Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F2/00—Processes of polymerisation
  • C08F2/38—Polymerisation using regulators, e.g. chain terminating agents, e.g. telomerisation
  • C08F2/40—Polymerisation using regulators, e.g. chain terminating agents, e.g. telomerisation using retarding agents
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C7/00—Purification; Separation; Use of additives
  • C07C7/20—Use of additives, e.g. for stabilisation

Definitions

• the present invention relates to the field of the preparation of powder compositions, that is to say in powder form, having inhibitory properties on the polymerization of monomers. More specifically, it relates to a process for the preparation of a pulverulent composition essentially comprising a compound based on at least two solids each acting as a polymerization inhibitor.
• the composition prepared according to the process of the invention is advantageously usable as an inhibitor of the radical polymerization of ethylenically unsaturated monomers.
• the polymerization inhibitors are intended to prevent the polymerization of monomers, for example the radical polymerization of ethylenically unsaturated monomers, during their industrial preparation.
• Ethylenically unsaturated monomers are prone to spontaneously polymerize under the action of heat.
• premature polymerization must be avoided during the manufacture, purification and storage of said monomers.
• early polymerization is detrimental since it causes a drop in production yields and a fouling of facilities often making it necessary to temporarily stop production for maintenance reasons, resulting in an additional cost of production.
• Polymerization inhibitors are generally specific for the stabilization of particular families of monomers.
• tert-butylcatechol is specific for preventing the radical polymerization of styrene and butadiene
• hydroquinone is specific for preventing the radical polymerization of monomers comprising a (meth) acrylic unit, especially vinyl chloride, ethyl acetate or vinyl, of acrolein, methacrolein, acrylic acid, methacrylic acid and esters of said acids such as methyl methacrylate.
• the present invention proposes to provide a new process for the preparation of a pulverulent composition at ambient temperature exhibiting inhibitory properties on the polymerization of monomers.
• One of the objectives sought by the present invention is the provision of a method based on a simple procedure to be implemented on an industrial scale, with the special aim of avoiding a very delicate control of the temperature for the production of a product.
• powdery composition and having inhibiting properties on the polymerization of monomers The present invention relates to a process for the preparation of a pulverulent composition having inhibiting properties on the polymerization of monomers and having a melting temperature Tf comprising:
• Said step i) of the preparation process according to the invention implements at least two elementary solids powder, that is to say in the form of powder.
• Said solids are monomer polymerization inhibitors. They are chosen so that the composition prepared according to the process of the invention is in pulverulent form at room temperature.
• the ambient temperature is defined by a temperature range generally ranging from 10 to 30 ° C, preferably from 15 to 30 ° C and more preferably from 15 to 25 ° C.
• said pulverulent elementary solids used as polymerization inhibitor advantageously have a melting point greater than or equal to 40 ° C, very advantageously greater than or equal to 50 ° C and even more advantageously greater than or equal to 100 ° C.
• Said elemental solids used as a polymerization inhibitor generally have a melting point of less than 220 ° C.
• said solids each having inhibiting properties on the polymerization of monomers consist of a molecule having at least one benzene ring and advantageously at least one heteroatom chosen from nitrogen, oxygen and sulfur. More preferably, said solids consist of a molecule having at least one benzene ring carrying at least one hydroxyl radical -OH.
• said solids are involved in mechanisms for inhibiting the polymerization of monomers, for example in the radical polymerization inhibition mechanisms of ethylenically unsaturated monomers. According to the invention, said solids are devoid of organoleptic properties.
• At least one of said powdery elemental solids is crystallized and even more preferably, said two powdery elemental solids are crystallized.
• said solids are selected from hydroquinone (para-dihydroxy-1,4-benzene, denoted HQ in the following description), catechol or pyrocatechol (ortho-dihydroxy-1,2-benzene, noted PC in the following description), resorcinol or resorcinol (meta-dihydroxy-1,3-benzene, noted R in the following description), pyrogallol (1,2,3-trihydroxybenzene, noted PYRO in the following of the description), para-methoxyphenol (or methylhydroquinone, noted PMP in the following description), 4-tert-butylcatechol (or 4-tert-butylpyrocatechol, noted TBC in the following description) and phenothiazine (PTZ noted in the following the description).
