WO1997003034A2

WO1997003034A2 - Polynitrile oxides

Info

Publication number: WO1997003034A2
Application number: PCT/US1996/011499
Authority: WO
Inventors: Zenon Lysenko; Ritchie A. Wessling; Dale M. Pickelman; Gene D. Rose; Mladen Ladika; Michael Krayushkin
Original assignee: The Dow Chemical Company
Priority date: 1995-07-10
Filing date: 1996-07-10
Publication date: 1997-01-30
Also published as: WO1997003034A3; EP0842147A2; AU6487696A; BR9609523A; AU709961B2; CA2226849A1

Abstract

The present invention is an aqueous dispersion of a stable polynitrile oxide represented by the structure: R-(C≡N-O-)x, whre x is an integer greater than 1, R 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. The present invention is also a method of curing a latex having a polyunsaturated disperse phase, comprising the steps of: a) mixing the latex with a stable polynitrile oxide; and b) removing water form the mixture. 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.

Description

POLYNITRILE OXIDES

The present invention relates to stable polynitrile oxides. Nitrile oxides react with unsaturated compounds to form cyclic compounds. For example, 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. (See Grundmann and Grunanqer, Nitrile Oxides, Springer, New York, pp. 85-139, 1971.) 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. Because 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. Nauk SSSR, Ser. Khim., No. 7, pp. 1609-1615 (1991) One such stable bis-nitrile oxide, 2,4,6-triethyibenzene-1 ,3-bis(nitrile oxide), has been shown to be useful for the vulcanization of natural rubber.

None of the above-cited art suggests the use of stable polynitrile oxides as curatives for latexes. It would be an advance in the art to cure latexes using a one-part, room- temperature curative.

The present invention is a water-insoluble aqueous dispersion comprising a stable polynitrile oxide represented by the structure:

G-(C ≡ N-0 )_χ where x is an integer greater than 1 , 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.

In a second aspect, 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.

In a further aspect, the present invention is a compound having the structure:

5 wherein each R' is independently C C-|₂-alkyl, F, Cl, Br, I, 0-C C₁₂-alkyl, or S-C Cι₂-alkyl; each R° is a substituent that does not spontaneously react with the nitrile oxide group; each n' is independently 0, 1, or 2; n" is an integer greater than 1 ; each X' is independently a bond or a connecting group; and Y' is a polyvalent radical containing an ether, ester, amide, amine, carbonate, ketone, urethane, arylene, or thioether moiety; or each X' and Y' together are a _Q bond connecting the benzene rings.

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. The term "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. The term "unsaturated" is used herein to denote a site of the type A= A', or A≡A', where A is a carbon atom, and A' is a carbon, oxygen, nitrogen, sulfur, or phosphorus atom. For the purposes of this invention, a nitrile oxide group is not an unsaturated group. The term "polyunsaturated" ₀ is used herein to denote more than one unsaturated group. The preferred unsaturated groups include olefins and alkynes.

Each nitrile oxide is 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. 5 Traditionally, nitrile oxides are prepared in situ in the presence of an unsaturated substrate with which the nitrile oxides are intended to react. However, 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. Preferably, 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. Examples of hindered aromatic polynitrile oxides include:

R4

where R¹, R2, and R3, and R⁴ are each independently H, R, halo, SH, SR, SOR, S0₂R, hydroxy, or OR, with the proviso that at least one of R¹, R², R³, and R⁴that is adjacent to a nitrile oxide group is not H; R5, R6, 7_f and R⁸ are each independently H, R, halo, S-H, SR, SOR, S0₂R, hydroxy, or OR, wherein R is a C₁-C₁₂ linear, branched, or cyclic alkyl group, preferably a C₁-C₄ linear or branched alkyl group, more preferably ethyl or methyl; or R⁵ and R⁶, or R⁷ and R⁸ together with the carbon atoms to which they are attached, form a benzene ring, wherein at least one of R⁵ or R⁷ is not H, and at least one of R⁶ or R⁸ is not H; i is 2 or 3; m and n are each 0, 1, or 2, and n + m ≥ 2, preferably 2 or 3.

