WO2013092729A1 - Process for preparing a vinyl chloride polymer - Google Patents
Process for preparing a vinyl chloride polymer Download PDFInfo
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- WO2013092729A1 WO2013092729A1 PCT/EP2012/076176 EP2012076176W WO2013092729A1 WO 2013092729 A1 WO2013092729 A1 WO 2013092729A1 EP 2012076176 W EP2012076176 W EP 2012076176W WO 2013092729 A1 WO2013092729 A1 WO 2013092729A1
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- 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
- C08F14/00—Homopolymers and copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen
- C08F14/02—Monomers containing chlorine
- C08F14/04—Monomers containing two carbon atoms
- C08F14/06—Vinyl chloride
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- the term "medium” is intended to define the contents of the reactor, excluding the monomer(s) introduced and the polymer formed.
- the polymerization step is advantageously continued until 60% to 98% by weight and preferably 80% to 95% by weight of the monomer(s) are converted, with concomitant reduction of the autogenous pressure of VC in the reactor.
- polycarboxylic acids that may be used as complexing agents, mention may be made of succinic acid, tartaric acid, maleic acid and hydroxymaleic acid.
- a high-pressure homogenizer connecting the mixing autoclave to the reactor was switched on.
- the homogenization pressure was adjusted.
- the contents of the mixing autoclave were transferred into the reactor via this homogenizer.
- the operating conditions of the homogenizer were such that a fine aqueous dispersion of VC droplets comprising the liposoluble initiators and the peak suppressant was obtained at its outlet.
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Abstract
Process for preparing a vinyl chloride polymer, comprising a step of polymerization of at least vinyl chloride, performed in aqueous dispersion in the presence of at least one liposoluble radical initiator and of an activating system comprising a water-soluble transition metal salt and a complexing agent, and continued up to the point of reduction of the autogenous pressure of the vinyl chloride. The water-soluble salt is a zinc salt that is introduced at the very latest at the start of the said polymerization step and the complexing agent is introduced from the start of the polymerization step and at the very latest up to the said pressure reduction.
Description
Process for preparing a vinyl chloride polymer
This application claims priority to French application No. 1162279 filed on December 22, 2011, the whole content of this application being incorporated herein by reference for all purposes.
The present invention relates to a process for preparing a vinyl chloride polymer (PVC). The invention relates more particularly to a process for preparing such a polymer, including a polymerization step performed in aqueous dispersion, usually as an aqueous microsuspension. The invention also relates to the vinyl chloride polymers obtained via this process.
It is known practice to prepare vinyl chloride polymers via a process known conventionally as "microsuspension polymerization". This process includes a step during which droplets of at least one monomer, which is vinyl chloride (VC), are finely and homogeneously dispersed in an aqueous medium, in the presence of liposoluble radical initiators (also known more simply as liposoluble initiators), by means of powerful stirring and the presence of emulsifiers, such as alkali metal or ammonium carboxylates and alkylsulfonates, optionally in combination with liposoluble cosurfactants, such as long-chain alcohols. This process, which leads to polymer particles with a diameter of between 0.05 and 5 microns approximately, is particularly suitable for the manufacture of PVC plastisols.
However, the microsuspension polymerization of VC has a drawback: the start of the polymerization is relatively slow, which has the consequences of lengthening the polymer production cycles and of using relatively higher doses of liposoluble initiators. In addition, this polymerization of exothermic nature is frequently performed in at least one reactor of tank type with mechanical stirring. The heat exchange required for the thermal control (temperature regulation) then takes place advantageously by means of a jacket inside which circulates a heat- exchange fluid (water), generally counter-currentwise. Given the slow kinetics of the polymerization, the cooling capacity of the jacket is not used optimally during part of this polymerization.
It has already been proposed (see documents US-A-4 091 197 (I) and US-
A-4 331 788 (II), but also EP 0 826 703 Al (III)) to improve the VC
polymerization kinetics via the "seeded microsuspension" method (i.e. a microsuspension polymerization in which the reaction medium contains a "seed"
which is in the form of an aqueous dispersion of PVC particles containing all of the liposoluble initiator necessary for the polymerization), via the addition, to the polymerization medium, of an activating system. This activating system is an organosoluble metal complex, which is preformed or formed by reaction of a water-soluble metal salt with a complexing agent.
The complexing agent should be capable of modifying the water-soluble form of the metal salt into a VC-soluble form and of not having any inhibitory action on the polymerization or on the activation of the initiator by the metal. Complexing agents that satisfy these conditions are monocarboxylic acids that are sparingly water-soluble; polycarboxylic acids and the corresponding anhydrides thereof; alkylphosphoric acids; lactones; ketones bearing, in the a or β position, groups that activate the carbonyl function; and carbazones. For the practical implementation of the invention, use is made of ascorbic acid, dihydroxymaleic acid, succinic acid, citric acid, tartaric acid, naphthenic acid or sulfosalicylic acid. The complexing agent is usually introduced gradually throughout the polymerization or over a part thereof.
The salt may be introduced into the reaction zone before or during the polymerization, and in the latter case it is in admixture with the complexing agent. The water-soluble metal salt used in practice is copper sulfate.
Document (I) also describes (Example 7, columns 7 and 8) a series of reference tests performed with various activating systems, in which the water- soluble metal salts and the constituent complexing agents are introduced together, before the polymerization starts, into a container containing VC and the other constituents necessary for the polymerization. This series of tests is aimed at demonstrating the effect of the activating systems on the start of the polymerization. Several of these systems (tests I and M to U) comprise lOxlO"5 mol of a metal salt and 5x10"5 mol of ascorbic acid. The salts introduced, together with the ascorbic acid, are copper, iron, nickel, zinc, vanadium, manganese and chromium sulfates, and silver and cobalt nitrates. The tests of Example 7 of document (I) show that, for the same complexing agent (ascorbic acid) and in the case where the two constituents of the activating system are introduced together into the polymerization medium before the polymerization starts, the effect of this system on the polymerization start kinetics can vary to a large extent as a function of the nature of the salt used and, for the same salt, as a nature of the metal from which it is derived.
The Applicant has, for its part, observed that the effect, on certain properties of the polymer obtained, of the activating systems described and used according to document (I) (in the case of their formation by reacting the metal salt with the complexing agent introduced gradually throughout the
polymerization) can also vary to a large extent. Thus, the Applicant has observed, for example, that certain metal salts have the drawback of colouring the polymer obtained via their intervention, of reducing its thermal stability and of increasing its residual monomer content.
A need consequently remains to obtain a process that has the advantage of making it possible to achieve an advantageous compromise between the polymerization kinetics and the properties of the polymer obtained.
The present invention is thus directed towards providing a process for preparing PVC that does not have the drawbacks mentioned above and that makes it possible to achieve the abovementioned compromise, by means of using certain zinc salts, which, in combination with a complexing agent, form activating systems that have a significant effect on the VC polymerization kinetics, in particular in microsuspension processes, while at the same time conserving advantageous properties for the polymer obtained.
