Abstract: The present invention provides a method of treating boiler and condensate water by the addition of an effective amount of a hydroxyamine-acid ester treatment reagent or an all-in-one treatment composition comprising a hydroxyamine-acid ester. Modification of a hydroxyamine to a hydroxyamine-acid ester generally reduces the odors of the amine while providing a means to formulate the composition into a solid form. The ester typically decomposes at conditions in the boiler to release the hydroxyamine to treat the boiler water. Other components used to treat boiler water and condensate related problems may be formulated with the hydroxyamine-acid ester to form the all-in-one treatment composition.

Abstract: A heat stabilizing composition for polyolefins comprises an oxidized, non-cationized, non-silylated sulfur black pigment, a hindered phenolic antioxidant a sulfur-containing secondary stabilizer, each in stabilizing amount, and a hindered amine. The heat stabilizing composition yields polyolefin compounds and articles having improved long term heat aging stability. Preferably, the sulfur black pigment is treated by washing, to thereby reduce the concentration of soluble sodium salts.

Abstract: A composition including 8-hydroxyquinaldine and an N-acyl taurate is useful in compounding elastomer compositions. Compositions are described containing elastomers such as rubbers, metal oxides, plasticizers, fillers, antidioxants and curing agents. Rubber compositions of the invention have utility in a wide variety of applications.

Abstract: Coatings comprising A) a binder based on an organic polymer and B) as stabilizer against damage by light, heat and oxygen, a 2-(2′-hydroxyphenyl)-1,3-pyrimidine of the formula I  in which the radicals R1 to R6 are as defined in claim 1 have an outstanding resistance to the damaging effects of light, oxygen and heat. Compounds of the formula Ib defined in claim 18 are suitable in general for the stabilization of organic material.

Abstract: A composition and process for inhibiting the corrosion of metallic substrates is revealed. The process utilizes an aqueous treatment solution comprising chitosan which has been reacted with an additive selected from the group consisting of phosphorus-containing compounds and sulfur-containing compounds and mixtures thereof. More preferably, the phosphorus-containing compound is a phosphonic acid and the sulfur-containing compound is a mercapto, thio, or thienyl containing compound or a mercapto functional silane. The composition and process are particularly useful in providing corrosion protection for aluminum and aluminum alloys.

Abstract: The present invention encompasses a novel organic based composition which includes at least one organic based heat stabilizer component, and at least one stabilizer modifying component selected from the group of liquid calcium soap and 1,3,5-tris (2-hydroxyethyl) cyanuric acid. The invention also encompasses heat stabilized polymer compositions made with the novel organic based composition disclosed herein.

Abstract: A treatment for pigments is provided. This treatment, which uses certain organosulfonic compounds, imparts improved physical and chemical qualities including lacing resistance, improved dispersion and decreased chemical reactivity when these treated pigments are incorporated into polymeric matrices. The addition of organosulfonic compounds may flexibly be incorporated into known processes at varying points, and are preferably added downstream of any filtering steps.

Abstract: Stablizing mixtures for organic polymers comprising: (a) at least one compound belonging to the group of 3-pyrazolidinones; (b) at least one compound belonging to the group of organic phosphites or phosphonites; (c) at least one compound belonging to the group of sterically hindered phenols; and, optionally, (d) at least one compound belonging to the group of sterically hindered amines. The above mixtures can be used as stabilizers of organic polymers to degradation caused by oxygen, heat and/or light.

Abstract: Crystalline modification of mixtures comprising (a) a nickel-quencher corresponding to [2,2′-thio-bis(4-t-octylphenolate)-n-butylamine Nickel (II)] and (b) a 2-hydroxy-4-alkyloxybenzophenone corresponding to 2-hydroxy-4-n-octyloxybenzophenone wherein it has two diffraction lines at angles 2{acute over (ø)}=6.291 and 2{acute over (ø)}=6.888 in the X-Ray diffraction spectrum from powders. The said crystalline modification can be used as a light stabilizer for agricultural films based on polyolefins or polyolefinic copolymers.

