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• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D261/00—Heterocyclic compounds containing 1,2-oxazole or hydrogenated 1,2-oxazole rings
  • C07D261/02—Heterocyclic compounds containing 1,2-oxazole or hydrogenated 1,2-oxazole rings not condensed with other rings
  • C07D261/04—Heterocyclic compounds containing 1,2-oxazole or hydrogenated 1,2-oxazole rings not condensed with other rings having one double bond between ring members or between a ring member and a non-ring member
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C291/00—Compounds containing carbon and nitrogen and having functional groups not covered by groups C07C201/00 - C07C281/00
  • C07C291/02—Compounds containing carbon and nitrogen and having functional groups not covered by groups C07C201/00 - C07C281/00 containing nitrogen-oxide bonds
  • C07C291/06—Nitrile oxides
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C317/00—Sulfones; Sulfoxides
  • C07C317/44—Sulfones; Sulfoxides having sulfone or sulfoxide groups and carboxyl groups bound to the same carbon skeleton
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C2603/00—Systems containing at least three condensed rings
  • C07C2603/02—Ortho- or ortho- and peri-condensed systems
  • C07C2603/04—Ortho- or ortho- and peri-condensed systems containing three rings
  • C07C2603/22—Ortho- or ortho- and peri-condensed systems containing three rings containing only six-membered rings
  • C07C2603/24—Anthracenes; Hydrogenated anthracenes

Definitions

• Nitrile oxides react with unsaturated compounds to form cyclic compounds.
• nitrile oxides react with a) olefins and alkynes to form isoxazolines and isoxazoles, respectively; b) aldehydes and ketones to form 1 ,3,4-dioxazoles; c) thiocarbonyls to form thiooxazoles; d) imino compounds to form 1 ,2,4-oxadiazolines; e) isocyanates to fo rm 1 ,2,4-oxadiazolinones; and f) carboxyls to form hydroximic acids.
• Nitrile oxides can be prepared by a number of methods, most notably from the dehydrohalogenation of the corresponding hydroximic acid halide, which can be prepared by the halogenation of the corresponding aldoxime.
• the aldoxime in turn, can be prepared by reacting the corresponding aldehyde with a hydroxyl amine.
• General methods that teach the preparation of nitrile oxides are described in Nitrile Oxides, supra, pp. 31-61.
• Nitrile oxides tend to dimerize in the absence of stabilizing groups, it is desirable to either prepare the nitrile oxides in situ, or to prepare stabilized nitrile oxides.
• Nitrile oxides can be stabilized by the presence of substituents, such as ethyl, methyl, methoxy, or methylsulfide groups adjacent to the nitrile oxide group (see Nitrile Oxides, supra, p. 14). Examples of stable nitrile oxides, including stable bis-nitrile oxides are disclosed in Nitrile Oxides, supra, pp. 16-21 ; Izv. Akad. Nauk SSSR, Ser. Khim., No. 5, pp. 1201-1203 (1991); and Izv. Akad.
• the present invention is a water-insoluble aqueous dispersion comprising a stable polynitrile oxide represented by the structure:
• the present invention is a method of curing a latex having a polyunsaturated disperse phase, comprising the steps of: a) mixing with the latex a water-insoluble, stable polynitrile oxide represented by the structure:
• G-(C * ⁇ N-0 ) x where x is an integer greater than 1 , preferably an integer from 2 to 6, G is an aromatic, aliphatic, or cycloaliphatic group having at least one substituent adjacent to each nitrile oxide group, the substituent characterized by inhibiting dimerization of nitrile oxide, and being non-interfering with a reaction between nitrile oxide groups and unsaturated groups; and b) removing water from the mixture, preferably by evaporation.
• the present invention is a compound having the structure:
• each R' is independently C C-
• the present invention provides a simple means of preparing one-part coating systems that can be cured at room temperature without the release of by-products.
• the polynitrile oxides suitable for the practice of the present invention are hindered polynitrile oxides.