• hydroquinone para-dihydroxy-1,4-benzene, denoted HQ in the following description
• catechol or pyrocatechol ortho-dihydroxy-1,2-benzene, noted PC
• said elementary solids used as a polymerization inhibitor are preferably chosen from the following binary combinations: HQ-PC, HQ-R, HQ-PYRO, HQ- PMP, HQ-TBC, PC-R, PC-PYRO, PC-PMP, PC-TBC, R-PYRO, R-PMP, R-TBC, PMP-PYRO, PMP-TBC, TBC-PYRO, and PMP-PTZ . More advantageously, said solids are chosen from the binary combinations: HQ-PC, HQ-R, HQ-PYRO, PC-TBC, and PC-PMP.
• said process is carried out in the presence of at least three pulverulent elementary solids each having a role of polymerization inhibitor.
• each of said three solids are selected from hydroquinone, catechol, resorcinol, pyrogallol, para-methoxyphenol, 4-tert-butylcatechol and phenothiazine.
• said elementary solids used as a polymerization inhibitor are preferably chosen from the following ternary combinations: HQ-PC-R, HQ-PC-PYRO, HQ-PC-PMP, HQ-PC-TBC, HQ R-PYRO, HQ-R-PMP, HQ-R-TBC, HQ-PYRO-PMP, HQ-PYRO-TBC, HQ-PMP-TBC, PC-R-PYRO, PC-R-PMP, PC-R -TBC, R-PYRO-PMP, R-PYRO-TBC, R-PMP-TBC, HQ-PMP-PTZ and PYRO-PMP-TBC.
• said elementary solids are introduced into the mixer at any molar ratio suitable for the preparation of said pulverulent inhibitor composition obtained according to the method of the invention.
• hydroquinone and catechol are introduced into said mixer in the following proportions: from 15 to 25%, preferably 18 to 22%, more preferably 20 to 22%, by weight of hydroquinone and 75 to 85%, preferably 78 to 82%, more preferably 78 to 80%, by weight of catechol.
• hydroquinone and resorcinol are introduced into said mixer in the following proportions: from 17 to 27%, preferably from 20 to 25%, more preferably from 21 to 23%, by weight of hydroquinone and from 73 to 83%, preferably from 75 to 80%, more preferably preferred from 77 to 79%, by weight of resorcinol.
• hydroquinone and pyrogallol are introduced into said mixer in the following proportions: from 20 to 30%, preferably from 22 to 27%, more preferably from 23 to 26%, by weight of hydroquinone and from 70 to 80%, preferably from 73 to 78%, more preferably from 74 to 77%, by weight. of pyrogallol.
• the catechol and para-methoxyphenol are introduced into said mixer in the following proportions: from 23 to 33 %, preferably 25 to 30%, more preferably 27 to 29%, by weight of catechol and 67 to 77%, preferably 70 to 75%, more preferably 71 to 73%, weight of para-methoxyphenol.
• said powdery elementary solids are introduced separately, that is to say each in the pure state, into said mixer.
• Said solids can be introduced simultaneously or one after the other in any order.
• Each of said solids can be introduced gradually or not.
• the enclosure of said mixer Prior to the introduction of said solids, the enclosure of said mixer is heated to a temperature T less than the melting temperature of the elemental solid having the lowest melting temperature, said solid being chosen from said elemental solids used in the process according to the invention.
• Said temperature T is below the melting start temperature of the composition prepared according to the method of the invention.
• the enclosure of said mixer is heated to a temperature T advantageously between 78 and 85 ° C. very advantageously between 80 and 85 ° C.
• HQ-R hydroquinone and resorcinol
• a pulverulent composition with inhibiting properties comprising a compound based on hydroquinone and pyrogallol (HQ-PYRO)
• the enclosure of said mixer is heated to a temperature T advantageously between 100 and 108 ° C, very advantageously between 102 and 107 ° C.
• HQ-PYRO hydroquinone and pyrogallol
• the enclosure of said mixer is heated to a temperature T advantageously between 26 and 33 ° C, very advantageously between 28 and 32 ° C.
• Said steps i) and ii) of the process according to the invention are carried out in a mixer. It is advantageously a mixer with plowshares, a vane mixer or a ribbon mixer (s), these mixers being well known to those skilled in the field of powder mixing. .
• Said mixer is advantageously provided with a double jacket to ensure the various heat transfers by circulating a coolant, preferably water or a silicone oil, in the jacket.
• the heat transfer fluid is maintained at a temperature greater than or equal to the temperature T inside the enclosure of said mixer.
• the coolant is maintained at a temperature greater than 1 to 5 ° C at said temperature T.
