CA1096548A - Vinyl chloride polymerisation process - Google Patents
Vinyl chloride polymerisation processInfo
- Publication number
- CA1096548A CA1096548A CA186,252A CA186252A CA1096548A CA 1096548 A CA1096548 A CA 1096548A CA 186252 A CA186252 A CA 186252A CA 1096548 A CA1096548 A CA 1096548A
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- Canada
- Prior art keywords
- cross
- process according
- polymerisation
- polymeric material
- vinyl chloride
- Prior art date
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F2/00—Processes of polymerisation
- C08F2/002—Scale prevention in a polymerisation reactor or its auxiliary parts
- C08F2/004—Scale prevention in a polymerisation reactor or its auxiliary parts by a prior coating on the reactor walls
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- Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
- Polymerisation Methods In General (AREA)
- Phenolic Resins Or Amino Resins (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE:
Vinyl chloride is polymerised in aqueous dispersion, preferably in aqueous suspension, in a reactor with walls coated with a layer of a cross-linked polymeric material containing polar groups formed from a reaction mixture having an aldehyde, preferably formaldehyde, as one component thereof.
Vinyl chloride is polymerised in aqueous dispersion, preferably in aqueous suspension, in a reactor with walls coated with a layer of a cross-linked polymeric material containing polar groups formed from a reaction mixture having an aldehyde, preferably formaldehyde, as one component thereof.
Description
~0~654~ P~ 2~62~
The present invention relates to the production of vinyl chloride polymers by an aqueous dispersion polymerisation process.
It is well known to produce vinyl chloride polymers using an aqueous dispersion polymerisation process, e.g.
by polymerising vinyl chloride, or vinyl chloride and an ethylenically unsaturated monomer copolymerisable therewith, in aqueous suspension in a reactor (conveniently made of a metal such as stainless steel) using a protective colloid as a suspension agent and a free~radical-yielding substance (usually monomer soluble) as initiator. While this type of process has now been comm~rcially developed to a high~degree of sophistication, one important drawback that has remained obstinately outstanding is the formation of a layer of build-up upon the inner surface of the polymerisation reactor. ~his build-up necessitates inter-batch cleaning, by which we mean that the deposited build-up is removed as completely as possible (e.g.
by scraping, solvent cleaning or pressure-washing) from the inner wall of the reactor after completing each polymerisation in a given reactor. If this were not done, then parts of the hard polymeric material constituting the build-up could find their way into the particles made in subsequent batches in the i~
~ 48 P.~5629 , same reactor and deleteriously affect the properties of the resulting polymers. Even more seriously, the formation of build-up reduces the heat transfer ability of the reactor wall to the cooling fluid (usually water) circulatin~ in a jacket surrounding the reactor (many polymeri~ation reactor~ are cooled b',y thi~
type of arrangement) which necessitates an increased cooling requirement to maintain the desired polymerisation temperature. It is clearly seen that this situation could rapidly worsen with successive batches made in a given reactor if the inner surface of the reactor was not cleaned after the completion of each polymerisation batch and adequate temperature control could quickly become impossible. In fact, adequate temperature control could become questionable or even ~mpossible in the very next polymerisation carried out in a reactor (particularly a very large reactor) which, for the first time, has not had its build-up removed, ~his seemingly invariable formation of build-up which increases with polymerisation time is also a major difficulty in the development of trouble-fre~
continuous processes for the aqueous dispersion polymerisation of vinyl chloride.
We have now disco~ered a process whereby vinyl chloride polymers may be prepared in ,, :.
.25 .
aqueous dispersion without the or with a much reduced formation of build-up. ~his process may substantially reduce the cleaning effort required between each batch polymerisation and may even allow two or more successive batch polymerisations to be carried out in the same reactor without the necessity for inter-batch removal ; of build-up. The avoidance of the necessit~ for inter-batch cleaning in batch polymerisations is of great economic significance since it not only avoids the e~pense of the equipment and manpower required to carry out such cleaning but also shortens the turn-round time of a given reactor leading to increased productivity.
I~ addition, the process of our invention could be applied with advantage to the continuous polymerisation of vinyl chloride since it may overcome the drawback of an ever-thickening skin of build-up~
According to the present invention we provide a process for the production of vinyl chloride polymers which process comprises polymerising vinyl chloride, ; or vinyl chloride and up to 2~/o by weight thereof of at least one ethylenically unsaturated monomer copolymerisable therewith, in aqueous dispersion, preferably in aqueous suspension, in a reaetor with an ~5 inner wall(s) on which there has been deposited an ~96~
insoluble layer of a cross-linked polymeric material containing polar groups formed from a reaction mixture having an aldehyde, preferably formaldehyde, as one component thereof.
It is to be u~derstood that the other component or at least one of the other cornponents (if more than one) ; of the reaction mixture should have more than two sites of reactivity in order to form a cross-linked polymer with the aldehyde.
