FR2645159A1 - Process for the manufacture of vinyl chloride polymers modified with lactone polymers - Google Patents

Abstract

In a first stage a lactone is polymerised ionically in vinyl chloride with the intervention of a catalyst consisting of the reaction product, complexed with tetrahydrofuran, of an alkyl metal in which the metal is chosen from aluminium and/or zinc with an ethylenically unsaturated alcohol, optionally in the presence of water and, in a second stage, the said vinyl chloride is polymerised by a radical route in aqueous suspension and in the presence of the polymerisation mixture originating from the first stage, to which other unsaturated monomers have been optionally added.

Description

Process for the manufacture of polymers
vinyl chloride modified by
polymers of lactones
The present invention relates to an improved process for the production of polymers of vinyl chloride modified with lactone polymers.

 In the French patent application FR-A-86.13204 of 18.9.1986 (SOLVAY & CIE), there is described a process for obtaining polymers of vinyl halides modified with polymers of oxygenated heterocyclic compounds. According to this method, an oxygen-containing heterocyclic compound in a vinyl halide is polymerized in a first step and, in a second step, is polymerized by radical means in an aqueous dispersion and in the presence of the polymerization medium from the first step said vinyl halide, optionally supplemented with other unsaturated monomers radically polymerizable. The process in question is suitable, in particular, for the manufacture of polymers (homo- and copolymers) of vinyl chloride modified with polymers (homo- and copolymers) of lactones. In the exemplary embodiments relating to the manufacture of such modified polymers of vinyl chloride, the ionic catalyst used consists of an alkylated and alkoxylated derivative of aluminum, complexed with tetrahydrofuran, and obtained by means of trialkylaluminium, a diol and water. These catalysts produce lactone polymers having very high molecular weights and viscosities. In industrial practice, it has now been found that the significant increase in the viscosity of the lactone polymerization medium leads to stirring difficulties which may affect the homogeneity of the modified polymers of vinyl chloride obtained at the end of second step and, therefore, the surface appearance of the finished articles manufactured by them.

 The use of a similar catalyst in which butanediol was replaced by butanol resulted in polylactones of reduced molecular weight and thus solved the problem of the high viscosity of the lactone polymerization medium. However, it has been found that flexible articles made from modified polyvinyl chloride using such reduced molecular weight polylactones give rise to exudation.

 The present invention aims to provide an improved process for the manufacture of polymers of vinyl chloride modified with lactone polymers which does not have the aforementioned drawbacks while enjoying the advantages, simplicity and economy of the process of the prior art and which leads to modified polymers with even greater homogeneity.

 For this purpose, the present invention provides a process in which, in a first step, a lactone optionally containing other oxygenated heterocyclic compounds is polymerized by ionic chloride in vinyl chloride and, in a second step, is polymerized by a radical route. in aqueous dispersion and in the presence of the polymerization medium of the first step, said vinyl chloride, optionally supplemented with other radical-polymerizable unsaturated monomers, characterized in that the ionic catalyst of the first step consists of the product of the reaction , complexed with tetrahydrofuran, of an alkyl metal in which the metal is selected from aluminum and / or zinc with an ethylenically unsaturated alcohol, optionally in the presence of water.

 The vinyl chloride polymers modified with lactone polymers obtained according to the process of the invention have an appreciable degree of grafting, generally of several tens of percent, so that the flexible articles made from these modified polymers do not do not exude.

 The method according to the invention therefore comprises a first step during which an lactone is polymerized, by ionic route, or a lactone is copolymerized with an oxygenated heterocyclic compound.

 Lactone means any lactone. However, lactones whose heteroatomic ring comprises from 4 to 16 atoms are preferred. By way of examples of such lactones, mention may be made of ss-propiolactone, γ-butyrolactone, valerolactone, ε-caprolactone, capryllactone and laurolactone, as well as their alkylated and / or halogenated substitution derivatives, such as that ss, 6, ss-bis (chloromethyl) ss-propiolactone, pivalolactone, methylcaprolactones and chlorocaprolactones. Particularly preferred lactones are unsubstituted lactones whose heteroatomic ring comprises 4, 7 or 8 atoms, ie ie, ss propiolactone, s-caprolactone and # -oenenantholactone. A most preferred lactone is ε-caprolactone.