• polynitrile oxide is used herein to refer to two or more c aromatic nitrile oxide groups per molecule. It is to be understood that the term “aromatic” includes heteroaromatic moieties such as pyridines, furans and thiophenes.
• a nitrile oxide group is not an unsaturated group.
• polyunsaturated 0 is used herein to denote more than one unsaturated group.
• the preferred unsaturated groups include olefins and alkynes.
• nitrile oxides are adjacent to at least one substituent that is 1) unreactive with nitrile oxide and 2) non-interfering with the reaction between the nitrile oxide groups and unsaturated groups, preferably olefinically or acetylenically unsaturated groups.
• nitrile oxides are prepared in situ in the presence of an unsaturated substrate with which the nitrile oxides are intended to react.
• the stable polynitrile oxide used as a curing agent in the present invention can be prepared separately and is sufficiently stable in the absence of the reactive substrate to be effective as a curing agent.
• the stable polynitrile oxide forms less than 10 percent, more preferably less than 5 percent, and most preferably less than 1 percent dimers in 30 days at room temperature.
• hindered aromatic polynitrile oxides include:
• R 1 , R2, and R3, and R 4 are each independently H, R, halo, SH, SR, SOR, S0 2 R, hydroxy, or OR, with the proviso that at least one of R 1 , R 2 , R 3 , and R 4 that is adjacent to a nitrile oxide group is not H;
• R5, R6, 7 f and R 8 are each independently H, R, halo, S-H, SR, SOR, S0 2 R, hydroxy, or OR, wherein R is a C 1 -C 12 linear, branched, or cyclic alkyl group, preferably a C 1 -C 4 linear or branched alkyl group, more preferably ethyl or methyl; or R 5 and R 6 , or R 7 and R 8 together with the carbon atoms to which they are attached, form a benzene ring, wherein at least one of R 5 or R 7 is not H, and at least one of R 6 or R 8 is not H; i
• hindered aromatic polynitrile oxides include compounds represented by the following structures:
• R9, RTM, R", and Ri2 a re each independently H, R, halo, SH, SR, SOR, S0 2 R, hydroxy, or OR with the proviso that at least one of R9 and R 11 is not H when a nitrile oxide group is adjacent to
• R 9 and RU both R 9 and RU, and at least one of R 10 and R 12 is not H when a nitrile oxide group is adjacent to both Rio and R 12 ;
• m, p, and r are each 0, 1, or 2, and p + r > 2;
• X is CH 2 , C(R) 2 , carbonyl, O, S, SO, S0 2 , NH, S0 2 NH, S0 2 NR, or NR;
• t and u are each 0, 1 , 2, or 3; and t + u ⁇ 2;
• Y is a bond, CH 2 , C(R) 2 , carbonyl, O, S, SO, S0 2 , NH, NR, 9,9'-fluoreno, or phenylene.
• Examples of specific hindered aromatic polynitrile oxides that are suitable for the practice of the present invention include the following compounds:
• Stable aliphatic or cycloaliphatic polynitrile oxides can be prepared from a suitably functionalized aliphatic or cycloaliphatic polyaidehyde.
• the poiyaldehyde can then be reacted with hydroxylamine to form the polyaldoxime, which can then be treated with bleach and caustic treatment to form the desired aliphatic polynitrile oxide.
• a suitably functionalized aromatic mononitrile oxide or monoaldehyde can be used to prepare a polynitrile oxide represented by the following formula:
• each R' is independently C C 12 -alkyl, F, Cl, Br, I, 0-C C ⁇ 2 -alkyl, or S-C C ⁇ 2 -alkyl; more preferably ethyl, methyl, n-propyl, isopropyl, n-butyl, isobutyl, methoxy, ethoxy; most preferably ethyl, methyl, or methoxy; each R° is a substituent that does not spontaneously react with the nitrile oxide group, preferably ethyl, methyl, n-propyl, isopropyl, n-butyl, isobutyl, methoxy, ethoxy, F, Cl, Br, or i; each n' is independently 0, 1, or 2; n' is an integer greater than 1 , preferably 2, 3, or 4, more preferably 2 or 3, and most preferably 2; each X' is independently a bond or a connecting group such as an alkylene, cycl
• Suitably functionalized hindered aromatic mononitrile oxides or monoaldehydes preferably include 2,6-disubstituted benzonitrile oxides or benzaldehydes having an ester, acetate, hydroxy, epoxy, fluorine, chlorine, bromine, or iodine group connected directly to the benzene ring or indirectly through a connecting group.