The present invention thus relates mainly to a process for preparing a vinyl chloride polymer, comprising a step of polymerization of at least vinyl chloride, performed in aqueous dispersion in the presence of at least one liposoluble radical initiator and of an activating system comprising a water-soluble transition metal salt and a complexing agent, and continued up to the point of reduction of the autogenous pressure of the vinyl chloride, the water-soluble salt being a zinc salt that is introduced at the very latest at the start of the said polymerization step, and the complexing agent being introduced from the start of the polymerization step and at the very latest up to the said pressure reduction.
In the present description, the terms "monomer" and "polymer" are used indiscriminantly in the singular and in the plural. The liposoluble radical initiator will also be referred to more simply as the "liposoluble initiator" or the
"initiator".
The polymer prepared according to the invention is a vinyl chloride polymer. In the present description, the term "vinyl chloride polymer", or "polymer" for short, is intended to denote any polymer containing at least 50 % by weight, preferably at least 60% by weight, particularly preferably at least 70 % by weight and most particularly preferably at least 85% by weight of
monomer units derived from vinyl chloride (monomer), and thus both vinyl chloride homopolymers (containing 100% by weight of monomer units derived from vinyl chloride) and copolymers of vinyl chloride with one or more ethylenically unsaturated monomers. As examples of ethylenically unsaturated monomers that can be copolymerized with vinyl chloride, mention may be made of chlorinated monomers such as vinylidene chloride, fluorinated monomers such as vinylidene fluoride, monomers containing both chlorine and fluorine such as chlorotrifluoroethylene, vinyl esters such as vinyl acetate, vinyl ethers such as methyl vinyl ether, dialkyl maleates such as dibutyl maleate,
(meth) acrylic monomers such as n-butyl acrylate and methyl methacrylate, styrene monomers such as styrene, and olefinic monomers such as ethylene, propylene and butadiene. Among all the vinyl chloride polymers mentioned above, preference is given to vinyl chloride homopolymers.
The polymerization step included in the process for preparing the VC polymer according to the invention is performed in aqueous dispersion in a stirred reactor. In the present description, the expression "polymerization... in aqueous dispersion" is intended to denote polymerizations performed according to a radical mechanism in dispersed medium with the intervention of at least one liposoluble initiator. These polymerizations include not only the polymerization conventionally known as "suspension" polymerization, but also polymerizations known as "microsuspension" and "seeded microsuspension" polymerization. Preferably, the polymerization step is performed in microsuspension or in seeded microsuspension.
The term "suspension polymerization" is intended to denote any polymerization process that is performed with stirring in an aqueous medium in the presence of at least one dispersant and of at least one liposoluble initiator.
The term "microsuspension polymerization" is intended to denote any polymerization process (already mentioned hereinabove) in which is used at least one liposoluble initiator and in which is prepared an emulsion, also known as a "fine dispersion", of monomer droplets by means of powerful mechanical stirring and the presence of at least one emulsifier, the nature of which will be specified later in the present description.
The mechanical stirring may be produced by a suitable mechanical means, for instance a colloidal mill, a rapid pump, a vibrating agitator, an ultrasonic generator, a high-pressure homogenizer, etc.
According to one practical embodiment, this mechanical stirring may be performed by homogenizing the emulsion, originating from a premixing autoclave, before it is introduced into the polymerization reactor or therein. The homogenization of the emulsion may advantageously take place, before it is introduced into the polymerization reactor, in a colloidal mill as described, for example, in document US-A-4 355 142.
Devices that are suitable for homogenizing the emulsion are sold, for example, by the company IKA under the name Dispax Reactor and by the company BWS under the name Supraton® Homogeniser.
The homogenization of the emulsion in a colloidal mill is made more efficient by adding to the emulsion at least one organic compound that is insoluble in water but is soluble in VC. Organic compounds that are preferred for this purpose are compounds known for their PVC plasticizing effect, in particular adipic and phthalic acid esters, such as dioctyl adipate (also known as bis(2- ethylhexyl) adipate or designated as DO A), diisononyl adipate and diisononyl phthalate, for example.
The term "seeded microsuspension polymerization" is understood to denote any microsuspension polymerization process performed in the presence of at least one "seeding product", also known as "seed", which may be, as mentioned hereinabove, a dispersion of particles of vinyl chloride polymer with a diameter advantageously between 0.01 and 1 micron and preferably between 0.05 and 0.2 micron. This seed may itself be prepared by polymerization, for example by using water, VC and an optional comonomer, at least one emulsifier and the initiator.
In the present description, the term "medium" is intended to define the contents of the reactor, excluding the monomer(s) introduced and the polymer formed.
Constituents that are common to the media in which the polymerization step is performed are:
- water,
- VC and optionally at least one of the monomers mentioned above,
- at least one liposoluble initiator, and
- an activating system.
When the polymerization is performed in suspension, the medium also contains at least one dispersant.
When the polymerization is performed in microsuspension or in seeded microsuspension, the respective media also contain at least one emulsifier. These media may also optionally contain at least one liposoluble cosurfactant. The medium in which the seeded microsuspension polymerization is performed also contains a seeding product (seed). The weight of the seeding product relative to the total weight of the monomer(s) is at least 1% and preferably at least 3%.
The weight of the seeding polymer(s) relative to the total weight of the monomer(s) is not more than 25% and preferably not more than 10%.
In the polymerization medium, the ratio of the weight of water to the weight of the monomer(s) is advantageously at least 0.4 and preferably at least 0.8.
In the polymerization medium, the ratio of the weight of water to the weight of the monomer(s) is advantageously not more than 2 and preferably not more than 1.5.
The media in which the polymerizations are performed may optionally contain additives other than the constituents mentioned above. They are then conventional additives, which make it possible, in a known manner, to improve the implementation of the process and/or the characteristics of the resulting polymer. Examples of such additives are chain-transfer agents, for instance chloroform, trichlorofluoromethane and C2-C5 dialkyl carbonates; chain extenders, for instance diallyl maleate and dialkyl phthalate; anticaking agents; antistatic agents; antifoams; cosolvents; and pH regulators, for instance ammonia, buffer salts, for example sodium phosphate, polyphosphate and hydrogen carbonate, and alkali metal carbonates, preferably sodium carbonate, the latter advantageously being added to the polymerization medium, in particular to the aqueous microsuspension polymerization medium or to the aqueous seeded microsuspension polymerization medium, at the start of the said polymerization.
The polymerization step included in the process for preparing the VC polymer according to the invention is performed with the intervention of at least one liposoluble initiator. These liposoluble initiators are advantageously organic peroxide compounds or liposoluble diazo compounds.
Examples of organic peroxide compounds that may be mentioned include peroxides such as dilauryl peroxide, di-ieri-butyl peroxide or dibenzoyl peroxide; hydroperoxides such as ferf-butyl hydroperoxide; peresters such as ferf-butyl perpivalate, ferf-butyl peroxy-2-ethylhexanoate and ferf-butyl perneodecanoate;
percarbonates such as diethyl, diisopropyl, diethylhexyl and dimyristyl peroxydicarbonate. Examples of diazo compounds that may be mentioned include azobisisobutyronitrile and 2,2'-azobis(methoxy-2,4- dimethylvaleronitrile). Preferred organic peroxide compounds are, in particular, dilauryl peroxide and percarbonates, in particular dimyristyl peroxydicarbonate. The amount of liposoluble radical initiator used ranges advantageously between 0.2%o and 3.5%o by weight and preferably between 0.8%o and 3%o by weight relative to the weight of monomer(s) used.
