IL27043A - Process for the low-temperature polymerization of vinyl chloride - Google Patents

Description

Process the polymerization of vinyl chloride and Societfi Italiana per e Fibre Artificiali fhis invention relates to the preparatio of vinyl chloride polymers and copolymers at More the invention relates to a continuous process for polymerising at low temperatures vinyl chloride either alone or with minor quantities of one or more copolymerisable monomers which can he effected continuously and which can he stopped at a predetermined polymerisation degree so that subsequent operations can be effected at tures considerably exceeding the polymerisation substantially without of residual monomers is particularly undesirable in the preparation of polyvinyl chloride having a high degree of where the polymerisation temperature is usually siderably lower than room temperature and generally lies around In such processes it is in order to give the best quality to keep the temperature of the polymerisatio mass at a level lower than or at maximum equal to that of not only during the polymerisation but also during subsequent purification and recovery of the polymer formed within the reaction If in any of these subsequent steps of the process the temperature of the reaction mixture containing besides the polymer also unreacted monomer in the presence of the still active exceeds the low temperature of the even for a relatively short then the final properties of the polymer may be considerably Since the tion rate increases considerably with the increase of the the fraction of the undesirable polymer formed at In order to overcome this serious various processes have been suggested for the separation of the reaction mixture components at very low considerably lower in fact than the polymerisation the reaction mass can be first cooled to a temperature about lower than the polymerisation and then the is centrlfuged at the low The monomer which is separated is again cooled to hinder or reduce to a minimum degree the further formation of and is then recycled to the polymerisation The polymer with a residual part of absorbed is then further purified by washing with a solvent for the monomer and cooled at a low or the monomer may be evaporated by heating with warm water o at 60 in the presence of oxygen in order to inhibit the activit of the catalyst still present in the Removing the monomer by separating a solvent volves the use of complicated and expensive Onthe other separating the vinyl chloride by tion and then gives vinyl having oxygen dissolved therein which prejudices its further use since oxygen interferes with the action of the polymerisation All of such processes are in general of difficult execution and involve an expensive the quality of the polymer obtained is not altogether This is particularly of colour of polymers which are to be used in the preparation of synthetic The invention been made with these points in According to the invention there is provided a process chloride comprising continuously polymerising chloride on its own or with minor quantities of monomers at a temperature below in the presence of a catalyst system comprising as bores compound and an organic compound of the general in which R and which may be the same or represent hydrogen atoms or or the molar ratio of to organometallic boros compound being increased during the polymerisation by addition of being from to 5 at a predetermined degree of polymerisation when the treated with aqueous alkaline which preferably has a of at least process preferably effected in two or more reactors connected in a reaction mixture of the vinyl chloride alone or with the the organometallic boron derivative and the compound having the formula fed to the first partially polymerised reaction mixture from the first or preceding reactor and further compound having the formula being o the second or last and further partially polymerised reaction mixture being removed f om the s or final reactor and treated with the aqueous alkaline the molar ratio of to metallic boron compound in the last reactor from to 5 calculated in relation to the quantity of boron compound fed to the first and the molar ratio being less than at least in the first In the process according to the invention it has been quite that the reaction mass thus obtained after the treatment with the alkaline aqueous solution say subjected to operations for its separation into its vario e that into the system and other at room temperature or even at higher substantially without thereby incurring At the same time the properties of the polymer and especially its molecular syndiotactic index and are excellent and the polymers can be used in