Chemistry: electrical and wave energy – Processes and products – Electrophoresis or electro-osmosis processes and electrolyte...
Reexamination Certificate
2000-05-16
2002-04-16
Mayekar, Kishor (Department: 1741)
Chemistry: electrical and wave energy
Processes and products
Electrophoresis or electro-osmosis processes and electrolyte...
C204S504000, C523S415000
Reexamination Certificate
active
06372108
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to polymeric binders and, more particularly, to polymeric binders having particular utility in cathodic electrodeposition coatings (“cathodic electrodeposition binders”).
The cathodic electrodeposition coating process is a coating process which is used in particular for applying corrosion protection primer layer:s on metallic substrates, wherein the substrate acts as the cathode. The particular suitability of the cathodic electrodeposition coating process for this purpose is due to its ability to coat three-dimensional substrates with a complicated geometry, such as for example automotive bodies. One essential property of a cathodic electrodeposition (“CED”) coating composition in this context is its throwing power behavior. “Throwing power” is a term of art used to identify the ability of an electrodeposition coating agent to be deposited within voids of a three-dimensional substrate, which is significant for effective corrosion protection.
CED-coating compositions containing binders with active hydrogen atoms and beta-hydroxyurethane compounds as cross-linking agents are known from EP-A-0 102 566. The beta-hydroxyurethanes can be prepared by reacting isocyanate compounds with 1,2-polyols. Such coating compositions can be cured at low temperatures.
WO 93/02231 describes CED-coating compositions, which contain binders with active hydrogen atoms and gamma-hydroxyurethaie compounds as cross-linking agents. The gamma-hydroxyurethanes can be prepared by reacting isocyanate compounds with 1,3-polyols. The CED-coating compositions can be cured at low temperatures and are notable for their excellent throwing power.
SUMMARY OF THE INVENTION
It is an object of the present invention to increase the throwing power of CED coating compositions. This objective is accomplished according to the invention by providing novel alkaline polymeric binders containing beta-hydroxyalkyl urethane groups and CED coating compositions containing same.
Thus, in one embodiment, the invention provides a polymeric binder for use in cathodic electrodeposition coatings, said binder having a number average molecular mass of 1000 to 3000, an amine value of 150 to 250 mg KOH/g binder and 50 to 230 milliequivalents/100 g binder of beta-hydroxyalkyl urethane groups of the formula HOC
n
H
2n
OC(O)NH— where n=2 to 3.
In another embodiment, the invention provides a process of making polymeric cathodic electrodeposition binders having a number average molecular mass of 1000 to 3000, an amine value of 150 to 250 mg KOH/g binder and 50 to 230 milliequivalents/100 g binder of beta-hydroxyalkyl urethane groups of the formula HOC
n
H
2n
OC(O)NH— where n=2 to 3, said process comprising the step of reacting a compound having at least one primary amino group with a carbonate compound selected from the group consisting of ethylene carbonate, propylene carbonate, and mixtures thereof.
In yet another embodiment, the invention provides a process of making polymeric cathodic electrodeposition binders having a number average molecular mass of 1000 to 3000, an amine value of 150 to 250 mg KOH/g binder and 50 to 230 milliequivalents/100 g binder of beta-hydroxyalkyl urethane groups of the formula HOC
n
H
2n
OC(O)NH— where n=2 to 3, said process being selected from the group consisting of radical polymerization, condensation polymerization and addition polymerization and comprising the step of polymerizing at least one compound which contains at least one beta-hydroxyalkyl urethane group of the formula HOC
n
H
2n
OC(O)NH— where n=2 to 3 and at least one further fictional group.
In a further embodiment, the invention provides an aqueous binder composition comprising at least one polymeric cathodic electrodeposition binder having a number average molecular mass of 1000 to 3000, an amine value of 150 to 250 mg KOH/g binder and 50 to 230 milliequivalents/100 g binder of betahydroxyalkyl urethane groups of the formula HOC
n
H
2n
OC(O)NH— where n=2 to 3 and water, wherein said at least one binder has been neutralized with an acid.
