FR2844789A1 - Use of 4-hydroxy-2,2,6,6-tetramethyl-piperidinyloxy as a polymerization blocking agent during preparation of alkylimidazolidone (meth)acrylates, especially ethylimidazolidone methacrylate - Google Patents

Abstract

The use of 4-hydroxy-2,2,6,6-tetramethyl-piperidinyloxy as an agent blocking polymerization forming a solid during preparation of alkylimidazolidone (meth)acrylates. The use of 4-hydroxy-2,2,6,6-tetramethyl-piperidinyloxy as an agent blocking polymerization forming a solid during preparation of alkylimidazolidone (meth)acrylates. The alkylimidazolidone (meth)acrylates are of formula (I) and are prepared by transesterification of an alkyl methacrylate of formula (II) with a heterocyclic alcohol of formula (III). R1 = H, methyl; A, B = 2-5C hydrocarbon chain; and R2 = 1-4C alkyl. An Independent claim is also included for a process of preparation of a compound of formula (I) in which the progress of the transesterification reaction is monitored and if the start of a polymerization capable of forming a solid polymer is observed, the blocking agent is injected into the reaction medium.

Description

H2C = C-C-O-A-N

1 1 R B

/ NH INH

he

2 H2C = C-C-O-R

B

/ N N-A-OH HN N-A-OH

  C R c O (I) (I I) (III)! USE OF 4-HYDROXY-2,2,6,6-TETRAMETHYLlPIPERIDINYLOXY AS POLYMERIZATION STOP AGENT IN

  THE MANUFACTURE OF (METH) ACRYLATES OF ALKYLIMIDAZOLIDONE.

  The present invention relates to the manufacture of a compound of formula:

O B

He / \

H2C = C-C-O-A-N NH (I)

I1 \ /

R C

  II O in which: - R represents hydrogen or methyl; - A and B each independently represent a straight or branched hydrocarbon chain, having from 2 to 5 carbon atoms, by reaction of at least one (meth) acrylate of formula: II

H2C = C-C-O-R (II)

  R in which: - R has the above-mentioned meaning; and - R represents a C1-C4 alkyl group, with a heterocyclic alcohol of formula: B

/ \

HN N-A-OH (III)

\ / VS

OI 40 0

  in which A and B have the abovementioned meanings.

  These compounds of formula (I) are known for their role in the constitution of polymers useful as coatings and adhesives, for the treatment of paper and textiles, in particular by American patent 5 US-A-2 871 223, as well as for their uses as leather treatment agents, and in the production of emulsion paints. Ethylimidazolidone methacrylate (MEIO) is mainly used in

  paints as a wet adhesion promoter.

  During these transesterification reactions and under industrial conditions, hard polymers appear randomly which grow and propagate in the reactor until the solidification of the

entire reaction medium.

  These polymers will be designated in the following

as "popcorn" polymers.

  To solve this problem, the Applicant Company has discovered that 4hydroxy-2,2,6,6-tetramethyl-1piperidinyloxy (commonly known as 4hydroxy-TEMPO) is an effective abrupt polymerization agent.

("short stopper" or "killer").

  If 4-hydroxy-TEMPO has been described as an acrylate stabilizer (EP-A10 902 017), to the knowledge of the Applicant Company, it has never been presented until now as a agent for stopping the formation of

  "popcorn" polymer in the above reaction.

  The present invention therefore firstly relates to the use of 4hydroxy-2,2,6,6-tetramethyl-1piperidinyloxy (4-hydroxy-TEMPO) as an agent for blocking the propagation of a polymerization forming a solid polymer in the manufacture of a (meth) acrylate of formula (I) as indicated in the first paragraph of the

present description.

  Advantageously, 4-hydroxy-TEMPO is used in the form of an aqueous formulation at a concentration of 0.01% to 90% by weight, preferably from 10% to 70% by weight. Furthermore, it is preferably used at a rate of 200 ppm to 10,000 ppm, in particular from 1,000 ppm to 6,000 ppm, relative to the reaction medium, each time it is desired to stop a polymerization tending to

form "popcorn" polymers.

