Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
1998-07-17
2001-04-24
Moore, Margaret G. (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C525S423000, C523S414000, C523S418000, C523S417000, C523S420000
Reexamination Certificate
active
06221934
ABSTRACT:
FIELD OF INVENTION
This invention relates to aqueous dispersions oE epoxy resins. In one aspect, the invention relates to improved aqueous dispersions of epoxy resins, which provide improved coating properties and a process to prepare such dispersions.
BACKGROUND OF THE INVENTION
Aqueous dispersions of epoxy resins have been knosn for many years. However, the performance of these dispersions as elements of coatings has been viewed as inferior to their solvent borne counterparts. It is knovn that the surfactants employed to render the epoxy component emulsifiable such as nonylphenol ethoxylates, alkylphenol initiated poly(oxyethylene) ethanols, alkylphenol initiated poly(oxypropylene) poly(oxyethylene) ethanols, and block copolymers containing an internal poly(oxypropylene) block and two external poly(oxyethylene) ethanol blocks readily migrate to surface interfaces where, it is speculated, they deleteriously affect film performance.
Further as aqueous dispersions of epoxy resins have become more widely used in industry, improved handling properties such as storage stability, uniformity, small particle size, higher inversion temperature, viscosity reproducibility, and ease of transferring the dispersions become more desirable. Therefore, there is a growing need for aqueous dispersions of epoxy resins that have improved, user friendly handling properties.
SUMMARY OF THE INVENTION
According to the invention, an aqueous dispersion of an epoxy resin is provided comprising:
a) water;
b) at least one epoxy resin having a functionality of greater than 0.8 epoxide group per molecule; and
c) from 0.1 to 20 weight percent, based on the epoxy resin of at least one epoxy-functional surfactant prepared by reacting an amidoamine having the structures:
wherein R
1
is an alkyl, aryl, or arylalkyl group or mixtures thereof having 1 to 15 carbon atoms, R
2
is aliphatic, cycloaliphatic, or aromatic group having 2 to 18 carbon atoms optionally containing non-reactive oxygen or at most an average of 4 secondary and/or tertiary nitrogen atoms per structure in the backbone, X and Y are independently a hydrogen, methyl or ethyl group with the provision that if X is methyl or ethyl, Y is hydrogen or if Y is methyl or ethyl, X is hydrogen, and n+m+o is a real number from 40 to 400, and n+o is a real number in an amount effective to provide resin emulsification, and at least one epoxy resin having a functionality of from greater than 0.8 epoxide group pe:r molecule in an amine to epoxy equivalent ratio of at least 1:2, preferably from 1:6 to 1:500. The ratio of (I) to (II) by weight is in the range of 100:0 to 0:100, the ratio of (I) to (III) by weight in the range of 100:0 to 0:100, and the ratio of (II) to (III) by weight in the range of 100:0 to 0:100.
Further, curable epoxy resin compositions comprising these epoxy resin dispersions and water-compatible curing agents are provided.
DETAILED DESCRIPTION OF THE INVENTION
It has been found that by using a certain epoxy-functional surfactant an effective aqueous epoxy resin dispersion can be formed having an average particle size of generally less than 1 &mgr; that has good shelf-life and handling properties. These dispersions are stable, retaining consistent viscosity and epoxy functionality for suitable periods of time. Further, it has been found that these dispersions can be obtained at higher inversion temperature and higher resin concentration using these surfactants resulting in shorter preparation time, greater ease of handling and higher temperature storage stability.
