the temperature, but each reaction can usually be completed within from 1 to 3, preferably from 2 to 2.5, hours.
Suitable organic peroxides which may be employed.
as vulcanization agents include, for example, aliphatic peroxides such as, for example, di-t-butyl peroxide, t-butyl hydroperoxide and aromatic peroxides, such as, for example, dicumyl peroxid.e, t-butyl-cumyl peroxide, methyl cumyl peroxide, mixtures thereof and the like.
The organic peroxide vulcanization agent is ' employed. in quantities of from 1.5 to 10, preferably from3 to 4, parts by weight per 100 parts by weight of the reactive polymer modifier employed.
I
' The sulfur vulcanization agent is employed in quantities of from 3 to 15, preferably from 9 to 11, parts by weight per 100 parts by weight of the polymer modifier ~ 20 employed.
; Suitable liquid epoxy resins which can be employed in the present invention include but are not limited to those represented. by the following formulas.
A. O X X
25CH2_cH_cH2 ~ o ~ A ~ O-CH2-CH-CH2 ~ 0 X X OH
CH2-CH-CE~2-O~A ~ i 16,540-F -3-1037~88 wherein A is a divalent hyd.rocarbon group having from 1 to 6 carbon atoms, O O O
.. .. ..
-S-, -S-S-, -S-, -S-, -C-, or -0-;
o X is hydrogen or a halogen atom such as chlorine or S bromine; and n is an integer having an average value of from about 0 to about 5.5.
B. O O
CH2-\H-CH2 / \
O ~R O
0 ~C ~H
X X R X X m ~ wherein m has an average value of from about 1.01 to about : 5~ preferably from about 1.05 to about 4; each X is . ind.ependently hydrogen, halogen, such as chlorine or bromine, or an alkyl group of from 1 to 4 carbon atoms and each R is independently hyd.rogen or an alkyl group of from l to 4 carbon atoms.
Suitable dihyd.roxy compound.s which can be employed to prepare the polymer modified solid epoxy resins of the present invention include but are not limited to those represented by the general formulas:
HO ~ A ~ OH HO ~ A ~ OH
X X X X
wherein each X is independently hydrogen, chlorine or bromine, and A is a d.ivalent hydrocarbon group having from .~ l to 6 carbon atoms, 16,540-F -4-iO37~8 o o o .. .. ..
-S-, -S-S-, -S-, -S-, -C- or -0-o OH
X ~ OH ~
X X OH
wherein each X is independently hydrogen, chlorine, bromine or an alkyl group having from about 1 to 6 carbon atoms.
Suitable reactive polymer modifiers which may be employed include acrylonitrile-butadiene polymers, methacrylonitrile-butad.iene polymers, or acrylonitrile-methacrylonitrile-butadiene polymers, mixtures thereof and. the like which also contain terminal or pendant reactive -COOH groups, -OH groups or -SH groups. Suitable polymers have average molecular weights of from about 2,000 to about 20,000, a reactive group functionality of from 1.2 to 5, preferably from 1.7 to 2.4, and contain from 10 to 30, pre-ferably from 15 to 20, percent by weight of acrylonitrile, methacrylonitrile or mixtures thereof.
; These polymers are known in t:he art and. can be prepared by any suitable process for polymerizing ethyl-enically unsaturated compounds and such processes usually employ free radical catalysts such as 4,4'-azobis(cyano-valeric acid), azobisisobutyronitrile and. the like. Pend.ant or terminal COOH groups can then be converted to an -OH or -SH group if desired.
Another method. is to employ ethylenically un-saturated monomers containing -COOH, -OH or -SH groups in the initial polymerization. Suitable such monomers include, 16,540-F _5_ lQ37~88 for example, acrylic acid., methacrylic acid, allyl alcohol, allyl mercaptan, mixtures thereof and the like.
The modified epoxy resins of the present invention can be employed in adhesives, coatings, laminates and the like.
The mod.ified epoxy resins of the present invention can be cured with the usual curing agents or curing catalysts for epoxy resins including primary, secondary, and. tertiary aliphatic amines, aziridines, polycarboxylic acid.s and. anhydrides thereof, Lewis acids, polythiols, dicyandiamid.es, aromatic amines, mixtures thereof and the like. The curing agents or curing catalysts may be employed in quantities known in the art and the curing agents are usually employed in quantities of from 80% to 200% of the theoretical stoichiometric quantity.
The modified epoxy resins of the present invention can be employed.with the usual modifiers and additives including fire retardant agents, pigments, dyes, flow control agents, curing accelerators, fillers, mold release agents, mixtures thereof and the like.
Example 1 A. Preparation of Modified Solid Epoxy Resin Vulcanized. With DicumYl Perox de To a reaction vessel equipped with stirrer and temperature control means, was added 15 grams of a butadiene-acrylonitrile polymer containing 1.85 carboxyl groups per ; molecule, 18~8% by weight of acrylonitrile and an average molecular weight of 3,500, 150 grams of the diglycidyl ether of bisphenol A having an epoxid.e equivalent weight of about 190 and 43 grams of bisphenol A. The mixture was heated to 100C and .3 gram of tetrabutyl phosphonium acetate-acetic 16,540-F -6-~037~8B
acid complex catalyst as a 70% solution in methanol was added. The mixture was heated at 140C for 30 minutes.
This 30 minute interval was to permit the carboxyl groups to react with the epoxy. After 30 minu~es .5 gram of dicumyl peroxide was added. The reaction temperature has usually started to exotherm prior to addition of the peroxide and the exotherm continues to a temperature of approximately 180C.
The temperature was then maintained at approximately 160C
for 2.5 hours to complete the reaction between the epoxy resin and the bisphenol A. The resultant modified solid resin was light yellow in color and had an epoxide content of 7. 8~o (EEW 555) and a ~urran's softening point of 70C.
