Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Patent
1989-11-20
1992-02-04
Kight, III, John
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
523416, 523417, 523421, 528109, 528 45, C09D 544, C08G 5966
Patent
active
050860917
DESCRIPTION:
BRIEF SUMMARY
The invention relates to cathodic water-dilutable binders which contain primary amino groups neutralized with acids and introduced via ketimine groups.
Cathodic water-dilutable binders are required for the production of electrocoating paints for cathodic electro-coating. Cationic electrocoating is a coating process frequently used in particular for priming, in which water-dilutable synthetic resins carrying cationic groups are applied to electrically conductive articles with the aid of direct current.
It has been found that the presence of primary amino groups in the binder molecules has a positive effect on the quality of the coatings obtained.
In order to introduce primary amino groups into the binder molecules, it has been suggested that synthetic resins containing epoxy groups be reacted with poly(ketimines) which contain hydroxyl groups or secondary amino groups, and the primary amino groups then be liberated hydrolytically (cf. U.S. Pat. No(s). 3,947,339, 4,017,438, 4,104,147 and 4,148,772).
The introduction of primary amino groups via ketimine derivatives containing hydroxyl or secondary amino groups has, inter alia, the disadvantage that these ketimine derivatives react so slowly with the epoxy groups that troublesome side reactions may take place and unconverted ketimine derivatives remain in the reaction mixture. These unconverted ketimine derivatives are hydrolyzed in the aqueous phase to give low molecular weight amines, which have a negative effect on the properties of the electrically deposited and baked coatings.
The object of the present invention is to provide improved binders of the type stated at the outset.
This object is achieved by binders which have been prepared by reacting reactive toward epoxy groups, also possesses at least one ketimine group and, if required, and/or further primary and/or secondary amines,
All synthetic resins which contain epoxy groups and are suitable as starting materials for the preparation of cathodic, water-dilutable binders can be used as component (A) (cf. for example U.S. Pat. No(s). 3,947,399, 4,017,438, 4,104,147, 4,148,772 and European Patent 4090). Unmodified or modified polyglycidyl ethers of polyphenols, polyglycidyl esters, polyacrylates containing epoxy groups and epoxidizied polybutadiene may be mentioned as examples.
Polyglycidyl ethers prepared from polyphenols, preferably bisphenol A, and epihalohydrins are preferably used as component (A).
The well known modified polyglycidyl ethers of polyphenols, preferably bisphenol A, are particularly preferably used. Particularly preferably used modified polyglycidyl ethers of polyphenols, preferably bisphenol A, are the polyglycidyl ethers of polyphenols, which ethers have been modified by reaction with at least one compound which contains, per molecule, one or more, preferably two, hydroxyl groups bonded to aromatic and/or (cyclo)-aliphatic molecular fragments (cf. for example German Patent Application P 36 18 157.9).
Compounds which, in addition to a mercapto group which is reactive toward epoxy groups, also possess at least one ketimine group are used as component (B). The compounds can, in addition to the mercapto and ketimine group, also contain further functional groups if these groups do not interfere with the binder synthesis.
Compounds of the general formula R.sup.2 and R.sup.3 represent organic groups, preferably alkyl groups having 1 to 4 C atoms, and R.sup.2 and R.sup.3 together can also form a cycloaliphatic ring, and n represents an integer 1, are preferably used as component (B). These compounds can readily be prepared by ketiminization of mercapto compounds of the general formula HS--R.sup.1 --(NH.sub.2).sub.n (R.sup.1 represents an organic group, preferably an alkylene group, and n represents an integer .gtoreq.1) with ketones of the general formula O=CR.sup.2 R.sup.3 (R.sup.2 and R.sup.3 represent organic groups, preferably alkyl groups having 1 to 4 C atoms, and R.sup.2 and R.sup.3 together can also form a cycloaliphatic ring). (B) components according to the invention can be prepar
REFERENCES:
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patent: 4148772 (1979-04-01), Marchetti et al.
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Cibura Klaus
Fobbe Helmut
Geist Michael
Ott Gunther
BASF Lacke & Farben AG
Kight III John
Krass Frederick
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