Organic compounds -- part of the class 532-570 series – Organic compounds – Carboxylic acid esters
Reexamination Certificate
1998-12-30
2003-10-07
Wu, David W. (Department: 1713)
Organic compounds -- part of the class 532-570 series
Organic compounds
Carboxylic acid esters
C548S321100, C548S537000
Reexamination Certificate
active
06630599
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a process for preparing blocked derivatives of m- or p-isopropenyl-&agr;, &agr;-dimethylbenzyl isocyanate (m-TMI® polymerizable isocyanate and its p-isomer), which derivatives are particularly suitable for use as wet adhesion promoters for latex polymers and paints derived therefrom. More specifically, the invention relates to the preparation of these monomers directly from in or p-isopropenyl-&agr;,&agr;-dimethylbenzyl carbamic acid ester which are Intermediates in the production of the corresponding Isocyanates. The invention additionally relates to the use of m- and p- isopropenyl-&agr;,&agr;-dimethyl benzylamines (m- and p-TMA) as adhesion promoters for latex polymers, paints, sealants and caulks.
2. Description of Related Art
EP127802 discloses producing isopropenyl-&agr;,&agr;-dimethylbenzyl amines (m-TMA and p-TMA) by the hydrolysis of the corresponding isocyanates, m- and p-TMI, respectfully. U.S Pat. No. 4,927,969 discloses an alternate process whereby M-TMI is reacted with ethanolamine followed by thermal cracking of the resulting hydroxyalkylurea to m-TMA and ethylene carbonate. Isopropenyl-&agr;,&agr;-dimethylbenzyl amines are recognized by those of ordinary skill in the art to be particularly useful as monomers which can be incorporated into polymers to introduce crosslinking sites.
The conventional method of preparing blocked derivatives of isopropenyl-&agr;, &agr;-dimethylbenzyl isocyanate (TMI®) involves reacting the isocyanate TMI® with an appropriate blocking group which is either an amine, a hydroxy or a lactam derivative. For example, W091/12243 discloses reacting TMI® with an aminoethylethyleneurea (AEEU) to produce the wet adhesion monomer shown below:
WO91/12243 discloses that this reaction is advantageously carried out in a solvent such as ethyl acetate.
U.S. Pat. Nos. 5,252,689 and 5,208,347 similarly disclose the preparation of blocked derivatives of TMI® using TMI as the staring material.
A limitation to the commercial use of blocked derivatives of TMI® has been that the conventional preparation methods, employing TMI® as the staring material, can be somewhat expensive. TMI, like other isocyanates, requires special handling procedures and the reaction with amino-functional blocking derivatives can be exothermic and thus require careful manipulation.
It has now been surprisingly discovered that certain blocked derivatives of TMI can be prepared more economically, that is, directly from the precursor m-or p-isopropenyl-&agr;, &agr;-dimethylbenzyl carbamate ester, by heating the precursor with an appropriate hydroxy, amino lactam or cyclic urea functional blocking group.
The monomers prepared by the process of this invention are useful to promote adhesion in polymers and copolymers, including use in aqueous emulsion copolymer latices which are used to prepare latex paints.
Latex-containing surface coatings and coating compositions having superior wet adhesion properties may therefore be produced by including in the monomer system one or a mixture of monomers produced by the present invention's novel process. Also, blends of latices modified with the monomers of the present invention may be used with unmodified latices to achieve the desired degree of wet adhesion.
It has also been discovered that wet adhesion properties can be imparted to aqueous emulsion copolymer latices by incorporating into such latices isopropenyl-&agr;,&agr;-dimethylbenzyl amines (m- and p-TMA).
SUMMARY OF THE INVENTION
In accordance with the present invention, there is provided a novel process for preparing blocked derivatives of isopropenyl-&agr;,&agr;-dimethylbenzyl isocyanate (i.e., blocked derivatives of p- or m-TMI®), comprising the step of contacting m-or p-isopropenyl-&agr;, &agr;-dimethylbenzyl carbamate ester with a hydroxy, an amino, a lactam or a cyclic urea functional blocking group at a temperature and for a length of time sufficient to prepare a blocked derivative of p- or m-TMI®.