When the polymerization step included in the process for preparing the VC polymer according to the invention is performed in suspension, the
polymerization medium also contains at least one dispersant. Examples of dispersants that may be mentioned include water-soluble cellulose ethers and partially saponified polyvinyl alcohol, and mixtures thereof. Along with the dispersants, surfactants may also be used. The amount of dispersant used ranges advantageously between 0.7%o and 2.0%o by weight relative to the weight of monomer(s) used.
When the polymerization step included in the process for preparing the VC polymer according to the invention is performed in microsuspension or in seeded microsuspension, the polymerization medium also contains at least one emulsifier. These emulsifiers are advantageously ionic emulsifiers chosen from anionic emulsifiers, cationic emulsifiers and amphoteric emulsifiers. Preferably, these emulsifiers are chosen from anionic emulsifiers. Particularly preferably, these emulsifiers are chosen from the following anionic emulsifiers: alkyl sulfates, alkyl sulfonates, alkylaryl sulfonates, dialkyl sulfosuccinates and alkyl carboxylates. The salts may optionally be ethoxylated and may comprise, as counterion, a sodium, potassium, lithium, caesium or ammonium cation. These emulsifiers are most particularly preferably chosen from the following non- ethoxylated sodium salts: alkyl sulfates, for instance sodium dodecyl sulfate, alkyl sulfonates, for instance primary or secondary sodium alkyl sulfonates, alkylaryl sulfonates, for instance sodium dodecylbenzenesulfonate, dialkyl sulfosuccinates, for instance dioctyl sulfosuccinate, and alkyl carboxylates, for instance sodium ammonium myristates.
The amount of emulsifier used ranges advantageously between 0.1% and 3% by weight relative to the weight of monomer(s) used.
The polymerization medium intended for suspension, microsuspension or seeded microsuspension polymerization is heated under the autogenous pressure to a temperature determined by the molar mass that it is desired to obtain for the polymer.
The polymerization temperature is advantageously between 30 and 100°C, preferably between 30 and 90°C and more particularly between 45 and
85°C. The polymerization is advantageously performed at a pressure between 0.3 and 2.5 MPa and preferably between 0.5 and 1.5 MPa.
The polymerization step is advantageously continued until 60% to 98% by weight and preferably 80% to 95% by weight of the monomer(s) are converted, with concomitant reduction of the autogenous pressure of VC in the reactor.
The content of solid polymer in the aqueous dispersion obtained at the end of the polymerization step is advantageously between 20% and 55% by weight and preferably between 40% and 50% by weight.
As a consequence of incomplete conversion of the monomer, the amount thereof that remains in the aqueous dispersion obtained at the end of the polymerization step must be removed.
This removal may be performed conventionally by degassing the dispersion, which is usually performed in a depressurization tank,
advantageously followed by a distillation operation, steam entrainment of the residual monomer or, preferably, boiling under vacuum.
The solid polymer or the aqueous polymer dispersion derived from the abovementioned separation treatment may then be subjected to a final drying operation performed in any drying device known for this purpose. In the case of aqueous microsuspension or seeded aqueous microsuspension leading to the production of an aqueous dispersion (commonly known as a latex), the aqueous dispersion may be stored and used in this form without being dried.
The polymer synthesized by suspension polymerization is in the form of particles with a diameter advantageously between 50 and 150 microns.
The polymer synthesized by microsuspension or seeded microsuspension polymerization is in the form of elemental particles with a diameter
advantageously between 0.1 and 5 microns before drying and of particles with a diameter advantageously between 30 and 100 microns after drying.
The medium in which the polymerization step included in the process for preparing the VC polymer according to the invention is performed contains, during at least part of this polymerization (as will be specified later), an
activating system comprising a water-soluble transition metal salt and a complexing agent.
According to the invention, the water-soluble transition metal salt, which is the first constituent of the activating system, is a zinc salt. Any water-soluble zinc salt may be used as constituent of the activating system. These salts may be mineral or organic. Among the water-soluble mineral zinc salts that may be mentioned are the sulfate, the chlorate, the chloride and the nitrate of this metal. Among the water-soluble organic zinc salts that may be mentioned is the acetate of this metal. Mineral zinc salts are preferred as constituents of the activating system, and, among these, zinc sulfate is particularly preferred. The zinc salt that is thus particularly preferred is zinc sulfate.
The second constituent of the activating system is a complexing agent. In the present description, the term "complexing agent" is intended to denote any chemical compound that is capable of changing zinc from its water-soluble form to the form of a complex that is soluble in VC, without exerting any inhibitory action on the polymerization or on the activation exerted by the zinc on the liposoluble initiator.
Complexing agents that satisfy these conditions may be chosen especially from monocarboxylic acids, polycarboxylic acids, alkylphosphoric acids, lactones, ketones and carbazones.
As monocarboxylic acids that may be used as complexing agents, mention may be made of those that are sparingly water-soluble, such as perfluorobutyric acid, a-bromolauric acid, sulfosalicylic acid, naphthenic acid and octanoic acid.
As polycarboxylic acids that may be used as complexing agents, mention may be made of succinic acid, tartaric acid, maleic acid and hydroxymaleic acid.
As alkylphosphoric acids that may be used as complexing agents, mention may be made of bis(2-ethyl)hexylphosphoric acid.
As lactones that may be used as complexing agents, mention may be made of ascorbic acid, its stereoisomer erythorbic acid, and esters thereof, and also γ- butyrolactone.
As ketones that may be used as complexing agents, mention may be made of ketones bearing, in the γ or β position, groups that activate the carbonyl function, such as acetylacetone, 1,3-dihydroxyacetone and benzoin.
As carbazones that may be used as complexing agents, mention may be made of diphenylthiocarbazone.
The complexing agent is preferably chosen from monocarboxylic acids, polycarboxylic acids and lactones. The complexing agent is particularly preferably chosen from sulfosalicylic acid, tartaric acid, maleic acid, and also ascorbic acid, its stereoisomer erythorbic acid, and esters thereof.
The presence of several water-soluble zinc salts and/or of several complexing agents in the same activating system is not at all excluded from the scope of the invention.
The amounts in which the constituents of the activating system are introduced into the polymerization step included in the process for preparing the VC polymer according to the invention may vary to a large extent.
Advantageously, the amount of water-soluble zinc salt introduced, expressed relative to the amount of initiator present in the polymerization step, is greater than or equal to 10"5 mol of zinc salt per mole of initiator. Preferably, the amount of water-soluble zinc salt introduced, expressed relative to the amount of initiator present in the polymerization step, is greater than or equal to 10"4 mol of zinc salt per mole of initiator. Even more preferably, the amount of water-soluble zinc salt introduced, expressed relative to the amount of initiator present in the polymerization step, is greater than or equal to 5x10"3 mol of zinc salt per mole of initiator.