By the term "insoluble" we mean that the coated layer of polymeric material should not be dissolvable by or react with the aqueous medium (whether it be acidic, neutral or alkaline) or with the organic medium ; used in the polymerisation.
~he layer of cross-linked polymeric material may be formed by applying solutions or dispersions of the components required to form the cross-linked polymer to the autoclave wall, e.g~ by spraying or flushing the wall with the solutions or dispersions~ Each component may be applied to the wall as a separate solution or dispersion or may be applied in admixture with one or more of the other components. It is also possible to apply all the components required for the formation of the cross-linked polymer to the wall in the same solution or dispersion, although this i5 not ' ~ 48 P.~562~
, preferred because of the danger of premature reaction before the components have been deposited on the wall.
Once the components have been deposited on ~ha wall they react, either of their own accord or after the application of heat, to form the layer of cross-linked polymeric material.
It is preferred that the liquid for carrying the components when they are added to the wall is water, although other liquids such as organic solvents may sometimes be used.
It is thought that the cross-linked polymeric materials become ~chored to the reactor wall by means of some of the polar groups and thus cannot be readil~ removed by the polymerisation medium.
It is al80 thought th~t these polar groups or other groups in the molecule inhibit the formation of build-up without inhibiting the polymerisation in the main dispersed massO The use of less strongly adsor~ed molecules may suppress build-up for~ation but this may only be at the expense of retarding the overall polymerisation. Cle~rly such an effect is undesirable from the economic stand point.
Additionall~, less strongly adsorbed materials may affect the ~uality of the product (notably colour ' ~09G548 P-~5~29 qualit~) deleterious1y. Examples of polar groups include carboxyl, hydroxy, amino, imino and amido groups.
Suitable cross-linked polymeric materials include the materials obtained by condensing monomeric phenols such as phenol and para-hydroxy-benzoic acid with an aldehyde and the materials obtained by cross-linking polar monomeric or polymeric materials such as melamine, diamino diphenyl ether, urea and polyethylene imine with an aldehyde.
It is preferred that the aldehyde employed is formaldehyde since cross-linked products are easily obtainable with this material. It is to be understood that many of the polar groupings in such cross-linked materials may not have taken part in the cro~s-linking reaction.
In the case of the basic (i.e ~lkaline) types of coating material it is preferred t~at the polymerising medium is kept at a pH of greater than ZO 4 by the use (where necessary) of buffers or alkaline substances. Suitable alkaline substances include sodium, potassium, calcium and ammonium hydroxides, carbonates a~d bicarbonates, and buffers include mixtures of the disodium ~nd monosodium hydrogen 6~i48 P. 25~
ortho phosphates (Na~HP04 and NaH2P04). It is of course to be understood that the pH of the reaction medium may of its own accord remain at above 4 in which case the addition of a buffer or alkaline substance ma~ not be necessary.
In the process of our invention, the amount of cross-linked pol~meric material used is preferably 1 to 2000 parts per million (particularly 10-200 parts per million) based on the charge of the vinyl chloride (in the case of batch polymerisations).
In the preferred process of our invention, vinyl chloride is polymerised in aqueous suspension and in such a process the ingredients conventionally used in vinyl chloride aqueous suspension polymerisations which include suspension agents and free-radical yielding initiators (usually monomer soluble) should be employed.
It is also possible in the process of our in~ention to incorpora~e an~ suitable additive (such as a heat ~tabiliser) into the polymerising reactantæ at any stage of the polymerisation, although if it is added at or towards the begin~ing of polymeri~ation it should not inhibit the polymerisation reaction.
~.25~
~g65~
~he present invention is illustrated by the following examples.
A series of vinyl chloride polymerisations was carried out in a stainless steel reactor the walls of which were treated either hot or cold with polyethylene imine (PEI) and formaldehyde. The basic recipe used consisted of pretreating the reactor walls as described in Table 1.
Polymerisation was then carried out using 100 parts of vinyl chloride (in aqueous suspension), 150 parts of water, a paddle stirrer rotating at 225 r.p.m., a polymerisation temperature of 51C, 0.06 parts of diethylperoxydicarbonate as initiator and a suspension agent conslsting of 0.11 parts of a par~ially hydrolysed polyvinylacetate resin. ~he polymerisation was buffered to an approximately neutral pH
using a mixture of ~a2XP04 (0.066 parts) and MaH2P04 (0.033 parts). The pol~merisation of each batch was continued until ; ~ the pressure in the reactor had fallen by 40 p.s.i. below the steady pressure during pol~merisation. In Examples 2 and 4, the reactor walls were cleaned before treatment and ; polymeri~ation. In Examples 3 and 5, however, the walls were not pretreated as such, but were used as obtained after dischargi~g the batch corresponding to the previous example. ~he amount of build up formed was estimated by removing the adherent film and weighing. Results are given in Table 1.
