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
2000-02-07
2001-08-07
Gorr, Rachel (Department: 1711)
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...
C528S074000, C428S423100, C428S425800, C428S421000, C428S422000
Reexamination Certificate
active
06271334
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a new coating composition based on oxazolidines and isocyanates.
BACKGROUND OF THE INVENTION
Coatings used for painting motor vehicles and repairing the original paint are required to have good physical properties such as hardness, mechanical strength, and resistance to water, acids, and solvents. The coatings are also required to have good appearance properties, which means that films must be smooth and have a high gloss and high distinctness of image (DOI). It is also desirable that all properties be retained under prolonged outdoor weathering.
For environmental reasons, it is required to use a coating composition which can be applied easily using spray application at a low volatile organic content (VOC). Coatings with a lower organic solvent content emit lower levels of solvent when they are used and so the atmosphere becomes less polluted.
One way to achieve a lower solvent content is to use so-called high-solids compositions. Such compositions comprise a relatively high level of non-volatile materials, such as film forming polymer, pigments and fillers, and a relatively low level of organic solvent. A problem when formulating high-solids coating compositions is that such compositions have an unacceptably high viscosity due to the high molecular weight of the conventional film forming polymer. The high viscosity gives rise to problems in spray application with poor paint atomization and poor flow-out and, consequently, low gloss levels and poor appearance.
The use of low-molecular weight film forming polymers, which results in adequate application viscosities, has as a disadvantage that the resulting coating is soft and marks easily. The hardness build-up of the coating is therefore unacceptable.
Another way to reduce the amount of volatile organic compounds in coating compositions is the use of reactive diluents. Examples of reactive diluents include amidines and ketimines. In EP-A-0 686 654 such compounds are discussed. Other reactive diluents, such as oxazolidines, are mentioned but it is stated that they have limited utility as a sole reaction partner with isocyanate because of generally slow setting film properties.
Amidines are used as reactive diluents for low VOC paint systems. These diluents are commercially available and use of such amidines is referred to in U.S. Pat. No. 5,214,086 and EP-A-0 686 654. In general these reactive diluents offer good cure and hardness development. However, they are known to cause skin irritation and to cause adhesion failure when applied in low VOC clearcoats.
Bicyclic oxazolidines are also used as reactive diluents for low VOC paint systems. These diluents are commercially available and use of such bicyclic oxazolidines are referred to in WO 95/14528. In general, these reactive diluents offer good durability and color stability and low toxicity. However, compositions based on bicyclic oxazolidines may exhibit an unacceptably long time to cure.
Monocyclic oxazolidines are also used as reactive diluents for low VOC paint systems. Coating compositions based on monocyclic oxazolidines are also referred to in EP 0 499 188 A1. Monocyclic oxazolidines and dimers of the same are commercially available. Coating compositions based on monocyclic oxazolidines may exhibit a loss of adhesion over time.
While the use of mono- or bi-cyclic oxazolidines has been described (see, e.g., U.S. Pat. No. 5,126,421), nowhere is there described the use of both monocyclic and bicyclic oxazolidines. WO 92/13907 refers to the use of monocyclic and bicyclic oxazolidines (page 7, lines 20-21), but this reference relates to the use of these compounds in the alternative and does not disclose a mixture of the two oxazolidines.
Surprisingly it was found that the use of mixtures of bicyclic and monocyclic oxazolidines in low VOC coatings provide properties that can compete with those of imines, but without loss of adhesion.
SUMMARY OF THE INVENTION
The present invention relates to a coating composition comprising:
(a) a bicyclic oxazolidine compound;
(b) a monocyclic oxazolidine compound; and
(c) an isocyanate functional compound.
The variables recited in the following formulae are intended to be chosen independently both within one moiety to the next, and from one component to the next.
