Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From carboxylic acid or derivative thereof
Reexamination Certificate
2002-09-26
2004-08-10
Hightower, P. Hampton (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From carboxylic acid or derivative thereof
C528S044000, C528S060000, C528S061000, C528S064000, C528S068000, C528S076000, C528S272000, C528S288000, C525S411000, C525S419000, C525S420000
Reexamination Certificate
active
06774206
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to polyaspartate resins prepared from low molecular weight polyether polyamines and their use for the production of polyureas having improved flexibility.
2. Description of the Prior Art
Two-component coating compositions containing a polyisocyanate component and a polyaspartate component are known and disclosed in U.S. Pat. Nos. 5,126,170, 5,236,741, 5,489,704 and 5,516,873. The polyaspartates may be used as the only isocyanate-reactive component or they may be blended with polyols, polyamines or blocked polyamines, such as ketimines, aldimines or oxazolidines. The compositions are suitable for the preparation of high quality coatings that are abrasion resistant, solvent resistant and weather resistant.
One of the deficiencies of these polyaspartates is that when reacted with polyisocyanates they do not form flexible coatings, which can be seen from the low elongations of the resulting coatings. One method for improving the flexibility is to prepare the polyaspartates from high molecular weight polyamines, such as Jeffamine D-2000 (available from Huntsman). However, as disclosed in WO 01/07504, the reaction of equimolar amounts of this polyether polyamine with diethyl maleate to form the polyaspartate is only 78% complete after 73 days, and it takes more than 2 years for the reaction to be 100% complete.
Other alternatives for reducing the reaction time are also not feasible. For example, if a large excess of the ester of maleic or fumaric acid is used to reduce the reaction time, then it is necessary to remove the unreacted excess when the reaction is completed, which is a time-consuming, expensive procedure. It is also not feasible to prepared large quantities of the polyaspartates resins in advance because it is extremely difficult to predict customers' needs for the products and because of expensive storage and inventory costs.
Accordingly, it is an object of the present invention to provide polyasparate resins that can be reacted with polyisocyanates to obtain coatings with improved flexibility. It is an additional object of the present invention to provide polyaspartate resins that can be prepared with a short reaction time.
Surprisingly, these objects may be achieved with the polyaspartate resins according to the present invention which are prepared from low molecular weight polyether amines. When reacted with polyisocyanates the resulting coatings possess excellent flexibility. In addition, the polyaspartate resins can be prepared with a relatively short reaction time, which is surprising in view of the prior art that teaches that excessively long reaction times are required to prepare polyaspartates from polyether polyamines.
SUMMARY OF THE INVENTION
The present invention relates to polyaspartates corresponding to the formula
wherein
X
1
represents the residue obtained by removing the amino groups from a polyether polyamine having a functionality of n and a number average molecular weight of less than 600, wherein the amino groups are attached to primary carbon atoms and the ether groups are separated by at least two carbon atoms,
R
1
and R
2
are identical or different and represent organic groups which are inert to isocyanate groups at a temperature of 100° C. or less,
R
3
and R
4
are identical or different and represent hydrogen or organic groups which are inert towards isocyanate groups at a temperature of 100° C. or less and
n is 2 to 4.
The present invention also relates to polyureas prepared by reacting the polyaspartates and optionally other isocyanate-reactive compounds with polyisocyanates.
DETAILED DESCRIPTION OF THE INVENTION
The polyaspartates according to the present invention correspond to formula I
wherein
X
1
represents the residue obtained by removing the amino groups from a polyether polyamine having a functionality of n and a number average molecular weight of less than 600, preferably less than 300, wherein the amino groups are attached to primary carbon atoms and the ether groups are separated by at least two carbon atoms,
R
1
and R
2
are identical or different and represent organic groups which are inert to isocyanate groups at a temperature of 100° C. or less, preferably alkyl groups having 1 to 9 carbon atoms, more preferably alkyl groups having 1 to 4 carbon atoms, such as methyl, ethyl or butyl groups,
R
3
and R
4
may be identical or different and represent hydrogen or organic groups which are inert towards isocyanate groups at a temperature of 100° C. or less, preferably hydrogen and
n is 2 to 4, preferably 2 or 3 and more preferably 2.
