Background of the Invention
The present invention concerns multifunctional epoxy resins prepared by dehydrohalogenating the reaction product of (1) a polyglycidyl ether of a polyhydroxyl-containing material said glycidyl ether having an average of at least 0.05 aliphatic hydroxyl group per molecule and an average of more than one glycidyl ether group per molecule such as a diglycidyl ether of bisphenol A, (2) a hydrolyzed monoglycidyl ether of a material having one aromatic hydroxyl group or one aliphatic hydroxyl group per molecule, (3) a hydrolyzed glycidyl ether of a material having an average of more than one aromatic hydroxyl group or aliphatic hydroxyl group per molecule, (4) the reaction product of a monoglycidyl ether with a polyphenolic compound, or (5) a combination of (1), (2), (3) or (4) with an epihalohydrin.
Multifunctional epoxy resins such as the epoxy novolac resins are well known. They are useful for many applications such as powder coatings, electronic circuit encapsulation, electrical laminates and the like. While these epoxy novolac resins have relatively good properties, the multifunctional epoxy resins possess an improvement in one or more of the properties such as toughness and/or heat distortion temperature, acid resistance and the like. These new multifunctional epoxy resins are particularly useful in the preparation of electrical laminates.
Summary of the Invention
One aspect of the present invention pertains to multifunctional epoxy resins obtained by dehydrohalogenating the reaction product of (A) an epihalohydrin with (B) a material selected from (1) a polyglycidyl ether of a polyhydroxyl-containing material said glycidyl ether having an average of at least 0.05 aliphatic hydroxyl group per molecule and an average of more than one glycidyl ether group per molecule such as a diglycidyl ether of bisphenol A, (2) a hydrolyzed monoglycidyl ether of a material having one aromatic hydroxyl group or one aliphatic hydroxyl group per molecule, (3) a hydrolyzed glycidyl ether of a material having an average of more than one aromatic hydroxyl group or an average of more than one aliphatic hydroxyl group per molecule, (4) the reaction product of a monoglycidyl ether with a polyphenolic compound, or (5) a combination of (1), (2), (3) or (4).
Another aspect of the present invention pertains to a multifunctional epoxy resin represented by the formula ##STR1## wherein each A is independently the residue which would remain if the hydroxyl groups of a material having two hydroxyl groups were removed; A' is the residue which would result if the hydroxyl groups of a material having from 2 to about 10, preferably from 2 to about 4 aromatic hydroxyl groups were removed; A" is a monovalent hydrocarbyl group having from 1 to about 20, preferably from about 4 to about 10 carbon atoms; each R is independently hydrogen or an alkyl group having from 1 to about 4 carbon atoms; R.sup.1 is an aliphatic or aromatic or alkyl or halogen substituted aliphatic or aromatic hydrocarbon group; n has an average value of from about 0.05 to about 150, preferably from about 0.1 to about 30 and n' has a value from 2 to about 10, preferably from 2 to about 4.
Another aspect of the present invention pertains to a mixture of epoxy resins comprising (I) from about 1 to about 99, preferably from about 50 to about 99, most preferably from about 75 to about 99 percent by weight of at least one of the aforementioned multifunctional epoxy resins and (II) from about 99 to about 1, preferably from about 50 to about 1, most preferably from about 25 to about 1 percent by weight of at least one epoxy resin having an average of more than one 1,2-epoxy group per molecule which is different from the multifunctional epoxy resin of component (A).
A further aspect of the present invention pertains to the product resulting from curing the aforementioned mixture of epoxy resins with a curing quantity of a suitable curing agent or catalyst or combination thereof.
Detailed Description of the Invention
The multifunctional epoxy resins of the present invention are prepared by reacting an epoxy resin having an average of more than one 1,2-epoxide groups and an average of at least about 0.05, preferably at least about 0.4 aliphatic hydroxyl group per molecule with an epihalohydrin in the presence of a suitable catalyst thereby producing a chlorohydrin intermediate product which is subsequently dehydrohalogenated with a suitable dehydrohalogenation agent thereby producing the desired multifunctional epoxy resin.
The ratio of epihalohydrin to aliphatic hydroxyl groups is from about 1:1 to about 20:1, preferably from about 1:1 to about 5:1. This reaction can be carried out at any suitable temperature, usually at a temperature of from about 0.degree. C. to about 100.degree. C., preferably from about 0.degree. C. to about 60.degree. C. The dehydrohalogenation reaction likewise can be carried out at any suitable temperature, usually at a temperature of from about 0.degree. C. to about 100.degree. C., preferably from about 0.degree. C. to about 60.degree. C.