• the suitably functionalized 2,6-disubstituted benzonitrile oxide or benzaldehydes is represented by the following structure:
• R', R°, X', and n' are previously defined;
• Q is -C ⁇ N + 0- or -CHO; and
• Z' is an ester, acetate, amine, hydroxy, epoxy, amide, keto, aldehyde, fluorine, chlorine, bromine, or iodine group.
• 3-hydroxymethyl-2,4,6-trimethylbenzonitrile oxide or its corresponding benzaldehyde precursor can be: (a) transesterified with a diester or condensed with a diacid chloride to form a dinitrile oxide diester; (b) reacted with phosgene to form a dinitrile oxide containing a carbonate group; (c) reacted with a diisocyanate to form a dinitrile oxide containing urethane groups; (d) reacted with a dibenzyl chloride to form a dinitrile oxide containing two ether groups; (e) reacted with a diglycidyl ether to form a dinitrile oxide containing ether groups and hydroxy groups reacted with an acid to form a dinitrile oxido dibenzyl ether.
• the suitably functionalized hindered aromatic nitrile oxide can be reacted with a second suitably functionalized hindered aromatic nitrile oxide to form a dinitrile oxide.
• a second suitably functionalized hindered aromatic nitrile oxide can be reacted with 3-chloromethyl-2,6-dimethylbenzene nitrile oxide to form a bis(nitrile oxide) dimethyl ether.
• Polynitrile oxides having a functionality of greater than 2 can readily be prepared by reacting a dinitrile oxide with a compound having more than 2 unsaturated sites.
• a trinitrile oxide for example, 2,4,6-triethylbenzene-1,3-dinitrile oxide can be reacted with trimethylol propane triacrylate to form the following trinitrile oxide:
• aqueous dispersion of the stable polynitrile oxide is prepared, then advantageously combined with an aqueous dispersion of a polyunsaturated monomer or polymer or a combination thereof, to make a stable multicomponent dispersion.
• stable multicomponent dispersion is used herein to mean that microscopic mixing (and therefore, the reaction rate) of the polynitrile oxide and the polyunsaturated monomer and/or polymer is slower than it would be in the absence of the aqueous medium.
• the extent of the reaction between the polynitrile oxide and polyunsaturated monomer and/or polymer dispersions is less than 10 percent in 8 hours, more preferably less than 10 percent in 30 days, and most preferably less than 10 percent in 1 year.
• the aqueous dispersion of the polynitrile oxide can be prepared by emulsifying an emulsifiable concentrate of the polynitrile oxide. This concentrate can be prepared, for example, by mixing a solution of the polynitrile oxide with a surfactant.
• X" is a hydrophilic group, such as a poly(oxyethylene), a carboxylate, or a sulfate.
• polynitrile oxide surfactant examples include reacting the polynitrile oxide with a polymeric surfactant having polyunsaturation: where b is an integer greater than 1.
• Aqueous dispersions of polyunsaturated polymers are disperse polymers having a plurality of unsaturated sites, which dispersions can be prepared by emulsion polymerization of suitable monomers or by emulsification of previously prepared polymers (artificial latexes).
• Suitable emulsion polymers can be prepared from the emulsion polymerization of ⁇ -olefinically unsaturated aromatic monomers and dienes, preferably conjugated dienes, such as styrene-butadiene latex, ⁇ -methylstyrene-butadiene latex, styrene-isoprene latex, and ⁇ - methylstyrene-isoprene latex.
• the unsaturated latexes need not be prepared from conjugated diene monomers, but may be prepared by polymerizing or copolymerizing unsaturated monomers containing unsaturated groups having different reactivity.
