RU2575708C1 - Method of producing halogen-substituted polymers - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: method is carried out by aqueous suspension, microsuspension, emulsion or microemulsion polymerisation of at least one halogen-substituted monomer, e.g. vinyl chloride, as an independent component or combined with one or more other vinyl monomers, preferably with content of less than 50 wt % of the one or more other vinyl monomers. The method is characterised by that it includes adding at least one agent which slows down radical polymerisation, which is dialkyl-N,N-substituted hydroxylamine, and at least one perhalogenate as a bleaching agent, wherein the perhalogenate-anion counterion is selected from lithium (Li), sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), zinc (Zn), aluminium (Al), lanthanum (La) and cerium (Ce). Also disclosed is the use of the agent which slows down radical polymerisation with at least one perhalogenate, as indicated above, in the method of producing halogen-substituted polymers, as well as a composition for use in the method of producing halogenated polymers.

EFFECT: obtaining polymers with good whiteness properties and stability of whiteness.

13 cl, 1 tbl, 11 ex

Description

The present invention relates to a polymerization method (process), in particular to a method for conducting aqueous suspension or emulsion polymerization for the production of halogen-substituted polymers, in particular halogen-substituted vinyl polymers, such as polyvinyl chloride (PVC) and PVC copolymers, for example, produced with improved color in particular with a high whiteness index, wherein said method is characterized by the use of combinations of polymerization inhibitors, such as, for example, N-substitution ennye hydroxylamines.

Upon receipt of such halogenated polymers of the vinyl series, in particular polyvinyl chloride, it is important, from a commercial point of view, to obtain a better yield and better quality at minimum cost. Production costs and operational characteristics of both polymerization initiators and polymerization inhibitors can be important factors in controlling the yield and quality of the products released.

In an ideal approximation, halogen-substituted polymers and copolymers of the vinyl series, in particular PVC, should be produced with the participation of polymerization inhibitors and effective polymerization initiators, which are cheap and non-toxic. Currently, there are a large number of polymerization inhibitors that can be used in such polymerization reactions, including compounds with a structure characteristic of hydroxylamines. It was shown that they demonstrate good performance when terminating the process of radical polymerization of monomers, but there is still a wide field for improvement in the production of resins with even greater whiteness, which is less susceptible to thermal decomposition in the processing method, in particular for polymerization with using energy efficient radicals.

In some cases, yellowing of the polymers is observed, in particular, after they are shaped or processed by extrusion, injection molding, molding or calendering, as well as other types of heat treatment. This fact, in particular, occurs when certain polymerization initiators are used, in particular initiators using peroxide radicals.

By way of example, di (2-ethylhexyl) peroxydicarbonate and di (sec-butyl) peroxydicarbonate sold by Arkema under the trade names Luperox® 225 and Luperox® 223 are two initiators that are well known to those skilled in the art that are cheap and which are characterized by high efficiency, but in some cases lead to the production of PVC with an undesirable color (after shaping or processing them), in particular, when they are used with commercial polymerization inhibitors, which Some are famous and widely used.

Examples of polymerization inhibitors that are commonly used for aqueous suspension polymerization of vinyl chloride are ATSC (thiosemicarbazone acetone), bisphenol A (4,4'-isopropylidene diphenol), sodium nitrite, α-methylstyrene, butylhydroxyanisole, butylhydroxytoluene, 24, 2-product Iroxide, 4-dimethyl-6-sec-hexadecylphenol), used individually or in admixture with a product of the Irganox® 1076 brand (octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenylpropionate), a product of the Irganox® 1141 brand ( hereinafter referred to as IGX 1141), which is a commercial mixture of 80 weights s of the Irganox® 245 brand product and 20 parts by weight of the Irganox® 1076 brand product.

Compounds with a structure characteristic of hydroxylamine are also known in the industry as inhibiting radical polymerization agents for the synthesis of PVC, however, most experiments have revealed that N, N-diethylhydroxylamine (DEHA) as an independent component, even when used at high concentrations, not only cannot improve the bleaching of the resin, but also does not improve its thermal stability after processing the specified resin and, therefore, does not always lead to a whiteness value satisfying the requirements s.

US Pat. No. 3,222,334 has already shown that N, N-dialkylhydroxylamines can be used to stop the emulsion polymerization of vinyl chloride. However, none of the examples can be used to identify any specific advantage associated with the use of these N, N-dialkylhydroxylamines. This document suggests that N, N-dialkylhydroxylamines are characterized by a non-toxic and non-bleaching nature, but only with respect to their use in various rubbers, and therefore no difference can be established between the non-bleaching effect and color stabilization.

International application WO 1998/051714 describes the use of ethyl hydroxylamine as an agent inhibiting radical polymerization, also characterized by "surprising non-volatility", as well as low corrosivity and good solubility in water.

However, although this application claims the use of such agents that inhibit radical polymerization for all types of radical polymerization, only emulsion polymerization of rubbers is considered in this international application, and all examples illustrate the polymerization of such polymers.

US Pat. No. 4,749,757 describes the use of DEHA (as well as other polymerization inhibitors) in combination with a suspending agent, polyvinyl alcohol (PVA), in order to simultaneously increase the density and porosity of PVC, while maintaining a low concentration (5-10 ppm) in the reactor. However, DEHA is not offered as a radical polymerisation inhibitor for the case of PVC.

In JP 02235912, Canolo et al. describe the "product of the interaction of DEHA, cyclopentadiene and pyrogallol", which when applied to the walls of the reactor prevents the formation of sediment. This document relates to a well-known application that uses the properties of hydroxylamines in the composition of coatings in order to give the walls of polymerization reactors for the production of PVC anti-fouling properties.

US Pat. No. 6,340,729 describes the use of DEHA with certain initiators such as organic peroxides in order to improve the color and thermal stability of PVC. This patent compares the use of DEHA with other radical polymerization inhibiting agents used in everyday practice, and discusses the use of an excess of the radical polymerization inhibitor leading to yellowing of the polymer.

The use of DEHA as an agent that is capable of killing a polymerization initiator in order to halt the development of an uncontrolled polymerization of vinyl chloride is also known in the art. Due to its excellent and quick solubility in water, DEHA is able to effectively prevent the polymerization of vinyl chloride when, for example, an unexpected power outage occurs or mechanical problems arise that lead to malfunctions in the mixing system.

International application WO 2010/084130 describes systems that bind hydroxylamine derivatives with low concentrations of fully or partially spatially hindered phenolic antioxidant compounds in order to obtain a slightly colored polyvinyl chloride. However, a similar system was tested in order to obtain oligomers with a very high degree of whiteness, evaluated using standardized tests, the requirements of which are considered very stringent; there is still a wide scope for improvement.

One of the objectives of the present invention relates to the production of halogen-substituted polymers and copolymers, in particular PVC, which have good whiteness and lack of color, or at least very weak color, and which are characterized by the manifestation of only a slight or complete lack of yellowing after shaping or processing of these polymers.

In fact, under certain conditions, in particular for processing or shaping, halogen-substituted polymers and copolymers, in particular PVC, obtained using methods of production of the prior art, may have a color, usually yellowing, which may mean that the quality is not sufficient for the intended use.

The inventors have now unexpectedly discovered that it is possible to produce halogen-substituted polymers of the vinyl series, in particular PVC, with fairly good whiteness properties, in particular the stability of the whiteness index.

In the present invention, it was found that the use in a method for the production of halogen-substituted polymers and copolymers, in particular PVC, a combination of at least one radical polymerisation inhibitor and at least one perhalogenate, for example metal perhalogenate, alkali metal or alkaline earth metal, leads to the fact that halogen-substituted polymers and copolymers, in particular PVC, can be obtained with good whiteness and stability properties of whiteness.

Thus, in a first aspect, the present invention relates to the use of a combination of at least one radical polymerization inhibitor with at least one perhalogenate, for example, perhalogenate of a metal, alkali metal or alkaline earth metal, in a production method halogenated polymers and copolymers, in particular PVC. This means that the halogen-substituted polymers and copolymers used, in particular PVC, can be obtained with good whiteness and stability properties.

In a further aspect, the invention relates to a method for aqueous suspension, microsuspension, emulsion or microemulsion polymerization of at least one halogen-substituted monomer, in particular chlorinated monomers, for example vinyl chloride, as an individual component or in admixture with one or more other vinyl monomers, where preferably at a content of less than 50% by weight of one or more other vinyl monomers, characterized in that at least one inhibitory agent is added to it ikalnuyu polymerization, and, at least one perhalogenates, acting as a bleaching agent.