Advantageously, the amount of water-soluble zinc salt introduced, expressed relative to the amount of initiator present in the polymerization step, is less than or equal to 50 mol of zinc salt per mole of initiator. Preferably, the amount of water-soluble zinc salt introduced, expressed relative to the amount of initiator present in the polymerization step, is less than or equal to 5 mol of zinc salt per mole of initiator. Even more preferably, the amount of water-soluble zinc salt introduced, expressed relative to the amount of initiator present in the polymerization step, is less than or equal to 0.5 mol of zinc salt per mole of initiator.
When expressed relative to the amount of VC present in the polymerization step, the amount of water-soluble zinc salt introduced is advantageously greater than or equal to 1 ppm and preferably greater than or equal to 5 ppm.
When expressed relative to the amount of VC present in the polymerization step, the amount of water-soluble zinc salt introduced is advantageously less than or equal to 300 ppm and preferably less than or equal to 200 ppm.
Advantageously, the amount of complexing agent introduced, expressed relative to the amount of water-soluble zinc salt introduced into the
polymerization step, is greater than or equal to 0.05 mol of complexing agent per mole of zinc salt. Preferably, the amount of complexing agent introduced, expressed relative to the amount of water-soluble zinc salt introduced into the polymerization step, is greater than or equal to 0.1 mol of complexing agent per mole of zinc salt. Even more preferably, the amount of complexing agent introduced, expressed relative to the amount of water-soluble zinc salt introduced into the polymerization step, is greater than or equal to 0.5 mol of complexing agent per mole of zinc salt.
Advantageously, the amount of complexing agent introduced, expressed relative to the amount of water-soluble zinc salt introduced into the
polymerization step, is less than or equal to 50 mol of complexing agent per mole of zinc salt. Preferably, the amount of complexing agent introduced, expressed relative to the amount of water-soluble zinc salt introduced into the polymerization step, is less than or equal to 20 mol of complexing agent per mole of zinc salt. Even more preferably, the amount of complexing agent introduced, expressed relative to the amount of water-soluble zinc salt introduced into the polymerization step, is less than or equal to 5 mol of complexing agent per mole of zinc salt.
For the practical execution of the process according to the invention, it should be noted that the complexing agent of the activating system may be introduced - as will be specified later - in a single batch (batchwise) or continuously into the polymerization medium, and, in the latter case, at a constant rate or at a decreasing rate. The ratios defining the amount of complexing agent introduced into this medium express this amount at the time when the concentration of this agent is at a maximum.
According to the invention, the zinc salt of the activating system is introduced at the very latest at the start of the polymerization step.
For the purposes of the present description, the expression "start of the polymerization step" should be understood as meaning the moment (referred to as to) at which the polymerization temperature is reached (to within + 1°C).
For the purposes of the present description, the expression "introduced at the very latest at the start of the polymerization step" should be understood as meaning introduced at a moment between the introduction of the first of the
constituents of the medium in which the polymerization step is performed and the moment ¾.
The zinc salt of the activating system is thus advantageously introduced at any moment between the introduction of the first of the constituents of the medium in which the polymerization step is performed and the moment ¾ at which the polymerization temperature is reached (to within + 1 °C) (commonly referred to as "initial"). Preferably, the zinc salt is introduced with the other constituents of the medium in which the polymerization step is performed before raising the temperature.
In the case of a seeded microsuspension polymerization, the zinc salt of the activating system may be introduced via the "seed".
The zinc salt may be introduced into the polymerization step in solid form, in the form of an aqueous solution or as a mixture with an emulsifier solution. The zinc salt is preferably introduced in solid form.
According to the invention, the complexing agent of the activating system is introduced from the start of the polymerization step and at the very latest up to the reduction of the VC autogenous pressure.
For the purposes of the present description, the expression "from the start of the polymerization step" should be understood as meaning from the moment ¾ at which the polymerization temperature defined above is reached (to within + 1°C).
The expression "reduction of the VC autogenous pressure" is intended to denote the pressure reduction generated taking into account the disappearance of VC in the gaseous phase (since it is consumed by the polymerization reaction). This reduction in the VC autogenous pressure is advantageously not induced by a reduction in the polymerization temperature. This reduction of the VC autogenous pressure indicates advantageously that the polymerization is close to completion and is advantageously followed by the phenomenon conventionally defined by the term "self-heating", which corresponds to an increase in temperature at the end of polymerization (the heat being supplied mainly by the heat of the polymerization itself).
If we call tx the moment at which the reduction of the VC autogenous pressure starts, the complexing agent is thus introduced from ¾ and at the very latest up to tx.
The moment tx is detected by a pressure reduction advantageously of the order of at least 0.1 bar and preferably of the order of at least 0.2 bar, relative to the mean pressure at which the polymerization step is performed.
If we call x the time elapsed between the start of the polymerization step (moment ¾ at which the polymerization temperature is reached (to within + 1 °C)) and the moment tx at which the reduction of the VC autogenous pressure starts, the complexing agent is advantageously introduced
- in a single batch at any fraction of x between ¾ and tx including addition in a single batch at to,
- in several successive batches of the same weight or of uniformly decreasing weight distributed over the duration x,
- continuously over x at a constant rate,
- continuously over x at a decreasing rate,
- continuously over a fraction of x of between ¾ and tx at a constant rate, or - continuously over a fraction of x of between ¾ and tx at a decreasing rate.
The complexing agent is preferably introduced continuously, over x or over a fraction of x between ¾ and tx, at a constant rate or at a decreasing rate.
The complexing agent may be introduced into the polymerization step in solid form, in the form of an aqueous solution or as a mixture with an emulsifier solution. The complexing agent is preferably introduced in the form of an aqueous solution.
A subject of the present invention is also the vinyl chloride polymers obtained via a process comprising a step of polymerization of at least vinyl chloride, performed in aqueous dispersion in the presence of at least one liposoluble radical initiator and of an activating system comprising a water- soluble transition metal salt and a complexing agent, and continued up to the point of reduction of the autogenous pressure of the vinyl chloride, the said water-soluble salt being a zinc salt that is introduced at the very latest at the start of the said polymerization step, and the complexing agent being introduced from the start of the polymerization step and at the very latest up to the said pressure reduction.
The process according to the invention has the advantage of achieving a compromise of polymerization kinetics/properties of the polymer obtained (coloration, thermal stability, residual monomer) that is more advantageous than in the case of the processes according to the prior art.
In particular, when compared with the process according to the prior art according to which the water-soluble transition metal salt and the complexing agent are introduced before the start of the polymerization step, the process according to the invention has the advantage of being characterized by improved polymerization kinetics (shorter polymerization time, greater maximum ΔΤ) and of producing a polymer latex that is characterized by a markedly lower residual monomer content.
When compared with the process according to the prior art according to which a copper salt, in particular copper sulfate, is introduced before the start of the polymerization step and the complexing agent is introduced from the moment at which this temperature is reached, the process according to the invention achieves a better compromise of polymerization kinetics/properties of the polymer obtained (less coloration (yellow index), greater thermal stability and lower residual monomer content).
Should the disclosure of any patents, patent applications, and publications which are incorporated herein by reference conflict with the description of the present application to the extent that it may render a term unclear, the present description shall take precedence.