 The term "oxygenated heterocyclic compound" is intended to denote the cyclic ethers and esters and their mixtures.

 Among the cyclic ethers, preference is given to those whose heteroatom ring comprises from 3 to 7 atoms. As examples of such cyclic ethers, there may be mentioned ethylene oxide (oxirane), oxetane and oxepane and their alkylated and / or halogenated substituents. The preferred cyclic ethers are the oxirane derivatives. A nonlimiting list of the oxirane derivatives which can be used in the first stage as lactone comonomers are epoxyalkanes, haloepoxyalkanes, glycidyl ethers and esters and, in particular, oxides of ethylene and propylene, epichlorohydrin, allylglycidyl ether, glicydyl methacrylate and mixtures thereof. Particularly preferred cyclic ethers are the saturated derivatives of oxirane, such as epoxyalkanes and haloepoxyalkanes and, in particular, ethylene oxides and the like. propylene and epichlorohydrin.

 Among the cyclic esters, preference is given to the lactones as defined above.

 One or more lactones, as defined above, may be used at the ionic polymerization, if appropriate at the same time as one or more oxygenated heterocyclic compounds, as defined above, and this, either simultaneously with the formation of random copolymers, either successively with the formation of block copolymers, it being understood that the resulting polymer contains at least 50% by weight of monomeric units derived from lactones. The properties of the lactone polymers (modifying polymers) can therefore be modified as a function of the choice of monomer (s) and of their mode of implementation.

 The unsaturated comonomers polymerizable with vinyl chloride in the second step can be chosen from all the usual vinyl chloride comonomers. Examples of such comonomers include olefins, halogenated olefins, vinyl ethers, vinyl esters, as well as esters, nitriles and acrylic amides.

By polymer of vinyl chloride is therefore meant homopolymers and copolymers, random or block vinyl chloride containing at least 50% by weight and preferably 65% by weight of vinyl chloride
By modified vinyl chloride polymer is therefore meant polymers, homo- and copolymers of vinyl chloride, as defined above, modified by polymers of lactones as defined above.

 The catalyst used in the first step of the process according to the invention is chosen from the reaction products, complexed with tetrahydrofuran, of an alkyl metal in which the metal is chosen from aluminum and / or zinc with an ethylenically alcoholic alcohol. unsaturated, possibly in the presence of water. Advantageously, alkylmetals are used, the alkyl groups, which are identical or different, are chosen from alkyl groups, with straight or branched chains, containing from 1 to 18 carbon atoms. Preference is given to alkylmetals whose alkyl groups are identical and contain from 2 to 12 carbon atoms and more particularly to those whose identical alkyl groups contain from 2 to 5 carbon atoms.

 The term "ethylenically unsaturated alcohol" is intended to denote primary, secondary or tertiary alcohols containing at least one ethylenic unsaturation. The ethylenically unsaturated alcohols that can be used according to the process of the invention can therefore comprise one or more ethylenic unsaturations and these can be located in the chain or at the end of the chain.

Nevertheless, preference is given to ethylenically unsaturated alcohols whose (or) unsaturation (s) is located at the end of the chain and, more particularly, to monoethylenically unsaturated alcohols whose unsaturation is at the end of the chain. In addition, preference is given to primary alcohols. Particularly preferred ethylenically unsaturated alcohols in the context of the present invention therefore consist of monoethylenically unsaturated primary alcohols whose unsaturation is at the end of the chain. The total number of carbon atoms of the ethylenically unsaturated alcohol is not critical. Generally, it contains from 3 to 20 carbon atoms and in most cases from 3 to 12 carbon atoms. The ethylenically unsaturated alcohols are therefore preferably chosen from monoethylenically unsaturated primary alcohols whose unsaturation is at the end of the chain. and which contain from 3 to 12 carbon atoms and more particularly from those containing from 3 to 6 carbon atoms. An especially preferred ethylenically unsaturated alcohol is allyl alcohol. Catalysts which are particularly preferred are therefore constituted by the products of the reaction of an alkylmetal whose identical alkyl groups contain from 2 to 5 carbon atoms with a monoethylenically unsaturated primary alcohol whose unsaturation is at the end of the chain and which contains from 3 to 6 carbon atoms, possibly in the presence of water.