Abstract: Halogen-containing polymer compositions comprising a latent mercaptan-containing heat stabilizer composition substantially free from the offensive odor typically associated with mercaptans are protected during processing by the degradation products of the latent (i.e., blocked) mercaptan which include a free mercaptan. Other products of the degradation are believed to include carbocations of the blocking moiety which are stabilized by a molecular structure in which the electron deficiency is shared by several groups. The latent mercaptan may be the sole heat stabilizer additive but the free mercaptan released during processing may also synergize the activity of metal-based heat stabilizers such as metal salts and organometallic stabilizers such as organotin carboxylates and mercaptides in the polymer composition. The odor of primary mercaptan-containing heat stabilizers in halogenated polymer compositions is masked by a small amount of a latent mercaptan.

Abstract: A novel composition of thiazolidines of the following formula and a method to prepare the same are disclosed. The method involves reacting a dihydrothiazole with a mixture comprising formic acid and an aldehyde. These new thiazolidines are useful as corrosion inhibitors.

Abstract: The present invention provides a composition and method for inhibiting hydrogen permeation in metal refinery equipment comprising incorporating into a product stream handled by said equipment a polyamine amide of 3-hydrocarbyl thiopropionic acid in an amount sufficient to inhibit said hydrogen permeation. In a preferred embodiment, the polyamine amide of 3-hydrocarbyl thiopropionic acid is selected from the group consisting of propanamide, N-[2-[2-[3-(dodecenyl)-2,5-dioxo-1-pyrrolidinyl]ethyl]amino]ethyl]-3-[dodecylthio]-2-methyl and 15-thia-5,8,11-triazaheptacosanoic acid, 2-(dodecenyl)-13-methyl-4,12-dioxo, and combinations thereof.

Abstract: The corrosion of metal equipment which is cleaned with an inorganic acid is inhibited by treating the equipment with a corrosion inhibitor composition containing at least one quaternary ammonium compound, a sulfur-containing compound and a nonionic surfactant in a solvent.

Abstract: Halogen-containing polymer compositions comprising a latent mercaptan-containing heat stabilizer composition substantially free from the offensive odor typically associated with mercaptans are protected during processing by the degradation products of the latent (i.e., blocked) mercaptan which include a free mercaptan. Other products of the degradation are believed to include carbocations of the blocking moiety which are stabilized by a molecular structure in which the electron deficiency is shared by several groups. The latent mercaptan may be the sole heat stabilizer additive but the free mercaptan released during processing may also synergize the activity of metal-based heat stabilizers such as metal salts and organometallic stabilizers such as organotin carboxylates and mercaptides in the polymer composition. The odor of primary mercaptan-containing heat stabilizers in halogenated polymer compositions is masked by a small amount of a latent mercaptan.

Abstract: A composition and process for inhibiting the corrosion of metallic substrates is revealed. The process utilizes an aqueous treatment solution comprising chitosan which has been reacted with an acid selected from the group consisting of phosphonic acids, carboxylic acids and mixtures thereof. The composition and process are particularly useful in providing corrosion protection for aluminum and aluminum alloys.

Abstract: A novel composition of thiazolidines of the following formula and a method to prepare the same are disclosed. The method involves reacting a dihydrothiazole with a mixture comprising formic acid and an aldehyde. These new thiazolidines are useful as corrosion inhibitors.

Abstract: Granular form of a mixture comprising: (a) a nickel-quencher corresponding to [2,2′-thio-bis(4-t-octyl-phenolate)-n-butylamine Nickel (II)]; (b) a 2-hydroxy-4-alkyloxybenzophenone corresponding to 2-hydroxy-4-n-octyloxybenzophenone; characterized in that it has two diffraction lines at angles 2&thgr;=17.593 and 2&thgr;=22.023 in the X-Ray diffraction spectrum from powders. The above granular form can be used as a light stabilizer for agricultural films based on polyolefins or olefinic copolymers.

Abstract: Disclosed herein is a method for inhibiting the premature polymerization of ethylenically unsaturated monomers comprising adding to said monomers an effective amount of: A) at least one stable hindered nitroxyl compound having the structural formula:  wherein R1 and R4 are independently selected from the group consisting of hydrogen, alkyl, and heteroatom-substituted alkyl and R2 and R3 are independently selected from the group consisting of alkyl and heteroatom-substituted alkyl; and X1 and X2 (1) are independently selected from the group consisting of halogen, cyano, COOR7, —S—COR7, —OCOR7, (wherein R7 is alkyl of 1 to 15 carbon atoms, or (2) taken together, form a ring structure with the nitrogen; and B) at least one phenylenediamine, and, optionally, C) at least one nitroaromatic compound.