Other examples of hindered aromatic polynitrile oxides include compounds represented by the following structures:

where R9, R™, R", and Ri2 _are each independently H, R, halo, SH, SR, SOR, S0₂R, hydroxy, or OR with the proviso that at least one of R9 and R¹¹ is not H when a nitrile oxide group is adjacent to

both R⁹ and RU, and at least one of R¹⁰ and R¹² is not H when a nitrile oxide group is adjacent to both Rio and R¹²; m, p, and r are each 0, 1, or 2, and p + r > 2; X is CH₂, C(R)₂, carbonyl, O, S, SO, S0₂, NH, S0₂NH, S0₂NR, or NR; t and u are each 0, 1 , 2, or 3; and t + u ≥ 2; Y is a bond, CH₂, C(R)₂, carbonyl, O, S, SO, S0₂, 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:

wherein each R' is independently C C₁₂-alkyl, F, Cl, Br, I, 0-C Cι₂-alkyl, or S-C Cι₂-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, cycloalkylene, or arylene group, more preferably a bond, a methylene group, or a phenylene group; and Y' is a polyvalent radical, preferably a divalent radical, containing an ether, ester, amide, carbonate, ketone, urethane, arylene, or thioether group; or each X' and Y' together are a bond connecting the benzene rings. 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. Preferably, the suitably functionalized 2,6-disubstituted benzonitrile oxide or benzaldehydes is represented by the following structure:

where 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.

For example, 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.

Similarly, the suitably functionalized hindered aromatic nitrile oxide can be reacted with a second suitably functionalized hindered aromatic nitrile oxide to form a dinitrile oxide. For example, 3-hydroxymethyl-2,4,6-trimethylbenzonitrile 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 (for example, a trinitrile oxide) can readily be prepared by reacting a dinitrile oxide with a compound having more than 2 unsaturated sites. For example, 2,4,6-triethylbenzene-1,3-dinitrile oxide can be reacted with trimethylol propane triacrylate to form the following trinitrile oxide:

An 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. The term "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. Preferably, 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.

The polynitrile oxide may itself be prepared as a surfactant, for example, by reacting an excess of a dinitrile oxide with a polyunsaturated surfactant: Ar- ( C ≡N⁺-0^" ) ₂ + = = X "

( excess )

or, for example, by reacting a trinitrile oxide with a monounsaturated surfactant:

Ar- ( C ≡ N⁺-0^_ ) 3 + = χ .ι

where X" is a hydrophilic group, such as a poly(oxyethylene), a carboxylate, or a sulfate.

Other methods of forming a polynitrile oxide surfactant 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 α-olefinically unsaturated aromatic monomers and dienes, preferably conjugated dienes, such as styrene-butadiene latex, α-methylstyrene-butadiene latex, styrene-isoprene latex, and σ- methylstyrene-isoprene latex.

However, 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. For example, 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. Similarly, 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 α-methylstyrene-butadiene-α- methylstyrene, α-methylstyrene-isoprene-α-methylstyrene, styrene-isoprene-styrene, and styrene-butadiene-styrene are also suitable.

Other 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. I O 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. Preferably, the concentration of polynitrile oxide is in the range of about 0.01 to about ^■\ t- 1.10 nitrile oxide groups per unsaturated group.

The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

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

2,4,6-Triethylbenzene-1 ,3-Dinitrile Oxide

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

Carbide) and 18.4 parts t-butyl peroctoate were heated to 90°C in a stirred glass reactor and blanketed with an inert atmosphere of nitrogen. A mixture of 433.1 parts styrene, 144.4 parts

2-ethylhexyl acrylate, 35.0 parts glycidyl methacrylate and a separate feed of 18.4 parts t-butyl peroctoate were added continuously and proportionately to the reactor over 1.5 hours. During 30 this addition period, the reaction temperature reached a maximum temperature of 99°C.