B. Preparation of Modified Solid Epoxy Resin Vulcanized With Sulfur To a reaction vessel equipped with stirrer and temperature control means was added 15 grams of a poly-butadiene-acrylonitrile polymer containing 1.85 carboxyl groups per molecule, 18. 8% by weight of acrylonitrile and an average molecular weight of 3J500, 150 grams of diglycidyl ether of bisphenol A having an epoxide equivalent weight of about 190 and 43 grams of bisphenol A. The mixture was heated to 100C and .3 gram of tetrabutyl phosphonium acetate-acetic acid complex catalyst as a 70/O solution in methanol was added. The mixture was heated at 140C for 30 minutes. This 30 minute interval was to permit the carboxyl groups to react with the epoxy. After 30 minutes 1.5 grams of sulfur was added. The reaction temperature has usually started to exotherm prior to addition of the sulfur and the exotherm continues to a temperature of approximately 180C. The temperature was then maintained at approximately 160C for 2.5 hours to complete the reaction between the 16,540-F -7-103~1W
epoxy resin and the bisphenol A. The resultant modified solid resin was light yellow in color and had. an epoxide content of 7~/O (EEW 544) and a Durran~s softening point of 70C.
C. Preparation of Mod.ified.Solid Epoxy Resin Without Vulcanization (For Comparative Purposes) The reactants and. procedure of Part A above was repeated except that the dicumyl peroxide was omitted. The resultant solid epoxy resin was white opaque in color and had an epoxide content of 8.~/o (an average epoxide equivalent weight, EEW, of about 525) and a Durran's softening point of about 69C.
D. PreParation of Adhesives From A, B and C PrePared Above The following adhesive formulation was melt mixed.
and applied to aluminum, Type 2024 T-3 strips. Two such strips were overlapped. 1/2 inch and cured at 175C for about 1.5 hours. The resultant test strips were tested accord.ing to ASTM D-1002-64 at 77F and 250F. The results are given in Table I.
Ad.hesive Formulation 20 grams of solid epoxy resin prepared in A, B or C.
lO grams of aluminum powder 0.4 grams of colloidal silica 0.6 grams of d.icyand.iamide TABLE I
EPOXY Resin EmPloYed Tensile Shear Strenath, PSi 77 F. 250F.
A (vulcanized with dicumvl peroxide) 6450 3300 B (vulcanized with sulfur) 5750 1500 C (unvulcanized) 5680 1100 16,540-F I -8-. . .
~037~88 Example 2 A. Preparation of Vulcanized Carboxyl Containing Polymer Modified Epoxy Resin To a reaction vessel equipped.with stirrer and temperature control means was add.ed. 15 grams of an acrylo-nitrile-butadiene copolymer having an average molecular weight of 3,400, an acrylonitrile content of l~/o and carboxyl functionality of 2.4, and 103.5 gm of the di-glycidyl ether of bisphenol A having an epoxid.e equivalent weight of about 190. The mixture was heated to 100C and.
.2 gm of tetrabutyl phosphonium acetate~acetic acid complex catalyst as a 70% solution in methanol was added. The mixture was held at 100C for 30 minutes. This 30 minutes interval was to permit the carboxyl groups to react with the epoxy.
After 30 minutes the temperature was raised to 145C and 18 grams of bisphenol S was added. After 5 minutes to allow mixing of the bisphenol S, .5 gm dicumyl-peroxide was added The reaction was continued. for one hour at 145C. The . average EEW of the resultant solid epoxy resin was about 380.
B. Preparation of Unvulcanized Carboxyl Containing PolYmer Modified EPOXY Resin (ComParative) The procedure was the same as in A. above except for the final step in that no d.icumyl peroxide was ad.ded.
The average EEW of the resultant solid epoxy resin was about 375.
C. PreParation and Testinq of Adhesives from A and B
Adhesives were prepared from the resins prepared in A and B above employing the following formulation.
20 grams of epoxy resin 10 grams of aluminum powder .4 grams of colloidal silica .6 grams of dicyandiamide 16,540-F _g_ 10371~8 The adhesives were applied to aluminum strips and cured at 175C for 2 hours, and. the lap shear strengths at 77F and 250F were determined according to ASTM D-1002-64.
The results are given below.
Lap Shear Strenqth, psi Epoxy Resin Employed~ 77F. 250F.
A. Vulcanized 5650 3750 B. Unvulanized 4600 2100 Example 3 A. Prepaxation of Vulcanized Mercaptan (SH) Containinq PolYmer-Modified EpoxY Resin To a reaction vessel equipped with stirrer and temperature control means was added 15 grams of an acrylo-nitrile-butadiene copolymer having an average molecular weight of 3,000, an acrylonitrile content of 24% and mercaptan (SH) functionality of 1.6, and 150 grams of the diglycidyl ether of bisphenol A having an epoxide equivalent weight of about 190. The mixture was heated. to 100C and .16 gm of tetrabutyl-phosphonium acetate-acetic acid complex catalyst as a 70/O solution in methanol was added. The mixture was held at 100C for 30 minutes.
This 30 minutes interval was to permit the mercaptan groups to react with the epoxy. After 30 minutes the tempera-ture was raised to 145C. and..5 gram of dicumyl-peroxide was ad.ded.. The reaction was continued. for one hour at 145C.
The resultant vulcanized polymer modified epoxy resin was a light amber colored. liquid having an average EEW of about 205.
B. Preparation of Unvulcanized Mercaptan Containing Polymer Modified EPoxY Resin (Comparative) The procedure was the same as in A above except that the reaction was completed. after 30 minutes at 100C and no d.icumyl peroxide was employed.
16,540-F -10-103718~
The average EEW of the light amber liquid resin was about 205.
C. PreParation and Testing of Adhesives from A and B
Adhesives were prepared from the resins prepared in A and B above employing the following formulation.
20 grams of epoxy resin 13 grams of aluminum powder 1.0 gram of colloidal silica 1.0 gram of dicyandiamide The adhesives were applied to aluminum strips and, cured at 175C for 2 hours, and the lap shear strengths at 77F and 250F were determined according to ASTM D-1002-64.
The results are given below.
Lap Shear Strenqth. PSi Epoxy Resin EmPloYed 77F. 250F.
A. Vulcanized 3766 1530 B. Unvulcanized 4133 1300 ExamPle 4 To a reaction vessel equipped with stirring and temperature control means was added 150 grams of a diglycidyl ether of bisphenol A having an average EEW of 187 and 30 grams of a carboxyl containing acrylonitrile butadiene polymer having an average molecular weight of about 3500, containing about 18.6% by weight of acrylonitrile and, containing about
2.7 weight percent of COOH groups and an average function-ality of COOH groups of about 2. After degassing resultant mixture at 80C for 15 minutes, 75 milligrams of tetrabutyl phosphonium acetate-acetic acid complex catalyst was added and the reaction conducted at 120C for 2 hours.
