MXPA98000280A

MXPA98000280A - Stabilization with oximes of peroxide organ

Info

Publication number: MXPA98000280A
Application number: MXPA/A/1998/000280A
Authority: MX
Inventors: Frenkel Peter
Original assignee: Witco Corporation
Priority date: 1997-01-10
Filing date: 1998-01-09
Publication date: 1998-11-09

Abstract

The present invention relates to stabilizing peroxydicarbonate compounds against decomposition by the presence of an effective amount of one or more oximes of the general formula (See Formula). In which RA and RB are optionally substituted alkyl or alkenyl of up to 22 carbon atoms or phenyl, they form a C4 to C8 cycloalkyl ring, or R8 is oxy

Description

STABILIZATION WITH OXIMES OF THE ORGANIC PEROXIDE FIELD OF THE INVENTION The present invention relates to organic peroxide compositions and, more particularly, to peroxydicarbonate compositions, in which one or more oximes have been added to retard the rate of decomposition of the peroxide compound. BACKGROUND OF THE INVENTION Organic peroxides, such as peroxy dicarbonates, are useful as free radial initiators in the polymerization or copolymerization of ethylenically unsaturated monomers. For example, organic peroxides are used as initiators in the polymerization of vinyl halides, such as vinyl chloride or vinyl bromide; vinylidene halides, such as vinylidene chloride; and other compounds containing polymerizable unsaturated units. The products of this polymerization process, well known, have extensive commercial applications. The polymerization of vinyl halides or the copolymerization of vinyl halides with vinylidene halides is usually carried out in an aqueous medium, that is, the emulsion, solution or suspension polymerization. In such polymerizations, the monomer or mixture of monomers is dispersed in water, in the presence of a tenso-active agent and then the polymerization is initiated with an organic peroxide. This is a well-known reaction, which has been widely reported. All organic peroxides are, by their nature, hazardous materials. Its usefulness depends on its ability to decompose into free radicals, as shown by the following reaction: RO - OR '- »RO + R'O- The rate of this decomposition reaction, at any given temperature, depends on the structure of R and R1. The decomposition reaction is exothermic. If exothermic decomposition occurs during production, storage or transport, when the peroxides are in a concentrated form, the development of excess pressure and / or fire or explosion may result. Consequently, many organic peroxides must be kept refrigerated. There are several reports, in recent years, of the delay in the decomposition rate of organic peroxides. The Journal of the American Chemical Society, Volume 72, pages 1254 to 1263 (1950) discloses the use of, for example, ethyl acetoacetate, iodine, trinitrobenzene, acetanilide, nitromethane, phenol, hydrogen peroxide and tetralin. to retard the decomposition rate of diisopropyl peroxydicarbonate. The patent of E. U. A., No. 4,515,929 (1985) discloses aqueous dispersions of organic peroxides, including peroxydicarbonates, which are stabilized against decomposition by the addition of diphenyl peroxydicarbonate or phenyl di (alkyl substituted) peroxydicarbonates. The patent of E. U. A., No. 4,552,682 (1985) discloses the use of phenolic antioxidants to retard the degradation regime of aqueous dispersions of organic peroxides.

The use of phenolic antioxidants is not convenient, because they produce discoloration. The patent of E. U. A., No. 5,155,192 (1992) discloses the use of organic hydroperoxides, for example tertiary butyl hydroperoxide, to retard the decomposition rate of peroxydicarbonates. The patent of E. U. A., No. 5,548,046 (1966) and 5,541,151 (1966) disclose the thermal stabilization of dialkyl peroxydicarbonates with the use of unsaturated nitriles or unsaturated acetylenic compounds.

