Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From carboxylic acid or derivative thereof
Reexamination Certificate
2000-10-30
2002-04-02
Acquah, Samuel A. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From carboxylic acid or derivative thereof
C528S288000, C528S271000, C528S290000, C528S298000, C528S403000, C528S423000, C528S425000
Reexamination Certificate
active
06365705
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to novel polymers that have net negatively charged backbones and spiro-ammonium cations. These polymers are particularly useful in heat-sensitive printing plate formulations.
BACKGROUND OF THE INVENTION
There is current interest in the development of polymers that undergo irreversible thermally driven reactions. Such reactions may result in crosslinking chemistry, changes in solubility, or changes in the surface energy of a polymer film. There is also considerable interest in the minimization of volatile organic compounds in coating compositions. Thus, thermally-sensitive polymers that are water-soluble or water-dispersible are of particular value. The ability of a polymer to undergo such thermally driven changes by means of a reaction in which small molecule byproducts are not emitted is also desirable for many chemical and coating processes in many industries.
U.S. Pat. No. 5,512,418 (Ma) describes the use of polymers having cationic quaternary ammonium groups that are heat-sensitive.
Low molecular weight (monomeric) spiro-ammonium salts (1-azoniaspiro salts) are known in the field of organic chemistry. Cationic polymers containing spiro-ammonium ions covalently bound within the main chain are also known in the art, having found uses as mordants. See, for example, Muellen et al,
Polym. Bull.
(Berlin), 1990, 24, 263, De Vynck et al,
Macromol. Rapid. Commun,
1997, 18, 149, and U.S. Pat. No. 3,741,768 (Van Paesschen et al).
These compounds, however, are undesirable for several reasons. First of all, the ammonium cations described in the prior art are immobilized within the polymer backbone. This would affect their solubility and usefulness in thermally-sensitive systems. Moreover, it is highly unpredictable as to what interactions or compatibility they might have with other common ingredients in industrial and coating formulations (such as surfactants, colorants, and thickeners). From the perspective of synthetic feasibility, it is typically more difficult to incorporate specific units (in this case, a spiro-quaternary ammonium ring system) into the main chain of a polymer than it is to introduce a desired counterion.
There is a need to provide thermally-sensitive polymers that do not exhibit the noted problems, and that are prepared from common and inexpensive starting materials.
SUMMARY OF THE INVENTION
This invention provides an ionomer having carboxylate recurring units in its backbone and an ammonium counterion for the carboxylate recurring units wherein one or more positively charged nitrogen atoms of the counterion are positioned at tetrahedral vertices of one or more spiro bicyclic ring systems.
The polymers (ionomers) of this invention are specifically designed to undergo thermally driven nucleophilic substitution reactions in which the carboxylate moieties ionically bound to the polymer backbone attack the carbon atoms in the &agr;-position in relation to the quaternary ammonium centers of spiro-ammonium counterions. This results in the cleavage of carbon-nitrogen bonds, the formation of ester bonds, and the dequaternization of the ammonium ions. This reaction will result in changes in solubility and surface energy of the polymer. The advantage of the spiro-ammonium counterion lies in the fact that no matter which of the carbon positions (&agr; to the quaternary ammonium center) are attacked, the tertiary amine product remains bound to the polymer backbone by an ester bond and no volatile compounds are emitted. This reaction is exemplified in Reactive Scheme 1 below.
Reactive Scheme 2 below shows a similar reaction in which a dicationic counterion is used in the polymer. In that situation, the resulting polymer is crosslinked and no volatile compounds are emitted.
The polymers of this invention may find utility in water-based thermally hardenable coating formulations. This class of novel materials is particularly useful for markets and applications having stringent environmental requirements. These polymers are also useful in thermal imaging applications, such as thermally-sensitive printing plates, as described in copending U.S. Ser. No. 09/454,151, filed Dec. 3, 1999 by Leon and Fleming.
It is also an advantage that some polymers of this invention can be derived from such common and inexpensive ethylenically unsaturated polymerizable monomers as acrylic acid and methacrylic acid, and hence can be easily copolymerized with other common monomers using known techniques and reliable methods.
DETAILED DESCRIPTION OF THE INVENTION
The polymers of this invention comprise random recurring units at least some of which comprise carboxylic acids groups and the particular spiro-ammonium cations described herein. The polymers generally have a molecular weight of at least 2000 Daltons and preferably of at least 5000 Daltons.
The carboxylate-containing polymers can be chosen or derived from a variety of polymers and copolymer classes including but not limited to polyamic acids, polyesters, polyamides, polyurethanes, silicones, proteins (such as modified gelatins), polypeptides, and polymers and copolymers based on ethylenically unsaturated polymerizable monomers such as acrylates, methacrylates, acrylamides, methacrylamides, vinyl ethers, vinyl esters, maleic acid/anhydride, itaconic acid/anhydride, styrenics, acrylonitrile, and olefins such as butadiene, isoprene, propylene, and ethylene. The starting polymers can contain more than one type of carboxylic acid-containing monomer. Certain monomers, such as maleic acid/anhydride and itaconic acid/anhydride may contain more than one carboxylic acid unit.
Preferably, the polymers are represented by the following Structure I or II:
wherein the carboxylate-containing recurring units are linked directly (r is 0) within the polymer backbone in the recurring units identified as “A” units, or are connected by linking spacer units (r is 1) identified as “W” in Structures I and II above. This spacer unit can be any divalent aliphatic, alicyclic or aromatic group that does not adversely affect the polymer's heat-sensitivity. For example, “W” can be a substituted or unsubstituted alkylene group having 1 to 16 carbon atoms (such as methylene, ethylene, isopropylene, n-propylene and n-butylene), a substituted or unsubstituted arylene group having 6 to 10 carbon atoms in the arylene ring (such as m- or p-phenylene and naphthylenes), substituted or unsubstituted combinations of alkylene and arylene groups (such arylenealkylene, arylenealkylenearylene and alkylenearylenealkylene groups), and substituted or unsubstituted N-containing heterocyclic groups. Any of these defined groups can be connected in a chain with one or more amino, carbonamido, oxy, thio, amido, oxycarbonyl, aminocarbonyl, alkoxycarbonyl, alkanoyloxy, alkanoylamino or alkaminocarbonyl groups. Particularly useful “W” spacers contains an ester or amide connected to an alkylene group or arylene group (as defined above), such as when the ester and amide groups are directed bonded to “A”.
While “r” can be 0 or 1 in Structure I, preferably r is 0.
Preferably, A represents recurring units derived from ethylenically unsaturated polymerizable acrylates, methacrylates, acrylamides, methacrylamides, maleic acid or anhydride, or itaconic acid or anhydride.
Additional monomers (non-carboxylate monomers) that provide the recurring units represented by “B” in Structure I above include any useful hydrophilic or oleophilic ethylenically unsaturated polymerizable comonomers that may provide desired physical or chemical properties or which provide crosslinkable functionalities. One or more “B” monomers may be used to provide these recurring units, including but not limited to, acrylates, methacrylates, styrene and its derivatives, acrylamides, methacrylamides, olefins, vinyl halides, vinyl ethers, and any monomers (or precursor monomers) that contain carboxy groups (that do not have spiro-quaternary ammonium counterions).
The quaternary ammonium counterions in the polymers can include any compounds that comprise a tetracoordinate nitrogen posit
Acquah Samuel A.
Eastman Kodak Company
Tucker J. Lanny
LandOfFree
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