With regard to the preceding definitions R
1
and R
2
may be different when the polyaspartates are prepared from mixed maleates, such as methylethyl maleate. In addition, one R
1
may be different from another R
1
. For example, when a mixture of maleates, e.g. dimethyl and diethyl maleate, is used to prepare the polyaspartate, one pair of R
1
and R
2
groups will be methyl and the other will be ethyl.
The polyaspartates may be prepared in known manner as described in U.S. Pat. No. 5,126,170, herein incorporated by reference, by reacting polyether polyamines corresponding to the formula
X
1
—(—NH
2
)
n
(II)
with maleic or fumaric acid esters corresponding to the formula
R
1
OOC—CR
3
═CR
4
—COOR
2
(III)
Suitable polyether amines corresponding to formula II are those having linear or branched hydrocarbon chains interrupted by ether groups and having a number average molecular weight of less than 600, preferably less than 300. The amino groups are attached to primary carbons and the ether groups are separated by at least two carbons. Preferably, the backbone of the polyether contains oxypropylene and/or oxyethylene groups.
Preferred polyamines are those corresponding to the formula
H
2
N—R
6
—O—R
5
—O—R
7
—NH
2
(IV)
wherein
R
5
represents the residue obtained by removing the hydroxyl groups from a linear or branched hydrocarbon radical having 2 to 15 carbon atoms, preferably 2 to 8 carbon atoms and more preferably 2 to 6 carbon atoms, wherein the carbon atoms may optionally be interrupted by ether groups, R
6
and R
7
may be the same of different and represent linear or branched hydrocarbon radicals containing 2 to 8 carbon atoms, preferably 2 to 6 carbon atoms and more preferably 2 to 4 carbon atoms.
Examples include 2-[2-(2-aminoethoxy)ethoxy]ethylamine (Jeffamine XTJ-504, available from Huntsman), 3-[2-(3-aminopropoxy) ethoxy]propylamine (Etheramine NDPA 10, available from Tomah Products), 3-[3-(3-amino-propoxy)propoxy]propylamine (Etheramine NDPA 11, available from Tomah Products), 3-[4-(3-aminopropoxy)butoxy]propylamine (Etheramine NDPA 12, available from Tomah Products) and 3-{2-[2-(3-aminopropoxy)ethoxy]ethoxy}propylamine (Etheramine DPA-DEG, available from Tomah Products or BASF TTD, available from BASF).
Examples of suitable maleic or fumaric acid esters corresponding to formula III include dimethyl, diethyl and dibutyl (e.g., di-n-butyl), diamyl, di-2-ethylhexyl esters and mixed esters based on mixtures of these and/or other alkyl groups of maleic acid and fumaric acid; and the corresponding maleic or fumaric acid esters substituted by methyl in the 2- and/or 3-position. The dimethyl, diethyl and dibutyl esters of maleic acid are preferred, while the diethyl esters are especially preferred.
The preparation of the polyaspartates takes place by reacting the polyamines with the maleic or fumaric acid esters at a temperature of 0 to 100° C. using the starting materials in such proportions that at least 1, preferably 1, unsaturated group is present for each primary amino group. The reaction may be carried out solvent-free or in the presence of suitable solvents such as methanol, ethanol, propanol, dioxane, aromatic solvents such as toluene and mixtures of such solvents. Preferably, the reaction is carried out solvent-free. The reaction is generally complete within two weeks after the reaction mixture
Britsch Catherine M.
Danielmeier Karsten
Gertzmann Rolf
Squiller Edward P.
Vargo Michele E.
Bayer Polymers LLC
Gil Joseph C.
Hampton Hightower P.
Matz Gary F.
Roy Thomas W.
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