 The molar proportions of the reactants (alkyl metal, alcohol and possibly water) and the complexing agent used for the manufacture of the catalyst used in the first step are not critical and can vary to a large extent. From 0.1 to 3 moles and preferably from 0.5 to 2 moles of ethylenically unsaturated alcohol per gram atom of active metal are generally used. In the case where water is also involved in the manufacture of the catalyst, 0.01 to 0.5 mole of water per gram atom of active metal is generally used. Tetrahydrofuran (complexing agent) is moreover generally used in a proportion of from 0.1 to 20 moles and, more particularly, from 1 to 5 moles per gram atom of active metal.

 The method of manufacturing the catalyst is not critical.

This can be used in pure form or in solution in an inert diluent, such as hexane, heptane, etc. The reaction can be carried out between -70 and + 700C, preferably between -30 and + 20C. It must be done away from the air. The order of introduction of the reagents and tetrahydrofuran has no effect on the activity of the catalyst. A particularly simple and preferred procedure consists in introducing dropwise the mixture of the hydroxyl reagent (alcohol and, if appropriate, water) and tetrahydrofuran in a solution of the alkylmetal (s) in an inert diluent, cooled to about -200.degree. The catalytic solution thus obtained may, if appropriate, be aged for a few days at ambient temperature and under an inert atmosphere. -
The catalytic concentration can vary to a large extent. The catalyst is generally used in an amount of from 0.001 to 0.1 gram atom of active metal and, preferably, from 0.01 to 0.05 gram atom of active metal per mole of ionically polymerizable monomer. (Lactone plus, where appropriate, one or more oxygenated heterocyclic compounds).

 The respective amounts of lactone and oxygenated heterocyclic compound, on the one hand, and vinyl chloride, on the other hand, used in the first step are not critical.

They depend essentially on the amount of modifying polymer that it is desired to incorporate into the vinyl chloride polymer. If necessary, the quantity of other unsaturated monomer (s) polymerizable by radicals which has been decided to be added to the polymerization medium resulting from the stage must be taken into account. first before starting the second step, that is to say the radical polymerization of vinyl chloride and, where appropriate, other monomer (s) polymerizable (s) by this route.

 The general conditions of the ionic polymerization of the lactone and, where appropriate, of the heterocyclic oxygenated comonomer compounds are those usually applied for this type of polymerization, except that the polymerization is carried out within the vinyl chloride and not in a usual organic solvent. To fix ideas, the temperature of the polymerization reaction is generally below 100au and usually between 15 and 600C and the operating pressure is equal to the saturation vapor pressure of vinyl chloride at the polymerization temperature. chosen. The progress of the polymerization reaction (exothermic) is followed by the measurement of the temperature difference between the coolant and the polymerization medium (At positive). The reaction is considered complete when the temperature difference Δt is equal to zero. . Usually, the medium at polymerization temperature is maintained for one hour.

 After the ionic (co) polymerization of the lactone, the polymerization medium is allowed to cool to room temperature. Subsequently, all the ingredients necessary for the conventional free-radical polymerization in aqueous dispersion of vinyl chloride are introduced, starting with water.

If necessary, the radical-polymerizable unsaturated comonomer (s) are introduced at the start of the second stage or at a later stage during the second stage.

 By aqueous suspension polymerization is meant aqueous suspension and microsuspension techniques.

 In the aqueous suspension polymerization, the polymerization is carried out by means of fat-soluble initiators in the presence of conventional dispersing agents such as finely dispersed solids, gelatins, water-soluble cellulosic ethers, synthetic polymers such as partially saponified vinyl polyacetates, polyvinylpyrrolidone, maleic anhydride vinyl acetate copolymers and mixtures thereof. It is also possible, at the same time as the dispersing agents, to use surfactants. The amount of dispersing agent used generally varies between 0.5 and 60% by weight relative to water.

 In the aqueous microsuspension polymerization, sometimes also called homogenized aqueous dispersion, is carried out an emulsion of monomer droplets, gracious with powerful mechanical stirring and usually in the presence of emulsifying agents such as for example anionic emulsifiers, and performs the polymerization using fat-soluble initiators.