_ g _ P~25629 i5~
~AB~E_1 Weight of build- Total Example Reactor up (parts per reaction ~o. pretreatmenthundred vinyl time chloride charged) (minutes) _ 1 ~one 0.015 380
The present invention relates to the production of vinyl chloride polymers by an aqueous dispersion polymerisation process.
It is well known to produce vinyl chloride polymers using an aqueous dispersion polymerisation process, e.g.
by polymerising vinyl chloride, or vinyl chloride and an ethylenically unsaturated monomer copolymerisable therewith, in aqueous suspension in a reactor (conveniently made of a metal such as stainless steel) using a protective colloid as a suspension agent and a free~radical-yielding substance (usually monomer soluble) as initiator. While this type of process has now been comm~rcially developed to a high~degree of sophistication, one important drawback that has remained obstinately outstanding is the formation of a layer of build-up upon the inner surface of the polymerisation reactor. ~his build-up necessitates inter-batch cleaning, by which we mean that the deposited build-up is removed as completely as possible (e.g.
by scraping, solvent cleaning or pressure-washing) from the inner wall of the reactor after completing each polymerisation in a given reactor. If this were not done, then parts of the hard polymeric material constituting the build-up could find their way into the particles made in subsequent batches in the i~
~ 48 P.~5629 , same reactor and deleteriously affect the properties of the resulting polymers. Even more seriously, the formation of build-up reduces the heat transfer ability of the reactor wall to the cooling fluid (usually water) circulatin~ in a jacket surrounding the reactor (many polymeri~ation reactor~ are cooled b',y thi~
type of arrangement) which necessitates an increased cooling requirement to maintain the desired polymerisation temperature. It is clearly seen that this situation could rapidly worsen with successive batches made in a given reactor if the inner surface of the reactor was not cleaned after the completion of each polymerisation batch and adequate temperature control could quickly become impossible. In fact, adequate temperature control could become questionable or even ~mpossible in the very next polymerisation carried out in a reactor (particularly a very large reactor) which, for the first time, has not had its build-up removed, ~his seemingly invariable formation of build-up which increases with polymerisation time is also a major difficulty in the development of trouble-fre~
continuous processes for the aqueous dispersion polymerisation of vinyl chloride.
We have now disco~ered a process whereby vinyl chloride polymers may be prepared in ,, :.
.25 .
aqueous dispersion without the or with a much reduced formation of build-up. ~his process may substantially reduce the cleaning effort required between each batch polymerisation and may even allow two or more successive batch polymerisations to be carried out in the same reactor without the necessity for inter-batch removal ; of build-up. The avoidance of the necessit~ for inter-batch cleaning in batch polymerisations is of great economic significance since it not only avoids the e~pense of the equipment and manpower required to carry out such cleaning but also shortens the turn-round time of a given reactor leading to increased productivity.
I~ addition, the process of our invention could be applied with advantage to the continuous polymerisation of vinyl chloride since it may overcome the drawback of an ever-thickening skin of build-up~
According to the present invention we provide a process for the production of vinyl chloride polymers which process comprises polymerising vinyl chloride, ; or vinyl chloride and up to 2~/o by weight thereof of at least one ethylenically unsaturated monomer copolymerisable therewith, in aqueous dispersion, preferably in aqueous suspension, in a reaetor with an ~5 inner wall(s) on which there has been deposited an ~96~
insoluble layer of a cross-linked polymeric material containing polar groups formed from a reaction mixture having an aldehyde, preferably formaldehyde, as one component thereof.
It is to be u~derstood that the other component or at least one of the other cornponents (if more than one) ; of the reaction mixture should have more than two sites of reactivity in order to form a cross-linked polymer with the aldehyde.
By the term "insoluble" we mean that the coated layer of polymeric material should not be dissolvable by or react with the aqueous medium (whether it be acidic, neutral or alkaline) or with the organic medium ; used in the polymerisation.
~he layer of cross-linked polymeric material may be formed by applying solutions or dispersions of the components required to form the cross-linked polymer to the autoclave wall, e.g~ by spraying or flushing the wall with the solutions or dispersions~ Each component may be applied to the wall as a separate solution or dispersion or may be applied in admixture with one or more of the other components. It is also possible to apply all the components required for the formation of the cross-linked polymer to the wall in the same solution or dispersion, although this i5 not ' ~ 48 P.~562~
, preferred because of the danger of premature reaction before the components have been deposited on the wall.
Once the components have been deposited on ~ha wall they react, either of their own accord or after the application of heat, to form the layer of cross-linked polymeric material.
It is preferred that the liquid for carrying the components when they are added to the wall is water, although other liquids such as organic solvents may sometimes be used.
It is thought that the cross-linked polymeric materials become ~chored to the reactor wall by means of some of the polar groups and thus cannot be readil~ removed by the polymerisation medium.