More specifically, the present invention relates to a method for the production of a halogen-substituted polymer or copolymer, comprising at least the following steps:

a) preparing an aqueous suspension, microsuspension, emulsion or microemulsion of at least one halogen-substituted monomer as an individual component or in a mixture with one or more other vinyl monomers, preferably with a content of less than 50% by weight of one or more other vinyl monomers;

b - carrying out the polymerization reaction;

c - stopping the polymerization by adding at least one agent inhibiting radical polymerization in the polymerization medium;

d - adding at least one perhalogenate as a bleaching agent before, during the process or after stage c to stop the polymerization; and

e - draining the liquid and drying the resulting polymer or copolymer.

In the polymerization or copolymerization production process described above, the polymerization step is preferably carried out in the presence of at least one polymerization initiator, while said polymerization reaction is preferably carried out at a temperature above ambient temperature and below 100 ° C, preferably at a temperature in the range of 45-80 ° C, more preferably in the range of 50-70 ° C.

The polymerization or copolymerization reaction is preferably carried out until the conversion of the starting monomer or monomers is in the range of 60-90% by weight, preferably in the range of 65-80%, after which at least one radical inhibiting agent is added polymerization.

An agent inhibiting radical polymerization, which can be used in the production method in accordance with the present invention, can belong to any class known to a person skilled in the art; in particular, the radical polymerization inhibitor is preferably selected from phenolic derivatives such as butylhydroxyanisole (BHA), butylhydroxytoluene (BHT), 2,4-dimethyl-6-sec-hexadecylphenol, octadecyl-3- (3,5-di- tert-butyl-4-hydroxyphenyl) propionate, as an independent component or in the form of a mixture, as well as from monoalkyl-N- or dialkyl-N, N-substituted hydroxylamines in which each alkyl radical contains 1-4 carbon atoms, for example diethylhydroxylamine , 4-OH-Tempo (1,4-dihydroxy-2,2,6,6-tetramethylpiperidine), as well as mixtures of two or olee of them in any ratio, for example a mixture of 2,4-dimethyl-6-sec-geksadetsilfenola and octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate.

Particularly preferably, monoalkyl-N- or dialkyl-N, N-substituted hydroxylamines are used in which each alkyl radical contains 1-4 carbon atoms, for example diethylhydroxylamine (DEHA), 4-OH-Tempo (1,4-dihydroxy- 2,2,6,6-tetramethylpiperidine); as well as mixtures of two or more of them in any ratio, for example a mixture of 2,4-dimethyl-6-sec-hexadecylphenol and octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate. Particularly preferably, in the context of the present invention, DEHA acts as an inhibitor of radical polymerization.

The perhalogenate used in the method according to the present invention in combination with at least one radical polymerization inhibitor can be used to produce polymers endowed with a high whiteness value. The perhalogenates that can be used can belong to any class, in particular organic or mineral perhalogenates, preferably selected from metal perhalogenates and alkali metal perhalogenates, or alkaline earth metals, most preferred, among which alkali metal or alkaline earth metal perchlorates and sodium perchlorate is highly preferred.

The method according to the present invention may also preferably comprise a step for introducing at least one polymerization initiator. This polymerization initiator (s) is (are) well known to the person skilled in the art and is preferably selected (selected) from dialkyl peroxydicarbonates, peroxy-tert-alkanoates, diacyl peroxides and alkyl-containing hydroperoxides, among others.

It has also been found that the use of at least one perhalogenate in combination with at least one radical polymerisation inhibitor having a hydroxylamine structure in a method for producing the synthesis of halogen-substituted polymers or copolymers enables an action that is quick and effective in stopping polymerization, which leads to high yields of high-quality polymers and copolymers with a low cost, and with a good whiteness indicator, minimal dyeing or even with no staining.

Thus, the total cost of production of PVC can be significantly reduced by using at least one combination in accordance with the present invention, that is, at least one radical polymerisation inhibitor and at least one perhalogenate .

In a preferred embodiment, the present invention relates to a method for the synthesis of halogenated polymers of a vinyl series and copolymers using a combination of at least one radical polymerisation inhibitor of at least one perhalogenate and using at least one peroxide type initiator selected, for example, from dialkyl peroxydicarbonates, peroxy-tert-alkanoates, diacyl peroxides and alkyl hydroperoxides, as stand-alone components or in forms f mixtures of two or more of them in any ratio.

In another aspect, the invention relates to improving the color of extruded halogen-substituted polymers and vinyl copolymers that have been subjected to molding, processing or extrusion, for example, by injection molding, molding, calendaring, etc., in particular extruded PVC, using a combination at least one agent inhibiting the radical polymerization of at least one perhalogenate in a method for the synthesis of said polymers or copolymers.

In another aspect, the present invention relates to an aqueous suspension, aqueous microsuspension or aqueous emulsion polymerization of vinyl chloride, in the form of an independent component or in the form of a mixture with one or more vinyl monomer (s), a polymerization initiator consisting of at least one organic peroxide preferably selected from dialkyl peroxydicarbonates, peroxy-tert-alkanoates, diacyl peroxides and alkyl hydroperoxides, and using as a radical inhibitor imerizatsiyu at least one mono- or dialkylhydroxylamine, and at least one perhalogenate. Polymers or copolymers obtained in this way are characterized by excellent whiteness.

In yet another embodiment, the present invention relates to a combination initiator system consisting of at least one compound selected from dialkyl peroxydicarbonates, peroxy-tert-alkanoates, diacyl peroxides and alkyl-containing hydroperoxides, and at least one radical inhibiting agent polymerization of, for example, consisting of at least one N-monoalkylhydroxylamine or N, N-dialkylhydroxylamine, as well as at least one perhalogenate, preferably at least m D, a perchlorate, said combination is used not only to stop effectively the polymerization reaction, but also to obtain, at the same time, the halogenated polymer or copolymer of the vinyl series such as PVC, with good properties of whiteness, in particular good stability whiteness index.

Thus, the invention provides a technology for aqueous suspension, microsuspension, emulsion or microemulsion polymerization of vinyl chloride as an independent component or in the form of a mixture with at least 50% by weight of another vinyl monomer in the presence of a polymerization initiator consisting of at least at least one compound selected from dialkyl peroxydicarbonates, peroxy-tert-alkanoates, diacyl peroxides and alkyl-containing hydroperoxides, and in this method the polymerization tseptura comprises at least one agent inhibiting the radical polymerization and at least one perhalogenates.

In another aspect, the present invention also relates to a polymerization control agent consisting of a combination of at least one radical polymerization inhibitor as described above, for example N-monosubstituted or N, N-disubstituted hydroxylamine with at least one perhalogenate.

The initiator system used in the suspension or microsuspension method is preferably soluble in the monomer or polymerizable monomers and, as a rule, consists of one or more compounds that are capable of forming free radicals that trigger the polymerization reaction of the specified monomer or monomers. The initiator system used in the emulsion (or microemulsion) method is usually soluble in the aqueous phase and initiates the polymerization reaction of the specified monomer or monomers.

These free radicals, as a rule, appear as a result of thermal decomposition of peroxide compounds; examples of such compounds that may be listed include diacyl peroxides, dialkyl peroxydicarbonates, peroxy tert alkanoates, and alkyl hydroperoxides.

In industrial practice, in order to express the amount of initiator (s) introduced into the reaction mixture, the total amount of active oxygen that can be released by the initiator system is expressed. The total amount of active oxygen typically used is in the range of 0.0005 parts by weight — 0.01 parts by weight, preferably in the range of 0.0015 parts by weight — 0.005 parts by weight per 100 parts by weight of monomer or monomers.

It is also possible to use a mixture of peroxide compounds, each of which is characterized by different half-lives at a given temperature, the ratio of one to the other, if possible, is 1-99% by weight, preferably 10-90%. At the same temperatures, the higher the concentration of initiator (s), the more rapid the kinetics of polymerization. Similarly, for a given polymerization time, the higher the reaction temperature, the faster the polymerisation kinetics.

Industrial methods for carrying out polymerization using, as a rule, halogen-substituted vinyl monomers are usually carried out in a batch mode, and in general it is necessary to stop the polymerization reaction after reaching a predetermined degree of conversion of said monomer or monomers in order to obtain a polymer with well-defined, unchanged characteristics. In most cases, the degree of conversion of the monomer or monomers is in the range of about 60% to about 90% by weight.