 Any lipid-soluble initiator can be used in suspension polymerization or microsuspension. By way of examples, mention may be made of peroxides such as di-tert-butyl peroxide, lauroyl peroxide and acetylcyclohexylsulfonyl peroxide, azo compounds such as azobisisobutyronitrile and azo-bis-2, 4-dimethylvaleronitrile, dialkyl peroxydicarbonates such as diethyl, diisopropyl, dicyclohexyl and di-tert-butylcyclohexyl peroxydicarbonates, and alkylbores. In general, these initiators are used in a proportion of 0.01 to 1% by weight relative to the monomers.

 It is particularly advantageous to apply the process according to the invention to the polymerization in aqueous suspension.

 In addition to dispersing or emulsifying agents and initiators, the polymerization medium may further comprise various additives normally employed in conventional aqueous dispersion polymerization processes. Examples of such additives include polymer particle size regulating agents, molecular weight controlling agents, stabilizers and dyes.

 The radical polymerization conditions do not differ from those usually used. The polymerization temperature is in general between 35 and 800 ° C. and the absolute pressure is generally less than 15 kg / cm 2. The quantity of water used is generally such that the total weight of the monomers represents 20 to 50% of the total weight of the water and the monomers.

 The vinyl chloride polymers obtained according to the process of the invention are conventionally isolated from their aqueous dispersion polymerization medium.

 The process according to the invention allows the simple and rapid manufacture, without intermediate separation of the modifying polymer, of homogeneous polymers of homogeneous vinyl chloride by means of the choice of the nature, the quantity and the mode of implementation ( simultaneous or successive) lactones and, where appropriate, oxygenated heterocyclic compounds.

 The polymers according to the invention can be used by all the usual techniques for implementing compositions based on vinyl chloride polymers such as, for example, injection, calendering or extrusion. They are particularly suitable for producing flexible objects that can be used in fields as diverse as the medical field (blood and physiological fluid bags), the automotive field (various profiles and joints) or the building industry ( waterproof sheets, sheaths for electric cables).

 The following examples are intended to illustrate the process of the invention. All relate to the manufacture of poly---caprolactone-modified polyvinyl chloride.

 In Example 1, according to the invention, the catalyst used consists of the product of the reaction of one mole of triisobutylaluminum and 1 mole of allyl alcohol, complexed with 3.7 moles of tetrahydrofuran.

 In Example 2, according to the invention, the catalyst used consists of the product of the reaction of one mole of triisobutylaluminum with 0.5 mole of allyl alcohol and 0.5 mole of water, complexed with 3, 7 moles of tetrahydrofuran.

 In Example 3, for comparison, the catalyst used is identical to that of Example 1, except that the allyl alcohol has been replaced by n-butanol.

 In Example 4, for comparison, the catalyst is identical to that of Example 3. This example differs from Example 3 in that, at the end of the polymerization of 1-caprolactone (in all respects in accordance with US Pat. Example 3), 3 moles of acryloyl chloride (ie 13 g) per 1 gram of aluminum are added to the polymerization medium and 15 minutes are waiting before loading the ingredients (initiator, water, dispersant) necessary for '2nd step.

 The catalytic concentration is 0.02 gram atom of aluminum per mole of caprolactone in all examples.

 For carrying out the four examples, use is made of a stainless steel laboratory reactor of 3 liters capacity, provided with a jacket for the circulation of a coolant, a conventional stainless steel blade stirrer, a set of gauging tubes for the introduction of reagents and a conventional temperature control system.

 The four examples were made according to the procedure described below.

Step 1
Three evacuations are carried out, followed by rinsing with nitrogen. Under nitrogen and 250C flushing, the catalyst is introduced. The reactor is isolated and the stirrer is started (250 rpm). The vinyl chloride is introduced, by measuring tube, and the reactor contents are heated to 400.degree. The set temperature reached, we introduced the s-caprolactone. The polymerization of? -Caprolactone is complete after 240 min.

 (tO + 240 min.) at 400 ° C. The conversion rate is estimated at 100% (blank test).