COMPENDIUM OF THE INVENTION The present invention relates to the use of certain non-peroxide compounds, which are effective in retarding the decomposition rate of organic peroxides, such as peroxydicarbonates. Thus, one aspect of the present invention relates to a composition containing an organic peroxide compound, such as a peroxydicarbonate, and one or more oximes, which reduce the rate of decomposition of the peroxide compound. Another aspect of the present invention is a method for stabilizing a peroxydicarbonate against decomposition, which comprises adding one or more oximes in an amount effective to achieve stabilization. Oximes useful in this invention include those of the formula (I): in which RA and RB represent, independently of each other, hydrogen; alkyl, branched or unbranched, substituted or unsubstituted, containing from 1 to 22 carbon atoms or alkenyl containing from 2 to 22 carbon atoms; phenyl; or substituted phenyl; or RA and RB, taken together with the carbon atom to which they are attached, can form a cycloalkyl ring, substituted or unsubstituted, containing from 4 to 8 carbon atoms; or RA can be -C (Rc) = N-0H, where Rc can be hydrogen; alkyl, branched or unbranched, substituted or unsubstituted, containing from 1 to 22 carbon atoms or alkenyl containing from 2 to 22 carbon atoms; phenyl; or substituted phenyl; or Rc taken together with RB and the carbon atom to which RB is attached, can form a cycloalkyl ring, substituted or unsubstituted, containing from 4 to 8 carbon atoms.

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to compositions containing an organic peroxide, such as a peroxy dicarbonate, and one or more oximes to retard the decomposition rate of the peroxide compound. In the above formula (I), the groups RA and RB (and the cycloalkyl group, which RA and RB can cooperate to form) can be substituted or unsubstituted. When substituted, preferred substituents include phenyl, hydroxyl, acyl containing 1 to 4 carbon atoms, alkoxy containing 1 to 4 carbon atoms, ethers, esters containing a total of 4 carbon atoms, aldehydes containing 1 carbon atoms. to 4 carbon atoms, ketones containing 1 to 4 carbon atoms, nitro or halogen (of which fluorine or chlorine are preferred). The hydrocarbon substituents may be branched or unbranched. Preferred oximes include acetone oxime (RA = RB = CH3), acetaldoxy a (RA = H, RB = CH3), 2-heptanone-oxime (RA = CH3, RB = n-C5H1: L), and 4-methyl-2-pentanone-oxime (RA = CH3 , RB = (CH3) 2CHCH2-) • Other preferred oximes include 2-butanone oxime, cyclohexanone oxime, 1,2-cyclohexanedione dioxy, dimethylglyoxime and 4-fluorobenzaldoxime. The liquid oxime can be added directly. The solid oxime can be dissolved in cheap solvents and then added to the organic peroxide. Solvents useful in this regard include alcohols, such as methanol, ethanol or 2-propanol; ethers, such as 2-methoxyethyl ether; glycols, such as ethylene glycol; esters, such as ethyl acetate; and ketones, such as methyl ethyl ketone and diethyl ketone. The amount of oxime, used in the compositions of the present invention, is an amount sufficient to retard the decomposition rate of the peroxide compound. The preferred amount of the oxime is at a concentration of 0.2 to 5.0% by weight of the peroxydicarbonate or other organic peroxide present. When the oxime is added as a solution, the amount of the solution used is adjusted according to the amount of the oxime present in the solution. The exact amount will vary and will depend on the organic peroxide compound and the conditions to which the peroxide composition is to be exposed. Peroxide compounds useful in this invention have the general structural formula: R1 - O - C (0) - O - O - C (0) - O - R2 wherein Rxy R2 may each be an aliphatic, cycloaliphatic or aromatic group having 22 carbon atoms, preferably 2 to 8 carbon atoms. R1 and R2 can be alkyl, alkenyl, cycloalkyl or aromatic groups, branched or unbranched, substituted or unsubstituted. Examples of groups R1 and R2 include phenyl, methyl, ethyl, n-propyl, isopropyl, n-butyl, secondary butyl, tertiary butyl, isobutyl, hexyl, octyl, neopentyl, 2-ethylhexyl, capryl, lauryl, myristyl, cetyl, stearyl, allyl, methallyl, crotyl, cyclohexyl, 4-t-butylcyclohexyl, 4-t-amylcyclohexyl, benzyl, 2-phenyl-ethyl, 2-phenylbutyl, α-carbetoxyethyl, β-methoxyethyl, 2-phenoxyethyl, 2-methoxyphenyl, 3-methoxyphenyl, 2-ethoxyethyl, 2-ethoxyphenyl, 3-methoxybutyl, 2-carbamyloxyethyl, 2-chloroethyl, 2-nitrobutyloyl and 2-nitro-2-methylpropyl. Specific examples of peroxydicarbonates include diethyl peroxydicarbonate, di-n-butyl peroxydicarbonate, diisobutyl peroxydicarbonate and di-4-tert.-butylcyclohexyl peroxydicarbonate. Preferably, the peroxydicarbonate is the di-sec peroxydicarbonate. -butyl, di-2-ethylhexyl peroxydicarbonate, di-n-propyl peroxydicarbonate or diisopropyl peroxydicarbonate.