the preparation of synthetic ibres having highly desirable such for substantially no shrinkage in boiling water and practically no shrinkage in triehloroethylene at Suitable boron compounds are example alkyl boron boron ides either alon or as a complex with an Particularly good results are by using triethyl as they or as complexes with oxygen contain ing compounds such for example as methyl ethyl ethyl dioxane and The erganometallic boron derivatives be present in an amount from to 3 parte by weight with respect to 100 parts by weight of the vinyl chloride of the merle vinyl chloride and other process of polymerisation according to the present invention will in general be effected at temperatures down to and preferably at a temperature of to Suitable organic compounds having the general include the aliphatic and aromaie and particularly good results are achieved for and The quantity of this organic compound of on the particular compound may vary within a wide for from to the case of hydroperoxide particularly good results are for example obtained with molar ratios compounds in the second reactor from to preferably from 2 to while in the preceding reactors such molar ratio may be below and preferably varies from to The polymerisation process to the invention can be effected in two or more polymerisation reactors arranged in to the or last of which the having the formula is added in a quantity exceeding that necessary to act as a simple activator of the organometalllo boron It is the quantity of compound present in the last in excess respect to the quantity necessary for the activation of the as a stabilizer of the reaction mass against In if the polymerisation mass obtained is discharged into a vessel containing an aqueous even if temperature is raised quite consi above the polymerisation no Thanks to the stabilisation of the reaction the mixture discharged from the last reaotor into the aqueous alkaline may be separated into its the polymer may be the monomer may be purified and then all at room or higher The polymerisation process may be carried out in the additional presence of liquids which act as fluid to maintain at a high level the fluidity of the taction even at high In this way one can achieve a better yield and a slower consumption of the ood fluidisin liquids include the halogenated aliphatic as for ethyl methyl chloride and methylene At the end of the the mixture treated with in which has been dissolved a substance capable of making the solution alkaline with a of at least Suitable substances include the alkali and alkaline earth hydroxides and water soluble salts and the alkali or alkaline earth metal pounds with a surfactant Preferred compounds for sodium sodium carbon sodium phosphate and sodium used in quantities of from to 10 g per litre of According to a preferred embodiment of the the first of a row of arranged fed the following reaction vinyl parts by weight to by weight substance to 40 parts by The compound is furthermore added amounts as to obtain the reactor a molar ratio catalyst of less than and preferably about The polymerisation temperature kept strictly constant and generally between and At the same an additional quantity of the compound is continuously fed into the last polymerisation reactor so as to bring the molar ratio of into the first to values of at least The polymerisation mixture is continuously discharged from the last reactor into a vessel containing an aqueous alkaline solution maintained at a temperature of from 10 to She aqueous solution contains the polymer in is continuously discharged from and ceatrifuged to give the polymer which is dried and the aqueous alkaline solution which The monomer evaporates together with fluidising and may be condensed again either at room pressure by cooling to below boiling or at a higher temperature after After the monomer and the fluidising substance are further cooled and then recycled to the first polymerisation By operating in two advantages are Firstly the polymer obtained has properties such as syndiotactic index and softening which enables the polymer to be used in the preparation synthetic fibres with excellent properties such as shrinkage in boiling water and practically no shrinkage i tricloroethylene at and secondly the monomer which evaporates spontaneously from containing the aqueous alkaline even when brought up to a high temperature does not therefore may be recycled back into the the invention is Illustrated by the following Examples in which all parts are by weight unless otherwise and Examples and 2 are comparative Examples demonstrating certain points of the A 2 litre glass polymerisation fitted with a a refrigerating a thermometer and a loading