Abstract: Dispersion powders with a reduced tendency to autoignition are obtained by adding antioxidants to dispersions before spray drying or to dispersion powders after spray drying.

Abstract: This invention relates to a vinyl aromatic, especially styrene, polymerization inhibitor system comprising an N-phenyl-1,4-benzoquinoneimine compound and optionally an aryl-substituted phenylenediamine.

Abstract: A stabiliser combination, mainly for PVC, is described, comprising A) at least one compound of formula I  wherein R*1 and R*2 are each independently of the other C1-C12alkyl, C3-C6lkenyl, C5-C8cycloalkyl that is unsubstituted or substituted by from 1 to 3 C1-C4alkyl, C1-C4alkoxy, C5-C8cycloalkyl or by hydroxy groups or by chlorine atoms, or C7-C9phenylalkyl that is unsubstituted or substituted at the phenyl ring by from 1 to 3 C1-C4alkyl, C1-C4alkoxy, C5-C8cycloalkyl or by hydroxy groups or chlorine atoms, and R*1 and R*2 may additionally be hydrogen and C1-C12alkyl, and Y is S or O, and B) at least one compound from the following groups: B1) perchlorate compounds, B2) glycidyl compounds, B3) beta-diketones and beta-keto esters, B4) dihydropyridines and polydihydropyridines, B5) polyols and disaccharide alcohols, B6) sterically hindered amines (tetraalkylpiperidine compounds), B7) alkali aluminosilicates (zeolites), B8) hydrotalcites, B9) alkali aluminocarbonates (dawsonite

Abstract: Organic materials having excellent stability against oxidative, thermal or light-induced degradation comprise as stabilisers (i) at least one compound of formula I ##STR1## wherein the general symbols are as defined in claim 1, and (ii) calcium lactate and/or calcium stearoyl-2-lactylate.

Abstract: The invention relates to 2-mercaptoimidazole derivatives substituted in the 4(or 5)-position.These 2-mercaptoimidazole derivatives are of the general formula (I) below: ##STR1## wherein: R.sub.1, R.sub.2, R.sub.5, R.sub.7 and R.sub.8 are hydrogen, a lower alkyl, an aralkyl or a substituted aralkyl, wherein at least one of R.sub.1 and R.sub.2 is hydrogen;R.sub.3 is (CH.sub.2).sub.n COR.sub.4, --(CH.sub.2).sub.n N.sup.+ (R.sub.5 R.sub.6 R.sub.7).X.sup.- or --CH.sub.2 CH(COR.sub.4)N.sup.+ (R.sub.5 R.sub.6 R.sub.7).X.sup.- ;R.sub.4 is OR.sub.8, --NHR.sub.5, --.alpha.-amino acid,--NHCH.sub.2 CH.sub.2 SO.sub.3.sup.-.Y.sup.+, --NHCH.sub.2 CH.sub.2 CO.sub.2.sup.- Y.sup.+, --OCH.sub.2 CH.sub.2 N.sup.+ (CH.sub.3).sub.3.X.sup.- ; ##STR2## n=1 or 2; X.sup.31 is an anion of an acid acceptable in cosmetics, pharmaceuticals or foodstuffs; andY.sup.+ is a cation of a base acceptable in cosmetics, pharmaceuticals or foodstuffs.

Abstract: This invention relates to a vinyl aromatic, especially styrene, polymerization inhibitor system comprising an N-phenyl-1,4-benzoquinoneimine compound and optionally an aryl-substituted phenylenediamine.

Abstract: A light-curing composite material is described which is characterized by a content of anaerobic stabilizer and/or stable organic radicals and which has a reduced light sensitivity and an improved vacuum stability and is therefore suitable in particular as a dental filling material.

Abstract: A photofading inhibitor compound comprising a singlet oxygen quenching moiety having a quenching rate of 1.times.10.sup.6 L mol.sup.-1 S.sup.-1 or faster and a cationic moiety.

Abstract: The freshness of meat, vegetables and fruits in a refrigerator or food storage box can be retained for a long period of time by using (1) a freshness retaining gel composition which comprises a freshness retainer component comprising an isothiocyanic acid compound and an aliphatic carboxylic acid or (2) a freshness retaining gel composition which comprises a freshness retainer component comprising an isothiocyanic acid compound, a nonionic surfactant or a fatty acid ester, and a gelling agent.