The peroxide compound may be symmetric or asymmetric, ie R1 and R2 may be the same or different. The peroxide can be a homogeneous mixture containing symmetrical peroxides, asymmetric peroxides, such as isopropyl peroxydicarbonate and secondary butyl or a mixture of symmetric and asymmetric peroxides, such as mixtures of diisopropyl peroxydicarbonate, di-sec peroxydicarbonate. -butyl and isopropyl peroxydicarbonate and secondary butyl, as disclosed in the patent of E. U. A., No. 4,269,726. The peroxydicarbonate compounds can be synthesized by conventional techniques, familiar to one of ordinary skill in the art. The peroxydicarbonates are typically prepared by the reaction of the corresponding alkyl chloroformate with the aqueous sodium peroxide at low temperatures, such as from 0 to 202C. See the patent of E. U. A., No. 2,370,588 and the publication The Journal of the American Chemical Society, Volume 72, page 1254 (1950). Other synthetic techniques will be familiar to an ordinary expert in the field. Preferably, the peroxydicarbonates useful in this invention include those which are liquid at OdC and, more preferably, liquids at -52C. Even more preferred are the peroxydicarbonates that are liquid at lower temperatures until -202C.

The present invention is especially applicable to aqueous dispersions of peroxydicarbonates which are useful as initiators in the polymerization of free radial of ethylenically unsaturated materials, in particular in an aqueous medium, for example suspension or emulsion polymerization. A dispersion of a peroxydicarbonate is prepared by dispersing it in water with a suitable dispersing aid, for example a surfactant or emulsifier. The surfactants and emulsifiers useful in the formation of these dispersions are well known in the art and are very numerous. To prepare dispersions, according to the present invention, the oxime or a solution thereof can be added to an already formed peroxide dispersion or to the water containing the surfactant, or to the peroxide, before forming the dispersion. The dispersions of the present invention generally contain 20 to 70% by weight, preferably 30 to 60% by weight of the peroxydicarbonate or other organic peroxide compound, and 0.2 to 5.0% (by weight of the peroxide) of the oxime. The manner of preparation of the peroxide dispersions is known to a person skilled in the art. A description of the peroxydicarbonate dispersions and their preparation can be found in the patent of E. U. A., No. 4,515,929; U.A. Patent No. 3,825,509; U.A. Patent No. 3,988,261 and U. U. Patent No. 4,092,470. The peroxydicarbonate compositions of the present invention can also be prepared as physical mixtures in the form of liquids, granules, powders or flakes. A physical mixture, according to the present invention, can be prepared by mixing a liquid peroxide compound, or a solution of a peroxide in a suitable solvent, with the desired amount of a liquid oxime or a solution thereof, in a solvent suitable in a conventional mixing apparatus. The resulting mixture is then granulated, pulverized or flaked if desired. The oxime may be added either (1) to the chloro-formate-containing reaction mixture, prior to the preparation of the peroxide compound or (2) to the unprocessed reaction mixture, immediately after the preparation of the peroxide compound. Either (1) or (2) will ensure that the two components are mixed as evenly as possible, in order to receive the greatest possible benefit from the stabilizing effect of the oxime. A solution of the present invention can be prepared by combining the desired amounts of oxime and peroxide in a suitable solvent. Suitable organic solvents include those normally used for peroxydicarbonates, such as the esters of phthalic acid, an example of which is dibutyl phthalate, and aliphatic and aromatic hydrocarbons and mixtures of these hydrocarbons, examples of which are hexane, odorless mineral spirits, mineral oil, benzene, toluene , xylene and (iso) paraffins, such as isododecane. Other suitable solvents will be familiar to an ordinary expert in the art. Solutions, according to the present invention preferably contain at least 10% by weight and, more preferably, at least 25% by weight of a peroxydicarbonate compound. The peroxide compositions of the present invention have numerous significant advantages. It is mainly the improved thermal stability, both in response to exposure to elevated temperatures and in response to a given constant temperature. The thermal stability of self-reactive substances, in response to elevated temperatures, can be determined by measuring the temperature of auto-accelerated decomposition or SADT. This SADT is one of the recognized tests to determine the storage and safe transport of materials, such as organic peroxides. [Recommendations on the Transport of Hazardous Products, 9th Ed., United Nations, NY 1995, Section 11.3.5, page 2641.