device for the was cooled to Then the following introducedί 1500 g of vinyl g of eumene hydroperoxide and g triethylboron so giving a molar ratio of The contents the reactor were then subjected to polymerisation at a temperature maintained strictly constant at At 15 minute samples of the polymerised mixture were drawn from the reactor and each time the conversion was determined as a percentage of vinyl chloride into polyvinyl In Table I all the conversion values are with reference to the reaction Polymerisation time in minutes 15 30 45 90 120 From the above values it will at after 60 minutes the was practically longer polymerisable at the temperature of A mple of the polymerised drawn after 120 was fed into a vessel containing a aqueous solution Of at The polymer was then while the monomer was Thereupon the polymer dried and then dissolved in and according to AST 1958 part page the Gardner colour of the solution was It was found that this colour corresponded to degree 1 of the Gardner The monomer separated by even at high did not further This polymer produced was particularly suited the manufacture of or at any rate synthetic The polymerisation tests ere then repeated but with a cooled to of the 1500 g of vinyl g of cumene g of so giving a molar ratio At 15 minute samples the polymerised mixture were drawn from the reactor and time the conversion was determined as a percentage of chloride transformed into polyvinyl In the following Table II all the conversion values are recorded in percentages with respect to the reaction Polymerisation time Conversion in minutes 15 30 45 60 2 Gardner colour of the polymer thus was degree 12 on the Gardner a polymer could not be used in the preparation of white or at any rate colourless synthetic Also the separated monomer clearly polymerised at temperatures below and the quality of the polymer obtained was thus seriously compromised in the subsequent treatments cause of this due to the presence of residual monomer in the polymerisation mass which was not stabilised against Further the influence of the ratios can clearly be seen both on the colour of the polymer obtained as well as on the capacity of the monomer to Z In the manner described in Example the following mixture was polymerised at 1500 g of monomeric vinyl g of cumene and g of so giving a molar ratio cumene boron of At 15 minute samples polymerised mixture were drawn in order to determine the degree of In the following Table III all conversion values are recorded in relation to the reaction 15 50 45 60 90 120 From this it will be seen 45 was practically no polymerisation the teaperature of a sample of the polymerisation after 120 was poured into a vessel containing a aqueous at polymer was then decanted while the monomer The polymer was dried and dissolved in eyelohexanone and the colour of the solution was determined according to 1958 part fhe resultant colour was degree 1 on Gardner a polymer was particularly suited or the manufacture white at any rate synthetic The separated by evea at temperatures did not polymerise fhe was using instead a 1500 g of vinyl e of cumene aad of triethlboron so giving a molar ratio of the following fable IT all the conversion values are recorded in relation to the polymerisation Polymerisation time Conversion 15 30 45 60 90 120 Prow the above will be how conversion increases continuously with a sample of the polymerisation fed into a vessel containing a aqueous solution of soda and subjected to the above described gave a polymer having a Gardner colour degree of 12 and a monomer even st tures below gave rise to evident A polymerisation was effected continuously in two reactors arranged in Both reactors had a capacity of 2 litres and were similar to those described the preceding Into which had previously been cooled to the following mixture was continuously loadedt 16 gminute of vinyl g minute of cumene and of so giving in the first reactor a molar ratio The feeding rates were so as to give a complete change of in the reactor every120 At the earns time g minute of hydroperoxide cumene and the mixture of the f irat reactor were continuously into the second reactor so giving a molar ratio equal to respect to the fed into the first At 30 minutes of polymerised ture were drawn from both reactors in order to establish the of In the following Sable V all the conversion values of the two reactors are reoorded with respect to the polymerisation time TABLE Y Polymerisation Conversion in Conversion in time in 2nd reaotor 30 60 90 120 180 4 210 240 270 300 330 360 390 420 450 from the above recorded values it will be seen that la the second reactor the degree of polymerisation was constant at and was considerably than in