Abstract: A description is given of novel stabilizer mixtures comprising at least one compound of the formula ##STR1## and at least one compound of the formula ##STR2## in which the variables are as defined in the claims. The novel stabilizer mixtures are suitable for stabilizing organic material, especially textile fibre materials, against damage by light, oxygen and heat.

Abstract: An aviation turbine oil of reduced deposit forming tendencies and improved anti-oxidancy is disclosed which comprises a major portion of a suitable aviation turbine oil base stock and a minor amount of a non-sulfur containing triazine derivative and a mercapto alkyl alcohol.

Abstract: A process for the production of a polyamide stabilizer concentrate in which the concentrate consists of at least two interactive stabilizer components with defined particle sizes and, optionally, micro-dispersed silicic acid, as well as a wax bonding agent with a solidification temperature t.sub.A between 65.degree. and 120.degree. C., in which a homogeneous mixture of these ingredients is compacted into tablets when subjected to a compression force p that is sufficient to heat the mixture to a temperature of at least 40.degree. C. and equal to t.sub.A minus 10.degree. to 50.degree. C.

Abstract: The present invention relates to a compound of the formula ##STR1## wherein n is an integer from 1 to 4, R is selected from the group consisting of hydrogen and methyl; wherein when n is 1, R.sup.1 is selected from the group consisting of alkyl radicals having 1 to 18 carbon atoms, aryl radicals having 6 to 12 carbon atoms, aralkyl radicals having 7 to 12 carbon atoms, cycloalkyl radicals having 5 to 12 carbon atoms and radicals of the formula: ##STR2## wherein x is an integer of from 1 to 7; wherein when n is 2, R.sup.1 is selected from the group consisting of alkylene radicals having 2 to 18 carbon atoms, cycloalkylene radicals having 5 to 12 carbon atoms, arylene radicals having 6 to 12 carbon atoms, ##STR3## polyalkyl glycol ether radicals having the following structure ##STR4## wherein x is an integer from 1 to 7.

Abstract: A mixture comprising a compound of the formula I and a compound of the formula II ##STR1## in which n is 1 or 2; R.sub.1, R'.sub.1, R.sub.2, R'.sub.2, R.sub.3 and R.sub.4, independently of one another, are H, C.sub.1 -C.sub.12 alkyl; C.sub.2 -C.sub.6 alkenyl; C.sub.1 -C.sub.12 alkoxy; C.sub.2 -C.sub.18 alkenoxy; halogen; trifluoromethyl; C.sub.7 -C.sub.11 phenylalkyl; phenyl; phenyl which is substituted by C.sub.1 -C.sub.18 alkyl, C.sub.1 -C.sub.18 alkoxy or halogen; phenoxy; or phenoxy which is substituted by C.sub.1 -C.sub.18 alkyl, C.sub.1 -C.sub.18 alkoxy or halogen;R.sub.6 is hydrogen, C.sub.1 -C.sub.24 alkyl, C.sub.5 -C.sub.12 cycloalkyl or C.sub.7 -C.sub.15 phenylalkyl;R.sub.7, in the case where n=1, and R'.sub.7, independently of one another, are hydrogen or C.sub.1 -C.sub.18 alkyl; or are C.sub.1 -C.sub.12 alkyl which is substituted by OH, C.sub.1 -C.sub.18 alkoxy, allyloxy, halogen, --COOH, --COOR.sub.8, --CONH.sub.2, --CONHR.sub.9, --CON(R.sub.9)(R.sub.10), --NH.sub.2, --NHR.sub.9, --N(R.sub.9)(R.

Abstract: Hydrophilic colloids, such as gelatin, which are employed in the manufacture of photographic elements are commonly treated with a hardening composition, among the most useful of which are hardening compositions containing vinyl sulfone hardening agents such as bis(vinylsulfonyl)methane. In accordance with this invention, citric acid or salts of citric acid are utilized as an effective inhibitor of homopolymerization in such hardening compositions.

Abstract: Compositions and methods for inhibiting the polymerization of vinyl aromatic monomers in oxygen-free processing systems are disclosed. The compositions comprise a hydroxylamine compound, a phenylenediamine compound and a vinyl aromatic monomer. The methods comprise adding to the monomer bis-N,N'(hydroxypropyl)hydroxylamine.