Preferred dialkyl peroxydicarbonates that can be used as polymerization initiators are those in which each alkyl radical contains 1-16 carbon atoms in an unbranched, branched or cyclic chain. Examples of the non-limiting nature of such dialkyl peroxydicarbonates are diethyl, diisopropyl, di-n-propyl, dibutyl, di-sec-butyl, dicetyl, dimyristyl, di- (4-tert-butylcyclohexyl) and di- (2 ethylhexyl) peroxydicarbonates.

Peroxydicarbonates are preferred, each alkyl radical of which contains 6-16 carbon atoms; more preferred peroxydicarbonate is di- (2-ethylhexyl) peroxydicarbonate. Dialkyl peroxydicarbonates used in the context of the present invention belong to the group of high-speed initiators. They are usually characterized by a half-life of 1 hour at a temperature of approximately 55 ° C-70 ° C and thus can be used at polymerization temperatures of vinyl chloride in the range of 45 ° C-70 ° C.

Examples of the non-limiting nature of high-speed initiators that can also be used are peroxy-tert-alkanoates, 1,1-dimethyl-3-hydroxybutyl peroxyneodecanoate, cumyl peroxyneodecanoate, 1,1,3,3-tetramethylbutyl peroxyneodecanoate, as well as 1,3-di- ( 2-neodecanoylperoxyisopropyl) benzene, tert-butyl or tert-amyl peroxyneodecanoate, tert-butyl peroxine heptanoate, 1- (2-ethylhexamyl peroxy) -1,3-dimethylbutyl peroxypivalate, 1,1,3,3-tetramethylbutyl peroxypivalate and tert-amyl -butyl) peroxypivalate. Peroxy-tert-alkanoates are high-speed initiators, which, as a rule, are characterized by a half-life of 1 hour at temperatures approximately in the range of 40 ° C-75 ° C.

It is also possible to use di-iso-butyryl-, di- (3,5,5-trimethylhexanoyl) -, dilauryl-, didecanoyl- or dibenzyl-containing peroxides as examples of the non-embarrassing nature of the fast initiators from the diacyl peroxides group; they are characterized by a half-life of 1 hour at a temperature in the range of approximately 39 ° C-92 ° C.

In the industrial method of aqueous suspension polymerization carried out in a batch mode, in general, it is necessary to stop the polymerization reaction after reaching a predetermined degree of conversion in order to obtain a polymer with well-characterized unchanged properties. It may also periodically prove necessary in order to stop or at least slow down the reaction in the final polymerization phase, i.e. when the degree of conversion reaches a value of more than 60% by weight, in order to avoid exothermic reactions upon completion of the reaction, which are difficult to control; as a rule, an agent inhibiting radical polymerization is used to stop the reaction.

Such radical polymerization inhibiting agents are well known to those skilled in the art. The most commonly used examples for the polymerization or copolymerization of vinyl chloride, which can be listed, are ATSC (thiosemicarbazone acetone), bisphenol A (4,4'-isopropylidene diphenol), sodium nitrite, α-methyl styrene, butylhydroxytoluene, butylhydroxyanisole® 24 product (brand Ir 2,4-dimethyl-6-sec-hexadecylphenol) as an independent component or as a mixture with a product of the brand Irganox® 1076 (octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate) and N , N-diethylhydroxylamine and its derivatives.

Hydroxylamine derivatives that can be used as radical polymerization inhibiting agents are preferably described by the formula HO-NR ¹ R ² , where R ¹ and R ² may be the same or different, and selected from hydrogen, hydrocarbon chains, which may be linear or branched, saturated or unsaturated, containing 1-14 carbon atoms, each hydrocarbon chain possibly substituted by one or more functional groups selected from -OH, -SO _3, benzyl, an amine group, merkaptogrup s, a keto group, a carboxyl group, or R ¹ and R ² may together form a cyclic structure (such as case piperidiniloksisoedineny), with the proviso that at least one of the radicals R ¹ and R ² is other than H.

Mixtures of two or more of these radical polymerization inhibiting agents can be used, including mixtures containing at least one radical polymerization inhibiting agent as defined above, as well as one or more other radical polymerization inhibiting agents, which known to specialists in this field. Examples that can be listed are mixtures of N, N-diethylhydroxylamine and bisphenol A.

The radical polymerization inhibiting agent, in particular the substituted hydroxylamine used in the method according to the present invention, is introduced in full, preferably in such a way as to achieve a conversion value of the monomer or monomers of 60% -90%, preferably in the range of 65% -80% s the moment when the pressure in the polymerization reactor begins to drop. Thus, the amount of radical polymerization inhibiting agent, in particular mono- or dialkylhydroxylamine to be used, can vary in the range of 0.0005-0.1 parts by weight, preferably in the range of 0.001-0.05 parts by weight per 100 parts by weight of monomer or monomers to be polymerized.

The radical polymerization inhibiting agents that can be used in the context of the present invention are preferably selected from dialkylhydroxylamines, most preferably from dialkylhydroxylamine, which is N, N-diethylhydroxylamine because of its solubility in water, the high yield induced by it, and also because the fact that it is widely commercially available.

Polymers that can be prepared using the process of the present invention include, but are not limited to, polyvinyl chloride. The invention can be applied in the same way to any halogen-substituted polymer or halogen-substituted copolymer, examples of the non-limiting nature that can be listed can be polyvinylidene fluoride, polyvinyl fluoride, PTFE and others.

In accordance with the present invention, at least one radical polymerization inhibitor is used in combination with at least one alkali metal or alkaline earth metal perhalogenate, the term "combination" means simultaneous, separate or sequenced introduction into the reaction polymerization medium.

This “combination” may also include any type of additives used in everyday practice in the art, for example additives to improve the thermal stability of halogenated polymers.

Perhalogenates that can be used in the context of the present invention are generally described mainly by the structural formula of the form M (XO ₄ ) _n , in which X represents a halogen atom, M represents a counterion of an anion perhalogenate, and index n represents the valency of a counterion M; typically n is 1, 2 or 3.

The halogen atom X in the perhalogenate compound used in the present invention is selected from a fluorine atom (in the case of perfluorates), a chlorine atom (in the case of perchlorates), a bromine atom (in the case of perbromates) and an iodine atom (in the case of periods). Particularly preferred perhalogenates in the present invention are perchlorates of the formula M (ClO ₄ ) _n .

The counterion M can be of any kind known to a person skilled in the art, for example, can be selected from metals, alkali metals, alkaline earth metals, rare earth elements and others. More specifically, the counterion M is selected from lithium (Li), sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), zinc (Zn), aluminum (Al ), lanthanum (La) and cerium (Ce). Obviously, mixtures of two or more perhalogenates can be used in the method according to the present invention.

Perhalogenates can be used in the form of solutions or in the form of complexes with one or more alcohols (polyols, cyclodextrins), ether alcohols or alcohol-containing esters. Alcohol-containing esters also include partial esters of polyhydric alcohols, examples of which can be listed and are glycerol monoesters and glycerol monothioesters. Other compounds are also described in patents EP 0394547, EP 0457471 and WO 1994/24200.

Alcohols can also be polyhydric alcohols (or polyols), their dimers, trimers, oligomers and polymers, such as, for example, di-, tri-, tetra- and polyglycols, as well as di-, tri- and tetrapentaerythritol or vinyl alcohol polymers , regardless of the degree of their polymerization. Other possible solvents for perhalogenates that can be used in the method according to the present invention are phosphates, as well as cyclic and acyclic carbonates.

In this context, perhalogenates, in particular perchlorates, can be used in various forms, for example, in the form of salts or solutions in water and / or in one or more organic solvents, or even adsorbed on a base material such as PVC, silicates calcium, zeolites or hydrotalcites, or they can be connected after a chemical reaction by at least one hydrotalcite or other compounds with a layered structure.

Particularly preferred perhalogenates are potassium, sodium and calcium perchlorates, in a more particular case, preferably sodium perchlorate and / or potassium perchlorate. As an example, in the context of the present invention, sodium perchlorate sold by Arkema may be used in the form of a solution in water at a content of about 70% by weight.

Additives that can be used to improve thermal stability are well known to those skilled in the art under the term thermal stabilizers or thermal joint stabilizers used for halogen-substituted polymers and can be used in combination with or independently of the combination of an “anti-radical polymerization inhibitor / perhalogenate” "As described in the present invention. Such stabilizers or shared stabilizers are described, for example, in patent WO 2006/058789.