Stage 2 - Hydrophilic Monomer Polymerization

The following feed solutions were added continuously and proportionately to the reactor over 1.5 hours with the reaction temperature decreasing from 99°C to 92^CC: 1 ) 87.5 parts 2-acrylamido-2-methylpropane sulfonic acid (AMPS) admixed with 87.5 parts deionized 3₅ (Dl) water, and 41.0 parts dibutyl amine; 2) 1176.7 parts TERGITOL'" NP-7; and 3) 0.7 parts

2-mercaptoethanol admixed with 15.8 parts Dl water. The reactor contents were maintained at

90°C for an additional 2 hours. The polymer/non-ionic/water reaction mixture (PC-3) was transferred to a steam still and the residual monomers were removed with the aid of a vacuum. A solution containing 1.9 g of 2,4,6-triethyibenzene-1 ,3-dinitrile oxide (TON-2) and 5.8 g butyl benzyl phthalate was prepared and mixed with 1.1 g of PC-3 along with 2.9 g of TERGITOL'" NP-7 to form the emulsifiable concentrate. B. The Curing Step The emulsifiable concentrate from Part A was diluted with 1 1.7 g of distilled water and shaken to form an aqueous dispersion. 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. In contrast, a comparable film that was prepared in the same manner, but did not contain the dinitrile oxide, was found to dissolve partially in toluene. Thus, the dinitrile oxide-treated film was found to be more highly crosslinked than the control that does not contain the dinitrile oxide curative.

Example 2 - Crosslinking of Crotyl Methacrylate-Containing Latex with TON-2 Phase (A): Synthesis of a Latex

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. 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). Using five syringes and syringe pumps, the following components were added to the flask while constantly maintaining the nitrogen atmosphere and the temperature of 60°C:

(a) crotyl methacrylate (43.2 g) and a portion of the basic monomer mixture (40 g); (b) the remaining basic monomer mixture (733.6 g);

(c) t-dodecyl mercaptan (16.64 g);

(d) the solution of t-butyl hydroperoxide (4.64 g of 70 percent active; 3.25 percent active) and DOWFAX™ (a trademark of The Dow Chemical Company) 2EP surfactant (17.76 g) in water (83.2 g); and (e) the solution of sodium formaldehyde sulfoxylate (SFS, 2.52 g in 28 g of water).

Component (b) was added over the first five hours, followed by the addition of component (a) over an additional hour. Components (c), (d), and (e) were added over six hours. After the addition of all components, stirring at 60°C was continued for an additional hour. The resulting latex was then filtered through a 200-mesh screen and cooled to ambient temperature. The conversion was 99.4 percent, and the recovery 97.8 percent. This latex had 50.4 percent solids, and particles with a mean and median size of 1442 Λ and 1341 A, respectively. Phase (B): Crosslinking of a Coating

An 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 RHODAPEX™ 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. In this example, 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. A reference coating prepared from the same latex, but without TON-2 added dissolved completely, confirming the absence of crosslinking in latex alone.

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 VERSENOL™ 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:

(a) butyl acrylate (779.60 g) and methacrylic acid (91.72 g);

(b) methyl methacrylate (657.31 g) and t-dodecylmercaptan (15.29 g); and

(c) the solution of ammonium persulfate (7.64 g) and DOWFAX™ 2EP surfactant (33.97 g) in water (152.86 g). After all the components were added, stirring at 90°C was continued for 30 minutes. The resulting latex was then filtered through a 200-mesh screen and cooled to ambient temperature. This latex had 51.9 percent solids, particles with a median size of 1380 A, and a pH of 2.2. The latex (250 g) was adjusted to a pH of 7.8, whereupon water (20 g) and 4-methoxyphenol (0.20 g) were added. This solution was placed into the 500-mL, 3-necked round-bottomed flask equipped with an air inlet, a reflux condenser with an air outlet, and a mechanical stirrer. The flask was immersed into a water bath, heated to 90°C, and the air-flow was established. Glycidyl methacrylate (5.2 g) was added over 3 hours, and the resulting latex was cooled to ambient temperature. A milky suspension with no coagulates was obtained, having 46.3 percent solids. Phase (B): Crosslinking of a Coating

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. The resulting latex/TON-2 mixture gave a coating which had 90.9 percent gel, a swell index of 4.9, and a tensile strength of 1032.2 psi. Example 5 - Preparation Of Di(3-Fulmido-2,4,6-trimethyl)-benzyl Ether

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.