  In particular, the compound (I) is the

  ethylimidazolidone (meth) acrylate.

  The present invention also relates to a process for the manufacture of the compound of formula (I), as defined above, characterized in that the progress of the transesterification reaction is monitored and, if the start is observed of a polymerization capable of forming a solid polymer, an injection is made into the medium of 4-hydroxy-TEMPO as agent for blocking the propagation of this polymerization. As indicated above, the 4-hydroxy-TEMPO is preferably injected in the form of an aqueous formulation.

  at a concentration of 0.01% to 90% by weight, in particular from 10% to 70% by weight, and preferably, with each injection, 200 ppm to 10,000 ppm, in particular from 1000 to 6000 ppm, are injected 4-hydroxy-TEMPO with respect to the reaction medium.

  As examples of reagents of formula (II), mention may in particular be made of methyl, ethyl, n-propyl, isopropyl, n-butyl acrylates and methacrylates

and isobutyl.

  As examples of heterocyclic alcohol of formula

  (III), there may be mentioned, in particular, 1- (2-hydroxyethyl) imidazolidinyl-2one (HEIO).

  The reaction of the process according to the invention can be carried out in the presence of an excess of either of the reactants. It is however advised that the molar ratio (meth) acrylate of formula (II) / heterocyclic alcohol of formula (III) is between approximately 1.1 and 7.0, preferably between 2.0 and 6, in particular between 2 , 5 and 4.5. By operating with a large molar excess of (meth) acrylate relative to the heterocyclic alcohol, there is obtained, at the end of the reaction, a solution of compound of formula (I) in (meth) acrylate which can be used directly for certain applications, such as obtaining paints and coatings or

leather processing.

  The reaction of the process according to the invention is generally carried out in the presence of at least one catalyst. The catalysts used are well known to those skilled in the art. Mention may be made, inter alia, of calcium acetylacetonate and, in general, of the calcium chelates used in an amount of 0.05% to 2 mol% relative to the heterocyclic alcohol of formula (III) . These catalysts, as well as others, are described for example in EP-Bl-0 619 309, EP-Bl-0 712 846 and

FR-A-2 753 446.

  The reaction of the process according to the invention is preferably carried out in the presence of at least one polymerization inhibitor, used, for example, in an amount of 0.003 to 0.5%, relative to the heterocyclic alcohol of formula ( III). As examples of polymerization inhibitors which can be used, mention may in particular be made of phenothiazine, methyl ether of hydroquinone, ditertiobutylcatechol, hydroquinone, panilinophenol, paraphenylene diamine and their mixtures in all proportions. The reaction of the process according to the invention is preferably carried out under a pressure not exceeding atmospheric pressure, for example a pressure between 0.3 and 1 bar. Advantageously, the reaction is carried out under air bubbling. It is carried out by mixing the (meth) acrylate of formula (II) and the heterocyclic alcohol of formula (III), and heating the reaction mixture generally to a temperature between 85 and 1200C approximately, this temperature obviously being dependent on the exact nature

alcohol and (meth) acrylate.

  In implementing the process according to the invention, it is advisable to reach maximum dehydration before the addition of the catalyst, so as to avoid deactivation of the latter by water. This can be achieved, for example, by heating the initial mixture of (meth) acrylate of formula (II), heterocyclic alcohol of formula (III) and polymerization inhibitors at reflux, while separating by distillation. the (meth) acrylate and water azeotrope when an (meth) acrylate and water azeotrope is formed. At this stage, the catalyst (s) are introduced into the reaction mixture

hot.

  The duration of the reaction according to the invention obviously depends on reaction conditions, such as the temperature, the pressure and the amount of catalyst (s) used, but is generally between 1 and 10 hours approximately. It obviously also depends on the nature

reagents used.