The SADT can be correlated directly with the start temperature, as measured by a differential thermal analyzer (DTA). The start temperature is the point at which uncontrolled thermal decomposition begins. This starting temperature can be measured by determining the point at which the rate of temperature increasing in a sealed cell exceeds a certain predetermined value. In addition, the start temperature can be measured by determining the point at which the rate of pressure that increases in the sealed cell exceeds a certain predetermined value. The thermal stability in response to a given constant temperature can be evaluated by means of accelerated aging tests at, for example, the presence of the oxime, according to the present invention, increases the starting temperature of the peroxydicarbonates. Likewise, oxime does not impair the effectiveness of the peroxide as a polymerization initiator. The following examples attempt to illustrate the claimed invention and, in no way, were designed to limit its scope. Numerous additional modalities, within the spirit of the claimed invention, will become apparent to those skilled in the art.

EXAMPLE 1 The start or attack temperature was measured for samples of pure di-2-ethylhexyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate diluted in odorless mineral spirits (OMS) and secondary di-butyl peroxydicarbonate diluted in OMS. The start temperature was also measured for the aforementioned peroxydicarbonate samples in the presence of various amounts of various oximes. The liquid mixtures were prepared by dissolving the required amount of the oxime solution in the peroxydicarbonate. With the use of a Differential Thermal Analyzer (Radex Solo Thermal Analyzer, sold by Astra Scientific International, Pleasanton, CA), with an isothermal retention temperature of 30se, for 15 minutes, and then a temperature increase of l ^ c / minute to 1302C, the start temperature for a one gram sample of the peroxydicarbonate was measured in a sealed cell. The start temperature was measured both by observing the point where the rate of increase (? T) of the sample temperature reaches 0.22C / minute and also, independently, the point where the rate of increase in pressure (? P) of the closed cell of the sample reaches 0.07 kg / cm2 per minute. ? T is the difference between the oven temperature and the sample temperature. ? P is the difference between a previously calibrated reference pressure and the pressure developed in the sealed vial of the sample. Table I presents the results of the tests carried out with samples of pure di-2-ethylhexyl peroxydicarbonate without oxime and with acetaldoxime, 2-heptanone-oxime, 4-methyl-2-pentanone-oxime and a 50% solution. % by weight of the acetone oxime in 2-propanol. Table II presents the results of similar tests, carried out with samples of di-2-ethylhexyl peroxy-dicarbonate in WHO. Table II presents the similar test results carried out with the secondary di-butyl peroxydicarbonate samples in OMS. The results show that the presence of oxime increases the temperature at which decomposition of self-acceleration of peroxydicarbonate begins. This shows that oxime is an effective stabilizer. The data also show that the effect is concentration dependent, with the decomposition starting at a higher temperature when more oxime is present.

Table I. Decomposition start temperature for 97.2% of unstabilized di-2-ethylhexyl peroxydicarbonate stabilized with oxime * Acetone-oxime was added as a 50% by weight solution in 2-propanol.