16,540-F -11-103~
Then 60 grams of the resultant unvulcanized product was removed~ and for the purposes herein, this is designated as resin 4-A and has an average EEW of about 235.
To the remaining product 0.3 gram of dicumyl peroxide was added and the reaction temperature was raised to 145C and the reaction conducted under vacuum for 2 hours.
The decomposition of the dicumyl peroxide was essentially complete and about 50% of the polymer-mod.ifier pres~ent was vulcanized. The resultant vulcanized. product, for purposes herein, is designated as resin 4-B and had an~average EEW
of about 236.
Adhesives were prepared from each of the above prepared modified.-resins employing the following formulation.
6 grams of mod.ified resin ! 15 5 grams of the unmodified. d.iglycidyl ether of bisphenol A having an average EEW of 187 8 grams of aluminum powder 0.5 gram of colloidal silica 0.8 gram of dicyandiamide 0.3 gram of dichlorophenyl dimethylurea . 20 Lap shear samples were prepared using 4 1/2" x 1" x .020" d.ichromate etched type 2024-T3 aluminum strips ; overlapped 1/2". The strips were then cured at 280F for 1 hour. Lap shear values were then obtained accord.ing to ASTM D-1002 at various temperatures. The results are reported in the following table as the average of three samples.
~`, .
16,540-F -12-1~37188 Resin 4-A Resin 4-B
UnvulcanizedVulcanized Test TemPerature,F. (ComParative)(Present Inv.) 77 2610 psi5390 psi ExamPle 5 To a reaction vessel equipped. with stirring and temperature control means was added 200 grams of a d.iglycidyl ether of bisphenol F (p,p'-methylenediphenol) having an average EEW of about 167 and 18 grams of a carboxyl containing acrylonitrile-butadiene polymer having about 28Yo acrylo-nitrile, an average COOH functionality of about 1.9~ 0. 047 equivalent of COOH per 100 grams of polymer and an average molecular weight of 3500. After devolatilizing the mixture at 80C under vacuum, the vacuum was replaced with an atmos-phere of nitrogen and 100 milligrams of tetrabutyl phosphonium acetate-acetic acid complex catalyst was ad.ded.. The tempera-ture was raised to 125C and maintained thereat for about 1 1/2 hour~. Then 0.6 gram of dicumyl peroxide was added ; and. the reaction continued for 2 hours at 145 C under vacuum.
One fourth, 54.5 grams of the resultant clear amber liquid product was removed and for the purposes herein designated as resin 5-A having a percent epoxide of 22.6 (190 EEW) and a viscosity of 9,200 centipoises. To the remaind.er of the product, .45 gram of d.icumyl peroxide was added and the re-action continued. at 150C for 2 hours. One-half of the 16,540-F -13-' ~.
resultant clear amber liquid product having a percent epoxide of 22.6 (EEW of about 190) and a viscosity of 18,200 centi-poises was removed. and for the purposes herein designated as resin 5-B. To the remainder of the resultant product 0.3 grams of dicumyl peroxid.e was added and the reaction continued under vacuum for 2 hours at 150~C. The resultant product was a clear, bright yellow liquid having a viscosity of 22,000 centipoises and. a percent epoxide of 22.5 (191 EEW) and for the purposes herein it was designated resin 5-C.
The mole ratio of peroxide/polymer modifier of each of the products prepared above was as follows:
Resin Peroxid.e/PolYmer Modifier Mole Ratio 5-A 0.5:1 5-B 1.0:1 5-C 1.5:1 Each of the three products were employed as adhesives employing the following composition.
10.9 grams modified resin 8 grams aluminum powder 0.5 grams colloidal silica 0.8 grams dicyand.iamide . 0.2 grams melamine The adhesives were applied. to etched. 4 1/2" x 1"
x .064" Type 2024-T-3 aluminum test strips for lap shear and Type 304 stainless steel strips for climbing drum peel, ~ and. after heating at 175C for 0.75 hours the lap shear and - climbing drum peel strength values were determined at 77F
as d.escribed in ASTM D-1002-64 and.ASTM D-1781-62. The results are given in the following table.
:"~
1~,540-F -14-1037~BB
Climbing Drum Lap Shear Strength Peel Strength Resin ~o. (psi) lb/inch `5-A 5930 108 The above example indicates that no particular advantage over a slight increase in the climbing drum peel strength is obtained by employing mole ratios of peroxide/
polymer mod.ifier greater than about 0.5:1.
Example 6 ~o a 500 ml 3-neck flask equipped for agitation, nitrogen purge, evacuation, and temperature control was added:
150 grams of a 2.1 functional epoxy novolac resin having an EEW of about 167 15 grams CTBN (carboxyl terminated butad.iene-acrylonitrile rubber containing 26% acrylo-nitrile and having an average molecular weight of about 3500) : 50 milligrams tetrabutylphosphonium acetate--acetic acid. complex catalyst The mixture was raised. to a temperature of 105C, ~evacuated and held 1/2 hr. to complete the reaction between carboxyl and epoxide. Then 0.50 gram of di-tertiary butyl : 20 peroxide was added. and. the temperature raised guickly to 180C (the temperature at which the rate of decomposition of this peroxid.e is the same as that for dicumyl peroxid.e at 155C). A limited vacuum was pulled (to 100 mm Hg.) and held 1/2 hr. Volatility of this peroxide requires caution in pulling a high vacuum at such an elevated. temperature.
To assure that peroxid.e was actually present under these conditions, at the end of this 1/2 hour interval the vacuum 16,540-F -15-was released using nitrogen, and 0.25 g. additional di-tert. butyl peroxid~e was added dropwise. The reaction mixture was then agitated under 1 atmosphere nitrogen pressure for 15 minutes and under full vacuum an additional 15 minutes, all at 180C. The product was then cooled and poured off as a clear amber liquid, with a viscosity at room temperature of 28,200 centipoises and. an epoxid.e content of 22.6% (191 EEW).
Adhesives were prepared from the above product employing the following composition.