• Said two elementary solids polymerization inhibitors in pulverulent form are introduced separately into said mixer and then mixed therein according to said step ii) of the process according to the invention.
• Said solids are for example in the form of crystals, granules or flakes. In particular, it is possible to mix a solid in the form of flakes and a solid in the form of crystals or else to mix two solids in the form of flakes.
• At least one of said elementary solids polymerization inhibitors is preheated to a temperature Ti before being introduced into said mixer, said temperature Ti being close to said temperature T at which mixing is carried out according to said step ii).
• said elementary polymerization inhibiting solids are introduced at a temperature Ti; said solids may be preheated and introduced into said mixer at the same temperature Ti or at a slightly different temperature Ti. More precisely, said temperature Ti is advantageously chosen such that T - 20 ° C ⁇ Ti ⁇ T + 20 ° C.
• the mixture of said polymerization inhibiting elemental solids, in pulverulent form is produced under isothermal conditions, that is to say at a constant temperature, equal to the temperature T at which the enclosure of the mixer was heated, as soon as said solids were introduced into said mixer.
• Preheating at least one of said two polymerization inhibiting elemental solids to a temperature T 1 as defined above, preferably both of said elementary polymerization inhibiting solids allows isothermal temperature mixing in said mixer.
• the mixture is naturally operated in the solid phase.
• Said mixer is advantageously subjected to agitation.
• the stirring conditions are chosen so that there are no significant shears. Thus, a slow stirring speed is preferred.
• the mixer is advantageously placed under an inert atmosphere throughout the duration of implementation of the method according to the invention.
• steps i) and ii) of the process according to the invention are advantageously carried out under an inert atmosphere, preferably under nitrogen. More preferably, said steps i) and ii) are carried out under a wet nitrogen or dry nitrogen atmosphere.
• the humidification of the nitrogen stream is advantageously ensured by bubbling nitrogen into the water.
• the flow of inert gas, preferably nitrogen is advantageously heated to a temperature equal to T ⁇ 10 ° C, the temperature T being that at which the chamber of the mixer is heated.
• the amount of water present in the nitrogen represents, for example, from 1 to 5% by weight of the weight of the nitrogen, preferably from 2 to 3% by weight of the weight of the nitrogen.
• Dry nitrogen means a stream of nitrogen comprising less than 0.5 g, preferably less than 0.3 g of water per kg of nitrogen.
• a preferred embodiment of implementing said step ii) of the method according to the invention consists in producing said mixture of said solids in a humid atmosphere.
• the humidity is for example ensured by a flow of dry steam, a flow of wet nitrogen.
• step ii) of the process according to the invention leads to the transformation of said solids into said composition with inhibiting properties. which is recovered according to said step Ni) of the method according to the invention.
• Said step ii) is carried out for a sufficient time in order to obtain the transformation, preferably the complete transformation, of solids into said composition. This duration is variable and is in particular a function of the elementary solids used and the agitation.
• Said composition is recovered before or after cooling. Operated inside or outside said mixer, the cooling of said composition obtained is carried out at a temperature below 40 ° C, preferably below 35 ° C.
• the lower limit of the cooling temperature is advantageously ambient temperature.
• Said composition is advantageously allowed to cool inside or outside said mixer.
• a cooling system outside the mixer is used in which the composition prepared according to the method of the invention is introduced.
• composition prepared according to the process of the invention results from the conversion of the elementary polymerization inhibiting solids used in said process into a defined compound.
• the composition prepared according to the process of the invention is a composition exhibiting inhibiting properties on the polymerization of monomers, preferably on the radical polymerization of ethylenically unsaturated monomers.
• composition prepared according to the process of the invention is a powdery composition, that is to say that it is in powder form.
• the composition is in the form of flakes, crystals, granules.
• composition prepared according to the process of the invention is further characterized by its melting temperature denoted Tf, which is different from each of the melting temperatures of each of said elementary solids used in the process according to the invention and lower than the most low melting temperatures of the solids used in the process according to the invention.
• said composition has a melting temperature Tf greater than or equal to 30 ° C, preferably greater than or equal to 40 ° C.
• a pulverulent composition with inhibiting properties comprising a compound based on hydroquinone and catechol (HQ-PC) has a melting temperature equal to 90 ⁇ 2 ° C.
• a pulverulent composition with inhibiting properties comprising a compound based on hydroquinone and pyrogallol (HQ-PYRO) has a melting temperature of 11 ⁇ 2 ° C.