The examples that follow are intended to illustrate the invention without however limiting the scope thereof.
Example 1R (comparative)
Preparation of the seed latex (seed latex S)
A PVC latex (seed latex S) was prepared via an emulsion polymerization step performed conventionally (emulsifier: solution of dodecylbenzenesulfonate at 180 g/kg; water-soluble initiator: aqueous ammonium persulfate solution at 66.5 g/L) in a 300L reactor equipped with a stirrer and a jacket.
The latex was emptied from the reactor. The latex was filtered through a screen with a mesh size of 1 mm. The latex was placed in a storage tank.
A sample of latex was taken from the storage tank and its solids content was measured by densimetry: the solids content of the seed latex S was 34.1%.
The distribution of the elementary polymer particles of the seed latex was also determined by photosedimentometry using a CPS machine from the company CPS Instruments Inc. The distribution of the elementary polymer particles of the seed latex S was unimodal; the mean diameter of these elementary particles was 105 nm.
Preparation of the fine dispersion (1st part)
7.56 kg of demineralized water were first placed in a 35 L mixing autoclave equipped with a stirrer and a jacket. The following were then placed in the mixing autoclave: 80.6 g of a commercial solution of sodium
dioctylsulfosuccinate at 75% in a water/ethanol mixture, a mixture of liposoluble initiators comprising 28.0 g of dilauryl peroxide (PL) and 8.4 g of dimyristyl peroxydicarbonate (MYPC), and 0.27 g of butylhydroxyanisole. The mixing autoclave was closed and the stirrer switched on. The mixing autoclave was then placed under vacuum.
Loading the reagents into the reactor (1st part)
9.24 kg of demineralized water, 98.5 g of a commercial solution of sodium dioctylsulfosuccinate at 75% in a water/ethanol mixture and 2.31 kg of the seed latex S containing 34.1% solids were successively introduced into a 35 L reactor equipped with a stirrer and a jacket. The reactor was closed and the stirrer switched on. The reactor was then placed under vacuum.
Preparation of the fine dispersion (2nd part)
5.04 kg of VC were placed in the mixing autoclave and vigorous stirring was maintained in order to constitute a homogeneous aqueous dispersion of VC droplets comprising the mixture of liposoluble initiators and the peak suppressant (butylhydroxyanisole).
Loading the reagents into the reactor (2nd part)
6.16 kg of VC were placed in the reactor.
Preparation of the fine dispersion (3rd part) and loading of the reagents into the reactor (3rd part)
A high-pressure homogenizer connecting the mixing autoclave to the reactor was switched on. The homogenization pressure was adjusted. The contents of the mixing autoclave were transferred into the reactor via this homogenizer. The operating conditions of the homogenizer were such that a fine aqueous dispersion of VC droplets comprising the liposoluble initiators and the peak suppressant was obtained at its outlet.
Polymerization
The contents of the reactor were brought to 51°C. Once this temperature was reached (to), 0.13 L of an aqueous ammonia solution at 30 g/L was introduced into the reactor.
During the polymerization, 2.24 kg of VC were introduced into the reactor.
After the time tx (in this case corresponding to a pressure reduction (ΔΡ) of 0.2 bar relative to the average pressure at which the polymerization step was performed), once a pressure reduction (ΔΡ) of 0.5 bar was detected, the contents of the reactor were brought to a higher temperature (self-heating), the polymerization time elapsed from ¾ up to this moment (ΔΡ = 0.5 bar) was recorded, and 0.34 L of an aqueous sodium carbonate solution at 10 g/L was added.
End operations
A purification treatment of the residual VC was performed.
The latex was emptied out and the reactor cleaned.
The wet cake present inside the reactor, especially on the walls and on the blades of the stirrer, was collected. After weighing, the wet cake was dried in an oven. The dry cake was in turn weighed.
The latex was filtered through a screen with a mesh size of 1 mm. The wet lumps retained on this screen were collected. After weighing, the wet lumps were dried in an oven. The dry lumps were in turn weighed.
Drying of the latex and recovery of the resin
The latex was dried by atomization. The dry resin of vinyl chloride polymer was recovered and ground.
Evaluation of the thermal stability
150 g of the PVC obtained were mixed with 60 g of dioctyl phthalate plasticizer using a planetary mixer. The thermal stability of the paste was evaluated using a Metrastat stabilimeter constructed by the company Dr Stapfer GmbH, and equipped with a Reflektomaster 517 reflectometer from the company Erichsen.
The sample gelled after conditioning in the heating chamber of the Metrastat exited automatically at a controlled speed. It showed the coloration spectrum reflecting the thermal degradation as a function of the exposure time at the chamber temperature.
The conventional thermal stability was defined as the exposure time at a temperature of 180°C leading to a 60% decrease in reflectance of the trichromatic value Y (illuminant C/2°, measured at 45 0°), relative to the value after 3 minutes of exposure. It is expressed in minutes and seconds.
Evaluation of the yellow index
A plastisol was manufactured by mixing 300 g of PVC resin, 120 g of diisononyl phthalate plasticizer, 36 g of benzyl butyl phthalate plasticizer, 9 g of a viscosity reducer (Viscobyk® 5050) and 6 g of a stabilizer (Irgastab® BZ505).
This plastisol was then coated as a layer 1 mm thick onto transfer paper, which was placed in a Werner-Mathis coating oven under determined gelation conditions (temperature, time).
The yellow index obtained on the film was measured using a Luci 100 spectrocolorimeter from the company DR Lange GmbH, using the illuminant D65 and the 10° observing angle.
The values measured in the defined colorimetric space were x, y and Y. The yellow index (YI) was defined by the formula YI = 100*((Cx*X)-Cz*Z)/Y with:
X = Y * x / y
Z = ((l-x-y)/y)*Y
Cx=1.3013
Cz=1.1498
In this example:
- the polymerization lasted 480 minutes;
- the maximum ΔΤ (which corresponds to the largest temperature difference observed between the jacket and the reaction medium: it is representative of the exothermicity of the reaction, and thus of the polymerization rate) was 5.8°C;
- the amount of dry lumps and cakes (expressed as a percentage of the VC introduced) was 4.10;
- the yellow index was 7.4 after 90 seconds of gelation at 180°C.
Example 2 (according to the invention)
Example 1R was repeated, except that:
- in the step of loading the reagents into the reactor (1st part), zinc sulfate monohydrate was added at a rate of 0.012 g per kg of VC used (the mole ratio of zinc sulfate to the initiator mixture was thus about 0.010);
- in the polymerization step, 0.013 g of maleic acid in aqueous solution form was also added continuously at a constant rate between (to and to+4h) (the mole ratio between maleic acid and zinc sulfate was thus about 1.25).
The results of this example were as follows:
- the polymerization lasted 383 minutes;
- the maximum ΔΤ was 7.4°C;
- the amount of dry lumps and cakes (expressed as a percentage of the VC introduced) was 2.40;
- the yellow index was 7.0 after 90 seconds of gelation at 180°C;
- the thermal stability of the plastisol sample obtained was 8 minutes 30 seconds.