Suitable epihalohydrins which can be employed to prepare the multifunctional epoxy resins of the present invention include those represented by the following Formula V: ##STR2## wherein R is hydrogen or an alkyl group having from 1 to about 4 carbon atoms and X is a halogen, preferably chlorine or bromine.
Suitable epoxy resins which can be employed to prepare the multifunctional epoxy resins of the present invention include essentially any epoxy resin which has an average of more than one 1,2-epoxy group and an average of at least about 0.05, preferably at least about 0.4 aliphatic hydroxyl group per molecule. Suitable epoxy resins which can be employed herein include those represented by the following Formulas VI, VII, VIII and IX: ##STR3## wherein each A, A', A", R, R', n and n' are as defined above.
Suitable epoxy resins which can be mixed with the multifunctional epoxy resins of the present invention include any epoxy resin which has an average of more than one 1,2-epoxy groups per molecule. Among those which are suitable are those represented by Formula VI wherein each A and R are as previously defined and n has an average value from zero to about 150, preferably from zero to about 30. Also suitable are those epoxy resins represented by the following Formulas X and XI: ##STR4## wherein each R' is independently a divalent hydrocarbyl group having from 1 to about 10, preferably from 1 to about 4 carbon atoms; R" is hydrogen or a hydrocarbyl group having from about 1 to about 10, preferably from 1 to about 4 carbon atoms; each X' is independently hydrogen, a halogen preferably chlorine or bromine, or a hydrocarbyl or hydrocarbyloxy group having from about 1 to about 10, preferably from about 1 to about 4 carbon atoms; and n" has an average value of from about 0.1 to about 8, preferably from about 1 to about 3.
The term hydrocarbyl as employed herein means any aliphatic, cycloaliphatic, aromatic, aryl substituted aliphatic or aliphatic substituted aromatic groups. Likewise, the term hydrocarbyloxy group means a hydrocarbyl group having an oxygen linkage between it and the object to which it is attached.
In each of the above Formulas I and V, each A is usually represented independently by any of the Formulas XII or XIII ##STR5## wherein X' is as previously defined; A.sup.1 is a divalent hydrocarbon group having from 1 to about 10, preferably from 1 to about 4 carbon atoms, --S--, --S--S--, ##STR6## or --O--; and m has a value of zero or 1.
If desired, the epoxy resins of the present invention can be blended with other epoxy resins. Suitable such epoxy resins which can be mixed with the multifunctional epoxy resins of the present invention include any aliphatic epoxy resin such as the polyglycidyl ethers of propylene glycol, dipropylene glycol, butanediol, hexanediol, polyoxypropylene glycol, polyoxybutylene glycol, glycerine, trimethylol propane, neopentyl glycol, dibromoneopentyl glycol, mixtures thereof and the like.
Suitable dehydrohalogenation agents which can be employed to prepare the multifunctional epoxy resins of the present invention include, for example, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, combinations thereof and the like.
Suitable catalysts which can be employed to catalyze the reaction between the epihalohydrin and the epoxy resin containing aliphatic hydroxyl groups include, for example, quaternary ammonium compounds, phosphonium compounds, crown ethers, combinations thereof and the like.
Suitable curing agents which can be employed herein include, for example, primary amines, secondary amines, amidoamines, carboxylic acids and anhydrides thereof, guanidines, imidazoles, phenolic resins, melamine resins, combinations thereof and the like.
Particularly suitable curing agents include, for example, cyclohexyl diamine, methylene dianiline, combinations thereof and the like.
The multifunctional epoxy resins of the present invention are useful in the preparation of coatings, castings, adhesives, laminates, composites, encapsulants and the like.
If desired, the curable compositions can be blended with fillers, colorants, flow control agents, fire retardant agents, reinforcing materials, accelerators, combinations thereof and the like.
The following examples are illustrative of the present invention but are not to be construed as to limiting the scope thereof in any manner.
Epoxy Resin A was a mixture of the oligomers of the diglycidyl ether of bisphenol A represented by the Formula VI wherein A is the residue of bisphenol A, 22% by weight of the resin has a value of n=zero, 43% by weight of the resin has a value of n=1 with the balance of the resin having a value of n=2 or more and wherein the resin had a percent epoxide value of 16.4% and an epoxide equivalent weight of 262.2.