• a pulverulent composition with inhibiting properties comprising a compound based on catechol and para-methoxyphenol (PC-PMP) has a melting point of 36 ⁇ 2 ° C.
• said composition prepared according to the process of the invention is a crystallized composition. It is advantageously characterized by an X-ray diffraction spectrum of its own having lines for angles 2 ⁇ different from those presented by the lines appearing on each of the X-ray diffraction spectra of the elementary solids from which said composition prepared according to the process of the invention.
• the composition prepared according to the process of the invention has a bulk density (not packed) higher than that presented by each of the elementary solids used in the process according to the invention.
• the bulk density (unpacked) is conventionally measured in a compaction volumenometer, for example in a Delta Labo type STAV apparatus.
• the solid phase transformation implemented according to the process of the invention preferentially leads to a densification of the mixture operated according to said step ii) of the process according to the invention.
• the composition obtained according to the method of the invention comprises at least 80% by weight, preferably at least 90% by weight of a defined compound derived from at least two elementary solids polymerization inhibitors. More preferably, said composition obtained according to the process of the invention consists entirely of such a compound.
• the process according to the invention is an advantageous and simple process to implement.
• the mixing of the polymerization inhibitor elementary solids, in powder form, under isothermal conditions, ie at a constant temperature, in accordance with said step ii) of the process according to the invention makes it possible to have 'a simplified process in wherein the preheating of at least one of said elementary solids, preferably said elemental solids, avoids the setting up of temperature sensitive programming.
• the elementary solids are introduced at the desired temperature as soon as they are mixed.
• the process according to the invention leads to the preparation of a composition generally having directly the desired particle size.
• composition prepared according to the process of the invention is advantageously used as an inhibiting composition for the immediate termination of polymerizations of monomers, preferably radical polymerizations of monomers having at least one ethylenic unsaturation.
• it is very advantageously used for the stabilization of said monomers during manufacture and purification. It is still very advantageously used to instantly terminate the undesired polymerization of monomers during transport and / or storage of mixture containing said monomers.
• composition prepared according to the process of the invention for immediately stopping the polymerization of one or more monomer (s), preferably the radical polymerization of one or more monomers (s) having at least one ethylenic unsaturation is implemented by the addition to said said monomer (s) of an effective amount of a composition obtained according to the method of the invention.
• the amount of said composition to be added to achieve effective inhibition of polymerization varies to a large extent. It is a function of the monomer (s) to be stabilized and the operating conditions to which the said monomer (s) are (are) subjected. It goes without saying that at high temperatures, the amount of said inhibiting composition will be greater. Thus the quantity of said composition will be evaluated on a case by case basis.
• the monomers exhibiting at least one ethylenic unsaturation are advantageously chosen from aromatic monomers with ethylenic unsaturation and aliphatic monomers with ethylenic unsaturation.
• aromatic ethylenically unsaturated monomers styrene, ⁇ -methylstyrene, vinyltoluene, divinylbenzene, vinylnaphthalene and styrenesulfonic acids are preferred.
• ethylenically unsaturated aliphatic monomers olefinic monomers comprising one or two unsaturations, halogenated unsaturated monomers, unsaturated acids, unsaturated esters, unsaturated resins, unsaturated amides, unsaturated nitriles, unsaturated ethers are preferred.
• said ethylenically unsaturated aliphatic monomers are preferably chosen from isoprene, butadiene, vinyl chloride, chloroprene, vinylidene chloride, vinylidene fluoride, vinyl fluoride, acrylic acid, and the like.
• methacrylic acid crotonic acid
• unsaturated esters of acrylic acid such as methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, acrylate, 2-hydroxyethyl, hydroxypropyl acrylate
• unsaturated esters of methacrylic acid such as methyl methacrylate, butyl methacrylate, lauryl methacrylate, dimethylaminoethyl methacrylate, stearyl methacrylate, vinyl, acrylated epoxy resins and polyethylene glycol diacrylate, acrylamide, ⁇ , ⁇ -dimethylacrylamide, methylenebisacrylamide and N-vinylpyrrolidone, acrylonitrile, methyl vinyl ether, vinylpyridines, diethyl vinylphosphonate.
• the inhibitory properties of the composition obtained according to the method of the invention on the polymerization of the monomers are evaluated with regard to a test which determines the induction time.
• the composition prevents polymerization for a period of time beyond which the polymerization reaction normally starts. This time is called induction time. The longer it is, the more effective the inhibition.