Examples of additives that can be used to improve the thermal stability that can be listed are mercaptocarboxylic acids, for example 2-ethylhexyl mercapto acetic acid and thioglycolic acid, and esters thereof; alkali metal carbonates, for example sodium carbonate; β-diketones; epoxidized vegetable oils, for example epoxidized soybean oil, epoxidized linseed oil; phosphites; β-ketone esters; metal or soap salts, in particular stearates, for example, calcium, barium and / or zinc stearates, adipates, for example disodium adipate; derivatives of aminouracil and / or thiouracil; hydrazides; mineral compounds such as hydrotalcites or zeolites; alcohols and polyhydric alcohols, in particular alcohols derived from saccharides; glycidyl derivatives of α-phenylindole; compounds of the dihydropyridine type, such as those described in patent documents FR 2429806, EP 0027439 or WO 2002/092686, and in particular dihydropyridine and poly (dihydropyridine) derivatives, more specifically dihydro-1,4-dimethyl-2,6-dicrbododecyloxy -3,5-pyridine (a product of the brand Stavinor® D507, manufactured by Arkema) or thiodiethanol bis- (5-methoxycarbonyl-2,6-dimethyl-1,4-dihydropyridine-3-carboxylate) (a product of the brand Synesal® M, production company Lagor); enamines, for example, those described in patent document DE 10118179; typical alkanolamine derivatives, etc., used as independent components or in the form of a mixture of two or more of them in any ratio.

More specific thermal stabilizers and thermal stabilizers of the type of polyols that can be listed are polyols and alcohols derived from disaccharides selected from pentaerythritol, dipentaerythritol, tripentaerythritol, trimethylol ethane, trimethylol propane, bis-trimethylol ethane, bis-trimethylol including inositol), polyvinyl alcohols, hexites (including sorbitol), maltites, isomaltites, cellobiite, lactitol, lycasin, mannitol, lactose, leukemia, tris (hydroxyethyl) iso cyanurate, tris- (hydroxypropyl) isocyanurate, palatinite, tetramethylolcyclohexanol, tetramethylol cyclopentanol, tetramethylol cyclopropanol, xylitol, pentites (including arabinite), tetrites, glycerol-diglycerol, polyglycerol-d-iodine-diode mannitol dihydrate. Of these compounds, disaccharide alcohols are particularly preferred.

Hydrotalcites that can be used as shared stabilizers are well known to those skilled in the art and are described, for example, in patent document DE 3581384, patent document EP 0062813 and patent document WO 1993/20135.

More specifically, compounds belonging to the hydrotalcite family can be represented by the following general formula:

G ²⁺ _1-x G ³⁺ _x (OH) ₂ (An ^b- ) _{x / b} dH ₂ O,

where G ²⁺ represents one or more metals selected from the group consisting of Mg, Ca, Sr, Zn and Sn;

G ³⁺ represents an aluminum atom (Al) or a boron atom (B);

An is an anion with valency n;

b is a number in the range of 1-2, including limits;

0 <x <0.5; and

d is a number in the range of 0-300, including limits, preferably in the range of 0.5-30, including limits;

and preferably An is selected from OH ^- , ClO ₄ ^- , HCO ₃ ^- , CH ₃ COO ^- , C ₆ H ₅ COO ^- , CO ₃ ^2- , (СНОСОСО) ₂ ^2- , (СН ₂ СОО) ₂ ^2- , CH ₃ CHOHCOO ^- , HPO ₃ ^- and HPO ₄ ^2- . Examples that fully satisfy the requirements of the present invention are Al ₂ O ₃ 6MgOCO ₂ · 12H ₂ O (i), Mg _4,5 Al ₂ (OH) ₁₃ CO ₂ · 3,5H ₂ O (ii), 4MgOAl ₂ About ₃ CO ₂ · 9H ₂ O (iii), 4MgOAl ₂ O ₃ CO ₂ · 6H ₂ O, ZnOZMgOAl ₂ O ₃ · CO ₂ and O ₂ 8-9N ZnOZMgOAl ₂ O ₃ · CO ₂ 5-6N ₂ O; of which the most preferred hydrotalcites are those indicated by the above footnotes i, ii and iii.

As indicated above, the hydrotalcite anion may be a perchlorate anion, and in this case represents a preferred embodiment of the invention. In the case where the additive for stabilization or for joint stabilization is hydrotalcite with a perhalogenate anion, in particular perchloratanion (ClO ₄ ^- ), the latter can be preferably partially or completely substituted by perhalogenates used as a bleaching agent in combination with an agent, inhibiting radical polymerization, in the method according to the present invention.

Stabilizers or shared stabilizers can also be selected from zeolites that are known to the person skilled in the art, in particular with the general formula:

T _{x / n} [(AlО ₂ ) _х (SiО ₂ ) _у ] wH ₂ О,

where T is an alkali or alkaline earth metal, preferably selected from Li, Na, K, Mg, Ca, Sr and Ba;

n represents a charge of cation T;

y: x represents a number in the range of 0.8-15, including limits, preferably in the range of 0.8-1.2, including limits; and

w is an integer in the range of 0-300, including limits, preferably in the range of 0.5-30, including limits.

Suitable examples of zeolites include sodium aluminosilicates A of zeolites, sodalite, Y zeolite, X zeolite, LSX type zeolite; as well as zeolites made by partial or complete replacement of sodium ions by Li, K, Mg, Ca, Sr or Zn ions, as well as P, MAP zeolites and other zeolites obtained after partial or complete replacement of sodium ions by Li, K or H ions such as KF zeolites, D-zeolites and others.

Examples of phosphites (phosphorus triesters), thiophosphites and thiophosphates that may be listed are triphenylphosphite, diphenylalkylphosphites, phenyl dialkylphosphites, tris- (nonylphenyl) phosphite, trilaurylphosphite, trioctadecylphosphite, distearyl-diphenyl-diphenyl-diphenyl-diphenyl-diphenyl-diphenyl-diphenyl-diphenyl-diphenyl-diphenyl-diphenyl-diphenyl-diphenyl-diphenyl-diphenyl-diphenyl-diphenyl-diphenyl-diphenyl-diphenyl-diphenyl-diphenyl-diphenyl-diphenyl-diphenyl-diphenyl-phosphonate , diisodecylpentaerythritol diphosphite, bis- (2,4-di-tert-butylphenyl) pentaerythritol diphosphite, bis- (2,6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphite, bis (isodecyloxy) pentaerythritol diphosphite, bis ( -di-tert-butyl-6-methylphenyl) pentaerythritol diphosph t, bis- (2,6-tri-tert-butylphenyl) pentaerythritol diphosphite, tri-searyl sorbitol triphosphite, bis- (2,4-di-tert-butyl-6-methylphenyl) methylphenyl) methylphosphite and bis (2,4-di tert-butyl-6-methylphenyl) ethylphosphite.

Particularly preferred compounds are trioctyl-, tridecyl-, tridedecyl-, tri-tetradecyl-, tristearyl-, trioleyl-, triphenyl-, tricresyl-, tris-p-nonylphenyl- and tricyclohexylphosphites, even more preferred are aryldialkyl- and alkyl-diaryl of compounds - phenyl didecyl phosphite, 2,4-di-tert-butyl phenyl di-dodecyl phosphite, 2,6-di-tert-butyl phenyl diodecyl phosphite and dialkyl and diaryl pentaerythritol diphosphites, such as distearyl pentaerythritol diphosphites, as well as non-stoichiometric tri formula, for example, (H ₁₉ C ₉ -C ₆ H ₄₎ O _1-5 P (OC _25,27 H _{12.13) 1.5,} or (C ₈ H _l7 -C ₆ H ₄₎ O ₂ P ( iC ₈ H ₁₇ O), or even (H ₁₉ C ₉ -C ₆ H ₄ ) O _1.5 P (OC _9.11 H _19.23 ) _1.5 .

Preferred organic phosphites are distearyl pentaerythritol diphosphites, tris-nonylphenyl phosphite and phenyl didecyl phosphite. Other phosphites that can be used are phosphoric diesters (with the radicals defined above) and phosphoric monoesters (with the radicals defined above), optionally in the form of their salts with alkali metals, alkaline earth metals, zinc or aluminum salts. These phosphoric esters can also be used as an “aluminum-salt” compound, as described, for example, in patent document DE-A-4031818.