It is al80 thought th~t these polar groups or other groups in the molecule inhibit the formation of build-up without inhibiting the polymerisation in the main dispersed massO The use of less strongly adsor~ed molecules may suppress build-up for~ation but this may only be at the expense of retarding the overall polymerisation. Cle~rly such an effect is undesirable from the economic stand point.
Additionall~, less strongly adsorbed materials may affect the ~uality of the product (notably colour ' ~09G548 P-~5~29 qualit~) deleterious1y. Examples of polar groups include carboxyl, hydroxy, amino, imino and amido groups.
Suitable cross-linked polymeric materials include the materials obtained by condensing monomeric phenols such as phenol and para-hydroxy-benzoic acid with an aldehyde and the materials obtained by cross-linking polar monomeric or polymeric materials such as melamine, diamino diphenyl ether, urea and polyethylene imine with an aldehyde.
It is preferred that the aldehyde employed is formaldehyde since cross-linked products are easily obtainable with this material. It is to be understood that many of the polar groupings in such cross-linked materials may not have taken part in the cro~s-linking reaction.
In the case of the basic (i.e ~lkaline) types of coating material it is preferred t~at the polymerising medium is kept at a pH of greater than ZO 4 by the use (where necessary) of buffers or alkaline substances. Suitable alkaline substances include sodium, potassium, calcium and ammonium hydroxides, carbonates a~d bicarbonates, and buffers include mixtures of the disodium ~nd monosodium hydrogen 6~i48 P. 25~
ortho phosphates (Na~HP04 and NaH2P04). It is of course to be understood that the pH of the reaction medium may of its own accord remain at above 4 in which case the addition of a buffer or alkaline substance ma~ not be necessary.
In the process of our invention, the amount of cross-linked pol~meric material used is preferably 1 to 2000 parts per million (particularly 10-200 parts per million) based on the charge of the vinyl chloride (in the case of batch polymerisations).
In the preferred process of our invention, vinyl chloride is polymerised in aqueous suspension and in such a process the ingredients conventionally used in vinyl chloride aqueous suspension polymerisations which include suspension agents and free-radical yielding initiators (usually monomer soluble) should be employed.
It is also possible in the process of our in~ention to incorpora~e an~ suitable additive (such as a heat ~tabiliser) into the polymerising reactantæ at any stage of the polymerisation, although if it is added at or towards the begin~ing of polymeri~ation it should not inhibit the polymerisation reaction.
~.25~
~g65~
~he present invention is illustrated by the following examples.
A series of vinyl chloride polymerisations was carried out in a stainless steel reactor the walls of which were treated either hot or cold with polyethylene imine (PEI) and formaldehyde. The basic recipe used consisted of pretreating the reactor walls as described in Table 1.
Polymerisation was then carried out using 100 parts of vinyl chloride (in aqueous suspension), 150 parts of water, a paddle stirrer rotating at 225 r.p.m., a polymerisation temperature of 51C, 0.06 parts of diethylperoxydicarbonate as initiator and a suspension agent conslsting of 0.11 parts of a par~ially hydrolysed polyvinylacetate resin. ~he polymerisation was buffered to an approximately neutral pH
using a mixture of ~a2XP04 (0.066 parts) and MaH2P04 (0.033 parts). The pol~merisation of each batch was continued until ; ~ the pressure in the reactor had fallen by 40 p.s.i. below the steady pressure during pol~merisation. In Examples 2 and 4, the reactor walls were cleaned before treatment and ; polymeri~ation. In Examples 3 and 5, however, the walls were not pretreated as such, but were used as obtained after dischargi~g the batch corresponding to the previous example. ~he amount of build up formed was estimated by removing the adherent film and weighing. Results are given in Table 1.
_ g _ P~25629 i5~
~AB~E_1 Weight of build- Total Example Reactor up (parts per reaction ~o. pretreatmenthundred vinyl time chloride charged) (minutes) _ 1 ~one 0.015 380
2 Sprayed first with None 385 0.0012 parts PEI and then wi-th 0.005 parts formaldehyde (both in water) without drying in between. Heated for 10 minutes at 80C.
3 No further treatment~race 400 (but no cleaning after <0.001 Example 2).
4 Sprayed first with None 360 0.003 parts PEI and then with 0.02 parts fo~maldehyde (both in water). Room temperature.
~o further treatment~one 360 (but no cleaning after Example 4).
~he results shown in ~able 1 indicate that the use of the product of polyethylene imine and formaldehyde produces a signific~nt build-up suppression without retardation of the polymerisation reaction.
~ 5 ~ ~ P.~5&~
138 g p-hydroxybenzoic acid were heated with 100 ml water and 100 g of 30% aqueous formaldehyde and 15 mlsconc. HCl at 98-100C for 2 hours. The initial white solid (p-hydroxybenzoic acid) dissolved and after about 1 hour, a white solid precipitated. After cooling to about 60C, 40% aqueous ~JaOH was added continuousl~ until all the white precipitate had dissolved and the pH of the medium was 9.6-10. This solution was divided into two equal parts~ A and B.