To a flask fitted by a 10-cm Vigeux column to which was attached a Barret trap and reflux condenser was added a mixture of 3-hydroxymethyl-2,4,6-trimethylbenzaldehyde (23 g, 0.129 mole) and sulfuric acid (0.2 g, 96 percent in 130 mL of benzene). The mixture was refluxed vigorously for 60 minutes. Benzene was removed in vacuo and the crude product was dissolved in chloroform (about 60 mL), whereupon isopropanol (about 200 mL) was added at 60°C. The mixture was cooled to 5°C, and a crystalline precipate was filtered and determined to be di(3-formyl-2,4,6-trimethyl)benzyl ether (18.7 g, 85 percent yield), m.p. 158°C to 161°C.

To a flask containing di(3-formyl-2,4-6-trimethyl)benzyl ether (9.8 g, 0.029 mole) and ethanol (110 mL) was added in one portion a solution of NaOH (4.64 g, 0.116 mole) and hydroxylamine hydrochloride (8.06 g, 0.116 mole) in water (20 mL). The mixture was heated for 2.5 hours with vigorous stirring, then cooled to 5°C, whereupon a crystalline precipitate was filtered and washed with ethanol (30 mL) and water. The precipitate was predetermined to be di(3-hydroximinomethyl-2,4,6-trimethyl)benzyl ether (8.9 g, 83 percent yield), m.p. 210°C to 213°C.

To a flask maintained at 5°C and containing a vigorously stirred suspension of di(3-hydroximinomethyl-2,4,6-trimethyl)benzyl ether (7.9 g 0.0215 mole) in methylene chloride (100 mL) was added (NaOCl (53 mL of a 15 percent solution). The reaction mixture was stirred for 2 hours at 5°C to 10°C, whereupon the organic layer was separated, and the aqueous phase was extracted with methylene chloride (50 mL). The organic phases were combined, then washed with water (3 x 200 mL). The solvent was then removed in vacuo, and the resultant mixture was cooled to 20°C. 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.

Claims

CLAIMS:

1. A composition comprising an aqueous dispersion of a stable polynitrile oxide represented by the structure:

G-(C- N-0-)_x where x is an integer greater than 1, 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.

2. The composition of Claim 1 which further comprises an aqueous dispersion of a polyunsaturated monomer or polymer.

3. The composition according to either Claim 1 or 2 wherein the stable polynitrile oxide is represented by the structure:

R4

where Ri, R², R3, and R⁴ are each independently H, R, halo, SH, SR, SOR, S0₂R, hydroxy, or OR, with the proviso that at least one of R1, R2, R3, and R⁴ that is adjacent to a nitrile oxide group is not H; where R5, R6, R7_; and R⁸ are each independentiy H, R, halo, SH, SR, SOR, S0₂R, hydroxy, or OR; or R⁵ and R6, or R⁷ and R⁸- together with the carbon atoms to which they are attached, form a benzene ring, wherein at least one of R⁵ or R⁷ is not H, and at least one of R6 or R⁸ is not H; is a Cι-Cι₂ linear, branched, or cyclic alkyl group; i is 2 or 3; m and n are each 0, 1, or 2, and n + m > 2.

4. The composition according to either Claim 1 or 2 wherein the stable polynitrile oxide is represented by the structure:

where R⁹, Rio, RU, and Ri²are each independently H, R, halo, SH, SR, SOR, S0₂R, hydroxy, or OR, with the proviso that at least one of R⁹ and R ¹ is not H when a nitrile oxide group is adjacent to both R⁹ and RH, and at least one of R¹⁰ and R ² is not H when a nitrile oxide group is adjacent to both Rio and R1²; R¹, R², and R3, are each independently H, alkyl, halo, SH, SR, SOR, S0 R, hydroxy, or OR, with the proviso that at least one of R¹, R², and R³ that is adjacent to a nitrile oxide group is not H; p and r are each 0, 1 , or 2, and p + r ≥ 2; X is CH₂, C(R) , carbonyl, O, S, SO, S0₂, NH, S0₂NH, or NR; t and u are each O, 1, 2, or 3; and t + u ≥ 2; Y is a bond, CH₂, C(R)₂, carbonyl, O, S, S0₂, NH, NR, 9,9'-fluoreno, or phenylene; and R is a C C₁₂ linear, branched, or cyclic alkyl group.