In still another embodiment of the invention, provided is a cathodic electrodeposition coating composition comprising at least one polymeric binder having a number average molecular mass of 1000 to 3000, an amine value of 150 to 250 mg KOH/g binder and 50 to 230 milliequivalents/100 g binder of betahydroxyalkyl urethane groups of the formula HOC
n
H
2n
OC(O)NH— where n=2 to 3, and wherein said at least one polymeric binder is present in an amount of 3 to 10 wt-% based on the total resin solids in said composition.
In yet another embodiment, the invention provides a process for coating electrically conductive substrates by cathodic electrodeposition comprising the steps of applying a cathodic electrodeposition coating to a substrate surface, wherein said coating comprises at least one polymeric binder having a number average molecular mass of 1000 to 3000, an amine value of 150 to 250 mg KOH/g binder and 50 to 230 milliequivalents/100 g binder of beta-hydroxyalkyl urethane groups of the formula HOC
n
H
2n
OC(O)NH— where n=2 to 3, and wherein said at least one polymeric binder is present in an amount of 3 to 10 wt-% based on the total resin solids in said composition; and then baking the coated substrate.
DETAILED DESCRIPTION OF THE EMBODIMENTS
The polymeric binders according to the invention are cathodic electrodeposition binders (hereinafter sometimes referred to as “CED-binders”). The binders are alkaline polymers having an amine value of 150 to 250, preferably 180 to 220 mg KOH/g binder. The amine value is derived from primary, secondary and/or tertiary amino groups of the CED-binders. The CED-binders also contain betahydroxyalkyl urethane groups of the formula HOC
n
H
2n
OC(O)NH—, where n=2 to 3. The beta-hydroxyalkyl urethane groups are present in an amount of 50 to 230 milliequivalents (“meq”)/100 g of binder, preferably 60 to 150 meq/100 g binder. Such groups are more particularly known as beta-hydroxyethyl urethane and beta-hydroxypropyl urethane. Combinations of such groups may, of course, also be present. The beta-hydroxyalkyl urethane groups are lateral and/or terminal beta-hydroxyalkyl urethane groups.
Apart from the above defined beta-hydroxyalkyl urethane groups, the binders can also contain non-terminal or non-lateral beta-hydroxyalkyl urethane groups and/or beta-hydroxyalkyl urethane groups of the following formula: —CHOHCH
2
OC(O)NHR; —CH(CH
2
OH)OC(O)NHR; —CCH
3
OHCH
2
OC(O)NHR; —CCH
3
(CH
2
OH)OC(O)NHR; —CHOHCHCH
3
OC(O)NHR; and —CH(OC(O)NHR)CHOHCH
3
; where R can be hydrogen or a lower alkyl, for example C1-C4-alkyl.
The CED-binders can also contain additional functional groups. For example, the CED-binders may contain hydroxyl groups sufficient to provide a hydroxyl value of 200 to 500 mg KOH/g binder, (exclusive of the hydroxyl groups of the beta-hydroxyalkyl urethane moieties). Such additional hydroxyl groups can provide for the chemically cross-linking of the CED-binders in the presence of external cross-linking agents.
The CED-binders can be prepared by reacting suitable resins containing a corresponding amount of primary amino groups (“educt resins”) with ethylene carbonate and/or propylene carbonate. The resins used as educt resins have a higher amine value than the CED-binders formed therewith through reaction with ethylene carbonate and/or propylene carbonate. The term “educt resins” means resins containing primary amino groups which can be converted into beta-hydroxyalkylurethane groups of the formula HOC
n
H
2n
OC(O)NH— with n=2 to 3 by reaction with ethylene carbonate and/or propylene carbonate, said conversion yielding CED-binder resins according to the invention as product resins. The amine value of the educt resins lies for example in the range of 200 to 350 mg KOH,/g resin. The amine value of the educt resins is derived from the content of primary amino groups and optionally secondary and/or tertiary amino groups. The primary amino groups can be present in a stoichiomet
Feola Roland
Gmoser Johann
Hoenig Helmut
Thausz Robert
Benjamin Steven C.
E. I. du Pont de Nemours and Company
Mayekar Kishor
LandOfFree
Binders for use in cathodic electrodeposition coatings,... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Binders for use in cathodic electrodeposition coatings,..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Binders for use in cathodic electrodeposition coatings,... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2842749