Examples of β-diketones and β-ketoesters that can be used that can be listed are linear or cyclic 1,3-dicarbonyl compounds. It seems preferable to use dicarbonyl compounds with the following formulas: R ' ₁ COCHR' ₂ -COR ' ₃ , in which R' ₁ represents a C ₁ -C ₂₂ alkyl radical, a C ₅ -C ₁₀ hydroxyalkyl radical, C ₂ -C ₁₈ alkenyl radical, a phenyl radical, HO-group, C ₁ -C ₄ alkyl radical, a C ₁ -C ₄ alkoxy or fenillny radical substituted by halogen atom (s), a C ₇ -C ₁₀ -fenilalkilny radical, C ₅ - A C ₁₂ cycloalkyl radical, a C ₅ -C ₁₂ cycloalkyl radical, a substituted C ₁ -C ₄ alkyl (s) radical (s), or an —R ′ ₅ -S-R ′ ₆ or R ′ ₅ -O-R ′ ₆ group; in which R ' ₂ represents a hydrogen atom, a C ₁ -C ₈ alkyl radical, a C ₂ -C ₁₂ alkenyl radical, a phenyl radical, a C ₇ -C ₁₂ alkyl phenyl radical, a C ₇ -C ₁₀ phenylalkyl radical or a group —CO — R ′ ₄ , the group R ′ ₃ is as defined for the group R ′ _1, or is a C ₁ -C ₁₈ alkoxy radical, the group R ′ ₄ is a C ₁ -C ₄ alkyl radical or phenyl radical, the R ′ ₅ group is a C ₁ -C ₁₀ alkyl radical and the R ′ ₆ group is a C ₇ -C ₁₈ alkyl phenyl radical, a C ₇ -C ₁₈ alkyl phenyl radical or a C ₇ -C ₁₀ phenyl alkyl radical.

Such compounds include the hydroxylated diketones described in patent document EP 0346279 and the oxo and thiodiketones described in patent document EP 0307358, as well as the isocyanic acid ketoesters described in patent document US 4339383. Examples of mercaptocarboxylic acid esters include thiol esters thioacid, mercaptopropionic, mercaptobenzoic and thiolactic acids, mercaptoethyl stearate and mercaptoethyl oleate, such as the compounds described in patent document FR 2459816, patent d Document EP 0090748, patent document FR 2552440 and patent document EP 0365483. The species definition of esters of mercaptocarboxylic acids also includes polyol esters and their partial esters, as well as their thioether derivatives. These molecules can also be latent mercaptides, such as mercaptides, which are described, for example, in patent document EP 0945485.

Examples of the non-limiting nature of metal-containing soaps that can be used as stabilizers or shared stabilizers in the context of the present invention include metal carboxylates of relatively long chain carboxylic acids. Typical examples are stearates and laurates, as well as oleates and salts of shorter chain carboxylic acids. Alkylbenzoic acids are also included as examples of metal-containing soaps.

Examples of metals that can be listed are Li, Na, K, Mg, Ca, Sr, Ba, Zn, Al, La, Ce, and rare earth metals. Often can also be used those metals that are known to form synergistic mixtures, such as mixtures of barium / zinc, magnesium / zinc, calcium / zinc, or calcium / magnesium / zinc stabilizers. Metal-containing soaps can be used as stand-alone components or in the form of mixtures. A list of commonly used metal-containing soaps is provided in Ullmann's Encyclopedia of Industrial Chemistry, 5 ^th Ed., Vol. A16 (1985), p. 361 ff. It seems advisable to use metal-containing soaps belonging to the C ₂ -C ₂₂ family of saturated aliphatic carboxylates, C ₃ -C ₂₂ unsaturated aliphatic carboxylates, C ₂ -C ₂₂ aliphatic carboxylates substituted by at least one OH group, cyclic and bicyclic carboxylates containing 5-22 carbon atoms, benzene carboxylates, unsubstituted or substituted by at least one OH group and / or C ₁ -C ₁₆ alkyl radical; naphthalenecarboxylate, not substituted or substituted by at least one OH group and / or C ₁ -C ₁₆ alkyl radical, phenyl-C ₁ -C ₁₆ -alkilkarboksilatov, naphthyl-C ₁ -C ₁₆ -alkilkarboksilatov or phenoxides, unsubstituted or substituted by a C ₁ -C ₁₂ alkyl radical; tallats and resins.

The mentioned examples that can be listed are zinc, calcium, magnesium or barium salts of monobasic carboxylic acids, such as acetic, propionic, butyric, valerianic, caproic, cenanthic (cenanthic), octane, neodecanoic, 2-ethylhexane, pelargonoic, decanoic undecanoic, dodecanoic, tridecanoic, myristic, palmitic, isostearic, stearic, 12-hydroxystearic, behenic, benzoic, p-tert-butylbenzoic, 3,5-di-tert-butyl-4-hydroxybenzoic, tolubyl, dimethyl, ynaya, n-propilbenzoynaya, salicylic, p-tert-oktilsalitsilovaya and sorbic acid; calcium, magnesium or zinc salts of monoesters of dibasic carboxylic acids, such as oxalic, malonic, succinic, glutaric, adipic, fumaric, pentane-1,5-dicarboxylic, hexane-1,6-dicarboxylic, heptane-1,7-dicarboxylic, octane -1.8-dicarboxylic, phthalic, isophthalic, terephthalic and hydroxyphthalic acids; and also diesters or triesters of tri- or tetra-basic carboxylic acids, such as hemimellitic, trimellitic, pyromellitic or citric acid.

Calcium, magnesium and zinc carboxylates obtained from carboxylic acids containing 7-18 carbon atoms (metal salts, in the narrow sense), such as, for example, benzoates or alkanoates, preferably stearates, oleates, laurates, palmitates, behenates, are particularly preferably used. , hydroxystearates, dihydroxystearates, or 2-ethylhexanoates. Stearates, oleates and p-tert-butyl benzoates are particularly preferred. Overbased carboxylates, such as overbased zinc octoate, are also preferred. Similarly, overbased calcium soaps are also preferred. If necessary, mixtures of carboxylates of various structures can also be used. In this case, compositions, such as those described above, consisting of an organozinc and / or organosalicon compound are preferred.

Other noteworthy representative examples of metal-containing soaps or salts that may be listed are the bimetallic salts of dicarboxylic acids, such as dilithium, disodium or dipotassium salts of dibasic carboxylic acids, such as oxalic, malonic, succinic, glutaric, adipic, fumaric, p 1,5-dicarboxylic, hexane-1,6-dicarboxylic, heptane-1,7-dicarboxylic, octane-1,8-dicarboxylic, phthalic, isophthalic or terephthalic acid. Disodium adipate is particularly preferred.

Other metal-containing stabilizers and shared stabilizers that may be listed are organometallic stabilizers, in particular organotin stabilizers. These stabilizers can be represented, in particular, by carboxylates, maleates, mercaptides and sulfides. Examples of such compounds are described in patent document US 4743640, patent document US 2567651, patent document US 2598936, patent document US 2567652, patent document US 6174941, patent document US 5925696, patent document US 6156830, patent document US 6084013, patent document US 6194494, US patent 4105627, US patent 4352903, as well as DE 2427853. Specific examples of aminouracils that can be listed are the structures described in US patent 4656209, US patent 5859100, patent document US 5925696, as well as in patent document US 6084013.

The term "aqueous suspension or microsuspension polymerization" means a polymerization carried out in the presence of at least one initiator, which is oil-soluble, and at least one unsaturated halogen-substituted monomer, for example, vinyl chloride, used as an independent component, or in the form mixtures with another vinyl monomer dispersible using any mechanical means in an aqueous medium containing at least one suspending agent.

The percentage of vinyl monomer in the suspension, as a rule, is at least 50% by weight, preferably more than 80% with respect to the total weight of the suspension. A percentage of vinyl monomer of less than 50% by weight relative to the total weight of the suspension may, however, also be contemplated in the context of the present invention.

Vinyl monomers that can be copolymerized in an aqueous suspension with a vinyl halide, in particular vinyl chloride, are well known to those skilled in the art; examples of the non-limiting nature of these compounds that may be listed are vinyl esters such as vinyl acetate, vinylidene halides such as vinylidene chloride and vinylidene fluoride, acrylic esters such as butyl acrylate, and methacrylic esters such as methyl methacrylate.

Dispersing or suspending agents, typically used in suspension polymerization, are also well known to those skilled in the art and, in particular, are selected from protective colloids, for example, water-soluble polymers, such as polyvinyl alcohols, polyethylene oxides, water-soluble cellulose derivatives, such as methyl cellulose, poly (vinylpyrrolidone), acetate copolymers of gelatin and vinyl / maleic anhydride and others, as well as from mixtures of two or more of these compounds in any percentage.

These suspending agents can be used as individual components or in the form of mixtures in amounts, typically in the range of 0.01-0.5 parts by weight, preferably in the range of 0.04-0.2 parts by weight per 100 parts by weight of monomeric component (s).

