Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From reactant having at least one -n=c=x group as well as...
Reexamination Certificate
1997-09-12
2001-12-11
Page, Thurman K. (Department: 1615)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From reactant having at least one -n=c=x group as well as...
C525S907000, C528S073000, C528S085000, C427S385500
Reexamination Certificate
active
06329491
ABSTRACT:
BACKGROUND OF THE INVENTION
The current invention relates to a composition and method of forming a single stage coating that does not utilize Isocyanate functional crosslinking agents. Currently, in the automotive refinish as well as general coatings marketplace, Isocyanate functional crosslinking agents are used in many applications where extreme durability is required. The toughness and chemical resistance of coatings that have been crosslinked by the Isocyanate/Hydroxyl reaction to form Urethane bonds are considered the industry standard for highly durable coatings applications.
In the current environment of regulations intended to reduce the amount of volatile organic compounds (or VOC) that are released into the atmosphere on application of coatings, it is very difficult to formulate coatings compositions that meet the regulatory limits without some kind of crosslinking mechanism that takes place after application. In order to achieve a suitable spray application viscosity (20-30 seconds #4 Ford cup @20° C.) as VOC regulations have mandated higher application non-volatiles it has been necessary to use resins with lower molecular weights and generally lower Tg. Both of these changes generally have the effect of lengthening the dry time of the applied coating since the number of crosslink reactions required to achieve a “dry to handle” condition increases significantly.
Due to the need to increase the number of crosslinking reactions to achieve the “dry to handle” condition, faster reaction rate crosslinking reactions are desirable.
One reaction well known to the art is that of carboxylic acid functionality and carbodiimide functionality. The problem with the carboxylic acid/carbodiimide chemistry is the reaction rate is extremely fast. There is very little time available after these materials are mixed in which the coatings may be applied to the intended substrate. Also, the cost of development and color matching of an automotive refinish coatings systems that employ acid functional backbone resins would be very high.
The present invention relates a chemistry and method for converting a product line, based on active hydrogen functionality, which was originally intended to be crosslinked with Isocyanate functional crosslinking agents, in situ, to carboxylic acid functionality. This carboxylic acid functionality will then readily react with carbodiimide functionality. While the carboxylic acid/carbodiimide reaction is very rapid, the “relay reaction” rate of active hydrogen to carboxylic acid by the ring opening of the anhydride by the active hydrogen group may be controlled by the choice of anhydride and, optionally, the use of catalyst. Also carbodiimide functional materials may be designed specifically to provide desired final properties.
SUMMARY OF THE INVENTION
The present invention relates to a novel single stage coating composition.
The coating composition typically comprises:
a) a coreactant having an active hydrogen functionality,
b) at least one anhydride functional coreactant, and
c) a carbodiimide compound having the structure:
X—Y—[—R
1
—N═C═N—R
2
—]
n
—[—Y—Z—Y—R
2
—]
m
—N═C═N—[—R
1
—N═C═N—R
2
—]
n−1
—Y—X
Wherein:
m is from 0 to 1
n is from 1 to 10
R
1
=A divalent hydrocarbon residue from a diisocyanate having a tertiary hydrocarbon such as:
R
2
=A divalent hydrocarbon residue from a diisocyanate selected from:
or residues from aliphatic, branched aliphatic or cycloaliphatic diisocyanates, including biurets, allophonates, isocyanurates or uretdiones thereof.
X=Any radical with substituents that are unreactive towards a carbodiimide. For example:
Aliphatic, branched aliphatic, cycloaliphatic or aromatic hydrocarbon, organosilane or salted sulfonic acid radicals.
Or:
A polymeric radical, for example, a polyether polyester, polyurethane, acrylic resin, polycarbonates and mixtures thereof.
Z=A polyvalent radical with substituents that are unreactive towards a carbodiimide to function as an extending or branching site.
For example:
Aliphatic, branched aliphatic, cycloaliphatic or aromatic hydrocarbon, organosilane or salted sulfonic acid radicals.
Or:
A polymeric radical, for example, a polyether, polyester, polyurethane, acrylic resin, polycarbonates and mixtures thereof.
d) at least one pigment,
e) additives known to the art,
f) and, optionally, one or more catalysts.
Alternatively, carbodiimide compounds having the structure:
X—Y—[—R—N═C═N—]
n
—R—Y—X
have shown utility in the current invention.
Wherein:
n is from 2-20, preferably 2 to 8
R=A divalent hydrocarbon radical having the following structure.
X=A n-butyl radical.
Y=—N═C═N—
Material having this structure is available from Union Carbide as Ucarlnk XL20E.
Alternatively, carbodiimide compounds having the structure:
X—Y—[—R—N═C═N—]
n
—R—Y—X
have shown utility in the current invention.
Wherein:
n is from 2-20, preferably 4 to 8
R=A divalent hydrocarbon radical having the following structure.
X=A methoxy terminated polyethylene oxide radical having the following structure:
CH
3
—O—[—CH
2
—CH
2
—O—]
n
—CH
2
—CH
2
—
Where: n=6-112
Material having this structure is available from Union Carbide as Ucarlnk XL29SE.
This invention also describes a method to reduce the volatile organic content (VOC) of a single stage paint composition by increasing the solids of the paint composition without adversely affecting the sprayable viscosity of the paint and also without significantly decreasing the durability or performance of the final paint film so produced. This invention also relates to a method of converting an already existing, commercial, isocyanate crosslinked product line to a non-isocyanate crosslinked product line.
REFERENCES:
patent: 4587301 (1986-05-01), Watson, Jr. et al.
patent: 5136006 (1992-08-01), Sunderman et al.
patent: 5264518 (1993-11-01), Amano
patent: 5357021 (1994-10-01), Tye et al.
patent: 5929188 (1999-07-01), Nakamura et al.
Mormile Patrick J.
Shepler Stewart
Tye Anthony J.
BASF Corporation
Joynes Robert M.
Page Thurman K.
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