  The reaction mixture is therefore heated to reflux until the head temperature reaches the distillation temperature of the (meth) acrylate azeotrope and the alcohol of formula R2OH formed by the reaction. Any excess of (meth) acrylate can then be removed by evaporation, so as to isolate the compound of formula (I) from the reaction medium, generally in the solid state: thus, 1 (2hydroxyethyl) imidazolidyl acrylate -2-one is a white crystalline solid with a melting point of 430C, cold soluble in ketones, alcohols, aromatic hydrocarbons and water, cold insoluble in saturated hydrocarbons and which precipitates at 0C in l 'ethyl acrylate. 1- (2hydroxyethyl) imidazolidyl-2-one methacrylate is a white crystalline solid with a melting temperature of 47 C, having the same solubility properties as the previous acrylate 5. At the end of the evaporation operation, the crystalline solid product can also be purified by filtration, then washing with petroleum ether, and drying. The following Examples illustrate the present invention without, however, limiting its scope. In these Examples, the percentages are by weight, unless otherwise indicated. In these Examples, the following abbreviations were used: HEIO: 1- (2-Hydroxyethyl) -imidazolidinyl-2-one MEIO: Ethylimidazolidone methacrylate MAM: Methyl methacrylate PTZ: Phenothiazine EMHQ: Hydroquinone methyl ether EXAMPLE 1: Preparation of raw MEIO in the laboratory In a glass reactor, with a double jacket, of liters, equipped with a temperature measurement probe, with a mechanical stirrer at variable speed, with an adiabatic column with topped packing 222.5 g of HEIO, 0.267 g of PTZ as a stabilizer and 798.2 g of MMA are introduced from a reflux head. We put into service a

  stabilization at the top of the column with a 0.1% solution of EMHQ in MAM.

  Under air bubbling and under reduced pressure, the contents of the reactor are brought to a boil, at a temperature of 80 ° C., for 1 hour, and the water is eliminated.

  by distillation of 80 g of the heteroazeotropic MAM-water.

  Then, 0.367 g of calcium acetylacetonate is introduced all at once into the reactor. The pressure is adjusted to maintain a temperature of 800C in the reactor. The withdrawal of the azeotrope MAM-MeOH is regulated by a set temperature at the top of the column equal to that of the boiling of the azeotrope under the pressure 5 considered plus 30C. When the amount of methanol

  withdrawn corresponds to the expected quantity, the reaction is extended for one hour, until no more formation of MeOH is observed (temperature at the top of the column measured at total reflux = boiling point of MMA 10 under the pressure considered).

  After cooling, raw MEIO is recovered,

free of solid.

  HPLC analysis of the crude mixture obtained (%) 15 - MAM: 60.6%

- HEIO: 1.6%

- MEIO: 36.5%.

  EXAMPLES 2 to 6: Simulation of a polymerization of the 20 "popcorn" type General procedure General In a 250 ml three-necked flask immersed in an oil bath heated to 1220C, 100 g of a mixture are placed

crude as obtained in Example 1.

  The temperature in the medium is measured using a probe and recorded continuously. She is

maintained at 1030C.

  The temperature is also measured in the oil bath using a thermometer. It is kept at

1220C.

  The medium is seeded with 5% by weight

  ratio in the middle of a "popcorn" polymer previously ground to a dimension of 1 to 8 mm.

  This "popcorn" polymer consists of a mixture of the homopolymer of MEIO and of the MAMMEIO copolymer. It was obtained by polymerization brought about by adding a radical polymerization initiator to a reaction mixture obtained in Example 1. Various tests were carried out, one without a blocking agent for "popcorn" polymerization (Example 3 and others with various agents capable of blocking the "popcorn" polymerization (Comparative Examples 3, 4 and 5 and Example 6 of the invention), with

  each time 2000 ppm of agent relative to the medium.

  The results are reported in Table 1 below.