• the emulsion copolymerization of a monofunctional alkyl acrylate or methacrylate, such as methyl or butyl acrylate or methacrylate, with a difunctional acrylate or methacrylate having a vinyl group and a less reactive double bond, such as crotyl acrylate or methacrylate can produce a latex having a plurality of pendant olefin groups.
• a suitably functionalized latex which need not be unsaturated, may be post- reacted with compounds that impart unsaturated sites to the latex, for example, by reacting a latex containing carboxyl functionality, such as a poly(methylmethacrylate/butylmethacrylate/methacrylic acid) latex, with glycidyl methacrylate.
• a latex containing pendant benzyl chloride groups can be reacted with a vinyl monomer containing a tertiary amine group to form the polyunsaturated latex.
• Artificial latexes particularly polyunsaturated triblock copolymers of unsaturated aromatic monomers and conjugated dienes, such as ⁇ -methylstyrene-butadiene- ⁇ - methylstyrene, ⁇ -methylstyrene-isoprene- ⁇ -methylstyrene, styrene-isoprene-styrene, and styrene-butadiene-styrene are also suitable.
• aqueous dispersions include those of polyester resins, such as maleate- and fumarate-containing polyesters and vinylically and allylically unsaturated acrylate 5 copolyesters; butadiene-acrylonitrile copolymers; ethylene-propylene-dicyclopentadiene terpolymers; polyisoprene; polybutadiene, including 1 ,2-polybutadiene; unsaturated polyurethanes; and polyether copolymers and terpolymers containing at least two unsaturated epoxide constituents, such as propylene oxide-allyl glycidyl ether copolymers and ethylene oxide-epichlorohydrin-allyl glycidyl ether terpolymers.
• Aqueous dispersions of polyunsaturated monomers include dispersions of conjugated or non-conjugated monomers, particularly monomers having a boiling point greater than 100°C.
• the polynitrile oxide is used at an effective amount to cure the polyunsaturated latex.
• concentration of polynitrile oxide is in the range of about 0.01 to about ⁇ ⁇ t- 1.10 nitrile oxide groups per unsaturated group.
• Example 1 Curing an S/B Latex with an Emulsifiable Concentrate of 2,4,6-Triethylbenzene- 1 ,3-Dinitrile Oxide 20 A. Preparation of a Polymeric Surfactant and an Emulsifiable Concentrate of
• a polymeric surfactant suitable for forming an emulsifiable concentrate of the dinitrile oxide was prepared in two stages as ollows:
• Stage 1 - Hydrophobic Monomer Polymerization 25 A mixture of 793.8 parts TERGITOL'" NP-7 surfactant (a trademark of Union
• This aqueous dispersion was then added to 76.6 g of a polyunsaturated styrene/butadiene/acrylic acid latex (54.7 percent styrene, 43.3 percent butadiene, 2 percent acrylic acid) having a pH of 3.5 and containing 38.7 g solids and 37.9 g water.
• This material was cast into 10-mil (0.25 mm) films on a glass substrate and cured upon evaporation of water, at room temperature for 24 hours. When a portion of the resultant film (0.42 g) was mixed with 8.5 g of toluene, the film swelled, but ddid not dissolve.
• a 5-L, five-necked round-bottomed flask equipped with a nitrogen inlet, a reflux condenser connected to an oil bubbler with a nitrogen outlet, a mechanical stirrer, and five feed streams was immersed into a water bath and purged with nitrogen a suspension of latex seed (prepared from styrene/acrylic acid 96/4; median particle size 240 A; 40 weight percent; 22.28 g) and VERSENOL'" 120 chelating agent (a trademark of The Dow Chemical Company, 8.32 g of 1 percent solution) in water (642.8 g) were placed into the flask and heated at 60°C.