DETAILED DESCRIPTION OF THE INVENTION
Preferably, the bicyclic oxazolidine component (a) has the structure:
wherein
z is from 0 to 9;
m and p are independently selected from 1 and 2;
R
3
, R
4
, R
5
and R
6
may be the same or different and are selected from the group of hydrogen, linear or branched (cyclo)alkyl, and linear or branched aryl, optionally substituted;
R
3
and R
4
, and R
5
and R
6
may be joined together to form a 5 or 6 carbon ring with the attached carbon atom of the ring in the formula, i.e. R
3
and R
4
, and R
5
and R
6
collectively represent a tetramethylene or a pentamethylene group; and
R
7
is a mono or multivalent aliphatic, aromatic, arylaliphatic or cycloaliphatic moiety which may optionally contain oxygen, nitrogen, sulphur, and silica; and R
7
may be H when z=0.
Preferably, z is from 0 to 3. Preferably m and p are 1. Preferably, R
3
, R
4
, R
5
and R
6
are selected from the group of hydrogen, phenyl, benzyl and a linear or branched C
1-12
alkyl group. More preferably, R
3
, R
4
, R
5
, and R
6
are selected from the group of hydrogen and isopropyl.
More preferably, z is 0 and R
7
is an alkyl group comprising 1 to 10 carbon atoms, more preferably methyl, ethyl or propyl. Most preferably, component (a) comprises 1-aza-3,7-dioxo-2,8-diisopropyl-5-ethyl bicyclo(3,3,0)octane, which is available commercially under the tradename “ZOLDINER®” RD-20 from Angus Chemical Company (Buffalo Grove, Ill.) and has the structure:
The bicyclic oxazolidine component (a) may comprise a mixture of bicyclic oxazolidines.
Preferably, the monocyclic oxazolidine (component (b) of the present invention has the general structure:
wherein
z is from 0 to 9;
n is 2 or 3;
R
1
and R
2
may be the same or different and are selected from the group of hydrogen, linear or branched (cyclo)alkyl, and linear or branched aryl, optionally substituted;
R
1
and R
2
may be joined together to form a 5 or 6 carbon ring with the attached carbon atom of the ring in the formula, i.e. R
1
and R
2
collectively represent a tetramethylene or a pentamethylene group; and R
7
is a mono- or multivalent aliphatic, aromatic, arylaliphatic or cycloaliphatic moiety which may optionally contain oxygen, nitrogen, sulphur, and silica; and R
7
may be H when z=0.
Preferably z is from 0 to 3. Preferably n is 2. Preferably R
1
and R
2
are selected from the group of hydrogen, phenyl, benzyl and a linear or branched C
1-12
alkyl group. More preferably, R
1
and R
2
are selected from the group of hydrogen and isopropyl.
Preferably, R
7
is multivalent and more preferably R
7
is an aliphatic, arylaliphatic or cycloaliphatic moiety comprising 2 to 15 carbon atoms and, optionally, ester, carbonate, and urethane groups. Monocyclic oxazolidines wherein R
7
comprises ester groups may be based on acrylate polymers such as described in GB-B-992,721.
More preferably, z is 1 and R
7
is a divalent moiety comprising either a carbonate group or at least two urethane groups. Compounds having an R
7
group comprising carbonate groups are described in EP-A-0 499 188. R
7
may be for example:
When R
7
comprises at least two urethane groups, R
7
may be selected from the group of the following multivalent moieties:
Most preferably, z is 1, n is 2, R
1
is hydrogen, R
2
iS isopropyl, and R
7
is:
This embodiment is commercially available under the tradename “INCOZOL™” LV (from Industrial Copolymers Ltd., Preston, Lancashire, UK).
The monocyclic oxazolidine component (b) may comprise a mixture of monocyclic oxazolidines.
The weight ratio of bicyclic oxazolidine to monocyclic oxazolidine is preferably in the range of 5:1 to 1:2. More preferably, there is a 3:1 to 1:1 ratio of bicyclic to monocyclic oxazolidine. Most preferably, there is a 2:1 rati
den Breejen Catharine Marie
Lamb Frances
Lemaire Ann Alfred J.
Lochbiler Heide Anne
Moos Jan Wilhelm E.
Akzo Nobel nv
Gorr Rachel
McGillycuddy Joan M.
LandOfFree
Sprayable coating compositions comprising oxazolidines and... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Sprayable coating compositions comprising oxazolidines and..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Sprayable coating compositions comprising oxazolidines and... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2550965