Table 1

  Examples Blocking agent Duration Observing the before polymerization "popcorn" polymerization 2 (0.75 h Reference polymer) hard 3 n Dodecyl mercaptan 0.5 h Polymer (comparative) hard 4 Hydroquinone 1 h Polymer (comparative) hard Dry - butyl (comparative) paraphenylene 0.75 h Diamine polymer * hard 6 No (invention) 4-Hydroxy-TEMPO ** 50 hours solidification of the medium * marketed by the company "UNIROYAL" under the name "Naugalube 403" ** 4-hydroxy-TEMPO is added in the form of a 50% aqueous solution (injection of 4000 ppm of aqueous solution) $

Claims (7)

  1 - Use of 4-hydroxy-2,2,6,6-tetramethyll-piperidinyloxy as agent for blocking the propagation of a polymerization forming a solid polymer in the manufacture of a (meth) acrylate of formula (I) : There 1 H2C = C-C-O-A-N   I R1 R NH (I) B C O 0l in which: - R represents hydrogen or methyl; - A and B each independently represent a straight or branched hydrocarbon chain, having from 2 to 5 carbon atoms, by transesterification of an alkyl methacrylate of formula (II): it 2 H2C = C-C-O-R   (II) R in which: i - R has the abovementioned meaning; and - R represents a C1-C4 alkyl group, with a heterocyclic alcohol of formula: B / \ HN N-A-OH (III) \ / VS II O   in which A and B have the abovementioned meanings.   2 - Use according to claim 1, characterized in that 4-hydroxy-2,2,6,6tetramethyl-1-piperidinyloxy is used in the form of an aqueous formulation at a concentration of 0.01% to   % by weight, in particular from 10% to 70% by weight.   3 - Use according to one of claims 1   to 3, characterized in that 4-hydroxy-2,2,6,6tetramethyl-lpiperidinyloxy is used at a rate of 200 ppm to 10,000 ppm, in particular from 1000 ppm to 6000 ppm, relative to the reaction medium, when it is desired to stop a polymerization.   4 - Use according to one of claims 1   to 3, characterized in that the compound (I) is the   ethylimidazolidone (meth) acrylate.   - Process for manufacturing a compound of formula: O B II He / \ H2C = C-C-O-A-N NH (I) I \ / R C   Il O in which: - R represents hydrogen or methyl; - A and B each independently represent a straight or branched hydrocarbon chain, having from 2 to 5 carbon atoms, by transesterification of at least one (meth) acrylate of formula: Il 2 (l H2C = C-C-O-R (II)   Il | 1 R in which: i - R has the abovementioned meaning; and - R represents a C1-C4 alkyl group, with a heterocyclic alcohol of formula: B / \ HN N-A-OH (III)   \ / C in which A and B have the abovementioned meanings, characterized in that the progress of the transesterification reaction is monitored and, if the start of a polymerization capable of forming a solid polymer is observed, an injection is made into the medium of 4-hydroxy-2,2,6,6-tetramethyl-11-piperidinyloxy as agent for blocking the propagation of this polymerization. 6 - Process according to claim 5, characterized in that the 4hydroxy-2,2-6,6-tetramethyl1-piperidinyloxy is injected in the form of an aqueous formulation at a concentration of 0.01l to 90% in weight, especially from 10% to 90% by weight.   7 - Method according to one of claims 5 and   6, characterized in that at each injection, 200 ppm to 10,000 ppm, in particular from 1000 ppm to 6000 ppm, of 4-hydroxy-2,2,6,6tetramethyl-1-piperidinyloxy are injected with respect to the reaction medium.   8 - Method according to one of claims 5 to 7,   characterized by the fact that the reaction is carried out temperature from 85 to 100 C.   9 - Method according to one of claims 5 to 8, 5 characterized in that the reaction is carried out during   a duration of 1 to 10 hours, under a pressure not exceeding not atmospheric pressure.   - Method according to one of claims 5 to   9, characterized in that the reaction is carried out in the presence of a catalyst.   it - Method according to one of claims 5 to   , characterized in that the reaction is carried out in the presence of at least one polymerization inhibitor chosen from phenothiazine, methyl ether of hydroquinone, di-tertiobutylcatechol, hydroquinone, p-anilinophenol, para-phenylene diamine and their mixtures in any proportion, the polymerization inhibitor or inhibitors being used in an amount of 0.003 to 0.5%, relative to the heterocyclic alcohol of formula (III). 20