5. The composition according to either Claim 1 or 2 wherein the stable polynitrile oxide is represented by the structure:

6. The composition of any of Claims 1, 2, or 5 wherein the hindered polynitrile

5

7. The composition of any of Claims 2 to 6 wherein the aqueous dispersion of the polyunsaturated polymer or monomer is an emulsion polymer of an α-olefinically unsaturated aromatic monomer and a conjugated diene.

8. The composition of Claim 7 wherein the emulsion polymer is a styrene- butadiene latex, an ct-methylstyrene-butadiene latex, a styrene-isoprene latex or an α- methylstyrene-isoprene latex.

9. The composition of any of Claims 2 to 6 wherein the aqueous dispersion of the polyunsaturated polymer or monomer is an emulsion polymer of α-methylstyrene- butadiene-α-methylstyrene,σ-methylstyrene-isoprene-α-methylstyrene, styrene-isoprene- styrene, or styrene-butadiene-styrene.

10. The composition of any of Claims 2 to 6 wherein the aqueous dispersion of the polyunsaturated polymer or monomer is a maleate- or fumarate-containing polyester; a vinylically or allylically unsaturated acrylate copolyester; a butadiene-acrylonitrile copolymer; an ethylene-propylene-dicyclopentadiene terpolymer; a polyisoprene; a polybutadiene; an unsaturated polyurethane; or a polyether copolymer or terpolymer containing at least two unsaturated epoxide constituents.

11. The composition of any of Claims 2 to 6 wherein the aqueous dispersion of the polyunsaturated polymer or monomer is an emulsion polymer of a monofunctional alkyl acrylate or methacrylate and crotyl acrylate or methacrylate.

12. The composition of any of Claims 2 to 6 wherein the aqueous dispersion of the polyunsaturated polymer or monomer is formed by the reaction of glycidyl methacrylate and an aqueous dispersion containing carboxyl functionality.

13. The composition of Claim 12 wherein the aqueous dispersion containing carboxyl functionality is an aqueous dispersion of poly(methylmethacrylate/butylmeth- acrylate/methacryiic acid).

14. The composition of any of Claims 2 to 6 wherein the aqueous dispersion of the polyunsaturated polymer or monomer is formed by the reaction of a latex containing pendant benzyl chloride groups and a vinyl monomer containing a tertiary amine group.

15. 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 , 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. 16. A compound having the structure:

wherein each R' is independently C C₁₂-alkyl, F, Cl, Br, I, 0-C C₁₂-alkyl, or S-C C₁₂-alkyl; each ^0 R° is a substituent that does not spontaneously react with the nitrile oxide group; each n' is independently 0, 1, or 2; n" is an integer greater than 1 ; each X' is independently a bond or a connecting group; and Y' is a polyvalent radical that comprises an ether, ester, amide, amine, carbonate, ketone, urethane, arylene, or thioether moiety; or each X' and Y' together are a bond connecting the benzene rings. ₁₅ 17. The compound of Claim 16 wherein each R' is independently methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, methoxy, or ethoxy; R° is ethyl, methyl, n-propyl, isopropyl, n-butyl, isobutyl, methoxy, ethoxy, F, Cl, Br, or I; n' is 0 or 1 ; n" is 2 or 3; and each X' is a bond, an alkylene group, a cycloalkylene group, or arylene group.

18. The compound of Claim 17 wherein each R° and each R' are independently 20 methyl, ethyl, or methoxy; each X' is a bond, a methylene group, or a phenylene group; n" is 2; and Y' is a divalent radical that comprises an ether or ester moiety.

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