11 grams mod.ified resin ~ grams aluminum powder 0.5 grams colloidal silica 0.8 grams dicyandiamide 0.2 grams melamine The adhesives were applied to etched 4-1/2" x 1" x .064" Type 2024-T-3 aluminum test strips for lap shear and Type 304 stainless steel strips for climbing drum peel, and. after heating at 175C for 0.75 hours the lap shear and climbing drum peel strength values were determined at 77F as described in ASTM D-1002-64 and ASTM D-1781-62.
. The lap shear strength was 5490 psi and. the climbing drum peel strength was 106 lb/in.
. ExamPle 7 - Thiol-Containinq Polymer Modifier . 25 A. . The procedure, reactants and concentration of ., reactants were the same as in Example l-A except that :: the polymer employed was an acrylonitrile-butadiene co-polymer having an average molecular weight of about 3000, :~ an acrylonitrile content of about 24% and a mercaptan (SH) functionality of about 1.6. The resultant modified epoxy 1~,540-F -16-~0371B8 resin had an EEW of about 558 and a Durran's softening point of about 71C.
B. The reactants and procedure of-A above was em-ployed except that no dicumyl peroxide was employed. The resultant modified epoxy resin had an EEW of about 558 and a Durran's softening point of about 71C.
C. Adhesives were prepared from A and B above according to the procedure in Example l-D. The results were as follows:
Tensile Shear Strenqth. PSi SamPle 77F. 250F.
ExamPle 8 A. Room TemPerature Curinq Structural Adhesive A structural epoxy ad.hesive must produce bonds that have three characteristics: (1) high lap shear and peel strengthJ (2) low creep (ability to carry a calculated load. indefinitely without yielding), and. (3) stability against various forms of environmental attack - temperature, humidity, etc.
Room temperature curing agents of which triethylene-tetraamine (TETA)~ diethylenetriamine (DETA), and poly-amides are most commonly used have never been able to provide adhesives with suitable peel strength, even with modified epoxies that give good peel strength when cured at elevated temperature. We have now prepared carefully selected epoxy-modifier-hard.ener systems that are found. to meet all the reguirements for a structural ad.hesive. Since the vulcaniza-tion of the nitrile rubber modifier is an important step in the preparation, examples are presented as a part of this patent application. The preparation and testing of the 1~,540-F -17-1037~88 adhesive is described, followed by a comparison to results obtained when the variables or their levels are changed from the optimum.
To a 10-gallon kettle was add.ed:
75 lb. of an epoxy novolac resin employed and described in Example 6, 13.5 lb. polymer modifier as employed and described in Example 6, 24 grams tetrabutyl phosphonium acetate-acetic acid complex catalyst as a 70O/o solution in methanol.
The charge was heated to the reaction temperature of 100C and held 1 hour to assure complete reaction of the carboxyls on the rubber with epoxide. Then 85 grams of dicumyl peroxid.e were added and the temperature raised to 150C for 2 hours reaction und.er vacuum. A product was then drummed out and cooled., analyzing 20.95% epoxide and having a viscosity of 53500 cp. at 25C.
An adhesive was formulated. from 118 parts of this ~: resin, 40 parts a-luminum powd.er, 10 parts colloidal silica, and 34 parts DEH~ 29 hard.ener, a polyethylene polyamine con-taining about 10.9% primary, 17.9% secondary and 5.9~
tertiary nitrogen and an average amine hyd.rogen equivalent weight of about 30.3.
Lap shear samples were prepared on aluminum sub-. strates as described previously and tested according to ASTM D-1002-64. The samples were cured four days at room ~ 25 temperature prior to testing.
; Test TemP. Lap Shear Strenqth : Room Temp. 4560 psi 150F. 3480 psi 180F. 2130 psi 210F. 1040 psi 16,540-F -18-1037~88 A climbing drum peel sample was prepared according to ASTM D-1781-62 using 1" x 12" x 0.020" Type 304 stain-less steel substrates, etched in conc. HCl at room tempera-ture. The peel strength after 4 days cure at room tempera-ture was measured as 89 lb/inch width. These strengths correspond to those we find for high temperature cured structural epoxies.
B. Variation in the Hardener Series Including DiethYlene Triamine and Its Homoloqs 150 grams of a diglycidyl ether of bisphenol A
having an EEW of about 189 epoxy plus 45 g. of an acrylo-nitrile-butadiene copolymer having an average molecular weight of 2200 and a COOH functionality of about 1.9 were mixed and reacted to give complete reaction of the carboxyls with epoxide. The vulcanization step was omitted in this case.
To 6.5 grams of this resin was added:
a. 1.0 gram aluminum powder b. 0.25 gram colloidal silica c. amount as specified in the Table of a hardener belonging to the diethylene-triamine family.
, , Test samples were prepared for the climbing drum , peel test, with a 4-day room temperature cure preceding the ; actual peel test.
Hardener Atnount Peel Value ; 25 DETA 0.522 g. 2 lb/inch TETA 0.725 g. 42 lb/inch av.
TEPA 0.930 g. 50 lb/inch D.E.H.~ 29 1.132 g. 75 lb/inch 16,540~F -19-~, . .
~ 03718B
This shows the improved performance given by the higher molecular weight hardener homologs. In each case, the hardener was assumed to be four-functional; that is, only the hydrogens attached to the terminal nitrogens were assumed reactive. Thus, excess hardener was pre~ent over the amount normally calculated as stoichiometric. That the excess hardener is beneficial is demonstrated in Example 8-C below.
C. To a 500 ml 3-necked flask equipped for agitation, nitrogen purge, evacuation, and temperature control, was added:
120 grams of a 2.1 functional epoxy novolac resin as defined in Example 6 21.6 grams polymer modifier as described in Example 6 lS 60 mg tetrabutyl phosphonium acetate acetic acid complex catalyst The contents were heated to 120C and held for 1 hour to assure complete reaction of the rubber carboxyls with epoxide. Then 0.292 grams of dicumyl peroxide was added and the temperature raised to 150C and held for two ; 20 hours under a full vacuum. The product was then cooled and poured off as a bright yellow liquid, analyzing 21.7% epoxide and with a viscosity of 39000 cp.