The method according to the present invention can also be carried out using a buffer system in order to control the pH of the reaction medium during the polymerization. Essentially, the pH of the aqueous medium is, for example, about 6-7 at the start of the reaction and can drop to about 3.5 as a result of the appearance of hydrohalic acid, in particular hydrochloric acid, in the reaction medium. Thus, in the context of the present invention, it is preferable, but not necessary, to buffer an aqueous suspension.

Typical buffer systems that can be used may include, but are not limited to, those systems that contain carbonate, bicarbonate, phosphate, or citrates. The pH range of the buffer system is in the range of 5-8, preferably in the range of 5.5-7.5. The buffer system is typically used in an amount in the range of 0.01-0.2 parts by weight, preferably in the range of 0.02-0.1 parts by weight per 100 parts by weight of monomer (s).

In another embodiment, the method according to the present invention can also use at least one antioxidant that is added to the reaction medium either at the initial moment of the reaction or when the desired conversion value is achieved. At least one antioxidant can be introduced into the reactor at a time or in several batches, or continuously during the polymerization reaction.

Preferred antioxidants that are known to those skilled in the art that can be used in the method of the present invention are antioxidants containing phenolic groups, preferably spatially hindered phenolic groups; non-limiting examples are compounds selected from butylhydroxyanisole, butylhydroxytoluene, Ciba's Irganox® 1076, Ciba's Irganox® 245, and lsonox® 132 (2,6-di-tert-butyl-4-sec-butylphenol) manufactured by Schenectady Chemical. The amount of antioxidant can vary in the range of 10-1000 ppm, more preferably in the range of 25-300 ppm.

The polymerization reaction of the production method according to the present invention can be carried out at any temperature adapted to the suspension, microsuspension, emulsion or microemulsion polymerization reaction, preferably in the temperature range of 45 ° C-80 ° C, more preferably in the temperature range of 50 ° C-70 ° C , which makes it possible to use a very wide range of polymerization initiators. If the selected polymerization temperature is not very large (for example, in the temperature range 30 ° C-50 ° C), it may be useful to use a combination of different initiators characterized by a half-life in the selected temperature range, consisting, for example, of a combination of dialkyl peroxydicarbonate and an initiator of groups of peroxy-tert-alkanoates, or combinations of various initiators from the group of peroxy-tert-alkanoates consisting of peroxy-tert-alkanoate and another peroxide-tert-alkanoate.

In the case when the selected value of the polymerization temperature is slightly higher (in the range of 55-65 ° C), it may seem appropriate to use a combination of various initiators characterized by a half-life at a selected temperature value, consisting of, for example, dialkyl peroxydicarbonate initiators from the group of peroxy-tert- dialkanoates, or a combination of peroxy-tert-alkanoates.

The peroxy-tert-alkanoates listed above are typically characterized by a half-life of 1 hour in the temperature range of 40-75 ° C and, thus, can be used at polymerization temperatures of vinyl chloride in the range of 50-70 ° C. Examples of the non-limiting nature of such peroxy tert alkanoates that may be listed are tert-butyl and tert-amyl peroxy tert alkanoates.

In the case of a relatively high polymerization temperature (in the range of 62-70 ° C), it may be appropriate to use a combination of various initiators characterized by a half-life at a selected temperature, consisting of, for example, dialkyl peroxydicarbonate or peroxy-tert-alkanoate initiator and a slow-acting initiator (long half-life) from the group of diacyl peroxides, such as dilauroyl peroxide.

The method according to the invention can be carried out using any method that is known to specialists in this field, consisting, for example, in dissolving a protective colloid in an aqueous medium or in a monomer, dispersing fat-soluble polymerization initiators in an aqueous medium or dissolving it in a monomer component, as well as not necessarily in dissolving the buffer system to regulate or control the pH of the reaction medium.

Trace amounts of oxygen are preferably eliminated in order to result in a residual amount of oxygen dissolved in water in the range of 0.0005-0.05 parts by weight, preferably in the range of 0.001-0.02 parts by weight per 100 parts by weight of water. At least one monomer to be polymerized is then introduced into the reactor, and the reaction mixture is stirred and heated to a temperature in the range of 45-80 ° C, preferably in the range of 50-70 ° C.

During the polymerization production process, it is not necessary to maintain the pressure and temperature of the reaction mixture at a constant level. An increase in the programmed temperature either at the beginning or at the end of the polymerization cycle leads to the fact that the rate of decomposition of the initiators and the degree of polymerization can be increased. In the event that the temperature and pressure are maintained at a constant level, the polydispersity of the molecular weights of the polymer chains is in the range of 1.8-2.5. In the case of polymerization with a programmed gradient temperature change during the polymerization, it is possible to observe polydispersity values in the range of 1.8-3.5. These practical points are well known to specialists in this field.

The polymerization reaction ends upon the depletion of the liquid monomer phase, which is characterized by a modification of the liquid monomer / vapor equilibrium, as well as a drop in reaction pressure. Immediately before the reaction pressure drops, the conversion value by weight of the monomer is typically in the range of 65-85%. In the case when the desired value of the degree of conversion is achieved, the agent inhibiting the radical polymerization is introduced into the reactor in order to destroy or make inactive any residual traces of the initiator.

After the polymerization is completed, the resulting polymer is separated from the aqueous medium, and then drained and dried. The resulting polymer, in particular in the case of a suspension or microsuspension process, is usually in the form of particles with a size, which, as a rule, is in the range of 80-250 microns.

In a preferred embodiment of the invention, the suspension polymerization of vinyl chloride is carried out using methods that are well known to those skilled in the art, using, in an optimized manner, a certain amount of a peroxydicarbonate type initiator (or a mixture of initiators, including peroxydicarbonate and a fast ester), then the polymerization is stopped by adding, during the pressure drop, an agent that inhibits radical polymerization, such as alkyl hydroxylamine; their numbers are based on empirical dependence.

In the method according to the present invention, it was found that the addition of at least one perhalogenate in combination with at least one radical polymerization inhibitor to the polymerization reaction medium results in a polymerization product which has excellent whiteness properties compared to the same polymerization products obtained without adding perhalogenate.

The addition of at least one perhalogenate to the polymerization reaction medium can be carried out at the beginning, in the course or at the end of the polymerization reaction, preferably in the course or at the end of the reaction, more preferably at the end of the reaction.

In the case where at least one perhalogenate is added at the end of the reaction, it can be added before, during or after the addition of an agent inhibiting radical polymerization. More specifically, perhalogenate or perhalogenates, as well as an agent inhibiting radical polymerization, or agents inhibiting radical polymerization, can be added simultaneously, sequentially or separately, preferably simultaneously.

The amount of added perhalogenate (s) can vary widely, but it is generally preferable to add this amount in the range of 0.1-10 mol perhalogenate (s) per 1 mol of an agent inhibiting radical polymerization; preferably, this amount is in the range of 0.5-5 mol, more preferably in the range of 0.5-2 mol. Fully satisfactory whiteness properties are obtained, for example, using one mole of perhalogenate (s) per mole of agent inhibiting radical polymerization.

In a more preferred embodiment, the peroxide used is di-2-ethylhexylperoxydicarbonate, the radical polymerization inhibitor is dialkylhydroxylamine, preferably N, N-diethylhydroxylamine (DEHA), and the perhalogenate is sodium perchlorate.

In accordance with another aspect, the present invention relates to a composition comprising at least one radical polymerization inhibitor and at least one perhalogenate, preferably at least one alkali metal or alkaline earth metal perhalogenate .

This composition can advantageously be used in methods for the production of polymerization and copolymerization of halogen-substituted vinyl monomers, as described above. This composition mainly contains at least one hydroxylamine derivative, for example diethyl hydroxylamine, and at least one perhalogenate, for example, sodium perchlorate.

The composition according to the present invention may also consist of one or more additives and / or solvents, for example, selected from water, alcohols, stabilizers and shared stabilizers (in particular thermal stabilizers and shared stabilizers described above), dyes and other additives and solvents known to those skilled in the art.

A particularly preferred composition consists of and, more preferably, includes at least one radical polymerisation inhibitor, at least one perhalogenate, at least one thermal stabilizer and / or a shared stabilizer selected from antioxidants, metal salts, mercaptocarboxylic acids, betadiketones, epoxidized oils, phosphites, aminouracil derivatives, mineral stabilizers, compounds such as dihydropyridine and water; as an example of a non-limiting nature, the composition according to the present invention consists of and preferably includes diethyl hydroxylamine, sodium perchlorate and water.