Comparison of the results of Example 2 with those of Example 1R shows the significant decrease in the polymerization time and the increase in the maximum ΔΤ obtained by means of the activating system according to the invention, reflecting activation of the polymerization kinetics. This system also makes it possible to achieve a compromise in terms of polymerization kinetics/properties of the polymers obtained (especially the yellow index) which is more advantageous than in its absence.
Example 3R (comparative)
Example 1R was repeated, except that:
- in the step of loading the reagents into the reactor (1st part), copper sulfate pentahydrate was added at a rate of 0.001 g per kg of VC used (the mole ratio of copper sulfate to the initiator mixture was thus about 0.0006);
- in the polymerization step, 13 mg of maleic acid in aqueous solution form were also added continuously at a constant rate between (to and to+4h) (the mole ratio between maleic acid and copper sulfate was thus about 2.15).
The results of this example were as follows:
- the polymerization lasted 462 minutes;
- the maximum ΔΤ was 6.2°C;
- the amount of dry lumps and cakes (expressed as a percentage of the VC introduced) was 4.80;
- the yellow index was 7.3 after 90 seconds of gelation at 180°C;
- the thermal stability of the plastisol sample obtained was 10 minutes 45 seconds.
Examples 4 and 5 (according to the invention)
The general procedure of Example 2 was repeated, except that
sulfosalicylic acid (Example 4) and tartaric acid (Example 5) were used as complexing agents for the activating system.
The particular features of the procedures of Examples 4 and 5 and the results thereof are collated in the table below.
Table
Comparison of the results of Example 3R with those of Examples 2, 4 and 5 shows that an activating system containing a copper salt does not make it possible to achieve a compromise in terms of polymerization kinetics/properties of the polymer obtained that is as advantageous as that of the activating systems containing a zinc salt. In particular, lengthening of the polymerization time and an increase in the yellow index are observed when a copper salt is used.
Example 6R (comparative)
Preparation of the seed latex (seed latex S)
The process was performed as described in Example 1R. The solids content of the seed latex S was 38.0%
Preparation of the fine dispersion (1st part)
51.3 kg of demineralized water were first placed in a 300 L mixing autoclave equipped with a stirrer and a jacket. The following were then placed in the mixing autoclave: 1.4 kg of a commercial solution of sodium
dodecylbenzenesulfonate at 31.95% in water, a mixture of liposoluble initiators comprising 78.1 g of dilauryl peroxide (PL) and 111.2 g of dimyristyl peroxydicarbonate (MYPC), 168.0 g of dioctyl adipate and 0.56 g of butylhydroxyanisole. The mixing autoclave was closed and the stirrer switched on. The mixing autoclave was then placed under vacuum.
Loading the reagents into the reactor (1st part)
63.36 kg of demineralized water, 2.1 kg of a commercial solution of sodium dodecylbenzenesulfonate at 31.95% in water, 12.27 kg of the seed latex
S containing 38.0% solids and 34.0 g of sodium carbonate were successively introduced into a 300 L reactor equipped with a stirrer and a jacket. The reactor was closed and the stirrer switched on. The reactor was then placed under vacuum.
Preparation of the fine dispersion (2nd part)
The process was performed as described in Example 1R, introducing 37.33 kg of VC into the mixing autoclave.
Loading the reagents into the reactor (2nd part)
56.0 kg of VC were placed in the reactor.
Preparation of the fine dispersion (3rd part) and loading of the reagents into the reactor (3rd part)
The process was performed as described in Example 1R.
Polymerization
The contents of the reactor were brought to 51°C. Once this temperature was reached (to), 18.66 kg of VC were introduced into the reactor during the polymerization.
After the time tx (in this case corresponding to a pressure reduction (ΔΡ) of 0.2 bar relative to the average pressure at which the polymerization step was performed), once a pressure reduction (ΔΡ) of 1.0 bar was detected, the contents of the reactor were brought to a higher temperature (self -heating), the
polymerization time elapsed from ¾ up to this moment (ΔΡ = 1.0 bar) was recorded, and 56.4 g of a commercial antifoam solution (Tego® KS53 sold by Evonik) were added.
End operations
The process was performed as described in Example 1R.
Drying of the latex and recovery of the resin
The process was performed as described in Example 1R.
Evaluation of the thermal stability
10 g of the PVC resin obtained were mixed with 4 g of diisononyl phthalate plasticizer. The thermal stability of the paste (0.5 g) was evaluated using a Thermomat PVC 763 constructed by the company Metrohm.
The PVC sample heated to 180°C breaks down with evolution of HC1, which is entrained by a gas stream (7 L/h of N2) into a measuring cell where it is absorbed by ultrapure water. The HC1 concentration of this water is measured continuously by conductimetry.
The conventional thermal stability was defined as the induction time of the dehydrochlorination reaction at a temperature of 180°C leading to an increase in conductimetry of 5 μ8/αη relative to the initial value. It is expressed in minutes and seconds.
Evaluation of the yellow index
The process was performed as described in Example 1R, except that the thickness of the plastisol layer was 0.5 mm.
Determination of the residual monomer in the latex
The residual VC content was measured on a Thermo Finnigan brand gas chromatograph (Trace GC) equipped with a flame ionization detector and an automatic headspace injector of the same brand (Triplus), having a stirring function and also a system for acquisition and processing of the chromatographic data (ChromCard). The assay was performed by the external calibration method (calibration with VC samples of known concentration in N,N-dimethylacetamide (DMA)).
The latex sample (1 ml) to be analysed dispersed in a water/DMA mixture (40/60 by weight, 5 ml) contained in a hermetically sealed penicillin-type flask was placed on the chromatograph sampler and subjected to incubation with stirring for 30 minutes at a temperature of 70°C. After this equilibration, the headspace was analysed by chromatography on a packed semicapillary column, divinylbenzene type (20 μιη), commercial name RT-Q Bond, 30 m long and 0.53
μηι inside diameter of the abovementioned chromatograph.
The residual VC content is expressed in mg/kg resin (ppm).
In this example:
- the polymerization lasted 363 minutes;
- the maximum ΔΤ was 24.0°C;
- the amount of dry lumps and cakes (expressed as a percentage of the VC introduced) was 0.31;
- the yellow index was 1.3 after 90 seconds of gelation at 180°C;
- the thermal stability of the paste sample obtained was 16.8 minutes;
- the residual monomer content in the latex was 34.1 ppm.
Example 7R (comparative)
Example 6R was repeated, except that:
- in the step of loading the reagents into the reactor (1st part), copper sulfate pentahydrate was added at a rate of 0.0625 g per kg of VC used (the mole ratio of copper sulfate to the initiator mixture was thus about 0.068);
- in the polymerization step, 0.0875 kg, per kg of VC used, of ascorbic acid in aqueous solution form was also added continuously at a constant rate between (to and to+4h) (the mole ratio between ascorbic acid and copper sulfate was thus about 2).
The results of this example were as follows:
- the polymerization lasted 318 minutes;
- the maximum ΔΤ was 50.3°C;
- the amount of dry lumps and cakes (expressed as a percentage of the VC introduced) was 0.20;
- the yellow index was 1.7 after 90 seconds of gelation at 180°C;
- the thermal stability of the paste sample obtained was 6 minutes 18 seconds.