The invention further provides compounds of the following general Formula I, below, as functional monomers useful for imparting wet adhesion to water based paint and coating compositions.
wherein X is —NH
2
or —NHCOZ;
wherein Z is —NHR
1
R
2
,
wherein R
1
or R
2
is, individually, H or a C
1
-C
4
alkyl and p is 1 or 2.
Thus, the invention is also directed to latex compositions comprising compounds of the general Formula I as wet adhesion promoters.
It is a further object of this invention to provide economically obtainable novel compounds of the Formula II, below:
wherein Y is
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention is a process for preparing blocked derivatives of TMI® via the direct reaction of m-or p-isopropenyl-&agr;,&agr;-dimethylbenzyl carbamate esters with a hydroxy, an amino, a lactam or a cyclic urea functional blocking group.
The term “TMI” in the context of the present invention, refers to isopropenyl-&agr;, &agr;-dimethylbenzyl isocyanate (m-TMI® polymerizable isocyanate and its p-isomer). TMI® is a commercially available product from Cytec Industries, Inc., West Paterson, N.J. Its synthesis is described in U.S. Pat. No. 4,439,616, which is herein Incorporated by reference for all purposes as if fully set forth.
The synthesis of m- and p-isopropenyl-&agr;,&agr;-dimethylbenzyl carbamate esters, designated as m-TMU and p-TMU, respectively, are disclosed in U.S. Pat. No. 4,439,616.
Process for Preparing Blocked Derivatives of m- and p-TMI®
This invention relates to the preparation of blocked derivatives of TMI, including compounds of the general Formula III, below:
wherein G is: NHR
1
R
2
wherein R
1
or R
2
is, individually, H or a C
1
-C
4
alkyl, n is an integer of from 2 to 4, inclusive, p is 1 or 2 and R
3
is a C
1
-C
4
alkyl.
The monomers of the present invention are useful as chemical intermediates. They copolymerize with many other monomers, both under solution and emulsion polymerization conditions. The polymers and copolymers are especially useful as adhesion and wet adhesion promoters.
The monomers shown in Formula III, above, are advantageously prepared by reacting m- or p-isopropenyl-&agr;,&agr;-dimethylbenzyl carbamate esters (i.e., m- or p-TMU) with an amino, a hydroxy, a lactam or a cyclic urea functional blocking group in the presence of heat and a suitable catalyst. The reaction is generally conducted at a temperature in the range of from about 70° C. to about 120° C. Preferably, the reaction is carried out at a temperature of between 80° and 100° C., until the removal of alcohol by-product is complete.
The resulting solid derivatives can be purified by crystallization, if desired, from a suitable solvent such as ethyl acetate, chloroform, and the like. The crude products may optionally be dissolved in appropriate solvents for further end-use applications. For example, in latex applications, the monomers may be dissolved in acrylic acid, methacrylic acid and their esters, styrene, &agr;-methylstyrene or mixtures thereof. Monomers which are soluble in water may be supplied for end use applications in water or mixtures of water and methacrylic acid.
The 4,439,616 patent discloses the preparation of mixtures of TMU and TMXDU which are thermally cracked directly to mixtures of corresponding isocyanates, TMI and TMXDI, respectively. The patent further discloses separation of TMU from TMXDU by vacuum distillation, which may result in poor yields of TMU due to its cracking to TMI under the distillation conditions (180-200° C.). In order to obtain high yields of TMU, in pure form, for the process of the present invention, the mixture of TMU and TMXDU, produced by reacting m-diisophenylbenzene (m-DIPEB) with methyl carbamate (MeC), is neutralized, excess MeC is removed by distillation, and the solvent heptane is subsequently added to the reaction mixture. Addition of the solvent heptane results in efficient extraction of TMU from the TMXDU, since TMU preferentially dissolves in heptane. Solvents similar to heptane which may also be employed to
Chang Laurence Wu-Kwang
Singh Balwant
Cytec Technology Corp.
Didamo Valerie T.
Jubinsky James A.
Schultz Claire M.
Wu David W.
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