138 g p-hydro~ybenzoic acid, 100 g of 30%
aqueous formaldehyde were mixed together and 40% aqueous NaOH
solution added until the initial solid dissolved and the pH was 9.6-100. This solution was divided into two equal parts, C and D.
Solutions A and C were mixed and refluxed for 45 minutes~ After about 30 mi~utes, a solid precipitated which was insoluble in ethanol. This product was discarded.
Solutions B and D were mixed and refluxed for 20 minutes. A thick red syrup formed which on acidification with dil. HCl gave a white precipitate. ~his was filtered off and washed with water. It was partially dried at room temperature by sucking air through it using a vacuum pump. This product was used i~ Examples 7-10.
~ 5 ; EXAMPLES ~_0 A series of vinyl chloride polymerisations was carried out to assess the effect of the p-hydro~Jbenzoic acid condensate described in Example 6 on build-up formation.
The basic recipe used consisted of pretreating the reactor wall as described in Table 2. Polymerisation was then carried out using 100 parts of vinyl chloride (in aqueous suspension), 210 parts of water, a paddle stirrer rotating at 300 r.p.mO, a polymerisation temperature of 50C, 0009 parts of diethylperoxydicarbonate as initiator and a suspension agent consisting of 0~2 parts of a partially hydrolysed polyvinyl acetate resin. ~he polymerisation of each batch was continued until the pressure in the reactor had fallen by 40 p.s.i. below the steady pressure - ; 15 during polymerisation. In ~xamples 8 and 9 the reactor walls were cleaned before treatment and polymerisation.
In Examples 10 and 11, however, the walls were not pretreated as such but were used as obtained after ,;
discharging the batch corresponding to the previous example. The amount of build-up was estimated visually.
:;
: ' ~09~54~ 5629 TAB~E 2 Example Reactor pretreatment Amount of build-up ~ Reaction (minutes~
7 None Skin over entire 33 surface of re-actor.
8Vertical strip of No build-up on 1 35 reactor painted with strip. Normal 10% ethanolic build-up on solution o~ conden- remainder.
sate. Heated for 10 minutes at 100C.
9 Vertical strip of ~o build-up on 35 reactor painted with strip. Normal 10% ethanolic build up on solution of conden- remainderO
sate Heated for 30 minutes at 80C. I, - 10 ~o further treatment Very fine skin on ~25 (but no cleaning treated partA
after ~xample 9~ Heavy build-up on remainder.
11 ~o further treatment Fine skin on 35 (but no cleaning treated part.
after Example 10) Ver~ hea~y build-up on remainder~
" _ ~ he results shown in Table 2 indicate that the use of the condensate of p-h~droxybenzoic acid described in ~xample 6 produces a significant reduction in build~up without retarding the polymerisation reaction~
_ 13 -'; ' ' ~96~ P~ 25629 A series of vinyl chloride polymerisations was carried out to assess the effect of the condensate of formaldehyde and diamino diphenyl ether on build-up formation. The basic recipe used consisted of pretreating the autoclave wall as described in Table ~. Polymerisation was carried out using 100 parts of vinyl chloride (in aqueous suspension), 210 parts of water~ a paddle stirrer rotating at 300 ~.p~m., a polymerisation temperature of 50C, 0908 par-ts of diethylperoxydicarbonate as initiator and a suspension agent consisting of 0.2 parts of a partially hydrolysed polyvinyl acetate resin. The polymerisation of each batch was continued until the pressure in the reactor had falle~ by 40 p.s.i. below the steady pressure during polymerisation~ In Examples 13 ~nd 14 the reactor walls were cleaned before -treatment and polymerisation. In Examples 15, 16 and 17 however~ the reactor walls were not pretreated as such but were used as obtained after discharging the batch corresponding to the previous example. The amount of build-up was estimated visually.
- ~4 -8 ~.~552 ~ABLE 3 Example Autoclave pretrea-tment Amount of build-up No. and reaction time 12 None Skin over entire surface of reactor.
13 Reactor sprayed with Very very thin skin a 3% methyl ethyl ketone over reactor surface.
solution of diamino Pol~merisation re-diphenyl ether. tarded.
14 Reactor treated as in No build-up.
Example 1~ and then Normal polymerisation with formaldehyde time.
solution. Heated at 70C for 30 minutes.
No further treatment ~o build-up. Normal (but no cleanin~ after polymerisation time.
~xample 14) 16 ~o further treatment No build-up. ~ormal (but no cleaning after polymerisation time.
E~xample 15) 17 ~o further treatment Some small patches of (but no cleaning after build-up. ~ormal Example 16) polymerisation time.
.... . , ., ,. J
~he results shown in ~able 3 indicate that the use of the condensate of formaldehyde and diamino diphenyl ether produces a si~nificant reduction in build-up without retarding the polymerisation reaction.