• MMA methyl methacrylate
• the effectiveness of the composition prepared according to the process of the invention for methyl methacrylate is determined by measuring the induction time which represents the time at which the monomer begins to polymerize when heated in a hot water bath. regulated temperature and presence of an initiator. This induction time corresponds to the time at the end of which appears a visible exotherm which indicates the beginning of polymerization.
• the protocol for determining the induction time is as follows:
• a solution is prepared based on pure methyl methacrylate (MMA) containing 2000 ppm of an inhibiting solid.
• MMA methyl methacrylate
• a solution B is prepared based on pure methyl methacrylate (MMA) containing 200 ppm of an initiator.
• the temperature in the tube is raised continuously until it begins to increase (increase of the order of 0.3 ° C).
• the induction time corresponds to the visible exotherm which indicates the beginning of the MMA polymerization.
• the temperature variation curve ⁇ as a function of time is recorded continuously. The greater the induction time, the more effective the inhibitory composition tested is at constant weight concentration. The induction time thus determined is compared with that obtained by testing a mixture which contains an initiator but which does not contain an inhibiting composition.
• the melting point or melting temperature of the composition prepared according to the method of the invention is measured by differential scanning calorimetry.
• the measurement is carried out using a Mettler differential analyzer DSC822e under the following conditions:
• the temperature programming is started and the fusion profile is obtained on a thermogram.
• the melting temperature is defined from a thermogram produced under the preceding operating conditions.
• the onset temperature is selected: temperature corresponding to the maximum slope of the melting peak. 2. X-ray diffraction spectrum.
• the X-ray diffraction spectrum of the composition prepared according to the process of the invention is determined using the X'Pert Pro MPD PANalytical device equipped with an X 'Celerator detector, under the following conditions:
• Example 1 An example is given below illustrating the present invention without limitation.
• Example 1 An example is given below illustrating the present invention without limitation.
• PC-PMP catechol and para-methoxyphenol
• the inlet / outlet coolant temperatures, as well as the internal temperature of the mixer are measured by Pt probe (100 ⁇ at 0 ° C) regulated and recorded throughout the process.
• the mixer is preheated for one hour at a temperature of 32 ° C +/- 1 ° C, maintaining the jacket at a temperature of 34 ° C +/- 1 ° C to compensate for heat losses.
• the mixer is swept by a nitrogen flow dry of 240 liters per hour.
• the granulator operates at atmospheric pressure. Lift granulator is equipped with a bag filter.
• the catechol and para-methoxyphenol crystals are preheated independently in an oven to obtain a homogeneous temperature for each of the solids: 2,271 kg of para-methoxyphenol (PMP) are preheated to a temperature of 35 ° C +/- 1 ° C in an oven and 0.883 kg of catechol (PC) are preheated to a temperature of 46.3 ° C +/- 1 ° C in another oven.
• PMP para-methoxyphenol
• PC catechol
• the pre-heated para-methoxyphenol (PMP) is introduced into the mixer and then introduced the preheated catechol.
• the mixture is endothermic (of the order of 2 kcal / kg of mixture).
• the agitation of the mixer is put into operation at a speed of 100 rpm for 5 minutes.
• stirring is reduced at a speed of 40 rpm and is maintained for 45 minutes.
• the temperature in the mixer is around 32 ° C throughout the stirring period during the transformation.
• a cooling step is then carried out by bringing the coolant to 15 ° C in the jacket.
• the cooling time is of the order of 30 minutes and the compound is thus cooled to a temperature of 22 ° C +/- 1 ° C.
• the agitation in the mixer and the nitrogen circulation are stopped.
• the mixer is then emptied and the defined compound resulting from the mixture of PC and PMP is recovered.
• the compound obtained is a powdery compound. It has a bulk density (unpacked) of 0.82 +/- 0.01 and a melting point of 36.7 ° C +/- 1 ° C.

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• Polymerisation Methods In General (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

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• 2011
  • 2011-08-25 FR FR1157522A patent/FR2979348B1/fr active Active
• 2012
  • 2012-08-13 KR KR1020147007646A patent/KR20140065424A/ko not_active Application Discontinuation
  • 2012-08-13 WO PCT/EP2012/065784 patent/WO2013026729A1/fr unknown
  • 2012-08-13 EP EP12747922.8A patent/EP2748133A1/fr not_active Withdrawn
  • 2012-08-13 CN CN201280052333.8A patent/CN103889939B/zh not_active Expired - Fee Related

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