2nd step
The reactor contents are cooled to 300C. 10 ml of a 12% solution in azobis-isobutyronitrile dichloromethane are then introduced. Stirring is stopped. Five minutes after stopping agitation, 1200 g of an aqueous solution containing 2 g / l of polyvinyl alcohol (hydrolysis rate: 72.5, dynamic viscosity at 200 ° C. in aqueous solution at 40 ° C.) are introduced via a measuring tube. g / l: 30 mPa.s) and 0.67 g / l of methylhydroxypropylcellulose (viscosity at 200C in aqueous solution at 20 g / l: 100 mPa.s, degree of substitution of methoxyl of 1.31 to 1.93 and degree of substitution of hydroxypropyl 0.05 to 0.25). The agitator is restarted (500 rpm). The contents of the reactor are brought to and maintained at 6 ° C. When the operating pressure drops from the value given in Table I in the annex, 8 ml of 2N ammonia are introduced, the contents of the reactor are cooled, the stirring is reduced to about 50 rpm. and we degass. At atmospheric pressure, a heat treatment is carried out (15 minutes at 750 ° C.), the contents of the reactor are cooled and the residual vinyl chloride is removed by treatment with steam.

 In each of the four examples, after spinning and drying, polyvinylprolactone modified polyvinyl chloride (PVC modified) was collected in the form of more or less transparent spherical, non - sticky grains having a mean diameter of 150-160 microns.

 In table I in the appendix, the amounts of caprolactone (CL), vinyl chloride (VC) and catalyst (CATA) used, lead only to the value of the pressure drop at the end of the polymerization (au), the conversion rate of vinyl chloride (TC), the amount of modified PVC collected, the weight composition of the modified PVC (proportion PVC / PCL) (PCL = poly-ε-caprolactone), as well as the grafting rate of the modified PVC .

 The four modified PVC samples were examined in a composition containing, per 100 parts by weight of resin, 3 parts of a calcium / zinc type thermal stabilizer, 2.5 parts of lubricant and 5 parts of epoxidized soybean oil. .

 Premixes of 150 g each were kneaded for 8 minutes at 1600 ° C. on a roll kneader. The pancakes obtained were then pressed for 4 minutes at 1650 ° C to form plates 4 mm thick.

 Appendix Table II summarizes the results of the crepe and plate evaluations of the four samples. On the plates manufactured according to Examples 1 and 2, according to the invention, the exudation was appreciated after storage for one month at room temperature. On the plates made according to Examples 3 and 4, for comparison, the exudation was assessed after one day of storage at room temperature. None of the plates made according to Examples 1-4 had ungelled points.

 Comparison of the results of Examples 1 and 2, according to the invention, with those of Example 3, for comparison, shows that the use of n-butanol instead of allyl alcohol in the preparation of the catalyst leads to to a soft polyvinyl chloride modified very weakly graft having problems of bonding on cylinder during mixing and, moreover, to a phenomenon of exudation of the pressed plates.

 Comparing the results of Examples 1 and 2, according to the invention, with those of Example 4, for comparison, shows that the introduction of an unsaturation in poly-ε-caprolactone after polymerization leads to polyvinyl chloride modified soft, poorly grafted, having all the aforementioned drawbacks (gluing, exudation).

Table I

Quantities <SEP> put <SEP> in
<tb> artwork, <SEP> g
<tb> No. <SEP> of <SEP>#P,<SEP> TC, <SEP> Quantity <SEP> Proportion <SEP> Rate <SEP> of
<tb> exem- <SEP> CATA <SEP> bar <SEP>% <SEP> of <SEP> PVC <SEP> weight <SEP> grafting,
<tb> ples <SEP> CL <SEP> VC <SEP> (expri- <SEP> changed, <SEP> PVC / PCL <SEP>%
<tb> m <SEP> in <SEP> g
<tb> Al)
<tb> 1 <SEP> 280 <SEQ> 520 <SE> 1.33 <SEP> 3.5 <SEP> 84 <SE> 718 <SE> 61/39 <SEP> 60
<tb> 2 <SEP> 240 <SE> 560 <SE> 1,14 <SEP> 5 <SEP> 91 <SE> 750 <SE> 68/32 <SEP> 52
<tb> 3 <SEP> 280 <SEQ> 520 <SE> 1.33 <SEP> 3.5 <SEP> 84 <SE> 718 <SE> 61/39 <SEP> 9
<tb> 4 <SEP> 280 <SEP> 520 <SEP> 1.33 <SEP> 3.5 <SEP> 81 <SEP> 700 <SEP> 60/40 <SEP> 22
<Tb>
Table II