A "masterbatch" was made from:
70.8 g. above resin 12 g. aluminum powder
16,540-F -11-103~
Then 60 grams of the resultant unvulcanized product was removed~ and for the purposes herein, this is designated as resin 4-A and has an average EEW of about 235.
To the remaining product 0.3 gram of dicumyl peroxide was added and the reaction temperature was raised to 145C and the reaction conducted under vacuum for 2 hours.
The decomposition of the dicumyl peroxide was essentially complete and about 50% of the polymer-mod.ifier pres~ent was vulcanized. The resultant vulcanized. product, for purposes herein, is designated as resin 4-B and had an~average EEW
of about 236.
Adhesives were prepared from each of the above prepared modified.-resins employing the following formulation.
6 grams of mod.ified resin ! 15 5 grams of the unmodified. d.iglycidyl ether of bisphenol A having an average EEW of 187 8 grams of aluminum powder 0.5 gram of colloidal silica 0.8 gram of dicyandiamide 0.3 gram of dichlorophenyl dimethylurea . 20 Lap shear samples were prepared using 4 1/2" x 1" x .020" d.ichromate etched type 2024-T3 aluminum strips ; overlapped 1/2". The strips were then cured at 280F for 1 hour. Lap shear values were then obtained accord.ing to ASTM D-1002 at various temperatures. The results are reported in the following table as the average of three samples.
~`, .
16,540-F -12-1~37188 Resin 4-A Resin 4-B
UnvulcanizedVulcanized Test TemPerature,F. (ComParative)(Present Inv.) 77 2610 psi5390 psi ExamPle 5 To a reaction vessel equipped. with stirring and temperature control means was added 200 grams of a d.iglycidyl ether of bisphenol F (p,p'-methylenediphenol) having an average EEW of about 167 and 18 grams of a carboxyl containing acrylonitrile-butadiene polymer having about 28Yo acrylo-nitrile, an average COOH functionality of about 1.9~ 0. 047 equivalent of COOH per 100 grams of polymer and an average molecular weight of 3500. After devolatilizing the mixture at 80C under vacuum, the vacuum was replaced with an atmos-phere of nitrogen and 100 milligrams of tetrabutyl phosphonium acetate-acetic acid complex catalyst was ad.ded.. The tempera-ture was raised to 125C and maintained thereat for about 1 1/2 hour~. Then 0.6 gram of dicumyl peroxide was added ; and. the reaction continued for 2 hours at 145 C under vacuum.
One fourth, 54.5 grams of the resultant clear amber liquid product was removed and for the purposes herein designated as resin 5-A having a percent epoxide of 22.6 (190 EEW) and a viscosity of 9,200 centipoises. To the remaind.er of the product, .45 gram of d.icumyl peroxide was added and the re-action continued. at 150C for 2 hours. One-half of the 16,540-F -13-' ~.
resultant clear amber liquid product having a percent epoxide of 22.6 (EEW of about 190) and a viscosity of 18,200 centi-poises was removed. and for the purposes herein designated as resin 5-B. To the remainder of the resultant product 0.3 grams of dicumyl peroxid.e was added and the reaction continued under vacuum for 2 hours at 150~C. The resultant product was a clear, bright yellow liquid having a viscosity of 22,000 centipoises and. a percent epoxide of 22.5 (191 EEW) and for the purposes herein it was designated resin 5-C.
The mole ratio of peroxide/polymer modifier of each of the products prepared above was as follows:
Resin Peroxid.e/PolYmer Modifier Mole Ratio 5-A 0.5:1 5-B 1.0:1 5-C 1.5:1 Each of the three products were employed as adhesives employing the following composition.
10.9 grams modified resin 8 grams aluminum powder 0.5 grams colloidal silica 0.8 grams dicyand.iamide . 0.2 grams melamine The adhesives were applied. to etched. 4 1/2" x 1"
x .064" Type 2024-T-3 aluminum test strips for lap shear and Type 304 stainless steel strips for climbing drum peel, ~ and. after heating at 175C for 0.75 hours the lap shear and - climbing drum peel strength values were determined at 77F
as d.escribed in ASTM D-1002-64 and.ASTM D-1781-62. The results are given in the following table.
:"~
1~,540-F -14-1037~BB
Climbing Drum Lap Shear Strength Peel Strength Resin ~o. (psi) lb/inch `5-A 5930 108 The above example indicates that no particular advantage over a slight increase in the climbing drum peel strength is obtained by employing mole ratios of peroxide/
polymer mod.ifier greater than about 0.5:1.
Example 6 ~o a 500 ml 3-neck flask equipped for agitation, nitrogen purge, evacuation, and temperature control was added:
150 grams of a 2.1 functional epoxy novolac resin having an EEW of about 167 15 grams CTBN (carboxyl terminated butad.iene-acrylonitrile rubber containing 26% acrylo-nitrile and having an average molecular weight of about 3500) : 50 milligrams tetrabutylphosphonium acetate--acetic acid. complex catalyst The mixture was raised. to a temperature of 105C, ~evacuated and held 1/2 hr. to complete the reaction between carboxyl and epoxide. Then 0.50 gram of di-tertiary butyl : 20 peroxide was added. and. the temperature raised guickly to 180C (the temperature at which the rate of decomposition of this peroxid.e is the same as that for dicumyl peroxid.e at 155C). A limited vacuum was pulled (to 100 mm Hg.) and held 1/2 hr. Volatility of this peroxide requires caution in pulling a high vacuum at such an elevated. temperature.
To assure that peroxid.e was actually present under these conditions, at the end of this 1/2 hour interval the vacuum 16,540-F -15-was released using nitrogen, and 0.25 g. additional di-tert. butyl peroxid~e was added dropwise. The reaction mixture was then agitated under 1 atmosphere nitrogen pressure for 15 minutes and under full vacuum an additional 15 minutes, all at 180C. The product was then cooled and poured off as a clear amber liquid, with a viscosity at room temperature of 28,200 centipoises and. an epoxid.e content of 22.6% (191 EEW).
Adhesives were prepared from the above product employing the following composition.
