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
1999-11-08
2001-01-30
Sergent, Rabon (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...
C252S182200, C252S182210, C528S049000, C528S068000, C528S073000, C528S082000, C528S084000, C564S032000, C564S058000, C564S059000, C564S060000, C544S067000, C544S222000, C548S951000, C548S952000, C560S330000, C560S355000, C540S202000
Reexamination Certificate
active
06180745
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to moisture-curable compositions containing (cyclo)aliphatically-bound isocyanate groups and succinyl urea groups, which can be cured in the presence of moisture to form coatings, adhesives and sealants.
2. Description of the Prior Art
It is known that polyisocyanate resins are curable in the presence of atmospheric moisture to form polyurea coatings. During the curing mechanism an isocyanate group reacts with moisture to form an amino group, which then reacts with another isocyanate group to form a urea group. One of the disadvantages of these moisture-curable resins is that the curing mechanism is relatively slow.
It has been suggested in U.S. Pat. Nos. 3,420,800 and 3,567,692 that the curing rate of moisture-curable polyisocyanates can be increased by incorporating either aldimines or ketimines. It is stated that the reaction of moisture with an aldimine or ketimine to form the corresponding amine is faster than the reaction of moisture with an isocyanate group to form an amine. A disadvantage of the use of aldimines and ketimines to accelerate the cure of polyisocyanates is that it requires the preparation of an additional component and requires some type of metering equipment to ensure that the two components are blended in the proper proportions.
It is an object of the present invention to increase the curing rate of moisture-curable polyisocyanates without the need for a co-reactant.
This object may be achieved with the compositions according to the present invention which contain isocyanate groups and succinyl urea groups as described hereinafter. The succinyl urea groups may be formed by the reaction of isocyanate groups with aspartate groups.
Copending applications, U.S. Ser. No. 09/172,751, now U.S. Pat. No. 6,005,047 and Ser. No. 09/172,584, disclose polyisocyanates that have been modified to contain alkoxysilane groups incorporated through amino or aspartate groups in order to improve the cure rate of the polyisocyanates. It is disclosed that the faster curing rates are surprising because alkoxysilane groups, which are also curable in the presence of moisture, cure more slowly than polyisocyanates. However, when both isocyanate groups and alkoxysilane groups are present, a faster curing rate is obtained.
SUMMARY OF THE INVENTION
The present invention relates to moisture-curable compositions which have
a) a content of (cyclo)aliphatically-bound isocyanate groups (calculated as NCO, MW 42) of 0.2 to 22% by weight and
b) a content of succinyl urea groups (calculated as —NH—CO—N—, MW 57) of 0.1 to 14% by weight, and
c) an equivalent ratio of (cyclo)aliphatically-bound isocyanate groups to succinyl urea groups of 4:1 to 1:1,
wherein the preceding percentages are based on resin solids content of the moisture-curable compositions.
The present invention also relates to coating, adhesive or sealing compositions containing these moisture-curable compounds as the binder.
DETAILED DESCRIPTION OF THE INVENTION
The moisture-curable compositions according to the present invention are based on the reaction products of polyisocyanates containing (cyclo)aliphatically-bound isocyanate groups and compounds containing aspartate groups. The succinyl urea groups are formed by the reaction of isocyanate groups with aspartate groups.
The moisture-curable compositions of the present invention have
a) a content of (cyclo)aliphatically-bound isocyanate groups (calculated as NCO, MW 42) of 0.2 to 22% by weight, preferably 2 to 20% by weight and more preferably 5 to 15% by weight,
b) a content of succinyl urea groups (calculated as —NH—CO—N—, MW 57) of 0.1 to 14% by weight, preferably 2 to 14% by weight and more preferably 3 to 10% by weight, and
c) an equivalent ratio of (cyclo)aliphatically-bound isocyanate groups to succinyl urea groups of 4:1 to 1:1, preferably 3:1 to 1:1 and more preferably 3:1 to 1.5:1,
wherein the preceding percentages are based on the weight of the moisture-curable compositions.
Suitable compounds containing aspartate groups, which may used to prepare the compounds containing succinyl urea groups, include those corresponding to formula I
wherein
X represents an organic group which has a valency of n and is inert to isocyanate groups at a temperature below 100° C., preferably an n-valent hydrocarbon group obtained by removing the amino groups from an aliphatic, araliphatic, cycloaliphatic or aromatic monoamine or polyamine, more preferably a linear or branched aliphatic monoamine or polyamine and most preferably a linear or branched aliphatic monoamine,
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 methyl, ethyl or butyl groups,
R
3
and R
4
are identical or different and represent hydrogen or organic groups which are inert to isocyanate groups at a temperature of 100° C. or less, preferably hydrogen and
n has a value of at least 1, preferably 1 to 4 and more preferably 1.
With regard to 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 a diaspartate, 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 the corresponding primary monoamines or polyamines corresponding to the formula
X—(—NH
2
)
n
(II)
with optionally substituted maleic or fumaric acid esters corresponding to the formula
ROOC
1
—CR
3
═CR
4
—COOR
2
(III)
Suitable monoamines include ethylamine, the isomeric propylamines, butylamines, pentylamines and hexylamines, and cyclohexylamine.
Suitable polyamines include ethylene diamine, 1,2-diaminopropane, 1,4-diaminobutane, 1,3-diaminopentane, 1,6-diaminohexane, 2-methyl-1,5-pentane diamine, 2,5-diamino-2,5-dimethylhexane, 2,2,4- and/or 2,4,4-trimethyl-1,6-diamino-hexane, 1,11-diaminoundecane, 1,12-diaminododecane, 1,3- and/or 1,4-cyclohexane diamine, 1-amino-3,3,5-trimethyl-5-aminomethyl-cyclohexane, 2,4- and/or 2,6-hexahydrotoluylene diamine, 2,4′- and/or 4,4′-diamino-dicyclohexyl methane and 3,3′-dialkyl-4,4′-diamino-dicyclohexyl methanes (such as 3,3′-dimethyl-4,4′-diamino-dicyclohexyl methane and 3,3′-diethyl-4,4′-diamino-dicyclohexyl methane), 2,4- and/or 2,6-diaminotoluene and 2,4′- and/or 4,4′-diaminodiphenyl methane.
Examples of optionally substituted maleic or fumaric acid esters suitable for use in the preparation of the compounds corresponding to formula I include dimethyl, diethyl and di-n-butyl esters of maleic acid and fumaric acid, the previously discussed mixed maleates and fumarates, 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 and the diethyl and dibutyl esters are especially preferred.
Suitable polyisocyanates for preparing the compounds containing succinyl urea groups are selected from monomeric polyisocyanates, polyisocyanate adducts and NCO prepolymers, preferably monomeric polyisocyanate and polyisocyanate adducts and more preferably polyisocyanate adducts. The polyisocyanates contain (cyclo)aliphatically-bound isocyanate groups and have an average functionality of 1.5 to 6, preferably 1.8 to 6, more preferably 2 to 6 and most preferably 2 to 4.
Suitable monomeric diisocyanates may be represented by the formula
R(NCO)
2
wherein R represents an organic group obtained by removing the aliphatically- and/or cycloaliphatically-bound isocyanate groups from an organic diisocyanate having a molecular weight of about 112 to 1,000, preferably about 140 to 400. Diisocyanates preferred for the pr
Bayer Corporation
Gil Joseph C.
Roy Thomas W.
Sergent Rabon
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