- the residual monomer content in the latex was 44.1 ppm.
Example 8 (according to the invention)
Example 6R was repeated, except that:
- in the step of loading the reagents into the reactor (1st part), zinc sulfate monohydrate was added at a rate of 0.050 g per kg of VC used (the mole ratio of copper sulfate to the initiator mixture was thus about 0.076);
- in the polymerization step, 0.0875 kg, per kg of VC used, of ascorbic acid in aqueous solution form was also added continuously at a constant rate between (t0 and t0+4h) (the mole ratio between ascorbic acid and copper sulfate was thus about 1.8).
The results of this example were as follows:
- the polymerization lasted 252 minutes;
- the maximum ΔΤ was 40.0°C;
- the amount of dry lumps and cakes (expressed as a percentage of the VC introduced) was 0.37;
- the yellow index was 1.5 after 90 seconds of gelation at 180°C;
- the thermal stability of the paste sample obtained was 9 minutes;
- the residual monomer content in the latex was 15.7 ppm.
Comparison of the results of Example 8 with those of Examples 6R and 7R reveals a significant decrease in the polymerization time obtained by means of the activating system according to the invention. Comparison of the results of Example 8 with those of Example 7R also shows that the polymer obtained in Example 8 is thermally more stable and has a less impacted yellow index and a markedly lower residual monomer content than the polymer obtained in Example 7R. The use of zinc sulfate thus leads to a better compromise in terms of polymerization kinetics/properties of the polymer obtained than that of copper sulfate.
Example 9R (comparative)
Preparation of the seed latex (seed latex S)
The process was performed as described in Example 1R. The solids content of the seed latex S was 37.0%
Preparation of the fine dispersion (1st part)
The process was performed as described in Example 6R, except that 50.1 kg of demineralized water and 3.135 kg of a commercial sodium
dodecylbenzenesulfonate solution at 32.15% in water were used.
Loading the reagents into the reactor (1st part)
The process was performed as described in Example 6R, except that 64.23 kg of demineralized water, 0.35 kg of a commercial sodium
dodecylbenzenesulfonate solution at 32.15% in water, and 12.60 kg of the seed latex S at 37.0% solids were used.
Preparation of the fine dispersion (2nd part)
The process was performed as described in Example 6R.
Loading the reagents into the reactor (2nd part)
The process was performed as described in Example 6R.
Preparation of the fine dispersion (3rd part) and loading of the reagents into the reactor (3rd part)
The process was performed as described in Example 6R.
Polymerization
The contents of the reactor were brought to 51°C. Once this temperature was reached (to), 18.66 kg of VC were introduced into the reactor during the polymerization.
After the time tx (in this case corresponding to a pressure reduction (ΔΡ) of 0.2 bar relative to the average pressure at which the polymerization step was performed), once a pressure reduction (ΔΡ) of 0.4 bar was detected, the contents of the reactor were brought, 1 hour after this time, to a higher temperature (self- heating), the polymerization time elapsed from ¾ up to this moment (ΔΡ = 0.4 bar + 1 hour) was recorded, and 56.4 g of a commercial antifoam solution (Tego® KS53 sold by Evonik) were added.
End operations
The process was performed as described in Example 6R.
Drying of the latex
Latex was coagulated, filtered and dried in an oven under vacuum at 50°C for evaluation of the thermal stability.
Evaluation of the thermal stability
The thermal stability of the dried latex (0.5 g) was evaluated using a Thermomat PVC 763 constructed by the company Metrohm.
The PVC sample heated to 180°C breaks down with evolution of HC1, which is entrained by a gas stream (7 L/h of N2) into a measuring cell where it is absorbed by ultrapure water. The HC1 concentration of this water is measured continuously by conductimetry.
The conventional thermal stability was defined as the induction time of the dehydrochlorination reaction at a temperature of 180°C leading to an increase in conductimetry of 5 μ8/αη relative to the initial value. It is expressed in minutes and seconds.
Evaluation of the yellow index
The process was performed as described in Example 6R.
Determination of the residual monomer in the latex
The process was performed as described in Example 6R.
In this example:
- the polymerization lasted 286 minutes;
- the maximum ΔΤ was 25.0°C;
- the amount of dry lumps and cakes (expressed as a percentage of the VC introduced) was 0.46;
- the thermal stability of the resin sample obtained was 7 minutes 12 seconds; - the residual monomer content in the latex was 119.6 ppm.
Example 10R (comparative)
Example 9R was repeated, except that:
in the step of loading the reagents into the reactor (1st part), copper sulfate heptahydrate was added at a rate of 0.097 g per kg of VC used (the mole ratio of copper sulfate to the initiator mixture used was thus about 0.108) and 0.0875 g, per kg of VC used, of ascorbic acid in aqueous solution form was added (the mole ratio between ascorbic acid and copper sulfate was thus about 1.27); and
at the step of polymerization, it was when a pressure reduction (ΔΡ) of 1.0 bar was detected, that the contents of the reactor were brought to a higher temperature (self -heating), that the polymerization time elapsed from to up to this moment (ΔΡ = 1.0 bar) was recorded and that 56.4 g of a commercial antifoam solution (Tego® KS53 sold by Evonik) were added.
The results of this example were as follows:
- the polymerization lasted 295 minutes;
- the maximum ΔΤ was 29.0°C;
- the amount of dry lumps and cakes (expressed as a percentage of the VC introduced) was 0.16;
- the thermal stability of the resin sample obtained was 2 minutes 48 seconds;
- the residual monomer content in the latex was 669.9 ppm.
Example 11R (comparative)
Example 9R was repeated, except that:
in the step of loading the reagents into the reactor (1st part), zinc sulfate monohydrate was added at a rate of 0.0486 g per kg of VC used (the mole ratio of zinc sulfate to the initiator mixture used was thus about 0.075) and 0.0875 g, per kg of VC used, of ascorbic acid in aqueous solution form was added (the mole ratio between ascorbic acid and zinc sulfate was thus about 1.83); and
- at the step of polymerization, it was when a pressure reduction (ΔΡ) of
1.0 bar was detected, that the contents of the reactor were brought to a
higher temperature (self -heating), that the polymerization time elapsed from to up to this moment (ΔΡ = 1.0 bar) was recorded and that 56.4 g of a commercial antifoam solution (Tego® KS53 sold by Evonik) were added.
The results of this example were as follows:
- the polymerization lasted 436 minutes;
- the maximum ΔΤ was 23.0°C;
- the amount of dry lumps and cakes (expressed as a percentage of the VC introduced) was 0.86;
- the thermal stability of the resin sample obtained was 4 minutes 12 seconds;
- the residual monomer content in the latex was 43.8 ppm.
Comparison of the results of Examples 9R, 10R and 11R with those of Example 8 shows certain advantages obtained by means of the process according to the invention, namely improved polymerization kinetics (shorter
polymerization time, higher maximumAT) and the production of a polymer latex that is characterized by a markedly lower residual monomer content, when compared with the process according to the prior art in which the water-soluble transition metal salt and the complexing agent are introduced before the start of the polymerization step.