Table II. Decomposition start temperature for a 74.9% solution of di-2-ethylhexyl peroxydicarbonate in OMS, not stabilized and stabilized with oxime The acetone oxime was added as a 50 wt% solution in 2-propanol.

Table III. Decomposition start temperature for a 75.9% solution of di-2-ethylhexyl peroxydicarbonate in OMS, not stabilized and stabilized with oxime The acetone oxime was added as a 50 wt% solution in 2-propanol.

EXAMPLE 2 The effect of the presence of acetaldoxime representative of the oxime group, on storage stability at 15dC, of pure di-2-ethylhexyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate diluted in odorless mineral spirits (WHO) , and secondary di-butyl peroxydicarbonate diluted in OMS, was determined as an accelerated aging test. The purity (active oxygen content) of the peroxydicarbonate was measured after 4, 11, 18 and 25 days. The results, presented in Table IV, show that oxime is an effective stabilizer of peroxydicarbonates. The values of the initial purity were corrected for the presence of the oxime additive.

Table IV - Purity vs. Time at 15 ° C for peroxydicarbonates stabilized with acetaldoxime.

Percent of the material not decomposed in relation to the initial quantity of the product in parentheses.

Claims

CLAIMS 1. A composition comprising: a) an organic peroxide component, selected from the group consisting of peroxycarbonate compounds and their mixtures; and b) a sufficient amount of an oxime of the formula (I), to retard the rate of decomposition of the organic peroxide component:

= N-OH (I) RB- in which RA and RB represent, independently of each other, hydrogen; alkyl, branched or unbranched, substituted or unsubstituted, containing from 1 to 22 carbon atoms or alkenyl containing from 2 to 22 carbon atoms; phenyl; or substituted phenyl; or RA and RB, taken together with the carbon atom to which they are attached, can form a cycloalkyl ring, substituted or unsubstituted, containing from 4 to 8 carbon atoms; or RA can be -C (R) = N-OH, where R can be hydrogen; alkyl, branched or unbranched, substituted or unsubstituted, containing from 1 to 22 carbon atoms or alkenyl containing from 2 to 22 carbon atoms; phenyl; or substituted phenyl; or Rc taken together with RB and the carbon atom to which RB binds, can form a cycloalkyl ring, substituted or unsubstituted, containing from 4 to 8 carbon atoms,
2. A composition, according to claim 1, wherein the organic peroxide component comprises at least one compound of the formula: R1 - 0 - C (0) - 0 - 0 - C (0) - 0 - R2 wherein Rxy R2 are, independently, aliphatic, cycloaliphatic or aromatic groups, containing 1 to 22 carbon atoms.
3. A composition, according to claim 2, wherein R1 and R2 are independently selected from the group consisting of phenyl, methyl, ethyl, n-propyl, isopropyl, n-butyl, secondary butyl, tertiary butyl, isobutyl, hexyl , octyl, neopentyl, 2-ethylhexyl, capryl, lauryl, myristyl, cetyl, stearyl, allyl, methallyl, crotyl, cyclohexyl, 4-t-butylcyclohexyl, 4-t-amyl-cyclohexyl, benzyl, 2-phenylethyl, 2-phenylbutyl , α-carbetoxyethyl, β-methoxyethyl, 2-phenoxyethyl, 2-methoxyphenyl, 3-methoxyphenyl, 2-ethoxyethyl, 2-ethoxyphenyl, 3-methoxybutyl, 2-carbamyloxyethyl, 2-chloroethyl, 2-nitrobutyl and 2-nitro-2 -methylpropyl.
4. A composition, according to claim 1, wherein the organic peroxide component is selected from the group consisting of diethyl peroxydicarbonate, isopropyl peroxydicarbonate and secondary butyl, di-n-butyl peroxydicarbonate, secondary diisobutyl peroxydicarbonate, peroxydicarbonate di-4-tert-butylcyclohexyl, di-2-ethylhexyl peroxydicarbonate, di-n-propyl peroxydicarbonate or diisopropyl peroxydicarbonate and mixtures thereof. 5. The composition, according to the claim 1, wherein the oxime comprises 0.2 to
5.0% by weight of the organic peroxide component.
6. The composition, according to the claim 2, in which the oxime is selected from the group consisting of acetone-oxime, acetaldoxime, 2-heptanone-oxime, 4-methyl-2-pentanone-oxime, 2-butanone-oxime, cyclohexanone-oxime, benzaldehyde-oxime, cyclopentanone-oxime, 1,2-cyclohexane-dione-oxime, dimethyl-glyoxal and 4-fluorobenzaldoxime.
7. The method for retarding the decomposition rate of an organic peroxide product, selected from the group consisting of peroxydicarbonate compounds and their mixtures, this method comprises adding to the organic peroxide product an oxime of the formula (I), in an effective amount to retard the rate of this decomposition: in which RA and RB represent, independently of each other, hydrogen; alkyl, branched or unbranched, substituted or unsubstituted, containing from 1 to 22 carbon atoms or alkenyl containing from 2 to 22 carbon atoms; phenyl; or substituted phenyl; or RA and RB, taken together with the carbon atom to which they are attached, can form a cycloalkyl ring, substituted or unsubstituted, containing from 4 to 8 carbon atoms; or RA can be -C (Rc) = N-OH, where Rc can be hydrogen; alkyl, branched or unbranched, substituted or unsubstituted, containing from 1 to 22 carbon atoms or alkenyl containing from 2 to 22 carbon atoms; phenyl; or substituted phenyl; or R taken together with RB and the carbon atom to which RB is attached, can form a cycloalkyl ring, substituted or unsubstituted, containing from 4 to 8 carbon atoms.
8. A method, according to claim 7, wherein the peroxydicarbonate compounds correspond to the formula: R1 - O - C (0) - O - O - C (0) - O - R2 wherein Rxy R2 are, independently, aliphatic, cycloaliphatic or aromatic groups, containing 1 to 22 carbon atoms.
9. A method, according to claim 8, wherein R1 and R2 are independently selected from the group consisting of phenyl, methyl, ethyl, n-propyl, isopropyl, n-butyl, secondary butyl, tertiary butyl, isobutyl, hexyl , octyl, neopentyl, 2-ethylhexyl, capryl, lauryl, myristyl, cetyl, stearyl, allyl, methallyl, crotyl, cyclohexyl, 4-t-butylcyclohexyl, 4-t-amylcyclohexyl, benzyl, 2-phenylethyl, 2-phenylbutyl, -carbetoxyethyl, ß-methoxyethyl, 2-phenoxyethyl, 2-methoxyphenyl, 3-methoxyphenyl, 2-ethoxyethyl, 2-ethoxyphenyl, 3-methoxybutyl, 2-carbamyloxy-ethyl, 2-chloroethyl, 2-nitrobutyl and 2-nitro-2 -methylpropyl.
10. A method according to claim 7, wherein the organic peroxide component is selected from the group consisting of diethyl peroxydicarbonate, isopropyl peroxy-dicarbonate and secondary butyl, di-n-butyl peroxydicarbonate, secondary diisobutyl peroxydicarbonate, peroxydicarbonate of di-4-tert.-butylcyclohexyl, di-2-ethylhexyl peroxydicarbonate, di-n-propyl peroxydicarbonate or diisopropyl peroxydicarbonate and mixtures thereof.
11. A method according to claim 7, wherein the oxime comprises 0.2 to 5.0% by weight of the organic peroxide component.
12. A method according to claim 8, wherein the oxime is selected from the group consisting of acetone-oxime, acetaldoxime, 2-heptanone-oxime, 4-methyl-2-pentanone-oxime, 2-butanone-oxime. , cyclohexanone-oxime, benzaldehyde-oxime, cyclopentanone-oxime, 1,2-cyclohexanedione-oxime, dimethyl-glyoxal and 4-fluorobenzaldoxime.