A composition that can be used to produce PVC with excellent thermal stability and excellent whiteness usually consists of:

5-40% by weight of diethylhydroxylamine, preferably 10% -30% by weight, for example, approximately 20% by weight;

5-40% by weight of sodium perchlorate, preferably 10% -30% by weight, for example, approximately 20% by weight;

- not necessarily, up to 20% by weight of one or more stabilizers and / or shared stabilizers; as well as

- in addition to 100% by weight of water.

The following examples serve to illustrate the present invention described above, and are not intended to limit the present invention to the scope of the precise embodiments described in the context of this document. Many other variations and modifications are possible in light of the above description and the above examples, which follow.

EXAMPLE 1: (Comparative) Production of C-PVC (suspension method)

[60 kg of demineralized water, 204.5 g of polyvinyl alcohol with a degree of hydrolysis of 88 mol%, 153.1 g of polyvinyl alcohol with a degree of hydrolysis of 72 mol%, 90.5 g of an aqueous solution (containing 40% of active substance) of polyvinyl alcohol with a degree of hydrolysis 55 mol% and 549 g of an emulsion of di (2-ethylhexyl) peroxydicarbonate, consisting of 60% of the active substance (product of the brand Luperox ^TM 223 EN60H manufactured by Arkema) were introduced into a reactor with a capacity of 1200 liters. The components listed above were introduced at ambient temperature and with stirring (100 rpm) into a 1200-liter reactor, which is equipped with a turbine-type three-blade mixing device, a heating jacket, an injection device and a condenser.

After closing the reactor, a partial vacuum (6.66 kPa) was pumped in it and the vacuum was maintained for 15 minutes. Stirring was then accelerated to 265 rpm and the pumps were turned on at the same time to inject 362 kg of vinyl chloride and 286 liters of hot water at 95 ° C. The vinyl chloride injection period was measured at 12 minutes. The hot water injection period was measured at 15 minutes. The temperature at the time the download was completed was approximately 50 ° C.

Heating was controlled by circulating a cold water / hot water mixture by adjusting the temperature in the heating jacket, so that the polymerization temperature reached 56.5 ° C after 10 minutes. The moment when the temperature of the polymerization medium reached the level of 56.5 ° C was considered the beginning of polymerization (= time t0), and the pressure value at this time (P0) was taken as the comparison value.

After 5 minutes of polymerization (i.e., time period t ₀ +5 min) was continuously fed 200 kg water in the reactor at a constant flow rate of 75 kg / h speed in order to improve the heat exchange while maintaining constant the exchange surface area heating jacket and in order to reduce the viscosity of the aqueous suspension.

After 7 minutes of polymerization (i.e., a period of time t ₀ +7 min), the condenser was activated in order to carry out heat transfer and to maintain the temperature in the reactor at a constant level. The actuation of the condenser was linear with the goal of achieving, after 30 minutes (i.e. a period of time t ₀ +37 min), a constant value of the heat transfer coefficient of 20,000 kcal / h

The depletion of the gas phase (monomer) in the reactor was expressed as a pressure drop with a conversion value of 65-70%. At the moment when the pressure dropped to 3 bar, in comparison with P0, the cooling of the polymerization medium by means of a condenser was stopped and the polymerization temperature increased. This increase was controlled by adjusting the cooling of the heating jacket. This control suggested that the temperature of the polymerization medium can be increased in the usual manner.

As soon as the temperature reached 65 ° C, the polymerization was stopped. This last stage of polymerization, until the temperature reached 65 ° C, was called thermal shock (TU). The end of the TU stage corresponded to the achievement of this temperature value of 65 ° C. The polymerization was then stopped by the addition of an aqueous 85% diethyl hydroxylamine solution (DEHA), which was introduced into the reaction medium for 1 minute. The amount added corresponded to 115 ppm by weight of DEHA relative to the initial weight of the monomer. The reaction medium was kept for 1 minute at a temperature of 65 ° C before being cooled. Rapid cooling of the medium was carried out using cold water supplied to the heating jacket.

Residual monomer was then removed from the reaction medium using standard techniques, for example, by returning the system to atmospheric pressure (degassing), and trace amounts of monomer were then removed by degassing under vacuum of 13.33 kPa at a temperature of 50 ° C (removal by distillation).

The PVC suspension thus obtained was then poured using a rotary centrifuge. Wet powdered PVC was then dried for 12 hours in a rotary vacuum convection drying unit heated to a temperature of 60 ° C. Dry powdered PVC was then sieved through 500 μm sieves.

The whiteness index (BF) of this oligomer was evaluated by measuring BF using a Minolta Konica CM2500D colorimeter in accordance with ISO 2470. The new value of the BF whiteness value for this thermally processed oligomer was obtained using the same measurement procedure.

Heat treatment was carried out using a crystallizer made of borosilicate glass with an outer diameter of 70 mm, a height of 40 mm, and a weight of 45 g, containing 9.5-10.5 g of a PVC oligomer in a Heraeus UT6 model of forced air convection oven. The furnace was heated to a stable temperature of 160 ° C. The mold was then placed in the center of the furnace and subjected to this temperature for 10 minutes.

The oligomer was then cooled in a desiccator and sieved through 250 μm sieves. The resin was considered ready for PB measurements following heat treatment.

EXAMPLE 2: (Comparative) Production of C-PVC (suspension method)

The polymerization was carried out in the same manner as in Example 1, with the exception that at the end of the TU stage, aqueous 50% sodium perchlorate (NaClO ₄ ) was introduced into the reaction medium for 1 minute. The amount introduced corresponded to 115 ppm by weight of NaClO ₄ relative to the initial weight of the monomer. The reaction medium was maintained at 65 ° C for 1 minute before being cooled. Degassing, stripping, emptying, centrifuging, drying and sieving were then performed in the same manner as in Example 1, and the polymer resins thus obtained were evaluated by a PB test using the same criteria.

EXAMPLE 3: Production of C-PVC (suspension method)

The polymerization of vinyl chloride was carried out using the procedural algorithm from Example 1, but with the difference that instead of DEHA as an independent component, a mixture consisting of DEHA, sodium perchlorate and water in appropriate proportions by weight 20/20/60 was added. The amount added corresponded to 575 ppm by weight of mixture A relative to the initial weight of the monomer. The reaction medium was maintained at 65 ° C for 1 minute before being cooled. Degassing, stripping, emptying, centrifuging, drying and sieving were then performed in the same manner as in Example 1, and the polymer resins thus obtained were evaluated by a PB test using the same criteria.

EXAMPLE 4: Production of C-PVC (suspension method)

The polymerization of vinyl chloride was carried out using the procedural algorithm from Example 1, but with the difference that after adding DEHA was added an aqueous solution of sodium perchlorate. The amount added corresponded to 115 ppm by weight of DEHA and 115 ppm by weight of NaClO ₄ with respect to the initial weight of the monomer. The reaction medium was maintained at a temperature of 65 ° C for 1 minute before being cooled. Degassing, stripping, emptying, centrifuging, drying and sieving were then performed in the same manner as in Example 1, and the polymer resins thus obtained were evaluated by a PB test using the same criteria.

EXAMPLE 5: Production of C-PVC (suspension method)

The polymerization of vinyl chloride was carried out using the procedural algorithm from Example 4, but with the difference that instead of DEHA, an aqueous emulsion of an Irgastab® PVC11EM product was added. Irgastab® PVC11EM was considered a polymerization agent inhibiting the radical polymerization of PVC. The amount added corresponded to 485 ppm by weight of the Irgastab® PVC11EM brand product relative to the initial weight of the monomer. An aqueous solution of sodium perchlorate, corresponding to 115 ppm by weight of NaClO ₄ , relative to the initial weight of the monomer, was still added following the input procedure in Example 4. The reaction medium was maintained at 65 ° C for 1 minute before as chilled. Degassing, stripping, emptying, centrifuging, drying and sieving were then performed in the same manner as in Example 1, and the polymer resins thus obtained were evaluated by a PB test using the same criteria.

EXAMPLE 6: Production of C-PVC (suspension method)

The polymerization of vinyl chloride was carried out using the procedural algorithm from Example 4, but with the difference that instead of DEHA, a BHA solution (tert-butyl hydroxyanisole; CAS number 25013-16-5) was added with a concentration of 20% by weight in ethanol. This solution was considered a polymerization agent inhibiting the radical polymerization of PVC. The amount added corresponded to 54 ppm by weight of BHA relative to the initial weight of the monomer. An aqueous solution of sodium perchlorate, corresponding to 115 ppm by weight of NaClO ₄ , relative to the initial weight of the monomer, was still added following the input procedure in Example 4. The reaction medium was maintained at 65 ° C for 1 minute before as chilled. Degassing, stripping, emptying, centrifuging, drying and sieving were then performed in the same manner as in Example 1, and the polymer resins thus obtained were evaluated by a PB test using the same criteria.

