Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2001-04-26
2002-06-25
Dawson, Robert (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C523S414000, C525S523000, C525S533000, C528S111000, C528S119000, C528S121000
Reexamination Certificate
active
06410617
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.
U.S. Pat. No. 4,315,044 describes a stable epoxy resin dispersion containing (1) an aqueous medium and (2) between 50 and 70% by weight of a self-emulsifiable epoxy resin which is the addition product of (a) 40 to 90% by weight of diglycidyl ethers of a dihydric phenol, (b) 5 to 35% by weight of a dihydric phenol and (c) 2 to 15% by weight of the diglycidyl ether of a polyoxyalkylene glycol and in which the molecular weight of the epoxy resin is between 500 and 20,000.
U.S. Pat. No. 4,608,406 describes a stable epoxy dispersion containing (1) an aqueous medium and (2) between 50 and 70% by weight of a self-emulsifiable epoxy resin with a molecular weight of 1,000 to 20,000 which is the addition product of (a) 40 to 90% by weight of diglycidyl ethers of a dihydric phenol, (b) 5 to 35% by weight of a dihydric phenol, (c) 2 to 15% by weight of the diglycidyl ether of a polyoxyalkylene glycol and (d) 2 to 15% by weight of an alkyl phenol/formaldehyde
ovolak resin.
EP-B-272 595 and DE-A-36 43 751 describe a process for the production and use of stable aqueous epoxy resin dispersions consisting of a) 50 to 80% by weight of an epoxy compound containing at least two epoxy groups per molecule and having an epoxy equivalent weight of 100 to 2,000, b) 35 to 17% by weight of an aromatic polyol and c) 15 to 3% by weight of a condensation product of an aliphatic polyol with a molecular weight (Mw) of 200 to 20,000 and an epoxy compound containing at least two epoxy groups per molecule and having an epoxy equivalent weight of 100 to 2,000, the equivalent ratio of the OH groups to the epoxy groups being from 1:0.85 to 1:3.5 and the epoxy equivalent weight of this condensation product being from 200 to at least 50,000.
WO 95/18165 (Henkel Corp.) describes a self-dispersible curable epoxy resin obtainable by reacting an epoxy resin (a) with a polyoxyalkylene amine (b) with a molecular weight of 3,000 to 15,000. The components mentioned are used in a ratio of (b) to (a) of 0.001:1.0 to 0.060:1.0 equivalent.
WO 96/20970 (Henkel Corp.) describes a self-dispersible curable epoxy resin obtainable by reacting (a) 1.0 equivalent of epoxy resin, (b) 0.01 to 1.0 equivalent of a polyhydric phenol and (c) 0.005 to 0.5 equivalent of an amine/epoxy adduct. The amine/epoxy adduct is a reaction product of 1.0 equivalent of a polyepoxide and 0.3 to 0.9 equivalent of a polyoxyalkylene diamine.
EP-A-747 413 describes a self-emulsifiable epoxy resin (A) obtainable from (A-1) 50 to 95% by weight of one or more epoxy compound(s) containing at least two epoxy groups per molecule and having an epoxy group content of 300 to 11,200 mmoles/kg, (A-2) 5 to 50% by weight of an aromatic polyol, (A-3) 0 to 25% of modifying compounds containing at least two epoxy-reactive groups, (A4) 5 to 35% of a condensation product—acting as emulsifier—of (A4-a) an aliphatic polyol with a weight average molecular weight M
w
of 200 to 20,000 g/mole and (A-4-b) an epoxy compound containing at least two epoxy groups per molecule and having an epoxy group content of 500 to 10,000 mmoles/kg, the ratio of the number of OH groups to the number of EP groups being from 1:2 to 1:10 and the epoxy group content of the condensation products (A4) being from 100 to 6,700 mmoles/kg.
BRIEF SUMMARY OF THE INVENTION
The present invention relates generally to self-dispersing, hardenable epoxy resins, the epoxy resins based on &agr;,&bgr;-unsaturated carboxylic acid esters, processes for their production, aqueous dispersions containing such epoxy resins, and to their use in coating solid substrates.
The problem addressed by the present invention was to provide self-dispersible curable epoxy resins. The expression “self-dispersible” in the context of the present invention means that the epoxy resins can be dispersed or emulsified spontaneously in aqueous medium without the use of additional additives, such as emulsifying or dispersing additives. In other words, the epoxy resins to be developed are those which would be capable of self-dispersion and/or self-emulsification in water. In the interests of simplicity, the term “self-dispersing” is used for this property throughout the present specification. Another problem addressed by the invention was to provide aqueous dispersions of self-dispersible curable epoxy resins which would be distinguished by high stability in storage under practical storage conditions. A further problem addressed by the invention was to provide coating compositions containing a self-dispersible curable epoxy resin, the coating obtained from the coating composition after the curing process being distinguished by excellent properties.
It has now surprisingly been found that epoxy resins obtainable by reaction of &agr;,&bgr;-unsaturated carboxylic acid esters with mono-, di- or polyaminopolyalkylene oxide compounds, subsequent reaction of the intermediate product obtained with an aromatic polyhydroxy compound and further reaction with an epoxy resin known from the prior art excellently satisfy the requirements mentioned in every respect.
The present invention relates first to self-dispersible curable epoxy resins obtainable by
(a) reacting one or more a,p-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, with
(b) one or more mono-, di- or polyaminopolyalkylene oxide compounds, compounds (a) and (b) being used in such quantities that the equivalent ratio of the reactive hydrogen atoms at the aminonitrogen atoms of (b) to the C═C double bond in the &agr;,&bgr;-position to the group COOR
1
shown in formula (I) in the carboxylic acid esters (a) is in the range from 10:1 to 1:10,
subsequently reacting the intermediate product Z1 obtained with
(c) one or more polyhydroxy compounds, the equivalent ratio of ester groups in the intermediate compound Z1 to hydroxy groups in the polyhydroxy compound (c) being adjusted to a value of 1:1.1 to 1-10,
and subsequently reacting the intermediate product Z2 obtained with
(d) one or more polyepoxides, the equivalent ratio of oxirane rings in polyepoxide (d) to hydroxyl groups in the intermediate product Z2 being adjusted to a value of 1.5:1 to 6:1.
The epoxy resins 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 self-dispersing, hardenable 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
Foglianisi Vincenzo
Huver Thomas
Sulzbach Horst
Thomas Hans-Josef
Aylward D.
Cognis Deutschland GmbH
Dawson Robert
Drach John E.
Ettelman Aaron R.
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