11 grams mod.ified resin ~ grams aluminum powder 0.5 grams colloidal silica 0.8 grams dicyandiamide 0.2 grams melamine The adhesives were applied to etched 4-1/2" x 1" x .064" Type 2024-T-3 aluminum test strips for lap shear and Type 304 stainless steel strips for climbing drum peel, and. after heating at 175C for 0.75 hours the lap shear and climbing drum peel strength values were determined at 77F as described in ASTM D-1002-64 and ASTM D-1781-62.
. The lap shear strength was 5490 psi and. the climbing drum peel strength was 106 lb/in.
. ExamPle 7 - Thiol-Containinq Polymer Modifier . 25 A. . The procedure, reactants and concentration of ., reactants were the same as in Example l-A except that :: the polymer employed was an acrylonitrile-butadiene co-polymer having an average molecular weight of about 3000, :~ an acrylonitrile content of about 24% and a mercaptan (SH) functionality of about 1.6. The resultant modified epoxy 1~,540-F -16-~0371B8 resin had an EEW of about 558 and a Durran's softening point of about 71C.
B. The reactants and procedure of-A above was em-ployed except that no dicumyl peroxide was employed. The resultant modified epoxy resin had an EEW of about 558 and a Durran's softening point of about 71C.
C. Adhesives were prepared from A and B above according to the procedure in Example l-D. The results were as follows:
Tensile Shear Strenqth. PSi SamPle 77F. 250F.
ExamPle 8 A. Room TemPerature Curinq Structural Adhesive A structural epoxy ad.hesive must produce bonds that have three characteristics: (1) high lap shear and peel strengthJ (2) low creep (ability to carry a calculated load. indefinitely without yielding), and. (3) stability against various forms of environmental attack - temperature, humidity, etc.
Room temperature curing agents of which triethylene-tetraamine (TETA)~ diethylenetriamine (DETA), and poly-amides are most commonly used have never been able to provide adhesives with suitable peel strength, even with modified epoxies that give good peel strength when cured at elevated temperature. We have now prepared carefully selected epoxy-modifier-hard.ener systems that are found. to meet all the reguirements for a structural ad.hesive. Since the vulcaniza-tion of the nitrile rubber modifier is an important step in the preparation, examples are presented as a part of this patent application. The preparation and testing of the 1~,540-F -17-1037~88 adhesive is described, followed by a comparison to results obtained when the variables or their levels are changed from the optimum.
To a 10-gallon kettle was add.ed:
75 lb. of an epoxy novolac resin employed and described in Example 6, 13.5 lb. polymer modifier as employed and described in Example 6, 24 grams tetrabutyl phosphonium acetate-acetic acid complex catalyst as a 70O/o solution in methanol.
The charge was heated to the reaction temperature of 100C and held 1 hour to assure complete reaction of the carboxyls on the rubber with epoxide. Then 85 grams of dicumyl peroxid.e were added and the temperature raised to 150C for 2 hours reaction und.er vacuum. A product was then drummed out and cooled., analyzing 20.95% epoxide and having a viscosity of 53500 cp. at 25C.
An adhesive was formulated. from 118 parts of this ~: resin, 40 parts a-luminum powd.er, 10 parts colloidal silica, and 34 parts DEH~ 29 hard.ener, a polyethylene polyamine con-taining about 10.9% primary, 17.9% secondary and 5.9~
tertiary nitrogen and an average amine hyd.rogen equivalent weight of about 30.3.
Lap shear samples were prepared on aluminum sub-. strates as described previously and tested according to ASTM D-1002-64. The samples were cured four days at room ~ 25 temperature prior to testing.
; Test TemP. Lap Shear Strenqth : Room Temp. 4560 psi 150F. 3480 psi 180F. 2130 psi 210F. 1040 psi 16,540-F -18-1037~88 A climbing drum peel sample was prepared according to ASTM D-1781-62 using 1" x 12" x 0.020" Type 304 stain-less steel substrates, etched in conc. HCl at room tempera-ture. The peel strength after 4 days cure at room tempera-ture was measured as 89 lb/inch width. These strengths correspond to those we find for high temperature cured structural epoxies.
B. Variation in the Hardener Series Including DiethYlene Triamine and Its Homoloqs 150 grams of a diglycidyl ether of bisphenol A
having an EEW of about 189 epoxy plus 45 g. of an acrylo-nitrile-butadiene copolymer having an average molecular weight of 2200 and a COOH functionality of about 1.9 were mixed and reacted to give complete reaction of the carboxyls with epoxide. The vulcanization step was omitted in this case.
To 6.5 grams of this resin was added:
a. 1.0 gram aluminum powder b. 0.25 gram colloidal silica c. amount as specified in the Table of a hardener belonging to the diethylene-triamine family.
, , Test samples were prepared for the climbing drum , peel test, with a 4-day room temperature cure preceding the ; actual peel test.
Hardener Atnount Peel Value ; 25 DETA 0.522 g. 2 lb/inch TETA 0.725 g. 42 lb/inch av.
TEPA 0.930 g. 50 lb/inch D.E.H.~ 29 1.132 g. 75 lb/inch 16,540~F -19-~, . .
~ 03718B
This shows the improved performance given by the higher molecular weight hardener homologs. In each case, the hardener was assumed to be four-functional; that is, only the hydrogens attached to the terminal nitrogens were assumed reactive. Thus, excess hardener was pre~ent over the amount normally calculated as stoichiometric. That the excess hardener is beneficial is demonstrated in Example 8-C below.
C. To a 500 ml 3-necked flask equipped for agitation, nitrogen purge, evacuation, and temperature control, was added:
120 grams of a 2.1 functional epoxy novolac resin as defined in Example 6 21.6 grams polymer modifier as described in Example 6 lS 60 mg tetrabutyl phosphonium acetate acetic acid complex catalyst The contents were heated to 120C and held for 1 hour to assure complete reaction of the rubber carboxyls with epoxide. Then 0.292 grams of dicumyl peroxide was added and the temperature raised to 150C and held for two ; 20 hours under a full vacuum. The product was then cooled and poured off as a bright yellow liquid, analyzing 21.7% epoxide and with a viscosity of 39000 cp.
A "masterbatch" was made from:
70.8 g. above resin 12 g. aluminum powder
3 g. colloidal silica Four adhesives were prepared by mixing 7.15 grams of the above formulation with the following amounts of D.E.H.~ 29 hardener.