EXAMPLE 7: Production of C-PVC (suspension method)

The polymerization of vinyl chloride was carried out using the procedural algorithm from Example 4, but with the difference that instead of DEHA a solution of a product of the brand Irganox® 1076 (octadecyl-3,5-di-tert-butyl-4-hydroxyhydrocinnamate, number CAS 2082-79-3 was added ) with a concentration of 10% by weight in isododecane (CAS number 31807-55-3). The amount added corresponded to 225 ppm by weight of a product of the brand Irganox® 1076 relative to the initial weight of the monomer. An aqueous solution of sodium perchlorate, corresponding to 115 ppm by weight of NaClO ₄ , relative to the initial weight of the monomer, was still added following the input procedure in Example 4. The reaction medium was maintained at 65 ° C for 1 minute before as chilled. Degassing, stripping, emptying, centrifuging, drying and sieving were then performed in the same manner as in Example 1, and the polymer resins thus obtained were evaluated by a PB test using the same criteria.

EXAMPLE 8: Production of C-PVC (suspension method)

The polymerization of vinyl chloride was carried out using the procedural algorithm from Example 3, but with the difference that before closing the reactor and first added a solution of the antioxidant brand lrganox® 1076 (octadecyl-3,5-di-tert-butyl-4-hydroxyhydrocinnamate, number CAS 2082- 79-3) with a concentration of 10% by weight in isododecane (CAS number 31807-55-3). The amount added corresponded to 225 ppm by weight of a product of the brand Irganox® 1076 relative to the initial weight of the monomer. The procedural algorithm subsequently remained identical to Example 3. The polymer oligomers obtained in this way were evaluated by testing for PB using the same criteria. This example demonstrated that the antioxidant added at the beginning of the polymerization did not affect the effect of the agent inhibiting the radical polymerization and perhalogenate, as evidenced by the magnitude of the whiteness index before and after heat treatment and that, therefore, standard known antioxidants could also be used in the method according to the invention.

EXAMPLE 9: (Comparative) Production of C-PVC (suspension method)

The polymerization of vinyl chloride was carried out using the procedural algorithm from Example 1, but with the difference that before closure of the reactor and initially added antioxidant grade Irganox® 1076 in the amount of 10% by weight in isododecane. The amount added corresponded to 225 ppm by weight of an antioxidant of the brand Irganox® 1076 relative to the initial weight of the monomer. The procedural algorithm subsequently remained identical to Example 1. The polymer oligomers obtained in this way were evaluated by testing for PB using the same criteria.

EXAMPLE 10: (Comparative) Production of C-PVC (suspension method)

The polymerization of vinyl chloride was carried out using the procedural algorithm from Example 1, but with the difference that instead of DEHA was added a solution of the antioxidant brand lrganox® 1076 with a concentration of 10% by weight in isododecane. The amount added corresponded to 225 ppm by weight of an antioxidant of the brand Irganox® 1076 relative to the initial weight of the monomer. The procedural algorithm subsequently remained identical to Example 1. The polymer resins obtained in this way were evaluated by a PB test using the same criteria.

EXAMPLE 11: (Comparative) Production of C-PVC (suspension method)

The polymerization of vinyl chloride was carried out using the procedural algorithm from Example 1, but with the difference that instead of DEHA was added a BHA solution with a concentration of 20% by weight in ethanol. The amount added corresponded to 54 ppm by weight of BHA relative to the initial weight of the monomer. The procedural algorithm subsequently remained identical to Example 1. The polymer resins obtained in this way were evaluated by a PB test using the same criteria.

Tests on the indicator of whiteness of PB lead to the results shown in Table 1:

Table 1 Example The initial value of the PB The value of PB after heat treatment one 96.7 77.4 2 96.4 65.8 3 97.0 85,2 four 96.9 84.6

5 96.2 80.0 6 93.2 78.1 7 96.1 76,2 8 97.4 84.9 9 96.9 77.4 10 95.6 66.5 eleven 93.1 70.3

Claims (13)

1. The method of aqueous suspension, microsuspension, emulsion or microemulsion polymerization of at least one halogen-substituted monomer, in particular chlorinated, for example, vinyl chloride as an independent component or in combination with one or more other vinyl monomers, preferably with a content of less than 50% by weight one or more other vinyl monomers, characterized in that at least one agent that inhibits radical polymerization is added, which is a th dialkyl-N, N-substituted hydroxylamine, and at least one perhalogenate acting as a whitening agent in which the counterion of the perhalogenate anion is selected from lithium (Li), sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), zinc (Zn), aluminum (Al), lanthanum (La) and cerium (Ce). 2. The method according to p. 1, characterized in that the polymerization is carried out in the presence of at least one polymerization initiator. 3. The method according to p. 1 or 2, characterized in that the agent inhibiting the radical polymerization is selected from dialkyl-N, N-substituted hydroxylamines, where each alkyl radical contains 1-4 carbon atoms, as well as mixtures of two or more of them in any ratio. 4. The method according to p. 1, characterized in that at least one perhalogenate is sodium perchlorate. 5. The method according to p. 1, characterized in that the polymerization is initiated by the action of at least one polymerization initiator selected from dialkyl peroxydicarbonates, peroxy-tert-alkanoates, diacyl peroxides and alkyl-containing hydroperoxides, and others. 6. The method according to p. 1, comprising an initiating system containing at least one compound selected from dialkyl peroxydicarbonates, peroxy-tert-alkanoates, diacyl peroxides and alkyl-containing hydroperoxides, and at least one radical polymerization inhibitor consisting of at least one N, N-dialkylhydroxylamine, as well as at least one perhalogenate, preferably at least one perchlorate. 7. The method according to p. 1, further comprising at least one thermostabilizing additive selected from the following thermostabilizers or shared thermostabilizers: 2-ethylhexyl mercapto-acetic acid, thioglycolic acid and their esters, alkali metal carbonates; β-diketones, epoxidized vegetable oils; phosphites, β-ketone esters, metal salts or soaps, in particular stearates, adipates, aminouracil derivatives and / or thiouracil derivatives; hydrazides; mineral compounds hydrotalcites and zeolites; alcohols and polyols; glycidyl derivatives; α-phenylindole; compounds such as dihydropyridine, enamines; derivatives such as alkanolamines, and others, in the form of independent components or in the form of a mixture of two or more of them, in any ratio. 8. The use of a combination of at least one radical polymerisation inhibiting agent, which is dialkyl-N, N-substituted hydroxylamine, with at least one perhalogenate, in which the perhalogenate anion counterion is selected from lithium (Li), sodium (Na ), potassium (K), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), zinc (Zn), aluminum (Al), lanthanum (La) and cerium (Ce), in a method for producing halogenated polymers and copolymers, in particular PVC. 9. The use according to claim 8, in which the agent inhibiting the radical polymerization is selected from dialkyl-N, N-substituted hydroxylamines, in the composition of which each alkyl radical contains 1-4 carbon atoms. 10. The use according to claim 9, wherein the radical polymerization inhibitor is selected from diethyl hydroxylamine and 4-OH-Tempo (1,4-dihydroxy-2,2,6,6-tetramethylpiperidine), as well as mixtures of two or more of them in any ratio. 11. A composition for use in a method for producing halogenated polymers and copolymers containing at least one radical polymerization inhibitor, which is dialkyl-N, N-substituted hydroxylamine, and at least one perhalogenate, in which the counterion of the perhalogenate anion is selected from lithium (Li), sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), zinc (Zn), aluminum (Al), lanthanum (La) and cerium (Ce). 12. The composition according to claim 11, wherein the radical polymerization inhibitor is diethyl hydroxylamine and the perhalogenate is sodium perchlorate. 13. The composition according to any one of paragraphs. 11 and 12, consisting of:
5-40% by weight, preferably 10-30% by weight, for example, approximately 20% by weight of diethyl hydroxylamine,
5-40% by weight, preferably 10-30% by weight, for example, approximately 20% by weight sodium perchlorate;
- optionally, up to 20% by weight of one or more stabilizers and / or shared stabilizers, and
- water in an amount supplementing up to 100% by weight.