Abstract: A process for preparing a solid particle dispersion of an epoxy compound of the formula SI, ##STR1## wherein R is H, an alkyl group, or an aryl group; L.sub.1 is an alkylene group or an arylene group; L.sub.2 is --O--, --CO--, --S--, --SO.sub.2 --, --PO.sub.2 --, --CO.sub.2 --, --NHCO-- or --NHSO.sub.2 --, wherein L.sub.2 may be orientated in either direction; L.sub.3 is an alkylene group; m is 0 or 1; p is 0 or 1; and X is ##STR2## wherein R' is H or an alkyl or aryl group, with the proviso that where L.sub.2 comprises an ionizable group, X may also be an alkyl group or an aryl group is disclosed. The process comprising the steps of: (a) forming a coarse aqueous slurry of solid particles of said compound; and (b) milling said slurry in the presence of a hydrophobic, photographically inert, liquid second component which has a logP.sub.(calc) greater than about 6.0 for time sufficient to provide particles of the desired average particle size.

Abstract: The invention relates to polyethers of the formula I ##STR1## in which m is 0 or 1; n is an integer in the range from 3 to 100; R.sup.1, in the case where m is 0 or 1, is C.sub.1 -C.sub.36 alkyl or C.sub.7 -C.sub.36 aralkyl, each of which is unsubstituted or substituted by C.sub.5 -C.sub.8 cycloalkyl, is interrupted in the aliphatic part by C.sub.5 -C.sub.8 cycloalkylene or by oxygen or sulfur or --NR.sup.11 -- or is substituted in the aromatic part by 1 to 3 C.sub.1 -C.sub.4 alkyl and/or C.sub.1 -C.sub.4 alkoxy radicals; C.sub.3 -C.sub.36 alkenyl; C.sub.5 -C.sub.12 cycloalkyl which is unsubstituted or substituted by 1 to 4 C.sub.1 -C.sub.4 alkyl and/or C.sub.1 -C.sub.4 alkoxy radicals; C.sub.6 -C.sub.10 aryl which is unsubstituted or substituted by 1 to 4 C.sub.1 -C.sub.4 alkyl and/or C.sub.1 -C.sub.4 alkoxy radicals; and R.sup.1, in the case where m is 0, can alternatively be hydrogen; C.sub.1 -C.sub.36 alkoxy or C.sub.7 -C.sub.36 aralkoxy, each of which is unsubstituted or substituted by C.sub.5 -C.sub.

Abstract: A method of improving the light fastness of textile materials using an aqueous dispersion of a compound of formula I, ##STR1## having a first (A) and a second (B) benzoxazine-4-one ring joined by a phenylene bridging member; a variable bond between the first benzoxazine-4-one ring (A) and the phenylene bridging member, said variable bond being meta- or para- to the bond between the second benzoxazine-4-one ring (B) and the bridging member; wherein each R.sub.1 is independently hydrogen, halogen, nitro, C.sub.1-2 alkyl, C.sub.1-4 alkoxy, carboxy, sulfonic acid, C.sub.1-3 alkylcarbonyl, benzoyl or C.sub.1-4 alkoxycarbonyl and; R.sub.2 is hydrogen, chlorine, bromine, methyl, C.sub.1-2 alkoxy, phenyl, hydroxy, nitro, carboxy or sulfonic acid.

Abstract: Hydrophilic colloids, such as gelatin, which are employed in the manufacture of photographic elements are commonly treated with a hardening composition, among the most useful of which are hardening compositions containing vinyl sulfone hardening agents such as bis(vinylsulfonyl)methane. In accordance with this invention, a sulfate, such as sodium sulfate, is utilized as both an effective conductivity marker and an effective inhibitor of homopolymerization in such hardening compositions.

Abstract: Methods for inhibiting the polymerization of vinyl aromatic monomers in oxygen-free processing systems are disclosed. The methods comprise adding from 1 to 10,000 parts of a combination of a hydroxylamine compound and a phenylenediamine compound to the vinyl aromatic monomer.

Abstract: Adducts of benzotriazole or substituted benzotriazole with formaldehyde or with thiadiazole or substituted thiadiazole are useful as ashless anti-wear/anti-friction/anti-oxidant additives for lubricants. Formulated lubricants containing such adducts exhibit compound levels of anti-wear, anti-friction and oxidation stability performance.