<tb> No. <SEP> of <SEP> Behavior <SEP> in <SEP> Appearance <SEP> of <SEP><SEP> Hardness <SEP> Shore <SEP> A
<tb> examples <SEP> mixing <SEP> initial <SEP> plate, <SEP> 230C
<tb><SEP> 1 <SEP> normal <SEP> transparent, <SEP> not <SEP> 62
<tb><SEP> exudation
<tb><SEP> 2 <SEP> normal <SEP> transparent, <SEP> not <SEP> 79
<tb><SEP> exudation
<tb><SEP> 3 <SEP> Paste <SEP> on <SEP> transparent, <SEP> 62
<tb><SEP> cylinders <SEP> exudation
<tb><SEP> 4 <SEP> Paste <SEP> on <SEP> transparent, <SEP> 58
<tb><SEP> cylinders <SEP> exudation
<Tb>

Claims (10)

 1 - Process for the production of vinyl chloride polymers modified with lactone polymers in which, in a first step, a lactone optionally containing other oxygenated heterocyclic compounds is polymerized ionically in vinyl chloride and, in a second stage, said vinyl chloride is polymerized by radical means in the aqueous suspension and in the presence of the polymerization medium of the first stage, optionally supplemented with other radically polymerizable ethylenically unsaturated monomers, characterized in that the ionic catalyst of the The first stage consists of the product of the reaction, complexed with tetrahydrofuran, of an alkyl metal in which the metal is chosen from aluminum and / or zinc with an ethylenically unsaturated alcohol, optionally in the presence of water.  2 - Process for the production of modified vinyl chloride polymers according to claim 1, characterized in that the alkylmetal comprises alkyl groups, straight or branched chains, containing from 1 to 18 carbon atoms and in that the ethylenically unsaturated alcohol is chosen from primary, secondary or tertiary ethylenically unsaturated alcohols whose ethylenic unsaturation (s) are at the chain end and which contain from 3 to 20 carbon atoms.  3 - Process for the production of modified vinyl chloride polymers according to claims 1 and 2, characterized in that the alkyl metal comprises identical alkyl groups containing from 2 to 5 carbon atoms and that the ethylenically unsaturated alcohol is selected from monoethylenically unsaturated primary alcohols whose ethylenic unsaturation is at the end of the chain and which contain from 3 to 6 carbon atoms.  4 - Process for the production of modified vinyl chloride polymers according to claim 1, characterized in that from 0.1 to 3 moles of ethylenically unsaturated alcohol and, where appropriate, from 0.01 to 0.5 mole of water per atomgram of active metal in the presence of 0.1 to 20 moles of tetrahydrofuran.  5 - Process for the production of modified vinyl chloride polymers according to claim 4, characterized in that from 0.5 to 2 moles of ethylenically unsaturated alcohol per gram atom of active metal are reacted in the presence of 1 to 5 moles of tetrahydrofuran.  6 - Process for the production of modified polymers of vinyl chloride according to claim 1, characterized in that the catalyst is used in a proportion of 0.001 to 0.1 gram-atom of active metal per mole of monomer ionizable polymerizable .  7 - Process for the production of modified polymers of vinyl chloride according to claim 6, characterized in that the catalyst is used in a proportion of 0.01 to 0.05 gram atom of active metal per mole of polymerizable monomer per ionic pathway.  8 - Process for the manufacture of modified polymers of vinyl chloride according to any one of claims 1 to 7, characterized in that the lactone is selected from 8-propiolactone, s-caprolactone and t-oenantholactone and in that the oxygenated heterocyclic compound is chosen from saturated derivatives of oxirane.  9 - Process for the manufacture of modified polymers of vinyl chloride according to claim 8, characterized in that the lactone is 1-caprolactone.  10 - Process for the production of modified polymers of vinyl chloride according to revendiation 1, characterized in that, in the second step, the radical polymerization is carried out in aqueous suspension.