Epoxy Resin B was a diglycidyl ether of bisphenol A having an EEW of 1814 commercially available from The Dow Chemical Company as D.E.R..RTM.667.
Epoxy Resin C was a diglycidyl ether of bisphenol A having an EEW of 489 commercially available from The Dow Chemical Company as D.E.R..RTM.661.
Epoxy Resin D was a brominated resin prepared by advancing a diglycidyl ether of bisphenol A having an epoxide equivalent weight of 189 with tetrabromobisphenol A having an EEW of 473, a percent epoxide of 9.09 and a percent bromine of 47.5.
Curing Agent A was methylene dianiline.
Example 1
In a reaction vessel equipped with a means for stirring, temperature recording and control, vapor condenser and bottom take-off valve 467 grams (1.87 equiv.) of Epoxy Resin A was dissolved in 1000 ml (1.78 equiv.) of epichlorohydrin. The mixture was heated to 60.degree. C. and 40 cc of a 50% by weight aqueous solution of tetrabutyl ammonium chloride was added. Then 400 ml (7.6 equiv.) of a 50% by weight aqueous solution of sodium hydroxide was added with vigorous stirring. The temperature and agitation were maintained for 15 min. (900 s). The mixture was cooled to 30.degree. C. and diluted with 500 ml of ice water using moderate stirring. The reaction mixture was allowed to separate and then the bottom aqueous layer was withdrawn through the bottom take-off valve. The organic layer was washed once with 200 ml of a 5% by weight aqueous solution of NaH.sub.2 PO.sub.4 so as to neutralize the sodium hydroxide and then with 200 ml of deionized water. The organic layer was then subjected to vacuum evaporation to remove the volatiles from the resin. The resulting resin was viscous, but still a liquid and had an epoxide equivalent weight of 218.1 and an epoxide content of 19.7%.
The multifunctional epoxy resin prepared above and Epoxy Resin A were each cured with methylene dianiline in an amount of 1 equiv. of methylene dianiline per epoxide equivalent at a temperature of 150.degree. C. for 2 hours (7200 s) and at 175.degree. C. for 5 hours (18,000 s) and at 200.degree. C. for 2 hours (7200 s). The glass transition temperature of the multifunctional resin prepared in Example 1 was 196.degree. C. as compared to a value of 140.degree. C. for Epoxy Resin A.
Example 2
In a reaction vessel equipped as in Example 1, 215 g (0.67 equiv.) of Epoxy Resin B was dissolved in 2000 ml (26 equiv.) of epichlorohydrin and heated to 45.degree. C. Then 50 ml of a 50% by weight aqueous solution of tetrabutyl ammonium chloride was added, followed by 400 ml (0.95 equiv.) of a 50% by weight aqueous solution of sodium hydroxide. The mixture was stirred vigorously for 40 min. (2400 s). The reaction mixture was cooled to 40.degree. C. and 600 ml of ice water was added with moderate stirring. The reaction mixture was allowed to settle and the lower aqueous solution separated. Then 200 ml (3.8 equiv.) of 50% aqueous NaOH was added and stirred at 35.degree. C. for 15 min. (900 s), after which 200 ml of deionized water was added and the stirring continued at 30.degree. C. for an hour (3600 s) so as to effect dehydrochlorination of the halohydrin ether intermediate product. The aqueous layer removed, the resin washed and the volatiles removed as in Example 1. The resultant multifunctional epoxy resin and Epoxy Resin B were cured as in Example 1. The percent epoxide, epoxide equivalent weight (EEW) and the glass transition temperatures are given in the following table.
Example 3
In a manner similar to Example 1, a multifunctional epoxy resin was prepared from the following components:
147 grams (0.3 equiv.) of Epoxy Resin C
1000 ml (13 equiv.) of epichlorohydrin
20 ml of 50% aqueous tetrabutyl ammonium chloride
200 ml (3.8 equiv.) of 50% aqueous NaOH
The results are given in the following table.
Example 4
In a manner similar to Example 1, a multifunctional epoxy resin was prepared from the following components:
100 grams (0.21 equiv.) of Epoxy Resin D
1000 ml (13 equiv.) of epichlorohydrin
20 ml of 50% aqueous tetrabutyl ammonium chloride
200 ml (3.8 equiv.) of 50% aqueous NaOH
The results are given in the following table.