_ 15 _
~o further treatment~one 360 (but no cleaning after Example 4).
~he results shown in ~able 1 indicate that the use of the product of polyethylene imine and formaldehyde produces a signific~nt build-up suppression without retardation of the polymerisation reaction.
~ 5 ~ ~ P.~5&~
138 g p-hydroxybenzoic acid were heated with 100 ml water and 100 g of 30% aqueous formaldehyde and 15 mlsconc. HCl at 98-100C for 2 hours. The initial white solid (p-hydroxybenzoic acid) dissolved and after about 1 hour, a white solid precipitated. After cooling to about 60C, 40% aqueous ~JaOH was added continuousl~ until all the white precipitate had dissolved and the pH of the medium was 9.6-10. This solution was divided into two equal parts~ A and B.
138 g p-hydro~ybenzoic acid, 100 g of 30%
aqueous formaldehyde were mixed together and 40% aqueous NaOH
solution added until the initial solid dissolved and the pH was 9.6-100. This solution was divided into two equal parts, C and D.
Solutions A and C were mixed and refluxed for 45 minutes~ After about 30 mi~utes, a solid precipitated which was insoluble in ethanol. This product was discarded.
Solutions B and D were mixed and refluxed for 20 minutes. A thick red syrup formed which on acidification with dil. HCl gave a white precipitate. ~his was filtered off and washed with water. It was partially dried at room temperature by sucking air through it using a vacuum pump. This product was used i~ Examples 7-10.
~ 5 ; EXAMPLES ~_0 A series of vinyl chloride polymerisations was carried out to assess the effect of the p-hydro~Jbenzoic acid condensate described in Example 6 on build-up formation.
The basic recipe used consisted of pretreating the reactor wall as described in Table 2. Polymerisation was then carried out using 100 parts of vinyl chloride (in aqueous suspension), 210 parts of water, a paddle stirrer rotating at 300 r.p.mO, a polymerisation temperature of 50C, 0009 parts of diethylperoxydicarbonate as initiator and a suspension agent consisting of 0~2 parts of a partially hydrolysed polyvinyl acetate resin. ~he polymerisation of each batch was continued until the pressure in the reactor had fallen by 40 p.s.i. below the steady pressure - ; 15 during polymerisation. In ~xamples 8 and 9 the reactor walls were cleaned before treatment and polymerisation.
In Examples 10 and 11, however, the walls were not pretreated as such but were used as obtained after ,;
discharging the batch corresponding to the previous example. The amount of build-up was estimated visually.
:;
: ' ~09~54~ 5629 TAB~E 2 Example Reactor pretreatment Amount of build-up ~ Reaction (minutes~
7 None Skin over entire 33 surface of re-actor.
8Vertical strip of No build-up on 1 35 reactor painted with strip. Normal 10% ethanolic build-up on solution o~ conden- remainder.
sate. Heated for 10 minutes at 100C.
9 Vertical strip of ~o build-up on 35 reactor painted with strip. Normal 10% ethanolic build up on solution of conden- remainderO
sate Heated for 30 minutes at 80C. I, - 10 ~o further treatment Very fine skin on ~25 (but no cleaning treated partA
after ~xample 9~ Heavy build-up on remainder.
11 ~o further treatment Fine skin on 35 (but no cleaning treated part.
after Example 10) Ver~ hea~y build-up on remainder~
" _ ~ he results shown in Table 2 indicate that the use of the condensate of p-h~droxybenzoic acid described in ~xample 6 produces a significant reduction in build~up without retarding the polymerisation reaction~
_ 13 -'; ' ' ~96~ P~ 25629 A series of vinyl chloride polymerisations was carried out to assess the effect of the condensate of formaldehyde and diamino diphenyl ether on build-up formation. The basic recipe used consisted of pretreating the autoclave wall as described in Table ~. Polymerisation was carried out using 100 parts of vinyl chloride (in aqueous suspension), 210 parts of water~ a paddle stirrer rotating at 300 ~.p~m., a polymerisation temperature of 50C, 0908 par-ts of diethylperoxydicarbonate as initiator and a suspension agent consisting of 0.2 parts of a partially hydrolysed polyvinyl acetate resin. The polymerisation of each batch was continued until the pressure in the reactor had falle~ by 40 p.s.i. below the steady pressure during polymerisation~ In Examples 13 ~nd 14 the reactor walls were cleaned before -treatment and polymerisation. In Examples 15, 16 and 17 however~ the reactor walls were not pretreated as such but were used as obtained after discharging the batch corresponding to the previous example. The amount of build-up was estimated visually.
- ~4 -8 ~.~552 ~ABLE 3 Example Autoclave pretrea-tment Amount of build-up No. and reaction time 12 None Skin over entire surface of reactor.
13 Reactor sprayed with Very very thin skin a 3% methyl ethyl ketone over reactor surface.
solution of diamino Pol~merisation re-diphenyl ether. tarded.