16,540-F -20-1~3~8B
A. 1.08 g. D.E.H~ 29 (stoichiometric) B. 1.61 g. "
C. 2.15 g. "
D. 4.22 g. polyamide having an amine hydrogen equivalent weight of about 150.
Lap shear samples were prepared as already described and Tee Peel samples were also prepared according to ASTM D-1876-61T, using 1" x 8" x 0.024" Type 2024-T3 aluminum strips, etched by the FPL procedure. Two strips were spread with the adhesive, then sandwiched~together and clamped with paper clips for the four day cure period.
Test Results Adhesive Sample LaP Shear Strenqth Tee Peel A 3540 psi (av. of 2) 11.2 lb/in.
B 3860 20.5 C 4850 32.0 D 2760 3.2 This test indicates improved performance for adheslves using greater amounts of the D.E.H~ 29 poly-ethylene polyamine hardener. However, results from environ-mental exposure tests and elevated temperature testing indicate a fall-off in performance at double stoichiometric D.E.H.~ 29 (as in C above) and thus the formulation becomes non-structural for this reason. Sample B above did not show reduced performance in this respect.
D. Optimum Rubber Modifier Level In addition to the test using 18 phr of the vulcanized rubber modifier, lower levels were tested by diluting with unmodified resin or by preparing separate modified epoxies. Results are given below, using 32 phr (parts per 100 parts of epoxy resin) D.E.H~ 29 polyethylene 16,540-F -21-polyamine hardener in all cases. In each instance the polymer modifier which was vulcanized was that described in Example 6 employing the vulcanization procedure of Example 8-C.
PHR of Modifier Lap ShearClimbinq Drum Tee Peel 18 3860 psi -- 20.5 lb/in.
4270 92 lb/in. 5.7 lb/in.
13 4300 88 7.0 9 4300 25 6.2 6 4300 9 6.4 E. Variation in Rubber ComPosition Vulcanized rubber modified 2.1 functional epoxy novolac resin was prepared containing 10 phr rubber using (A) 3500 av. M.W. acrylonitrile-butadiene polymer, 26% acrylonitrile, about 1.9 COOH average functionality, (B) 3500 av. M.W. acrylonitrile-butadiene polymer, 18.6% acrylonitrile, about 1.85 COOH average functionality.
Adhesives prepared and tested as in the examples above gave Lap Shear Climbinq Drum Tee Peel ; (A) 4150 psi 88 lb/inch 7.0 lb/inch (B) 4790 18 lb/inch 7.7 lb/inch F. Environmental Stabilitv of Bonds The adhesive formulations from Example 8-C were ; used to prepare lap shear samples that were subsequently - placed under an applied stress and exposed to a programmed temperature-humidity environment. The lap shear samples were held at these conditions until the ~ample failed (broke).
16,540-F -22-~ . .
Conditions Required to Cause Failure Sample (Av. of 2 samPles) A 57 C~ 1500 psi stress: 2 days d.ry ~ 2 hrs. ~ 98% rel. humidity B 57CJ 1500 psi: 2 d.ays d.ry I 1 hr.
@ 98% rel. humid.ity C 57C~ 1500 psi: 1 day d.ry, < 50%
rel. humidity D 40C~ 1500 psi: 1 hr. dry 16,540-F -23-
16,540-F -20-1~3~8B
A. 1.08 g. D.E.H~ 29 (stoichiometric) B. 1.61 g. "
C. 2.15 g. "
D. 4.22 g. polyamide having an amine hydrogen equivalent weight of about 150.
Lap shear samples were prepared as already described and Tee Peel samples were also prepared according to ASTM D-1876-61T, using 1" x 8" x 0.024" Type 2024-T3 aluminum strips, etched by the FPL procedure. Two strips were spread with the adhesive, then sandwiched~together and clamped with paper clips for the four day cure period.
Test Results Adhesive Sample LaP Shear Strenqth Tee Peel A 3540 psi (av. of 2) 11.2 lb/in.
B 3860 20.5 C 4850 32.0 D 2760 3.2 This test indicates improved performance for adheslves using greater amounts of the D.E.H~ 29 poly-ethylene polyamine hardener. However, results from environ-mental exposure tests and elevated temperature testing indicate a fall-off in performance at double stoichiometric D.E.H.~ 29 (as in C above) and thus the formulation becomes non-structural for this reason. Sample B above did not show reduced performance in this respect.
D. Optimum Rubber Modifier Level In addition to the test using 18 phr of the vulcanized rubber modifier, lower levels were tested by diluting with unmodified resin or by preparing separate modified epoxies. Results are given below, using 32 phr (parts per 100 parts of epoxy resin) D.E.H~ 29 polyethylene 16,540-F -21-polyamine hardener in all cases. In each instance the polymer modifier which was vulcanized was that described in Example 6 employing the vulcanization procedure of Example 8-C.
PHR of Modifier Lap ShearClimbinq Drum Tee Peel 18 3860 psi -- 20.5 lb/in.
4270 92 lb/in. 5.7 lb/in.
13 4300 88 7.0 9 4300 25 6.2 6 4300 9 6.4 E. Variation in Rubber ComPosition Vulcanized rubber modified 2.1 functional epoxy novolac resin was prepared containing 10 phr rubber using (A) 3500 av. M.W. acrylonitrile-butadiene polymer, 26% acrylonitrile, about 1.9 COOH average functionality, (B) 3500 av. M.W. acrylonitrile-butadiene polymer, 18.6% acrylonitrile, about 1.85 COOH average functionality.
Adhesives prepared and tested as in the examples above gave Lap Shear Climbinq Drum Tee Peel ; (A) 4150 psi 88 lb/inch 7.0 lb/inch (B) 4790 18 lb/inch 7.7 lb/inch F. Environmental Stabilitv of Bonds The adhesive formulations from Example 8-C were ; used to prepare lap shear samples that were subsequently - placed under an applied stress and exposed to a programmed temperature-humidity environment. The lap shear samples were held at these conditions until the ~ample failed (broke).
16,540-F -22-~ . .
Conditions Required to Cause Failure Sample (Av. of 2 samPles) A 57 C~ 1500 psi stress: 2 days d.ry ~ 2 hrs. ~ 98% rel. humidity B 57CJ 1500 psi: 2 d.ays d.ry I 1 hr.