Claims
1. Process for preparing a vinyl chloride polymer, comprising a step of polymerization of at least vinyl chloride, performed in aqueous dispersion in the presence of at least one liposoluble radical initiator and of an activating system comprising a water-soluble transition metal salt and a complexing agent, and continued up to the point of reduction of the autogenous pressure of the vinyl chloride, the said process being characterized in that the water-soluble salt is a zinc salt that is introduced at the very latest at the start of the said polymerization step, and in that the complexing agent is introduced from the start of the polymerization step and at the very latest up to the said pressure reduction.
2. Process according to Claim 1, characterized in that the polymerization step is performed in microsuspension or in seeded microsuspension.
3. Composition according to Claim 1 or 2, characterized in that the zinc salt is zinc sulfate.
4. Process according to any one of Claims 1 to 3, characterized in that the complexing agent is chosen from monocarboxylic acids, polycarboxylic acids and lactones.
5. Process according to Claim 4, characterized in that the complexing agent is chosen from sulfosalicylic acid, tartaric acid, maleic acid, and also ascorbic acid, its stereoisomer erythorbic acid, and esters thereof.
6. Process according to any one of Claims 1 to 5, characterized in that the amount of water-soluble zinc salt introduced, expressed relative to the amount of initiator present in the polymerization step, is greater than or equal to 5xl0"3 mol of zinc salt per mole of initiator.
7. Process according to any one of Claims 1 to 6, characterized in that the amount of water-soluble zinc salt introduced, expressed relative to the amount of initiator present in the polymerization step, is less than or equal to 5 mol of zinc salt per mole of initiator.
8. Process according to any one of Claims 1 to 7, characterized in that the amount of complexing agent introduced, expressed relative to the amount of water-soluble zinc salt introduced into the polymerization step, is greater than or equal to 0.1 mol of complexing agent per mole of zinc salt.
9. Process according to any one of Claims 1 to 8, characterized in that the amount of complexing agent introduced, expressed relative to the amount of water-soluble zinc salt introduced into the polymerization step, is less than or equal to 20 mol of complexing agent per mole of zinc salt.
10. Process according to any one of Claims 1 to 9, characterized in that the zinc salt of the activating system is introduced at any moment between the introduction of the first of the constituents of the medium in which the polymerization step is performed and the moment to at which the polymerization temperature is reached (to within + 1°C).
11. Process according to any one of Claims 1 to 10, characterized in that the zinc salt of the activating system is introduced with the other constituents of the medium in which the polymerization step is performed, before raising the temperature.
12. Process according to any one of Claims 1 to 11, characterized in that if we call x the time elapsed between the start of the polymerization step (moment to at which the polymerization temperature is reached (to within + 1 °C)) and the moment tx at which the reduction of the VC autogenous pressure starts, the complexing agent is introduced in a single batch at any fraction of x between ¾ and tx including addition in a single batch at to, in several successive batches of the same weight or of uniformly decreasing weight distributed over the duration x, continuously over x at a constant rate, continuously over x at a decreasing rate, continuously over a fraction of x of between ¾ and tx at a constant rate, or continuously over a fraction of x of between ¾ and tx at a decreasing rate.
13. Process according to Claim 12, characterized in that the complexing agent is introduced continuously, over x or over a fraction of x between ¾ and tx, at a constant rate or at a decreasing rate.
14. Vinyl chloride polymers obtained via a process comprising a step of polymerization of at least vinyl chloride, performed in aqueous dispersion in the presence of at least one liposoluble radical initiator and of an activating system comprising a water-soluble transition metal salt and a complexing agent, and continued up to the point of reduction of the autogenous pressure of the vinyl chloride, the said water-soluble salt being a zinc salt that is introduced at the very latest at the start of the said polymerization step, and the complexing agent being introduced from the start of the polymerization step and at the very latest up to the said pressure reduction.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR1162279A FR2984891B1 (en) | 2011-12-22 | 2011-12-22 | PROCESS FOR THE PREPARATION OF A POLYMER OF VINYL CHLORIDE |
| FR1162279 | 2011-12-22 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| WO2013092729A1 true WO2013092729A1 (en) | 2013-06-27 |
Family
ID=47469988
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/EP2012/076176 WO2013092729A1 (en) | 2011-12-22 | 2012-12-19 | Process for preparing a vinyl chloride polymer |
Country Status (3)
| Country | Link |
|---|---|
| FR (1) | FR2984891B1 (en) |
| TW (1) | TW201339180A (en) |
| WO (1) | WO2013092729A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2016056848A1 (en) * | 2014-10-08 | 2016-04-14 | 주식회사 엘지화학 | Vinyl-based thermoplastic resin composition, preparation method therefor, and vinyl-based thermoplastic resin prepared therefrom |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4091197A (en) | 1973-06-08 | 1978-05-23 | Nicolas Fischer | Process for polymerization of vinyl chloride micro-suspension with metal compounds |
| US4331788A (en) | 1979-08-28 | 1982-05-25 | Chloe Chimie | Process of polymerizing vinyl chloride in seeded microsuspension |
| US4355142A (en) | 1981-02-27 | 1982-10-19 | The B. F. Goodrich Company | Method for homogenizing monomer mixes for vinyl latex production |
| EP0826703A1 (en) | 1996-08-27 | 1998-03-04 | Elf Atochem S.A. | Latex with two-particle size populations of vinylchloride polymers, manufacturing method thereof and use in plastisols |
-
2011
- 2011-12-22 FR FR1162279A patent/FR2984891B1/en not_active Expired - Fee Related
-
2012
- 2012-12-17 TW TW101147859A patent/TW201339180A/en unknown
- 2012-12-19 WO PCT/EP2012/076176 patent/WO2013092729A1/en active Application Filing
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4091197A (en) | 1973-06-08 | 1978-05-23 | Nicolas Fischer | Process for polymerization of vinyl chloride micro-suspension with metal compounds |
| US4331788A (en) | 1979-08-28 | 1982-05-25 | Chloe Chimie | Process of polymerizing vinyl chloride in seeded microsuspension |
| US4355142A (en) | 1981-02-27 | 1982-10-19 | The B. F. Goodrich Company | Method for homogenizing monomer mixes for vinyl latex production |
| EP0826703A1 (en) | 1996-08-27 | 1998-03-04 | Elf Atochem S.A. | Latex with two-particle size populations of vinylchloride polymers, manufacturing method thereof and use in plastisols |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2016056848A1 (en) * | 2014-10-08 | 2016-04-14 | 주식회사 엘지화학 | Vinyl-based thermoplastic resin composition, preparation method therefor, and vinyl-based thermoplastic resin prepared therefrom |
| US10047180B2 (en) | 2014-10-08 | 2018-08-14 | Lg Chem, Ltd. | Vinyl-based thermoplastic resin composition, method for manufacturing thereof and vinyl-based thermoplastic resin manufactured therefrom |
Also Published As
| Publication number | Publication date |
|---|---|
| FR2984891A1 (en) | 2013-06-28 |
| FR2984891B1 (en) | 2014-01-10 |
| TW201339180A (en) | 2013-10-01 |
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