the first both reactors polymer samples vers and then treated in the way previously It was while from theftrst reactor were obtained with a colour degree of 12 and monomers which were still at temperatures above the samples drawn from the second reactor and treated as previously had a Gardner degree of the monomer separated by evaporation was no longer even at high temperatures A pair of reactors as described la Example 3 was used and the mixture had been cooled to was continuously fed into reactort monomerlo vinyl g min ethyl chloride gain oumene hydroperoxide gmin so as to give in the ftrst reactor a molar ratio of The feeding was effected to achieve a complete change of the contents of the or every 120 At the same time reaction mixture from the first reactor and an additional quantity of hydroperoxide of gainute were continuously fed into the reactor so giving a molar ratio with respect to the fed the of At 30 minute intervals samples of polymerised mixture were drawn from the two reactors to determine the degree of conversio In Table the conversion values calculated with regard to the polymerisation time are recorded for each of the two Conversion Conversion in 1st in minutes reactor 30 60 90 120 150 180 210 240 270 mm 300 330 360 390 420 450 480 From the above will be seen that in the second reactor the degree of polymerisation was constant at and was considerably greater than the degree of in the first The degree of polymerisation in this was lower than that of the preceding and this waa due to the presence of the the presence of allowed better control of the action Samples of polymer were drawn from each of the actors and were then treated as Polymer obtained from the first reactor had a Gardner degree of 12 while the monomer was still ca able of olmer ati a te eau whereas polymer the reactor had Gardner degree of 1 and the separated by evaporation was longer capable of even at high temperatures A polymerisation was ef ected in two reactors similar to those described Example following mixture was continuously in o the first reactor ter been cooled to vinyl chloride cumene hydroperoxide gminte triethylboron gminute ethyl ether so giving in first reactor a solar ratio of The feeding effected to achieve complete change of the contents of the reactor after 120 At the same the reaction mixture from the firat reactor and an additional quantity of cumene hydroperoxide of were into the second so giving a molar ratio respect to the fed into the first reactor of At 30 minute samples of the polymerised mixture were drawn from each reactor to determine the conversion and in the ollowing Table VII the conversion degrees are recorded for the two reactors with respect to the polymerisation 1β Polymerisation Conversion Conversion tine in 1st in 2nd minutes 30 60 90 120 150 180 210 240 270 300 330 360 390 420 450 480 the above values will be that in the second reactor the of polymerisation was constant at and was considerably higher than in the From both samples polymer were drawn and treated as before and it found that from the first reactor the polymer had a Gardner colour degree of 12 the monomer was still capable of polymerisation at higher than whereas from the second reaetor the polymer had a Gardner colour degree of 1 and the monomer separated by evaporation was no longer capable of polymerisation even at high temperatures Into the first of the eactors similar to those the mixture having first been cooled to vinyl chloride tertiary b riethyl boron gmin ethyl ether so giving the reaotor a molar ratio of The feeding was effected to achieve a complete change in the contents of the reactor 120 At the same time into the second reactor were the mixture from the first and addition tertiary at a rate of so giving a molar ratio respect to the fed to the first reaotor Samples of polymerised mixture were drawn at 30 minute intervals from the two reactors in order to determine degree of and the following Table conversion degree for the two reactors with reference to the reaction TABLE ΥΙΣΙ Polymerisation Conversion Conversion time in in 1st in 2nd minutes 30 90 120 150 180 210 240 270 300 360 350 420 450 430 From the values it will he e een that in the second reactor the degree of polymerisation was constant at and was considerably higher than in the first samples of polymer were drawn reactors and were treated as The polymer from the Arst reactor had a Gardner colour degree of 12 and the monomer was still of further polymerisation at temperatures above whereas the polymer from the second reactor had a Gardner dolour of 1 and the monomer separated by evaporation warn no longer capable of bei polymerised even at higher temperatures insufficientOCRQuality