@ 98% rel. humid.ity C 57C~ 1500 psi: 1 day d.ry, < 50%
rel. humidity D 40C~ 1500 psi: 1 hr. dry 16,540-F -23-
Claims (10)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A curable epoxy resin having more than one vicinal epoxy group per molecule modified by reaction with from 0.03 to 0.2 parts by weight, based on the weight of epoxy resin, of a polymer of butadiene and acrylonitrile, methacrylonitrile or mixtures thereof, said polymer having pendant reactive groups of COOH, OH, or SH and containing 70-90 weight percent butadiene and 30-10 weight percent acrylonitrile or methacrylonitrile, said epoxy resin characterized in that the modifying polymer is vulcanized with from 1.5 to 10 parts by weight or from 3 to 15 parts by weight, respectively, of an organic peroxide or sulfur, per 100 parts by weight of the reactive polymer modifier, at a temperature of from 120°C to 160°C for from 1.0 to 3.0 hours.
2. The composition of Claim 1 wherein the epoxy resin is the reaction product of (1) a liquid epoxy resin having an average of more than one vicinal epoxy group per molecule with (2) a dihydroxyl-containing compound.
3. The composition of Claim 2 wherein component (1) is diglycidyl ether of bisphenol A and component (2) is bisphenol A.
4. The composition of any one of Claims 1-3 wherein the modifying polymer is a butadiene-acrylonitrile polymer containing -COOH groups.
5. The composition of Claim 1 wherein the epoxy resin is an epoxy novolac resin.
6. A curable composition comprising the modified epoxy resin of claim 1, and a curing agent or curing catalyst.
7. A curable composition comprising the modified epoxy resin of claim 2 and a curing agent or curing catalyst.
8, A curable composition comprising the modified epoxy resin of claim 5, and a curing agent or curing catalyst.
9. The curable composition of claim 6, 7 or 8 wherein the curing agent is a polyethylene polyamine having an average amine hydrogen equiv-alent weight of at least about 27.
10. Method of modifying a curable epoxy resin having more than one vicinal epoxy group per molecule by reaction of said resin with from 0.03 to 0.2 parts by weight, based on the weight of epoxy resin, of a polymer of butadiene and acrylonitrile, methacrylonitrile or mixtures thereof, said polymer having pendant reactive groups of COOH, OH or SH and containing 70-90 weight percent butadiene and 30-10 weight percent acrylonitrile or methacrylonitrile, characterized by vulcanizing the modifying polymer with from 1,5 to 10 parts by weight or from 3 to 15 parts by weight, respectively, of an organic peroxide or sulfur, per 100 parts by weight of the reactive polymer modifier, at a temperature of from 120°C to 160°C for from 1.0 to 3.0 hours after reaction of the polymer with the epoxy resin.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US34039273A | 1973-03-12 | 1973-03-12 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1037188A true CA1037188A (en) | 1978-08-22 |
Family
ID=23333172
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA193,539A Expired CA1037188A (en) | 1973-03-12 | 1974-02-26 | Epoxy resin compositions |
Country Status (10)
| Country | Link |
|---|---|
| JP (1) | JPS49126798A (en) |
| BE (1) | BE812200A (en) |
| BR (1) | BR7401830D0 (en) |
| CA (1) | CA1037188A (en) |
| DE (1) | DE2411064A1 (en) |
| FR (1) | FR2221489B1 (en) |
| GB (1) | GB1461127A (en) |
| IT (1) | IT1011066B (en) |
| NL (1) | NL7403221A (en) |
| SE (1) | SE409212B (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5721450A (en) * | 1980-07-11 | 1982-02-04 | Toho Rayon Co Ltd | Epoxy resin composition |
| JPS57102919A (en) * | 1980-12-16 | 1982-06-26 | Nitto Electric Ind Co Ltd | Epoxy resin composition |
| EP0092336A3 (en) * | 1982-04-20 | 1984-01-18 | Dunlop Limited | Adhesive compositions |
| JPS61228059A (en) * | 1985-04-03 | 1986-10-11 | Nitto Electric Ind Co Ltd | Composition for epoxy resin coating compound |
| US4707518A (en) * | 1986-10-16 | 1987-11-17 | Shah Dilipkumar N | Rubber-modified epoxy adhesives |
| CN103764616B (en) * | 2011-08-31 | 2016-06-22 | 巴斯夫欧洲公司 | The method preparing EDDN and/or EDMN |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3208980A (en) * | 1960-12-30 | 1965-09-28 | Phillips Petroleum Co | Polymer compositions using liquid carboxy-terminated diene polymer and epoxidized compound |
| US3340224A (en) * | 1965-01-21 | 1967-09-05 | Chrysler Corp | Thermosetting, curable elastomeric composition and methods of making the same |
-
1974
- 1974-02-26 CA CA193,539A patent/CA1037188A/en not_active Expired
- 1974-03-08 IT IT4920474A patent/IT1011066B/en active
- 1974-03-08 DE DE19742411064 patent/DE2411064A1/en not_active Withdrawn
- 1974-03-11 BR BR183074A patent/BR7401830D0/en unknown
- 1974-03-11 SE SE7403234A patent/SE409212B/en unknown
- 1974-03-11 FR FR7408237A patent/FR2221489B1/fr not_active Expired
- 1974-03-11 NL NL7403221A patent/NL7403221A/xx not_active Application Discontinuation
- 1974-03-12 GB GB1096574A patent/GB1461127A/en not_active Expired
- 1974-03-12 JP JP2779974A patent/JPS49126798A/ja active Pending
- 1974-03-12 BE BE141924A patent/BE812200A/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| BE812200A (en) | 1974-09-12 |
| FR2221489A1 (en) | 1974-10-11 |
| BR7401830D0 (en) | 1974-11-19 |
| DE2411064A1 (en) | 1974-09-19 |
| NL7403221A (en) | 1974-09-16 |
| FR2221489B1 (en) | 1978-02-10 |
| IT1011066B (en) | 1977-01-20 |
| GB1461127A (en) | 1977-01-13 |
| JPS49126798A (en) | 1974-12-04 |
| AU6607574A (en) | 1975-08-28 |
| SE409212B (en) | 1979-08-06 |
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