• latex seed prepared from styrene/acrylic acid 96/4; median particle size 240 A; 40 weight percent; 22.28 g
• VERSENOL'" 120 chelating agent a trademark of The Dow Chemical Company, 8.32 g of 1 percent solution
• Butyl acrylate (399.36 g), methyl methacrylate (357.6 g), and methacrylic acid (16.64 g) were pre-mixed to give a basic monomer mixture (773.6 g).
• a basic monomer mixture 773.6 g.
• emulsion of TON-2 (12.5 weight percent in ethyl benzoate/water) was prepared by a slow addition of the solution of TON-2 (3.125 g) in ethyl benzoate (9.375 g) to a solution of RHODAPEXTM CO-436 surfactant (a trademark of Rhone Poulenc, 0.215 g of 58 percent aqueous solution) in water (12.285 g) with high shear. A portion (8.01 g) of this emulsion was added to the crotyl methacrylate-containing latex (42.00 g) described in Phase (A) of this example. The resulting latex/TON-2 mixture was cast and dried, and aged at 22°C and 50 percent relative humidity for 18 hours.
• a piece of the resulting film (about 1 g) was isolated and weighed, then placed in a vial with toluene (35 mL). The mixture was shaken at high speed for 1 hour, and the soluble phase was removed. The mass of the residual gel-state polymer in a wet state was recorded and the wet gel was then dried in vacuo at 65°C. The mass of the resulting dry gel was recorded, and the swell index (that is, the difference in weights of wet gel and dry gel divided by the weight of a dry gel) and percent gel (that is, the ratio of weights of dry gel and the initial sample multiplied by 100) measured.
• the swell index that is, the difference in weights of wet gel and dry gel divided by the weight of a dry gel
• percent gel that is, the ratio of weights of dry gel and the initial sample multiplied by 100
• the film prepared from the latex/TON-2 mixture hadsa swell index of 4.2 and 86.8 percent gel, indicating a high degree of crosslinking.
• Example 3 Crosslinking of Glycidyl Methacrylate- Containing Latex with TON-2 Phase (A): Synthesis of a Latex To a 1-gallon reactor equipped with a reflux condenser, a mechanical stirrer, and nitrogen inlet and outlet was placed a suspension of latex seed (prepared from styrene/acrylic acid 96/4; median particle size 270 A; 40 weight percent; 19.34 g) and VERSENOLTM 120 (15.29 g of 1 percent solution) in water (1255.32 g). The flask was maintained at a temperature of 90°C under a nitrogen purge. The following components were simultaneously added to the flask over 230 minutes:
• Example 4 An emulsion of TON-2 as prepared in Example 2 (12.5 weight percent in ethyl benzoate/water; 8.01 g) was added to the glycidyl methacrylate-containing latex (65.34 g) described in Phase (A) of this example. The resulting latex/TON-2 mixture was cast to give a coating with 61.3 percent gel.
• Example 4 Crosslinking of S/B Latex with TON-2
• the S/B latex used in this example was prepared using styrene (57.5 percent), butadiene (38 percent with a 1,2: 1,4 ratio of 15/85), and acrylic acid (4.5 percent).
• An emulsion of TON-2 (12.5 percent in toluene/water) was prepared by a slow addition of the solution of TON-2 (3.125 g) in toluene (9.375 g) to a solution of RHODAPEX'" CO-436 surfactant (0.215 g of 58 percent aqueous solution) in water (12.285 g) with high shear. A portion of this emulsion (6.40 g) was added to the S/B latex (100.0 g), and toluene was evaporated off.
• Di(3-fulmido-2,4,6-trimethyl)-benzyl ether was prepared in two steps from 3-hydroxymethyl-2,4,6-trimethylbenzaldehyde, which was prepared according to A. P. Yakubov et al. in Izv. Akd. Nauk SSR, Ser. Khim., No. 7, pp. 1609-1615.
• a crystalline precipitate was filtered and determined to be di(3-fulmido-2,4,6-trimethyl)benzyl ether (7.5 g, 96 percent yield), m.p. 156°C to 158°C. Infrared spectroscopy showed a strong narrow band at 2300 cm *1 corresponding to nitrile oxide.

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