Abstract: Tertiary amides have been developed which have low volatility and good thermal stability and which are effective in stabilizing organic materials that are normally susceptible to oxidative deterioration. The novel antioxidants are tertiary amides corresponding to the formula: ##STR1## wherein R is a mono-, di-, or trivalent aromatic or saturated aliphatic hydrocarbon group containing 1-20 carbons; n is an integer of 1-3 which is equal to the valence of R; R' is phenyl, benzyl, or C.sub.1 -C.sub.6 alkyl; m is an integer of 1-3; R" is a C.sub.1 -C.sub.4 alkylene group; Z and Z' are independently selected from hydrogen and alkyl; and Q is carbonyl or sulfonyl.

Abstract: Methods and compositions are provided for inhibiting the polymerization of vinyl aromatic monomers under distillation conditions. The compositions comprise a combination of a phenylenediamine compound and a hydroxylamine compound.

Abstract: A method of producing an antioxidant containing compound, and in particular, an antioxidant glyceride derivative, comprises reacting a first compound with a second medium. By this reaction, a product is formed whereby an active component of the first compound, e.g., the antioxidant, is covalently incorporated into the second medium.The second medium comprises glyceride derivatives, silicones, fluorocarbons and alkoxylates containing reactive groups such as hydroxy, amino, carboxyl, ester, or amides.

Abstract: The incorporation of the heterocyclic saccharin functionality into the alkenylsuccinimide dispersant structures via the Mannich alkylaminoalkylation procedure provides a class of ashless non-phosphorus dispersants with multifunctional antiwear, antioxidant and corrosion inhibiting properties in lubricant compositions.

Abstract: An aromatic functional fluid, specifically a monoalkylated tetradecyl diphenyl oxide synthetic lubricant, contains a polymer-supported reaction product of an organic quaternary ammonium salt, derived from a mercapto-heterocycle and a quaternary ammonium salt. To produce the polymer-supported organic quaternary ammonium salt, the salt is reacted with a dicarboxylic acid or anhydride, specifically 2-dodecen-1-ylsuccinic anhydride. An arylamine antioxidant, such as alkylated phenyl naphthylamine, can be added to the polymer supported organic quaternary ammonium salt-treated functional fluid to impart extra antioxidant and stability properties.

Abstract: Compositions of (a) a salt of a metal and a carboxylic acid having at least 6 carbon atoms and (b) at least one salt of a metal other than the metal of (a) and a carboxylic acid having at least 6 carbon atoms in a fluid medium are stabilized towards storage decomposition and precipitation by incorporating in the composition (c) a complexing agent such as a ketoxime.

Abstract: Compounds prepared by the addition of the mercaptan group of 3,5-dialkyl-4-aminobenzenethiol to activated ethylenic double bonds or the sulfenyl chloride of 3,5-dialkyl-4-aminobenzenethiol to trialkyl phosphites are effective stabilizers for organic materials subject to oxidative and/or thermal degradation.

Abstract: 2-(2-Hydroxy-3-perfluoroalkylthiomethyl-5-alkylphenyl)-2H-benzotriazoles are prepared by reacting the Mannich base hydrohalide or quaternary salt of a 2-(2-hydroxy-5-alkylphenyl)-2H-benzotriazole with a perfluoroalkyl mercaptan. The products exhibit outstanding efficacy in protecting organic substrates from light induced deterioration as well as good resistance to loss by volatilization or exudation during the processing of stabilized compositions at elevated temperatures.

Abstract: Sulfur-containing ester derivatives of arylamines and hindered phenols have been found to be effective antioxidant and antiwear additives for lubricants.

Abstract: The present invention relates to the preparation of antioxidant additives to lubricants and to their use in lubricating compositions. The additives according to the invention have the formula:ArAr'(H)N--(R--X).sub.a --R'Ywhere--Ar and Ar' are identical or different aromatic radicals, R and R', which are identical or different, denote a C.sub.2 -C.sub.18 linear or branched alkylene radical, X denotes an oxygen or sulphur atom or an --NH group, a is an integer between 0 and 5 and Y is chosen from the group consisting of --NR.sub.1 R.sub.2, where R.sub.1 and R.sub.2, which are identical or different, denote a hydrogen atom or a C.sub.1 -C.sub.12 alkyl, alkenyl, cycloalkyl or arylalkyl radical --N.dbd.CH--Ar.sub.1 where Ar.sub.1 is an aryl radical containing at least one phenolic group --NR.sub.1 --CO--Ar.sub.1 and ##STR1## where R.sub.3 denotes a saturated or unsaturated, linear or branched alkyl radical.