Claims (20)

1. A process for the preparation of polymers and/or copolymers of vinyl chloride, comprising continuously polymerising monomeric vinyl chloride on its own or with minor quantities of one or more copolymeriaable monomers at a temperature below 0°C in the presenoe of a catalyst system and an organic compound comprising an organometallic boron compound/of the general formula R - 0 - 0 - R' in whioh R and R*, which may be the Same or different, represent hydrogen atoms or alkyl, aryl, oyoloalkyl, or aralkyl groups, the molar ratio of H - 0 - 0 - R' to organometallic boron compound being increased during the polymerisation by addition of R - 0 - 0 - R* and being from 1.5 to 5» at a predetermined degree of polymerisation when the polymerisation reaction mixture is treated with an aqueous alkaline solution.

2. A process as claimed in Claim 1 in whioh the polymerisation is effected at a temperature of from -80 to 0°0.

3. · A process as claimed in Claim 2 in which the polymerisation is effected at a temperature of from -60 to -20°C.

4. · A process as claimed in any preceding claim in which the polymerisation is effected in the presenoe of a fluidising liquid capable of maintaining the reaction mixture highly fluid.

5. · A process as claimed in Claim 4 in which the fluidising substance is an halogenated aliphatic compound.

6. A process as claimed in Claim 5 in which the compound is ethyl chloride, dichloroethane, methyl chloride, or methylene chloride. 2703^2 — 22 -

7. A process as claimed in any preceding claim in which the organoaetallic boron compound is an alk l boron, boron hydride, boron alk lhydride either alone or as a complex with an electron-donating substance*

8. A process as claimed in Claim 7 in which the organometalllc boron compound is triethyl boron, tri-n- ropyl boron, or tri-n-butyl boron alone or as a complex with methyl ethyl ether, ethyl ether, dloxane or tetrahydrofurane.

9. A process as claimed in any preceding claim in which the organometalllc boron compound is present in an amount of from 0.005 to 3 parts by weight with respect to 100 parte by weight of vinyl chloride monomer or of the mixture of vinyl chloride monomer and the copolymerieable monomers.

10. A process as claimed in an preceding claim in which the compound of the general formula R - 0 - 0 - R* is tertiary-butyl-hydroperoxide or cumene hydroperoxide,

11. A rocess as claimed in any preceding claim in which the aqueous alkaline solution has a pH of at least 8.

12. · A process as claimed in any preceding claim in which the e ueous alkaline solution has dissolved in It an alkali or alkaline earth metal hydroxHe or water soluble salt, or a compound of an alkali or alkaline earth metal with a surfactant group.

13. A process as claimed in Claim 12 in which the aqueous alkaline solution has dissolved in it from 0.1 to 10 g per litre of solution of sodium hydroxide, sodium carbonate, sodium phosphate or sodium laurate. 2704¾2 which

14. A process as claimed in any preceding claim/is operated in t wo or more reactors connected in series, a reaction mixture of the monomeric vinyl chloride alone or with the copolymerisable monomers, the organometallic boron derivative and the compound having the formula R - 0 - 0 - R ' being fed to the first reactor, a partially polymerised reaction mixture from the first or preceding reactor and further compound having the formula R - 0 - 0 - B* being fed to the second or last reactor and further partially polymerised reaction mixture being removed from the second or final reactor and treated with the aqueous alkaline eolation, the molar ratio of R - 0 - 0 - R' to organometallic boron compound in the last reactor being from 1.5 to 5» calculated in relation to the quantity of boron compound fed to the first reactor, and the molar ratio being less than .5 at least In the first reactor*

15. · A process as claimed in Claim 14 in which the molar ratio of R - 0 - 0 - R* to organometallic boron compound is from 0.1 to 1 in the first reactor and froa 2 to 3 in the second or last reactor, the ratio being calculated in relation to the quantity of boron compound fed to the first reactor.

16. A process as claimed in Claim 5 In which the molar ratio of fi - 0 - 0 - R* compound to organometallic boron compound in the first reactor is about 0.4.

17. · A process as claimed in any preceding claim in which, after treatment with the aqueous alkaline solution, non-polymeri sed monomers are removed from the reaetlon material by evaporation and re-used.

18. A process for the preparation of polymers and/or copolymers of vinyl chloride in accordance with Claim 1 and substantially as herein described with reference to any one of the Examples.

19. Vinyl chloride polymers and/or copolymers vhen prepared by a process as claimed in any preceding claim.

20. Fibres, films and moulded articles prepared from the vinyl chloride polymers and/or copolymers claimed in Claim 19. For the Applicant* DR. R2ISHOL33-COHM AID PAR EERS RC:BH