14 Reactor treated as in No build-up.
Example 1~ and then Normal polymerisation with formaldehyde time.
solution. Heated at 70C for 30 minutes.
No further treatment ~o build-up. Normal (but no cleanin~ after polymerisation time.
~xample 14) 16 ~o further treatment No build-up. ~ormal (but no cleaning after polymerisation time.
E~xample 15) 17 ~o further treatment Some small patches of (but no cleaning after build-up. ~ormal Example 16) polymerisation time.
.... . , ., ,. J
~he results shown in ~able 3 indicate that the use of the condensate of formaldehyde and diamino diphenyl ether produces a si~nificant reduction in build-up without retarding the polymerisation reaction.
_ 15 _
Claims (18)
1. A process for the production of vinyl chloride polymers which comprises polymerising vinyl chloride, or vinyl chloride and up to 2% by weight thereof of at least one ethylenically unsaturated monomer copolymerisable therewith, in aqueous dispersion, in a reactor having an inner wall(s) on which there has been deposited an insoluble layer of a cross-linked polymeric material containing polar groups formed from a reaction mixture having an aldehyde as one component thereof.
2. A process according to Claim 1 in which the cross-linked polymeric material is formed from a reaction mixture having formaldehyde as one component thereof.
3. A process according to Claim 1 which is a batch polymerisation.
4. A process according to Claim 1 in which the polymerisation is carried out in aqueous suspension.
5. A process according to Claim 1 in which the layer of cross-linked polymeric material is formed by applying a solution or dispersion of each component from which the material is formed separately or in admixture with one or more of the other components to the reactor wall and allowing the componants to react on the wall.
P.25629
P.25629
6. A process according to Claim 1 in which the cross-linked polymeric material is formed by reacting formaldehyde and polyethylene imine.
7. A process according to Claim 1 in which the cross-linked polymeric material is formed by reacting formaldehyde and a monomeric phenol.
8. A process according to Claim 7 in which the monomeric phenol used is para hydroxy benzoic acid.
9. A process according to Claim 1 in which the cross-linked polymeric material is formed by reacting formaldehyde with diamino diphenyl ether.
10. A process according to Claim 1 in which the polymerisation medium is maintained at a pH greater than 4 if the cross-linked polymeric material is an alkaline substance.
11. A process according to Claim 1 which is batch polymerisation and in which the amount of cross-linked polymeric material used is within the range 1 to 2000 parts per million, based on the weight of the vinyl chloride used in the polymerisation.
12. A process according to Claim 11 in which the amount of cross-linked polymeric material used lies within the range 10 to 200 parts per million.
AS/MS/AW
AS/MS/AW
13. A polymerisation reactive vessel having on the internal surfaces thereof an insoluble protective coating comprised of polyethyleneimine cross-linked with an aldehyde, such that polymer build-up on said internal surfaces is substantially reduced.
14, The reaction vessel of Claim 13 wherein the aldehyde is formaldehyde,
15, A process for substantially reducing the build-up of polymer on the internal surfaces of a reaction vessel which comprises applying to said surfaces a coating composition comprising polyethyleneimine and an aldehyde and thereafter drying and curing said coating composition to react on the said surfaces to insolubilize it.
16. The process of Claim 15 wherein the aldehyde is formaldehyde.
17, A process for the polymerization of vinyl chloride alone or with a minor amount of at least one ethylenically unsaturated monomer copolymerizable therewith, in aqueous dispersion or suspension in a reactor whose internal surfaces have been coated with a cross-linked polyethyleneimine-aldehyde composition made insoluble by drying and curing said composition on said surface,
18. The process of Claim 17 wherein said aldehyde is formaldehyde.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB53490/72 | 1972-11-20 | ||
| GB5349072A GB1439339A (en) | 1972-11-20 | 1972-11-20 | Vinyl chloride polymerisation process |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1096548A true CA1096548A (en) | 1981-02-24 |
Family
ID=10468000
