Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
2002-04-26
2004-05-18
Short, Patricia A. (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S454000, C525S455000
Reexamination Certificate
active
06737477
ABSTRACT:
The present invention relates to novel polyurethanes and novel polyurethane-based graft copolymers. The present invention also relates to novel processes for preparing polyurethanes and polyurethane-based graft copolymers. The present invention additionally relates to the use of the novel polyurethanes and the novel polyurethane-based graft copolymers for preparing coating materials, adhesives and sealing compounds.
Graft copolymers which are dispersible or soluble in water are known from European patent EP-A-0 608 021. They are composed of a core comprising a hydrophobic olefinically unsaturated polyurethane, and a shell comprising a hydrophilic acrylate copolymer having an acid number of from 30 to 120 mg KOH/g. The hydrophobic olefinically unsaturated polyurethane is prepared by reacting low molecular mass diols or polyesterdiols with an acid number of less than 5 mg KOH/g with diisocyanates and 1-(1-isocyanato-1-methylethyl)-3-(1-methylethenyl)benzene (dimethyl-m-isopropenylbenzyl isocyanate) to give, in particular, terminal ethylenearylene groups. Subsequently, a mixture of olefinically unsaturated monomers is polymerized in solution in the presence of the hydrophobic olefinically unsaturated polyurethane, after which the resulting graft copolymer is neutralized and dispersed in water to give a secondary dispersion.
It is essential here that the olefinically unsaturated groups must be introduced into the polyurethanes by way of compounds which contain at least one olefinically unsaturated group and at least one isocyanate group in the molecule.
German patent DE-C-197 22 862 discloses a graft copolymer obtainable by polymerizing olefinically unsaturated monomers in a dispersion of an olefinically unsaturated polyurethane which contains hydrophilic functional groups and has on average from 0.05 to 1.1 polymerizable double bonds per molecule, thereby giving the primary dispersion of the graft copolymer. The German patent additionally discloses a graft copolymer obtainable by polymerizing, in an organic solution of an olefinically unsaturated hydrophobic polyurethane containing on average from 0.05 to 1.1 polymerizable double bonds per molecule, a mixture of olefinically unsaturated monomers comprising at least one monomer containing carboxylic acid groups. The resulting graft copolymer is neutralized and dispersed in an aqueous medium to give a secondary dispersion.
Comparable polyurethanes and graft copolymers based on them are also disclosed by German patent application DE-A-196 45 761 or European patent applications EP-A-0 522 419 or EP-A-0 522 420.
A common feature of these known olefinically unsaturated polyurethanes is that the olefinically unsaturated groups have to be introduced by way of compounds which contain at least one isocyanate-reactive functional group and at least one olefinically unsaturated double bond.
A disadvantage here is that in order to provide the compounds introducing olefinically unsaturated double bonds into polyurethanes, the synthesis effort required is high.
In some cases it is possible, not least, for the olefinically unsaturated group content of the polyurethanes to be too low for complete grafting, so that a large part of the monomers to be grafted on form separate homopolymers and/or copolymers alongside the polyurethane, which can detract from the performance properties of the graft copolymers and of the coating materials, adhesives and sealing compounds prepared using them. This disadvantage cannot be eliminated simply by raising the double bond fraction in the polyurethanes to be grafted, since this detrimentally affects other important performance properties of the polyurethanes.
It is an object of the present invention to provide novel olefinically unsaturated hydrophilic or hydrophobic polyurethanes which have a particularly high grafting activity and are simple to obtain. It is a further object of the present invention to provide novel graft copolymers based on the novel olefinically unsaturated hydrophilic or hydrophobic polyurethanes.
Found accordingly has been the novel olefinically unsaturated hydrophilic or hydrophobic polyurethane (B) which is preparable by
(1) reacting a polyurethane prepolymer (B1) preparable by reacting at least
(B1.1) at least one polyisocyanate and
(B1.2) at least one saturated and/or olefinically unsaturated high and/or low molecular mass polyol,
with one another in one or more stages so that on average there remains at least one free isocyanate group per molecule with (2) at least one compound (B1.3) containing at least two isocyanate-reactive functional groups, so that free isocyanate groups can no longer be detected, and then
(3) reacting the resulting polyurethane with at least one anhydride of an alpha,beta-unsaturated carboxylic acid.
Below, the novel olefinically unsaturated hydrophilic or hydrophobic polyurethane (B) is referred to as “polyurethane (B) of the invention”.
Also found has been the novel graft copolymer comprising
(A) at least one grafted-on (co)polymer and
(B) at least one polyurethane
and preparable by radically (co)polymerizing at least one monomer (a) in solution or in emulsion in the presence of at least one polyurethane (B) of the invention.
Below, the novel graft copolymer based on the polyurethane (B) of the invention is referred to as “graft copolymer of the invention”.
In the light of the prior art it was surprising and unforeseeable for the skilled worker that the object on which the present invention was based could be achieved by means of the polyurethanes (B) of the invention and of the graft copolymers of the invention. In particular it was surprising that the polyurethanes (B) of the invention and the graft copolymers of the invention can be prepared easily and in a targeted manner without any damage to the products of the invention. Another surprise is the extremely broad usefulness of the polyurethanes (B) of the invention and of the graft copolymers of the invention.
In the context of the present invention, the property of being hydrophilic refers to the constitutional property of a molecule or functional group to penetrate the aqueous phase or to remain therein. Accordingly, in the context of the present invention, the property of being hydrophobic refers to the constitutional property of a molecule or functional group to behave exophilically with respect to water, i.e., they display the tendency not to penetrate water or to depart the aqueous phase. For further details, refer also to Römpp Lexikon Lacke und Druckfarben, Georg Thieme Verlag, Stuttgart, N.Y., 1998, “hydrophilicity”, “hydrophobicity”, pages 294 and 295.
The polyurethane (B) of the invention contains at least one pendant and/or at least one terminal olefinically unsaturated group. In other words: the polyurethane (B) of the invention contains at least one pendant, at least one terminal, or at least one pendant and at least one terminal olefinically unsaturated group.
Examples of suitable olefinically unsaturated groups are (meth)acrylate, ethacrylate, crotonate or cinnamate groups, of which the methacrylate and acrylate groups, but especially the methacrylate groups, are particularly advantageous and are employed with particular preference in accordance with the invention.
Furthermore, the polyurethane (B) of the invention may contain further pendant and/or terminal olefinically unsaturated groups such as ethenylarylene, vinyl ether, vinyl ester, dicyclopentadienyl, norbornenyl, isoprenyl, isoprenyl, isopropenyl, allyl or butenyl groups; dicyclopentadienyl ether, norbornenyl ether, isoprenyl ether, isopropenyl ether, allyl ether or butenyl ether groups, or dicyclopentadienyl ester, norbornenyl ester, isoprenyl ester, isopropenyl ester, allyl ester or butenyl ester groups.
The polyurethane (B) of the invention is hydrophilic or hydrophobic in the aforementioned sense. In respect of their use for. preparing the graft copolymers of the invention, the hydrophilic polyurethanes (B) of the invention offer certain advantages and are therefore used with preference.
The hydrophilic polyurethanes (B) of the
BASF Coatings AC
Short Patricia A.
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