Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2001-05-07
2002-05-28
Sellers, Robert E. L. (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C523S404000, C523S414000, C523S420000, C525S524000, C525S530000, C525S531000, C525S532000, C528S110000, C528S111000
Reexamination Certificate
active
06395806
ABSTRACT:
BACKGROUND OF THE INVENTION
For many years, curable epoxy resins have been used as components in coating compositions. However, the properties of coatings produced using aqueous epoxy resin dispersions have long been considered inferior to those of coatings in which the resin is used in the form of a solution in an organic solvent. This was mainly attributed to the fact that the emulsifiers used, for example nonylphenol ethoxylates, migrate to the surface of the film where they adversely affect its properties. One way of solving this problem is to use so-called reactive emulsifiers which, where the epoxy resin is crosslinked with a diamine or polyamine or other hardener, react with the hardener and thus become part of the coating. Aqueous dispersions of special reactive emulsifiers are known from the prior art.
EP-A-605 and U.S. Pat. No. 4,197,389 describe a hardener in the form of a reaction product of a) at least one polyepoxy compound, b) at least one polyalkylene polyether polyol and c) at least one polyamine.
EP-A-387 418, EP-A-714 924 and U.S. Pat. No. 5,489,630 describe hardeners for epoxy resins which are obtained by reacting polyalkylene polyether amines with di- and/or polyepoxy compounds to form an intermediate product and reacting the intermediate product obtained with a primary or secondary amine.
EP-A-717 059 describes hardeners for epoxy resins which are obtained by reacting a polyalkylene oxide polyether monoalcohol with a polyepoxide to form an intermediate product and reacting the intermediate product obtained with a polyamine.
EP-A-717 063 describes hardeners for epoxy resins which are obtained by reacting a polyalkylene oxide monoamine with di- and/or polycarboxylic acids to form an intermediate product and reacting the intermediate product obtained with a diamine or polyamine.
EP-A-709 418 describes a hardener for epoxy resins which is obtained by reaction of (A) a polyamine, (B) an alkoxy polyethylene polyether compound containing epoxy groups and (C) a hydrophobic epoxy compound.
BRIEF SUMMARY OF THE INVENTION
The present invention relates generally to hardeners for epoxy resins, the hardeners based on &agr;,&bgr;-unsaturated carboxylic acid esters, processes for their production, aqueous dispersions containing such hardeners, and to their use in coating solid substrates.
The problem addressed by the present invention was to provide hardeners for curable epoxy resins which, unless they were soluble in water, on the one hand would be self-dispersible in water, but which in addition would also be suitable as dispersants for curable epoxy resins in aqueous media.
The expression “self-dispersible” in the context of the present invention means that the hardeners can be dispersed or emulsified spontaneously in aqueous media without the use of additional additives, such as emulsifying or dispersing additives. In other words, the hardeners to be developed are those which would be capable of self-dispersion and/or self-emulsification in aqueous media. In the interests of simplicity, the term “self-dispersing” is used for this property throughout the present specification.
The hardeners to be developed would be above all so-called reactive hardeners, i.e. over and above the properties mentioned, namely self-dispersibility in water and, in addition, suitability as dispersants for curable epoxy resins in aqueous media, would be capable of reacting with curable epoxy resins, i.e. of being hardeners for curable epoxy resins.
Another problem addressed by the invention was to provide aqueous dispersions of self-dispersible hardeners which would be distinguished by high stability in storage under practical storage conditions.
Another problem addressed by the invention was to provide coating compositions containing a self-dispersible hardener, the coating obtained from the coating composition after the hardening process being distinguished by excellent properties.
It has now surprisingly been found that hardeners obtainable by reaction of &agr;,&bgr;-unsaturated carboxylic acid esters with hydroxy compounds, subsequent reaction of the intermediate product obtained with mono-, di- or polyaminopolyalkylene oxide compounds, reaction of the intermediate product obtained with an epoxy resin known from the prior art and, finally, reaction with one or more primary and/or secondary amines excellently satisfy the requirements mentioned in every respect.
The present invention relates first to hardeners for curable epoxy resins obtainable by
(a) reacting one or more &agr;,&bgr;-unsaturated carboxylic acid esters (I)
R
2
R
3
C═C(R
4
)COOR
1
(I)
where R
1
is an aromatic or aliphatic radical containing up to 15 carbon atoms, the substituents R
2
, R
3
and R
4
independently of one another represent hydrogen, branched or unbranched, aliphatic or aromatic groups containing up to 20 carbon atoms or a group —(CH
2
)
n
—COOR
1
, where R
1
is as defined above and n is a number of 0 to 10, in the presence of a transesterification catalyst with
(b) one or more hydroxy compounds, compounds (a) and (b) being used in such quantities that the equivalent ratio of the hydroxyl groups in (b) to the ester groups COOR
1
in the &agr;,&bgr;-unsaturated carboxylic acid esters (a) is in the range from 1.5:1 to 10:1,
reacting the intermediate product Z1 obtained with
(c) one or more mono-, di- or polyaminopolyalkylene oxide compounds, an equivalent ratio of the reactive hydrogen atoms at the aminonitrogen atoms of (c) to the ester groups in the intermediate compound Z1 in the range from 1.0:1 to 1:10 being adjusted,
subsequently reacting the intermediate product Z2 obtained with
(d) one or more polyepoxides, the equivalent ratio of oxirane rings in polyepoxide (d) to reactive hydrogen atoms of the mono-, di- or polyaminopolyalkylene oxide compounds used in (c) being adjusted to a value of 100:1 to 1.5:1,
and subsequently reacting the intermediate product Z3 obtained with
(e) one or more primary and/or secondary amines, the equivalent ratio of oxirane rings in t he intermediate product Z3 to the reactive H atoms at the aminonitrogen atoms of (e) being adjusted to a value of 1:1.5 to 1:20.
The hardeners according to the invention are distinguished by excellent resistance to chemicals and in particular to acids. In addition, they have short pot lives.
The hardeners according to the invention are either liquid or solid substances, depending on their molecular weight.
The present invention also includes processes for the production of hardeners for curable epoxy resins.
DETAILED DESCRIPTION OF THE INVENTION
The expression “equivalent ratio” is familiar to the expert. The basic concept behind the notion of the equivalent is that, for every substance participating in a reaction, the reactive groups involved in the desired reaction are taken into consideration. By indicating an equivalent ratio, it is possible to express the ratio which all the various reactive groups of the compounds (x) and (y) used bear to one another. It is important in this connection to bear in mind that a reactive group is understood to be the smallest possible reactive group, i.e. the notion of the reactive group is not identical with the notion of the functional group. In the case of H-acid compounds, this means for example that, although OH groups or NH groups represent such reactive groups, NH
2
groups with two reactive H atoms positioned at the same nitrogen atom do not. In their case, the two hydrogen atoms within the functional group NH
2
are appropriately regarded as reactive groups so that the functional group NH
2
contains two reactive groups, namely the hydrogen atoms.
In one embodiment, the intermediate compound Z1 and the compound (c) are used in such quantities that the equivalent ratio of reactive hydrogen atoms at the aminonitrogen atoms of (c) to the ester groups in the intermediate compound Z1 is in the range from 4:1 to 1:4 and more particularly in the range from 2.5:1 to 1.5:1.
In another embodiment, the equivalent ratio of oxirane rings in the polyepoxide (d) to reactive hydrogen atoms of the mon
Foglianisi Vincenzo
Huver Thomas
Sulzbach Horst
Thomas Hans-Josef
Cognis Deutschland GmbH
Drach John E.
Ettelman Aaron R.
Sellers Robert E. L.
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