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA186,252A Expired CA1096548A (en) | 1972-11-20 | 1973-11-20 | Vinyl chloride polymerisation process |
Country Status (12)
| Country | Link |
|---|---|
| JP (1) | JPS5714365B2 (en) |
| AU (1) | AU476303B2 (en) |
| BE (1) | BE807530A (en) |
| BR (1) | BR7308959D0 (en) |
| CA (1) | CA1096548A (en) |
| DE (1) | DE2357869C2 (en) |
| ES (1) | ES420671A1 (en) |
| FR (1) | FR2207148B1 (en) |
| GB (1) | GB1439339A (en) |
| NL (1) | NL7315660A (en) |
| NO (1) | NO143027C (en) |
| SE (1) | SE403121B (en) |
Families Citing this family (16)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4007320A (en) * | 1974-05-21 | 1977-02-08 | Kemanord Aktiebolag | Process for reducing polymer build-up |
| CA1077197A (en) * | 1975-03-24 | 1980-05-06 | Kazuhiko Kurimoto | Method for bulk polymerization of vinyl chloride |
| JPS5213592A (en) * | 1975-07-23 | 1977-02-01 | Shin Etsu Chem Co Ltd | Polymerization of vinyl chloride |
| JPS5223187A (en) * | 1975-08-14 | 1977-02-21 | Shin Etsu Chem Co Ltd | Process for polymerizing vinyl monomers |
| JPS6059246B2 (en) * | 1977-04-18 | 1985-12-24 | 鐘淵化学工業株式会社 | Polymerization method of vinyl chloride |
| GB1589404A (en) * | 1976-12-23 | 1981-05-13 | Ici Australia Ltd | Halogenated a-olefin polymerisation process and reactor therefor |
| EP0003875B1 (en) * | 1978-02-24 | 1981-06-24 | Imperial Chemical Industries Plc | Coating product for use in a reactor for vinyl halide polymerisation process, the reactor and the process |
| JPS5554305A (en) * | 1978-10-17 | 1980-04-21 | Kanegafuchi Chem Ind Co Ltd | Polymerization of vinyl chloride |
| EP0027691B1 (en) * | 1979-10-18 | 1983-10-12 | Imperial Chemical Industries Plc | Vinyl chloride polymerisation process |
| EP0052421B1 (en) * | 1980-10-31 | 1986-11-26 | Imperial Chemical Industries Plc | Vinyl chloride polymerisation process |
| BR8108948A (en) * | 1981-01-16 | 1982-12-14 | Goodrich Co B F | INTERNAL COATED REACTION VASE FOR USE IN OLEFINIC POLYMERIZATION |
| FR2523979A1 (en) * | 1982-03-26 | 1983-09-30 | Chloe Chemie | PROCESS FOR TREATING A POLYMERIZATION REACTOR |
| JPS5926860U (en) * | 1982-08-12 | 1984-02-20 | 東芝電池株式会社 | battery storage case |
| US4902827A (en) * | 1988-05-03 | 1990-02-20 | Eastman Kodak Company | Process for the preparation of adipic acid |
| JP3317803B2 (en) * | 1994-11-15 | 2002-08-26 | 信越化学工業株式会社 | Polymer scale adhesion inhibitor and method for producing polymer using the same |
| EP2581421A1 (en) | 2011-10-12 | 2013-04-17 | Ineos Europe AG | Additive |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DD89707A (en) * | ||||
| ES355836A1 (en) * | 1967-08-02 | 1970-04-01 | Dow Chemical Co | A procedure to reduce the accumulation of polymer on the interior surfaces of a reaction vessel. (Machine-translation by Google Translate, not legally binding) |
| DE94210C (en) * | 1970-05-07 | |||
| DE2044259C2 (en) * | 1970-09-07 | 1985-08-22 | Shinetsu Chemical Co., Tokio/Tokyo | Process for the suspension polymerization of vinyl chloride |
-
1972
- 1972-11-20 GB GB5349072A patent/GB1439339A/en not_active Expired
-
1973
- 1973-11-07 NO NO429173A patent/NO143027C/en unknown
- 1973-11-09 AU AU62369/73A patent/AU476303B2/en not_active Expired
- 1973-11-14 BR BR895973A patent/BR7308959D0/en unknown
- 1973-11-15 NL NL7315660A patent/NL7315660A/xx unknown
- 1973-11-19 SE SE7315628A patent/SE403121B/en unknown
- 1973-11-19 FR FR7341054A patent/FR2207148B1/fr not_active Expired
- 1973-11-20 JP JP12977473A patent/JPS5714365B2/ja not_active Expired
- 1973-11-20 BE BE137929A patent/BE807530A/en unknown
- 1973-11-20 CA CA186,252A patent/CA1096548A/en not_active Expired
- 1973-11-20 DE DE19732357869 patent/DE2357869C2/en not_active Expired
- 1973-11-20 ES ES420671A patent/ES420671A1/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5087A (en) | 1975-01-06 |
| NO143027C (en) | 1980-12-03 |
| DE2357869C2 (en) | 1986-10-16 |
| GB1439339A (en) | 1976-06-16 |
| DE2357869A1 (en) | 1974-05-30 |
| NL7315660A (en) | 1974-05-22 |
| SE403121B (en) | 1978-07-31 |
| AU6236973A (en) | 1975-05-15 |
| ES420671A1 (en) | 1976-04-16 |
| FR2207148A1 (en) | 1974-06-14 |
| JPS5714365B2 (en) | 1982-03-24 |
| NO143027B (en) | 1980-08-25 |
| BE807530A (en) | 1974-05-20 |
| BR7308959D0 (en) | 1974-08-22 |
| FR2207148B1 (en) | 1977-06-10 |
| AU476303B2 (en) | 1976-09-16 |
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Legal Events
| Date | Code | Title | Description |
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| MKEX | Expiry |