Epoxy-Functional Surfactant
The epoxy-functional surfactant useful in the invention can be prepared by reacting (i) at least one amidoamine having the structures:
wherein R
1
is an alkyl, aryl, or alkylaryl group having 1 to 15 carbon atoms, preferably C
1
-C
4
alkyl or nonylphenyl, most preferably methyl, R
2
is aliphatic, cycloaliphatic, or aromatic group having 2 to 18 carbon atoms optionally containing non-reactive oxygen or nitrogen atoms in the backbone, X and Y are independently a hydrogen, methyl or ethyl group with the provision that if X is methyl or ethyl, Y is hydrogen or if Y is methyl or ethyl, X is hydrogen and n+m+o is a real number from 40 to 400, m is a real number from 0 to 70, preferably from 0 to 50, most preferably 0, and n+o is a real number in an amount effective to provide resin emulsification which is at least 15 and in a ratio of (I) to (II) by weight in the range of 100:0 to 0:100, a ratio of (I) to (III) by weight in the range of 100:0 to 0:100, and a ratio of (II) to (III) by weight in the range of 100:0 to 0:100, and (ii) at least one epoxy resin having a functionality greater than 0.8 epoxide group per molecule. The epoxy-functional amidoamine surfactant preferably has a molecular weight within the range of from 1,700 to 40,000, preferably to 20,000. In a preferred embodiment, the ratio of n+o to m is in the range of 100:1 to 55:45.
In formula (I), preferably m is a real number from 0 to 70 and n and o are independently a real number from 5 to 395. In formula (II), preferably m is a real number from 0 to 70, n is a real number from 0 to 395, and o is a real number from 0 to 400, more preferably from 20 to 380. In formula (III), preferably m is a real number from 0 to 70, n is a real number from 0 to 395, and o is a real number from 0 to 400, more preferably from 20 to 380. In all of the above formulae (I), (II), and (III), n+o must be a real number in an amount effective to provide resin emulsificatioin which is typically at least 15, preferably at least 35. In one preferred embodiment, m is 0.
In one embodiment, the surfactant can be prepared by reacting amidoamine of structures (I) and (II) in a ratio of (I) to (II) by weight in the range of 99:1 to 1:99, preferably in the range of 20:80 to 80:20, and at least one epoxy resin. In another embodiment, the surfactant can be prepared by reacting amidoamine of structures (II) and (III) in a ratio of (II) to (III) by weight in the range of 99:1 to 1:99, preferably in the range of 20:80 to 80:20, and at least one epoxy resin. In yet another embodiment, the surfactan.t can be prepared by reacting amidoamine of structures (I) and (III) in a ratio of (I) to (III) by weight in the range of: 99:1 to 1:99, preferably in the range of 20:80 to 80:20, and at least one epoxy resin. Further, the surfactant can be prepared by reacting amidoamine of structures (I), (II) and (III) in an amount of 4 to 98 percent by weight of (I), 1 to 95 percent by weight of (II), and 1 to 95 percent by weight of (III) with an epoxy resin.
The amidoamine is contacted with the epoxy resin under conditions effective to react the amine group and the epoxide group. Typically, the equivalent ratio of the amine to epoxy is at least 1:2, preferably in the range of from 1:6, to 1:500, more preferably in the range of from 1:6 to 1:30. The reaction is typically carried out at a temperature from ambient temperature to an elevated temperature sufficient to react the amine group and the epoxide group preferably in the range of from 50° C. to 150° C. for a time effective to produce the reaction products. The progress of the reaction can be monitored and targeted to produce the desired product by measuring the amine equivalent weight and the epoxy equivalent weight of the reactant mixture. Generally, the reaction mixture is heated until the epoxy equivalents equal to the amine equivalents added are consumed which is generally one hour or greater.
More than one epoxy resin can be reacted with the amidoamine. For example, the amidoamine can be reacted first with an monoepoxide resin and then with a diepoxy resin. In another example, the epoxy resin can be reacted with a novolac epoxy resin and a diepoxy resin stepwise or at the same time in any order.
If desired the surfactant can be recovered from the reaction mixture or made “in-situ.” To provide the surfactant in-situ in the desired epoxy resin component, the amidoamine can be reacted into the desired epoxy resin component. The in-situ method is preferre
Back Gayle Edward
Elmore Jimmy D.
Galgoci, Jr. Ernest Charles
Stark Charles J.
Wang Pen-Chung
Moore Margaret G.
Shell Oil Company
LandOfFree
Aqueous dispersions of epoxy resins does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Aqueous dispersions of epoxy resins, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Aqueous dispersions of epoxy resins will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2506866